CN103148443B - A kind of two free form surface thick lens in order to obtain uniform parallel light beam and array thereof - Google Patents

Abstract

The present invention proposes a double free-form surface thick lens and its array for obtaining uniform parallel light beams, and relates to the technical field of secondary optical elements of light sources such as cold cathode fluorescent tubes and LEDs. The double free-form surface thick lens described in the present invention In the lens and its array, the front and rear surfaces of the lens and its array are both free-form surfaces. Their specific surface shape is determined by the luminous characteristics of the light source and the spatial distribution and angle of the required beam energy according to the law of conservation of luminous flux and the law of refraction. determined by the distribution. The lens and its array can realize radiant light shaping of light sources such as cold-cathode fluorescent tubes and LEDs. After shaping, the distribution of beam energy in space and angle can be completely controlled at the same time, especially parallel beams with uniform energy can be obtained. The patent of the invention is used in the fields of special lighting, liquid crystal display backlight, etc., and can further reduce the space volume of the uniform light optical system, and at the same time greatly improve the lighting effect.

Description

A Thick Lens with Double Freeform Surface and Its Array for Obtaining Uniform Parallel Light Beam

technical field

The present invention relates to secondary optical elements of light sources such as cold cathode fluorescent lamps and LEDs, and more specifically, to a double-freeform thick lens and an array thereof for obtaining uniform parallel beams, which are the spatial distribution and angle of beam energy Distributing double free-form surface lens and its array to realize shaping at the same time.

Background technique

In the fields of general lighting and public display, traditional light sources (such as cold-cathode fluorescent lamps, etc.) The application range of LED is no longer limited to these two fields, but is increasingly used as the backlight of liquid crystal display. Especially LED, as a new generation of light source, has small size, long life and good color rendering , low power consumption, high luminous efficiency, and shows greater application prospects in the field of large-area flat panel display and portable display.

However, the radiated light of various light sources, including cold cathode fluorescent lamps and LEDs, has a certain angular distribution and spatial distribution. Therefore, in all the above-mentioned applications, corresponding optical light distribution components are essential. Among them, as the most basic light distribution element, the lens and its array capable of obtaining uniform illumination have been widely studied and applied. However, most of these devices can only obtain uniform illumination in a long distance and in a large area, that is, the divergence angle of the beam emitted from this type of device is large, the required uniform light distance is long, and the angular distribution of the energy of the outgoing beam cannot be controlled, so only Uniform illumination can be obtained on the detection surface at one location behind the lens and its array, which is no longer uniform at other locations. In liquid crystal display, because the transmittance of the liquid crystal panel to large-angle incident light is not high, it is necessary to control the divergence angle of the backlight source in order to improve the energy utilization rate; in order to miniaturize the display module, it is necessary to shorten the uniform light distance as much as possible; In order to reduce the impact of assembly errors on the lighting effect, it is necessary to maintain the uniform light effect within a distance as large as possible. Therefore, the shortcomings of the currently developed lenses and their arrays severely limit their application in liquid crystal backlight displays.

In addition, in special lighting occasions, such as sunlight simulation, outdoor extremely bright lighting display, specific viewing angle display, etc., the spatial distribution and angular distribution of beam energy are also very stringent requirements, which cannot be met by this type of lens.

The reason is that this type of lens has only one free-form surface, which can only control one of the position of light on the detection surface (corresponding to the spatial distribution of energy) and the angle (corresponding to the angular distribution of energy), and cannot take care of both . Aiming at this problem, the present invention proposes a thick lens and an array thereof whose front and rear surfaces are both free-form surfaces. It can be used to shape the radiated light of light sources such as cold cathode fluorescent lamps and LEDs, not only to obtain the required energy spatial distribution on the detection surface, but also to completely control the angular distribution of beam energy at the same time, so that behind the lens and its array This lighting effect can be maintained in a considerable distance, so it can be used in special lighting, backlight of liquid crystal display and other fields.

Contents of the invention

The main purpose of the present invention is to provide a kind of double free-form surface thick lens and its array for obtaining uniform parallel light beam, it is a kind of secondary optical element, utilize this secondary optical element to the radiation of light sources such as cold cathode fluorescent lamp and LED The light is shaped to obtain a beam whose direction and energy distribution meet the requirements at the same time, especially to obtain a parallel beam with uniform light intensity, so as to further improve the lighting effect and reduce the space volume of the uniform light optical system.

In order to achieve the above object, the present invention provides a thick lens with double free-form surfaces and an array thereof for obtaining a uniform parallel light beam, which is a thick lens with free-form surfaces on the front and rear surfaces and an array thereof, and the thick lens with double free-form surfaces The front and rear surfaces of the array and its array refract the light to control the direction of travel, and its thickness determines the offset of the light in the radial direction of the double free-form surface thick lens and its array, so that the radiated light of the light source passes through the double free-form surface thick lens After being arrayed, it is shaped into a beam whose energy has both the desired spatial and angular distribution.

Wherein, the front and rear surfaces of the double free-form surface thick lens and its array are free-form surfaces jointly determined by the luminous characteristics of the light source and the required energy spatial distribution and angular distribution after beam shaping according to the law of conservation of luminous flux and the law of refraction. .

Wherein, the front surfaces of the double free-form surface thick lens and its array are all refraction surfaces or part of the refraction surfaces are part reflection surfaces.

Wherein, the double free-form surface thick lens and its array adopt a Fresnel lens structure, that is, the front and rear surfaces are stepped free-form surfaces.

Wherein, the aperture shape of the double free-form surface thick lens is one of circular, rectangular, polygonal and arbitrary curves, the aperture size and the angle range of the light source light to be collected, the distance between the light source and the front surface of the lens, the lens The thickness, the divergence angle of the beam after shaping and the required spot size parameters are related.

Wherein, when the light source is a point light source such as an LED, the surface shape of the double free-form surface thick lens is rotationally symmetrical; when the light source is a filamentary light source such as a cold cathode fluorescent tube, the surface shape of the double free-form surface thick lens The shape is translationally symmetric.

Wherein, the illumination light source of the double free-form surface thick lens and its array is one of cold cathode fluorescent lamps and LED light sources.

Wherein, the double free-form surface thick lens and the illumination light source of the array have Lambertian or any other measurable luminous intensity distribution.

Wherein, the beam divergence angle after being shaped by the double free-form surface thick lens and its array is related to the geometric size of the light source, and the minimum control is within ±0.3°.

Wherein, the beam energy shaped by the double free-form surface thick lens and its array has a required spatial distribution in the detection surface, and the distribution remains unchanged within a few centimeters behind the lens, that is, within this range All detection surfaces have the same energy distribution.

Wherein, the aperture of the beam shaped by the double free-form surface thick lens and its array and the shape of the light spot on the detection surface are jointly determined by the aperture of the lens and the divergence angle of the beam after shaping.

Wherein, the double free-form surface thick lens array adopts one of the combinations of rectangular arrangement, hexagonal arrangement and triangular arrangement.

Wherein, the material of the double free-form surface thick lens and its array is selected from: one of crown glass, flint glass, and quartz glass materials; or selected from methacrylate resin, acrylate resin, polystyrene resin, One of polycarbonate resin, methyl methacrylate-styrene copolymer, acrylonitrile-styrene copolymer and polyethylene terephthalate organic resin materials.

According to the above solution, the secondary optical element provided by the present invention exhibits very excellent beam shaping ability. The lens and its array can shape the radiated light of light sources such as cold cathode fluorescent lamps and LEDs, and the beam energy after shaping has the required spatial distribution and angular distribution at the same time, and the required light can be formed close to the rear surface of the lens Spatial distribution, that is, the uniform light distance is greatly shortened; since the directionality of the beam can be completely controlled at the same time, in the application of the lens array, the crosstalk between the lenses is significantly reduced, so it can be used in a long distance Maintain uniform lighting over large areas. In particular, large-area illumination light with excellent uniformity and directionality can be obtained by using the double free-form surface lens, which is very suitable for use as a sunlight simulation device. In addition, the design method of the lens is simple, there is no need to solve partial differential equations, and the specific surface shape of the lens can be obtained directly by solving the binary quaternary equations, which is very suitable for the current processing and manufacturing technology.

Description of drawings

Fig. 1 is the schematic diagram of the principle of beam shaping realized by double free-form surface lens proposed by the present invention;

Figure 2 shows the spatial distribution and angular distribution of the energy of the beam on the detection surface after being shaped by the double free-form surface lens;

Figure 3 is a schematic diagram of the optical path of the beam shaping realized by the rectangular double free-form surface lens and the energy spatial distribution on the detection surface;

Fig. 4 is the shaping effect of the double free-form surface lens proposed by the present invention on the radiated light of a small-sized light source;

FIG. 5 is a schematic diagram of the optical path of the double free-form lens array proposed by the present invention to realize beam shaping;

Fig. 6 is the spatial distribution and angular distribution of the energy of the light beam on the detection surface after being shaped by the lens array described in Fig. 5;

Wherein, marks in the figure: 1 is a light source, 2 is a double free-form surface lens, and 3 is an energy detection surface.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Embodiment 1 Double free-form surface lens realizes beam shaping

Referring to FIG. 1 , it is a schematic diagram of the principle of beam shaping realized by the double free-form surface lens proposed by the present invention, including a light source 1 with known luminous characteristics, a double free-form surface lens 2 , and an energy detection surface 3 . The light emitted from the light source 1 is refracted by the front surface 21 and the rear surface 22 of the lens 2 in sequence, and finally reaches the detection surface 3 . The specific surface shapes of the free-form surfaces 21 and 22 are jointly determined by the luminous characteristics of the light source 1 and various parameters of the reshaped light beam according to the law of conservation of luminous flux and the law of refraction.

The distance between the light source 1 and the front surface 21 of the lens and the thickness of the center of the lens can be adjusted to optimize the surface parameters of the lens and the length of the entire optical system, making it more suitable for processing and meeting the requirements of the use environment.

For the lens structure in Fig. 1, when the light source 1 is a square LED with a luminous surface of 1mm×1mm and a Lambertian luminous intensity distribution, a detection plane 3 with a radius of 0.5mm from the rear surface of the lens is formed For a uniform spot of 8 mm, the two-dimensional distribution of the spot energy in space and the one-dimensional distribution through the center are shown in Figure 2 (a) and (b) respectively; on the detection plane 6.5 mm away from the rear surface of the lens, this distribution is As shown in Figure 2(c) and (d). The two-dimensional distribution of the spot energy in the angle and the one-dimensional distribution through the center are shown in Fig. 2(e) and (f), respectively. It can be seen that the uniformity (expressed by energy contrast) on the detection surface at the two positions is about (I _max -I _min )/(I _max +I _min )=0.08, and the divergence angle of the beam after lens shaping is ±3.1°. It is precisely because the divergence angle is so small that the energy contrast of the beam can be kept below 0.1 within a distance of 1 cm from the rear surface of the lens.

The aperture of the lens and the shape of the light spot after shaping are not limited to a circle, and may also be a rectangle or other shapes.

The lens can be processed by mechanical milling, compression molding and the like.

Embodiment 2 A dual free-form surface lens with a rectangular aperture realizes beam shaping

In some occasions (such as lens arrays), the aperture or spot shape of the required lens is rectangular or hexagonal. Figure 3(a) is a schematic diagram of the optical path of a double free-form surface lens with a rectangular aperture to achieve beam shaping, and Figure 3(b) shows that the light source 1 is a square LED with a light-emitting surface of 1mm×1mm and a Lambertian-type luminous intensity distribution When , the two-dimensional spatial distribution of the spot energy on the detection surface close to the rear surface of the lens, the energy contrast is about (I _max -I _min )/(I _max +I _min )=0.05, and this uniformity can be measured at a distance from the rear surface of the lens Nearly 1 cm is maintained on all probing surfaces. At this time, the divergence angle of the beam after shaping is 6.0°.

When the light emitting surface of the light source 1 is reduced to a square of 0.2mm×0.2mm, the two-dimensional spatial distribution of the spot energy on the detection surface close to the rear surface of the lens and the one-dimensional distribution through the center are shown in Fig. 4(a) and Fig. 4(b), the energy contrast is about (I _max -I _min )/(I _max +I _min )=0.04. The two-dimensional angular distribution of the spot energy and the one-dimensional distribution through the center are shown in Figure 4(c) and Figure 4(d), respectively, and the divergence angle is about 1.35°. With such a small divergence angle, the energy contrast of the shaped beam can be kept below 0.15 within a distance from the rear surface of the lens to several centimeters away from the rear surface of the lens. When the light emitting surface of the light source 1 continues to decrease, the energy uniformity of the shaped beam can be further improved, the divergence angle can be further reduced, and the distance for maintaining energy uniformity can be further increased.

In a lens with a purely refractive structure, the reflection of incident light at a large angle on the front surface of the lens will cause a huge loss. If a composite structure of refractive and reflective surfaces is used on the front surface of the lens, energy efficiency can be improved.

Embodiment 3 Double free-form surface lens array realizes beam shaping

Usually, in order to obtain a larger lighting area or improve the lighting brightness and reduce the homogenization distance, it is often necessary to arrange multiple lenses together to form a lens array to shape the radiated light of the light source array with the same arrangement. FIG. 5 is a schematic diagram of an optical path of a 2×2 double free-form surface lens array arranged in a rectangle to realize beam shaping. The lens array can shape the light emitted by the 2×2 LED array (the light-emitting surface is a square of 1mm×1mm, and the luminous intensity distribution is Lambertian). Figure 6(a) and Figure 6(b) respectively show the distance The two-dimensional spatial distribution of the spot energy on the detection plane of 1.5mm on the back surface of the lens array and the one-dimensional distribution through the center, the energy contrast is about (I _max -I _min )/(I _max +I _min )=0.09; Fig. Figure 6(c) and Figure 6(d) are the two-dimensional angular distribution and the one-dimensional distribution through the center, respectively, and the divergence angle is ±6.4°. Since the double free-form surface can completely control the angular distribution of the beam, the energy contrast value is not higher than 0.15 on all detection planes within the range from the rear surface of the lens array to the rear surface of the lens array within 13mm. It is pointed out here that the multiple small spots located at the edge of the rectangular spot in Figure 6(a) are caused by crosstalk, that is, the large-angle radiation of each LED is not collected by the corresponding shaping lens, but is projected into the adjacent shaping lens were aggregated afterwards. The angle of this part of the crosstalk light is generally about 40°, which is much larger than the divergence angle of the main spot, so its influence can be ignored in many occasions; if necessary, this crosstalk can be achieved by applying a diaphragm in front of the lens or changing the structure of the front surface of the lens (The front surface is a concave surface or a refraction-reflection compound surface) to further reduce or even eliminate.

The arrangement of the lens array is not limited to a rectangular arrangement, but can also be a hexagonal arrangement or other arrangement and combination; but at this time, the aperture of the lens and the shape of the light spot should be correspondingly changed to a hexagonal or other shape.

These embodiments realize the shaping of the radiated light of the LED light source through the lens and its array, and adopt the secondary optical element with a simple structure to obtain large-area illumination with excellent energy uniformity and directionality close to the rear surface of the lens. And this lighting effect can be maintained in a large distance behind the lens, especially parallel light with uniform light intensity can be obtained.

The specific embodiment of the present invention has been described above in conjunction with the accompanying drawings, but these descriptions can not be interpreted as limiting the scope of the present invention, the protection scope of the present invention is defined by the appended claims, any claims on the basis of the present invention All modifications are within the protection scope of the present invention.

Claims (6)

1. A double free-form surface thick lens and array thereof capable of simultaneously controlling beam direction and energy spatial distribution, characterized in that: The front and rear surfaces of the double-free-form-surface thick lens and its array are both free-form surfaces, which refract the light to control the direction of travel, and its thickness determines the offset of the light in the radial direction of the double-free-form-surface thick lens and its array, thereby After the radiant light of the light source passes through the double free-form surface thick lens and its array, it is shaped into a beam of energy with the required spatial distribution and angular distribution, which can meet the specific requirements for the direction and energy position distribution of the illumination light. In the application occasion, a uniform parallel beam can be obtained; The front and rear surfaces of the double free-form surface thick lens and its array are both free-form surfaces determined by the luminous characteristics of the light source and the required spatial and angular distribution of energy after beam shaping according to the law of conservation of luminous flux and the law of refraction. The free-form surface thick lens and its array show excellent beam shaping capabilities. The lens and its array can shape the radiated light of cold cathode fluorescent lamps and LED light sources. The shaped beam energy has the required spatial distribution and angle at the same time. Distribution, the required spatial distribution can be formed close to the rear surface of the lens, that is, the homogenization distance is greatly shortened; since the directionality of the beam can be completely controlled at the same time, in the application of the lens array, it is significantly reduced. The crosstalk between each lens can maintain uniform illumination of a large area over a long distance. The double free-form surface lens can obtain a large area of illumination with excellent uniformity and directionality, which is very suitable for sunlight simulation The device, the design method of the lens is simple, there is no need to solve the partial differential equation, and the specific surface shape of the lens can be directly obtained by solving the binary quaternary equation, which is very suitable for the current processing and manufacturing technology; The front surfaces of the double free-form surface thick lens and its array are all refraction surfaces or part of the refraction surfaces are divided into reflective surfaces; The double free-form surface thick lens and its array adopt a Fresnel lens structure, that is, the front and rear surfaces are stepped free-form surfaces; The aperture shape of the double free-form surface thick lens is one of circular, rectangular, polygonal and arbitrary curves, and the aperture size is related to the angle range of the light source light to be collected, the distance between the light source and the front surface of the lens, the thickness of the lens, It is related to the divergence angle of the shaped beam and various parameters of the required shaped beam; After limiting the outgoing light beam to be a uniform parallel light beam, when the light source is a point light source, the surface shape of the double free-form surface thick lens is rotationally symmetric; when the light source is a filamentary light source, the double free-form surface thick lens is translationally symmetric ; When the outgoing beam is defined as a uniform parallel beam, the divergence angle of the beam after being shaped by the double free-form surface thick lens and its array is related to the geometric size of the light source, and the minimum control is within ±0.3° Alternatively, when the outgoing beam is defined as a uniform parallel beam, the energy of the beam shaped by the double free-form surface thick lens and its array has a required spatial distribution in the target surface, and the distribution is within a distance of several centimeters behind the lens remains the same, i.e. all detection surfaces in this range have the same energy distribution. 2. The double free-form surface thick lens and its array according to claim 1, wherein the illumination light source of the double free-form surface thick lens and its array is one of cold cathode fluorescent lamps and LED light sources. 3. The thick double free-form surface lens and its array according to claim 1, wherein the illumination light source of the double free-form thick lens and its array has a Lambertian or any other measurable luminous intensity distribution. 4. The double free-form surface thick lens and its array according to claim 1, wherein when the outgoing light beam is defined as a uniform parallel light beam, the beam aperture and its shape after the double free-form surface thick lens and its array shaping The shape of the spot on the target surface is determined by the lens aperture and the divergence angle of the beam after shaping. 5 . The double free-form surface thick lens and its array according to claim 1 , wherein the double free-form surface thick lens array adopts one of the combinations of rectangular arrangement, hexagonal arrangement and triangular arrangement. 6. double free-form surface thick lens and array thereof according to claim 1, is characterized in that, the material of described double free-form surface thick lens and array thereof is selected from: one of crown glass, flint glass, quartz glass material or selected from methacrylate resin, acrylate resin, polystyrene resin, polycarbonate resin, methyl methacrylate-styrene copolymer, acrylonitrile-styrene copolymer and polyethylene terephthalate One of diester organic resin materials.