CN107726096A - The visible light projection system of remote LED - Google Patents

Abstract

The invention relates to a long-distance LED visible light projection system, comprising first and second reflective cups, an LED light source placed at the focal point of the first reflective cup, a built-in lens placed between the first and second reflective cups, and The secondary collimation system is set at the mouth of the second reflective cup. Part of the light emitted by the LED light source is reflected by the first and second reflective cups, and the other part is initially collimated by the built-in lens, and then the secondary collimation system secondary collimation. The present invention only uses simple reflective cups and lens groups to collimate the light emitted by the LED matrix of suitable size, the system structure is simple, the cost is low, the assembly is simple, the loss is low, and the divergence angle of the light is higher than that of the existing collimation device can reach the minimum, which has practical value.

Description

Long distance LED visible light projection system

technical field

The invention relates to the field of visible light projection, in particular to a long-distance LED visible light projection system.

Background technique

Visible light communication technology refers to the use of light in the visible light band as an information carrier, without the need for transmission media such as optical fibers, and directly transmits optical signals in the air. Broad development prospects.

As a common light source for visible light communication, LED has a faster response speed, lower energy consumption, and longer life than traditional light sources. However, the light emitted by the LED chip has a Lambertian distribution, and its illuminance attenuates rapidly with the increase of the angle between the light emitting direction and the normal line of the light-emitting surface, so it cannot be directly used for lighting. Therefore, different optical systems must be designed according to different requirements to adjust the light emitted by the LED chip and change its light intensity distribution. Although most future visible light communication applications will be within a short distance of a few meters, there are also some fields that require long-distance visible light communication, such as underwater communication, communication between vehicles, and communication between vehicles and roadside facilities, so the future can be seen Optical communication can not only achieve high communication rate, but also meet the technical requirements of long-distance transmission.

The existing LED light collimation system generally uses a concentrating lens or a reflector to turn the light into an adjustable outgoing light at an angle of 3°~120°, and then collimates the light through a curved lens to become collimated light. Collimation of LED light in this way has the problems of excessively large divergence angle and low utilization rate of light energy, which affects practical applications.

Contents of the invention

Based on this, the purpose of the present invention is to overcome at least one deficiency in the prior art, and provide a long-distance LED visible light projection system, which adopts a collimation system composed of a reflective cup and several lenses, and through secondary collimation, reduces the LED The divergence angle of the light emitted by the matrix realizes long-distance lighting and communication.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A long-distance LED visible light projection system is provided, comprising first and second reflective cups, an LED light source placed at the focal point of the first reflective cup, a built-in lens placed between the first and second reflective cups, facing the first Secondary collimation system set on the mouth of the second reflective cup, part of the light emitted by the LED light source is reflected by the first and second reflective cups, and the other part is initially collimated by the built-in lens, and then the secondary collimation system performs secondary collimation. collimation.

In the above solution, the LED light source is at the focal point of the reflective cup, the light is incident from one end of the reflective cup, and the light that hits the inner surface of the reflective cup is reflected and then reaches a preliminary collimated exit. The reflective cup is equipped with a built-in lens as a supplement to the reflection of the reflective cup wall , so that the light emitted directly through the mouth of the cup without being reflected by the reflective cup is initially collimated by the lens and then emitted. Since the actual light source is not an ideal point light source, the light processed by the reflective cup and its built-in lens cannot Ideal collimation, so it is necessary to perform secondary collimation; the light after secondary collimation by the secondary collimation system has a smaller divergence angle, which can realize long-distance lighting and communication. The reflector is disposed at the built-in lens For detachable two parts. Divide the reflector cup into two detachable parts to facilitate the installation of the built-in lens. .

In one of the embodiments, the secondary collimation system is composed of a concave lens and a convex lens. The Fresnel lens has a focusing effect similar to that of the convex lens. The convex lens in the secondary collimation system can also be replaced by a Fresnel lens. . The lens group composed of a concave lens and a convex lens performs secondary collimation on the primary collimated LED visible light, has a simple structure, is convenient to install, and can achieve better results.

In one of the embodiments, the secondary collimation subsystem includes a concave lens and a convex lens, and the light emitted by the LED light source first passes through the concave lens during secondary collimation, and then passes through a convex lens or a Fresnel lens with a corresponding focal length After exiting, the object focal point of the convex lens or Fresnel lens coincides with a point where the light after passing through the concave lens is reversely extended and then converges. The focal length of the convex lens or Fresnel lens is determined according to the required spot size. Through simulation, it is found that when the light source is at the focal point of the reflective cup, the light emitted by the reflective cup and its built-in lens tends to be slightly focused as a whole. After analysis, it is found that the main reason for the convergence of light is that the light source is no longer regarded as an ideal point. The light source is a light source with a certain size. Due to its small thickness, the light source can be regarded as a surface light source. After being reflected by the wall of the luminous cup and refracted by the lens placed inside the reflective cup, the light emitted by a point that is not on the optical axis The rays no longer exit in parallel, causing the rays to converge. The left and right deviation of the light source from the focus of the reflector may also cause the light emitted from the cup mouth to diverge or converge. During assembly, attention should be paid to the accuracy requirements to avoid this situation. After passing through the concave lens, the light tends to diverge, and then according to the focal position relationship and the calculation principle of the focal length of the combined lens, a convex lens with a suitable focal length is designed so that it can be collimated after passing through the convex lens; the corresponding focal length of the convex lens can be determined in this way, after selecting the concave lens After that, place it in a reasonable position (there is no special requirement for the selection of the concave lens here), the converging light emitted from the mouth of the reflector will diverge after passing through the concave lens, and the divergent light will converge at one point on the left side of the concave lens after extending in reverse. Select this point as the focal point of the convex lens, and finally determine the focal length of the convex lens according to the required spot size. The larger the selected focal length, the larger the spot size, and vice versa. The visible light of the LED collimated by this scheme is more concentrated, and the light energy utilization rate is higher, which can meet the needs of long-distance lighting and communication.

In another embodiment, the secondary collimation subsystem includes a concave lens and a convex lens. During secondary collimation, the light emitted by the LED light source first passes through the convex lens, and then exits through a concave lens with a corresponding focal length. The concave lens The focal point of the convex lens coincides with a point where the light after passing through the convex lens is extended and converges on one side of the concave lens, and the size of the concave lens is determined according to the required spot size. After simulation, it is found that when the light source is inside the focal point at the optical axis of the parabolic reflector, the light diverges, and when it is outside, the light converges. Due to the divergence of the light when it is on the inner side, it is possible to select a convex lens in the secondary collimation system and place it in a suitable position. There is no special requirement for the selection of the convex lens here. The light rays passing through the convex lens will converge at one point. The focal point on the right side of the concave lens. The size of the concave lens is determined according to the required spot size. The larger the selected focal length, the larger the spot size, and vice versa. Straight lens group.

Further, the LED light source is an LED matrix light source composed of several LED chips, and the LED

The size of the matrix light source matches the size of the reflector to meet the requirements of light projection and light energy utilization. After actual simulation, when there is only one LED, the projection effect of the optical system is the best. The more the number of light sources, the more the light-emitting points deviate from the pre-designed position, so that the expected projection effect cannot be achieved, and it is reflected on the receiving surface. The larger the number of light sources and the larger the size, the larger the spot, the more dispersed the light energy distribution on the receiving surface relative to the emitted light energy, and the lower the light energy utilization rate; at the same time, because of the need for long-distance projection, only 1 When using small-sized LEDs, considering the loss caused by the absorption of the transmission medium, the light energy that can be received is also very limited. By compromising the influence of the overall light source power and the number of LEDs on the light projection effect, combined in The comparison of the projection effect under the condition of different numbers of LEDs, select an appropriate number of LEDs to form a matrix light source, because the power of LEDs on the market is different, it is not easy to standardize the size ratio of the light source and the collimation system, the designer should base on different It is required to select an appropriate number and size of LEDs as the light source. The principle is that when the power meets the requirements, the smaller the size of the light source, the better the effect.

Further, the LED matrix light source is packaged in the form of COB (chip on board) to form a whole light source. The system adopting COB packaging has small thermal resistance and good heat dissipation performance; and since the package is a surface light source, the viewing angle is large and easy to adjust, reducing the loss of light refraction; the cost is low and it is easy to use.

Further, the preliminary collimating lens is selected as a convex lens with a focal length of d/tanα and a radius of d; wherein:

α is the angle between the focal point of the reflective cup and the inner edge of the cup mouth of the reflective cup and the central axis of the reflective cup in the section of the reflective cup including the central axis;

d is the distance between the light reflected by the reflective cup and the center line at the maximum emission angle of the light source.

When using this scheme, since most LED light sources are based on the light distribution curve of the Lambertian light source, 90° is the extreme value of the light emission angle of the Lambertian light source. Theoretically, the light emitted at 90° almost does not exist. The maximum light emission angle is 90°. According to α and d, select a lens with a focal length of d/tan α and a radius of d. When installing the built-in lens, its focus coincides with the focus of the reflector cup to ensure that it just does not affect the propagation of light reflected by the cup wall.

Further, the focal point of the built-in lens coincides with the focal point of the reflective cup. When the built-in lens is installed so that its focal point coincides with the focal point of the reflector cup, it can be guaranteed that it will not affect the propagation of light reflected by the cup wall.

Further, the LED light source is Lambertian or near Lambertian light source. Lambertian light source is a light source with isotropic brightness, which can adjust the light distribution through optical components to achieve long-distance projection.

In another embodiment, the first and second reflective cups (2, 4) are integrated. The reflector is set as a whole, which can reduce the deviation caused by the installation error when the light propagates.

Compared with prior art, the beneficial effect of the present invention is:

Only simple reflective cups and lens groups are used to collimate the light emitted by a suitable size LED matrix. The system has a simple structure, low cost, simple assembly, and low loss, and the divergence angle of the light can be achieved in existing collimation devices. Reaching the minimum has practical value.

Description of drawings

Fig. 1 is a schematic diagram of the decomposition structure of the present invention.

Fig. 2 is a schematic diagram of the overall structure and an optical path diagram of the present invention; the arrows in the figure indicate the direction of the optical path.

Figure 3 is a schematic diagram of the size of the built-in lens; the arrow in the figure indicates the direction of the optical path.

detailed description

The present invention will be further described below in combination with specific embodiments. Wherein, the accompanying drawings are only for illustrative purposes, showing only schematic diagrams, rather than physical drawings, and should not be construed as limitations on this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings will be omitted, Enlargement or reduction does not represent the size of the actual product; for those skilled in the art, it is understandable that certain known structures and their descriptions in the drawings may be omitted.

Example 1

In this embodiment, a long-distance LED visible light projection system, as shown in FIG. The built-in lens 3 between the second reflective cups, the secondary collimation system 7 arranged facing the mouth of the second reflective cup 4, the light emitted by the LED light source 1 is partially reflected by the first and second reflective cups, and the other After a part is initially collimated by the built-in lens, the secondary collimation system (7) performs secondary collimation. The radius of the bottom end of the first reflective cup used is 16.60 mm, and the radius of the second reflective cup mouth is 50.00 mm; holes matching the first or second reflective cup are provided around the built-in lens to facilitate fixing; The secondary collimation system 7 is a lens group composed of a concave lens 5 and a convex lens 6; the LED light source is a matrix light source composed of four 300mW Lambertian LED light chips, and each LED has a size of 1×1 (mm ² ) , the distance between the LEDs is set to 0.1mm; part of the emitted light is reflected by the first and second reflector cups, and the other part is initially collimated by the built-in lens 3, then diverged by the concave lens 5, and then processed by the convex lens 6 of the corresponding focal length. For secondary collimation, the focal point of the convex lens on the object side coincides with a point where the light after passing through the concave lens is reversely extended and then converges on one side of the concave lens. The focal length of the convex lens is determined according to the required spot size; in this scheme, the first Focus points of the first reflective cup, the second reflective cup, the built-in lens, the concave lens and the convex lens are on the same optical axis.

When implementing this scheme, as shown in the optical path diagram in Figure 2, the LED matrix light source 1 is placed in the first reflective cup

At the focal point of 2, the light emitted by the LED matrix light source 1 belongs to the near-Lambertian distribution, and the part that shoots to the first and second reflective cups is initially collimated after reflection, and exits from the cup mouth; without passing through the first and second reflective cups The light reflected by the inner wall of the two reflective cups and directly directed to the mouth of the cup will go out after being collimated by the built-in lens 3 placed between the first and second reflective cups; the initially collimated light tends to be slightly focused, and after passing through the concave lens After 5, it diverges, and then undergoes secondary collimation through a convex lens 6 with a suitable focal length.

In the present embodiment, the size of the built-in lens 3 is as shown in Figure 3, among the figure α is the angle between the line between the cup opening and the focal point and the horizontal line, and d is the light at the maximum emission angle of the light source through the light reflected by the reflective cup and the center The distance between the lines, the near-Lambertian light source used in this embodiment, according to its light distribution curve, 90° is the extreme value of the light emission angle of the Lambertian light source, the light emitted at 90° is theoretically almost non-existent, here for For convenience of calculation, it is approximately considered that the maximum light emitting angle is 90°. According to α and d, select a convex lens with a focal length of d/tanα and a radius of d as the built-in lens 3. When installing, make its focal point coincide with the focal point of the reflective cup to ensure that it just does not affect the propagation of light reflected by the cup wall .

The above embodiment is simulated, the receiving surface is placed 25 meters away from the system, the results show that the power received by the receiving surface is 1.01W, the light energy utilization rate is 83.9%, and the half-power divergence angle is 3°, which can realize the LED visible light Long range projection.

Example 2

This embodiment is the same as Embodiment 1, except that the first and second reflective cups (2, 4) are integrated. The reflector is set as a whole, which can reduce the deviation caused by the installation error when the light propagates, and it is more convenient for the light to be collimated and propagated.

Apparently, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. All modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (9)

1. the visible light projection system of remote LED, it is characterised in that including first, second reflector (2,4), it is anti-to be placed in first The LED light source (1) of light cup focal point, it is placed in first, second reflector（2,4）Between built-in lens (3), to face second anti- Light cup（4）The secondary colimated light system (7) that rim of a cup is set, the light portion of LED light source (1) transmitting are anti-by first, second Light cup (2,4) reflects, and another part carries out secondary standard after built-in lens (3) tentatively collimation, by secondary colimated light system (7) Directly.

2. the visible light projection system of remote LED according to claim 1, it is characterised in that the secondary colimated light system (7) The lens group being made up of concavees lens (5) and convex lens (6) or Fresnel Lenses.

3. the visible light projection system of remote LED according to claim 2, it is characterised in that the secondary colimated light system (7) Including a concave lens (5) and a convex lens (6) or Fresnel Lenses, the light of the LED light source transmitting is in secondary collimation When first pass around concavees lens (5), then convex lens by corresponding focal length（6）Or it is emitted after Fresnel Lenses；The convex lens or The object focus of Fresnel Lenses with converged after the light reverse extending after concavees lens a little overlap, the convex lens or The size of Fresnel Lenses focal length spot size needed for determines.

4. the visible light projection system of remote LED according to claim 1, it is characterised in that the LED light source（1）If for The LED matrix light source of dry LED chip composition, the size and reflector of the LED matrix light source（8）Size match, with full Sufficient light projection and the demand of the efficiency of light energy utilization.

5. the visible light projection system of remote LED according to claim 4, it is characterised in that the LED matrix light source（1） A light source entirety is formed in the form of COB encapsulation.

6. the visible light projection system of remote LED according to claim 1, it is characterised in that the built-in lens（3）Choose Focal length is d/tan α, and radius is d convex lens；Wherein：

α is reflector focus and reflector rim of a cup inward flange line and reflector center in the section that reflector includes central shaft The angle of axle；

D is the distance of light and center line of the light of light source maximum emission angle by reflector reflection.

7. the visible light projection system of remote LED according to claim 6, it is characterised in that the focus of the built-in lens Overlapped with reflector focus.

8. according to the visible light projection system of remote LED described in claim 1 ~ 7 any claim, it is characterised in that described LED light source（1）For lambert or nearly Lambertian illuminating source.

9. the visible light projection system of remote LED according to claim 1, it is characterised in that first, second reflector （2,4）It is integral.