Remote visible light communication system
By using collimating lenses, uniform lenses and condenser lenses in the light emitting module and the receiving module, the problems of large light loss and low signal-to-noise ratio in long-distance visible light communication systems are solved, and more efficient and high-quality communication is achieved.
Patent Information
- Application Number
- CN202411869815.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-18
- Publication Date
- 2025-04-25
AI Technical Summary
In the long-distance communication, existing visible light communication systems have problems such as large optical loss, large beam angle and low signal-to-noise ratio, resulting in low communication efficiency and quality.
By setting a collimating lens on the light surface of the LED array of the light emitting module, the beam angle is reduced; a uniform lens is used to increase the uniform spot area; a condenser lens is placed in front of the light receiving module to increase the signal reception force.
It effectively reduces optical loss, improves signal reception uniformity and signal-to-noise ratio, thereby extending communication distance, expanding application scenarios, and improving communication efficiency and quality.
Smart Images
Figure CN119892231A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of visible light communication, and in particular to a long-distance visible light communication system. Background Art
[0002] Visible light communication (VLC) uses visible light sources such as light emitting diodes (LEDs) to transmit information by emitting high-speed light signals that are difficult for the naked eye to distinguish. At the receiving end, a high-sensitivity photodetector is used to complete the photoelectric conversion, and then the electrical signal is regenerated and demodulated to complete the data transmission. Visible light communication has many advantages that traditional radio frequency communication does not have, such as: no electromagnetic interference. Traditional radio frequency communication has huge safety risks in electromagnetic sensitive environments such as nuclear warehouses, gas stations, and military chemical sites; low energy consumption, and can take into account the vehicle lighting function while transmitting data; flexible application scenarios, and can be used in scenarios such as information management, information transmission, and flexible scheduling. For the above reasons, visible light communication technology has become a hot topic of research at home and abroad.
[0003] For long-distance visible light communication, firstly, when LED is used as the transmitting light source, due to the large angle of the LED beam (usually 100°~130°) and the large power attenuation of light propagating in the free space medium, there will be a large light loss during communication, which reduces the efficiency of the visible light communication system; secondly, the distance between the transmitting and receiving ends is large. If the position and direction of the front receiving end are offset, it will not detect the effective optical signal; thirdly, the long-distance channel environment is complex, and the inevitable background light affects the signal-to-noise ratio of the signal received by the receiving end.
[0004] Therefore, how to reduce the beam angle of the emitting light source, ensure that the receiving end can receive effective light signals, and improve the signal-to-noise ratio of the receiving end signal, thereby improving the communication efficiency and quality of the long-distance communication system, is an urgent technical issue at present. Summary of the invention
[0005] The purpose of the present invention is to provide a long-distance visible light communication system, aiming to solve the problem that the existing visible light communication system has large light loss resulting in reduced efficiency.
[0006] To achieve the above-mentioned object, the present invention provides a long-distance visible light communication system, comprising an optical transmitting module and an optical receiving module; the optical transmitting module comprises a driving power, an LED array, a collimating lens and a uniform light lens; the optical receiving module comprises a focusing lens, a photodetector and a signal processing unit;
[0007] The driving power, the LED array, the collimating lens and the light homogenizing lens are connected in sequence; the focusing lens, the photodetector and the signal processing unit are connected in sequence.
[0008] Wherein, the LEDs in the LED array are single-chip LEDs, and the array is arranged in a form of 2 or more LEDs per row and per column.
[0009] Wherein, the collimating lens is a reflective cup or a TIR lens, and the collimating lens covers the light emitting surface of the LED array light source.
[0010] Wherein, the light homogenizing lens is a convex lens array.
[0011] Wherein, the focusing lens is a combination of a Fresnel lens and a hemispherical lens.
[0012] The photodetector is an APD detector with a receiving field angle of 10° or less and an effective area of 16 mm. 2 above.
[0013] A long-distance visible light communication system of the present invention comprises a light transmitting module and a light receiving module; the light transmitting module comprises driving power, an LED array, a collimating lens and a light homogenizing lens; the light receiving module comprises a focusing lens, a photodetector and a signal processing unit; the driving power, the LED array, the collimating lens and the light homogenizing lens are connected in sequence; the focusing lens, the photodetector and the signal processing unit are connected in sequence. The present invention reduces the beam angle of the transmitting light source and improves the transmitting performance of the light transmitting module by arranging a collimating lens on the light emitting surface of the LED array of the light transmitting module; at the same time, the light homogenizing lens is adopted to increase the uniform spot area of the transmitting light source irradiated on the receiving surface, and improve the possibility of receiving effective light signals when the position offset occurs at both ends of the transmitting and receiving ends; at the same time, by placing a focusing lens in front of the photodetector of the light receiving module, the light power received when the photodetector produces an angle offset is increased, and the receiving signal-to-noise ratio is improved, thereby extending the communication distance of the long-distance visible light communication system and expanding the application scenarios of the long-distance visible light communication system. Thereby, the problem of large optical loss and reduced efficiency of the existing visible light communication system is solved. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0015] Figure 1 It is a principle structural block diagram of a long-distance visible light communication system provided by the present invention.
[0016] Figure 2 The figure is a schematic diagram of the structure of the LED array, the collimating lens and the light homogenizing lens in a specific embodiment of the present invention.
[0017] 3A-3B are diagrams showing the simulation results of an LED array light source without a collimating lens using LightTools.
[0018] 4A-4B are diagrams showing the simulation results of using LightTools to set a collimating lens on the light-emitting surface of an LED array.
[0019] Figure 5 This is a result diagram of LightTools simulation in which a focusing lens is provided on the light incident surface of a photodetector in a specific embodiment of the present invention.
[0020] In the figure: 1-light transmitting module, 2-light receiving module; 10-LED array, 11-collimating lens, 12-uniform light lens, 13-driving power; 21-focusing lens, 22-hemispherical lens, 23-signal processing unit, 31-photodetector; 111-parabolic reflector, 112-refracting mirror, 113-convex mirror. DETAILED DESCRIPTION
[0021] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.
[0022] See also Figures 1 to 5 The present invention provides a long-distance visible light communication system, comprising an optical transmitting module 1 and an optical receiving module 2; the optical transmitting module 1 comprises a driving power 13, an LED array 10, a collimating lens 11 and a uniform light lens 12; the optical receiving module 2 comprises a focusing lens 21, a photodetector 31 and a signal processing unit 31;
[0023] The driving power 13, the LED array 10, the collimating lens 11 and the light homogenizing lens 12 are connected in sequence; the focusing lens 21, the photodetector 31 and the signal processing unit 31 are connected in sequence.
[0024] In this embodiment, if Figure 1As shown, the driving power 13 in the optical transmitting module 1 of visible light communication converts the electrical signal input from the host computer to the LED array 10 into an optical signal, and then reduces the divergence angle of the light emitted by the LED array 10 through the collimating lens 11, and uniformizes the collimated light through the uniform light lens 12, and transmits it to the optical receiving module 2 through the visible light channel. In the optical receiving module 2, the light is concentrated by the Fresnel lens and the hemispherical lens 22 in the focusing lens 21, and finally the uniformized light is focused on the receiving plane of the photodetector 31 for photoelectric conversion, and the electrical signal is demodulated and decoded by the signal processing unit 31, and the processed signal is transmitted to the host computer. The present invention reduces the beam angle of the emitting light source and improves the emission performance of the emitting module 1 by setting a collimating lens 11 on the light emitting surface of the LED array 10 of the light emitting module 1; at the same time, the uniform light spot area of the emitting light source on the receiving surface is increased by using a uniform light lens 12, and the possibility of receiving a valid light signal when the position offset occurs at both ends of the transmitter and receiver is increased; at the same time, by placing a focusing lens 21 in front of the photodetector 31 of the light receiving module 2, the light power received when the photodetector 31 produces an angle offset is increased, and the receiving signal-to-noise ratio is improved, thereby extending the communication distance of the long-distance visible light communication system and expanding the application scenarios of the long-distance visible light communication system. This solves the problem of reduced efficiency due to large optical loss in the existing visible light communication system.
[0025] Furthermore, the LEDs in the LED array 10 are single-chip LEDs, and the array is arranged in a manner such that the number of LEDs in each row and column is 2 or more.
[0026] In this embodiment, the LED array 10 emits light signals to the outside world by driving the electric power 13. Compared with the existing solution that uses a single LED as a light emitting antenna, this specific example uses multiple sub-light sources to form the LED array 10, and the sub-light sources are arranged in a rectangular arrangement, with 2 or more sub-light sources in each row and column. This specific embodiment uses an array light source to increase the transmission power of the LED array 10 and extend the distance of the visible light communication system proposed in this specific embodiment.
[0027] Furthermore, the collimating lens 11 is a reflective cup or a TIR lens, and the collimating lens 11 covers the light emitting surface of the light source of the LED array 10 .
[0028] In this embodiment, the collimating lens 11 refracts or reflects the light source to achieve light collimation, thereby reducing the light source beam angle. The reflective cup includes a parabolic reflector 111, a refractor 112, and a convex mirror 113. The reflective cup collimation is achieved by the principle of reflection of the parabolic reflector 111. The LED array 10 is placed at the bottom of the reflective cup. The large-angle emitted light is collimated by parabolic reflection, and the small-angle emitted light is not irradiated to the reflective cup and is not collimated. Therefore, this method can only collimate the large-angle light, which loses part of the energy. The TIR lens collimation is achieved by refraction and reflection. The large-angle light is reflected by the parabolic reflector 111 to achieve collimation, and the small-angle light is collimated by the refractor 112 and the convex mirror 113, which has better energy utilization efficiency. Therefore, the corresponding collimating lens 11 should be selected according to the actual situation. The visible light communication system of this specific embodiment selects a TIR lens to achieve collimation of the emitted light. Fig. 3A-B are the simulation results of the LED array 10 light source without the collimating lens 11 using LightTools. In Fig. 3B, it can be seen that the light of the LED array 10 is roughly distributed within -70° to 70°. Fig. 4A-4B are the simulation results of the LED array 10 light source with the collimating lens 11 set on the light emitting surface using LightTools. In Fig. 4B, it can be seen that the divergence angle of the light of the LED array 10 is significantly reduced.
[0029] Furthermore, the light homogenizing lens 12 is a convex lens array.
[0030] In this embodiment, the light homogenizing lens 12 is a non-imaging micro-convex lens array. After the light from the LED array 10 passes through the collimating lens 11 and is incident on the micro-convex lens array, each sub-lens of the micro-convex lens array divides the light into countless tiny sub-beams. Finally, the focusing lens 21 of the light receiving module 2 focuses these sub-beams on the receiving surface. The spot radius of the divided sub-beams will become smaller and the uniformity will increase, so that the uniformity of the spot after passing through the focusing lens 21 will also increase, and the beam conversion efficiency is high.
[0031] Furthermore, the condenser lens 21 is a combination of a Fresnel lens and a hemispherical lens 22 .
[0032] In this embodiment, Figure 5 The result diagram of LightTools simulation is that the emitted light passes through the Fresnel lens and the hemispherical lens 22 to form a focusing effect on the receiving surface of the photodetector 31. The main optical axes of the Fresnel lens and the hemispherical lens 22 are located in a straight line. The hemispherical lens 22 covers the photodetector 31 and focuses on the receiving plane of the photodetector 31 to achieve the reception of the optical signal.
[0033] Furthermore, the photodetector 31 is an APD type detector, the receiving field angle is 10° or less, and its effective area is 16 mm 2 above.
[0034] In this embodiment, the photodetector 31 is an APD type detector, and the center point of the receiving surface of the photodetector 31 is located on a straight line with the main optical axis of the focusing lens.
[0035] Beneficial effects:
[0036] First, by arranging a collimating lens on the light emitting surface of the LED array of the light emitting module, the beam angle of the emitting light source is reduced, and the emission performance of the light emitting module is improved.
[0037] Second, the use of a uniform light lens increases the uniform spot area of the emitting light source on the receiving surface, and increases the possibility of receiving effective light signals when the positions of the transmitting and receiving ends are offset.
[0038] 3. By placing a focusing lens in front of the photodetector of the optical receiving module, the light power received when the photodetector produces an angle deviation is increased, and the receiving signal-to-noise ratio is improved, thereby extending the communication distance of the long-distance visible light communication system and expanding the application scenarios of the long-distance visible light communication system.
[0039] The above disclosure is only a preferred embodiment of a long-distance visible light communication system of the present invention. Of course, it cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of implementing the above embodiments and making equivalent changes according to the claims of the present invention still fall within the scope of the invention.
Claims
1. A long-distance visible light communication system, characterized in that: It includes a light transmitting module and a light receiving module; the light transmitting module includes a driving power, an LED array, a collimating lens and a light homogenizing lens; the light receiving module includes a focusing lens, a photodetector and a signal processing unit; The driving power, the LED array, the collimating lens and the light homogenizing lens are connected in sequence; the focusing lens, the photodetector and the signal processing unit are connected in sequence.
2. The long-distance visible light communication system according to claim 1, wherein: The LEDs in the LED array are single-chip LEDs, and the array is arranged in a manner such that the number of LEDs in each row and column is 2 or more.
3. The long-distance visible light communication system according to claim 1, wherein: The collimating lens is a reflective cup or a TIR lens, and the collimating lens covers the light emitting surface of the LED array light source.
4. The long-distance visible light communication system according to claim 1, wherein: The light homogenizing lens is a convex lens array.
5. The long-distance visible light communication system according to claim 1, wherein: The condenser lens is a combination of a Fresnel lens and a hemispherical lens.
6. The long-distance visible light communication system according to claim 1, wherein: The photodetector is an APD type detector with a receiving field angle of 10° or less and an effective area of 16 mm 2 above.