Method for improving light energy utilization rate of photosynthesis, and scanning illumination apparatus and planting and breeding method

Abstract

A method for improving the light energy utilization rate of photosynthesis. A light beam emitted by a light source (11) is transformed into a moving light beam by means of a moving reflecting mirror (23, 21) and / or a lens to perform scanning illumination on an illuminated object (31), and the illuminated object (31) obtains scanning pulse light having a duty ratio and frequency within a specific range, so as to improve the light energy utilization rate of photosynthesis. The present invention further relates to a scanning illumination apparatus, which is used in cooperation with agricultural planting and breeding facilities, so as to implement the above method. The present invention further relates to a planting and breeding method for a microalgae or plant. Appropriate growth conditions are provided in agricultural facilities for the growth of a microalgae or plant, wherein at least some illumination is provided by a scanning illumination apparatus.

Description

A method for improving the utilization rate of photosynthetic light energy, a scanning lighting device and a breeding method Technical Field

[0001] The present invention relates to the field of agricultural supplementary lighting, and in particular to a method for improving the utilization rate of photosynthesis light energy, a scanning lighting device for implementing the method, and a microalgae or plant cultivation method based on the method and the device. Background Art

[0002] Agriculture is the biggest bottleneck in the development of human society. Among the four major aspects of food, clothing, housing and transportation, the efficiency of the other three aspects has been improved thousands of times since the modern industrial revolution, but the efficiency improvement in agriculture and food supply is very low. Most countries are facing the risk of food crisis.

[0003] The most fundamental reason for agricultural inefficiency is the low utilization rate of light energy during photosynthesis, the very source of agricultural production, typically only 1%. The total amount of sunlight received per unit area on Earth is relatively stable. Improving the efficiency of photosynthesis could significantly increase agricultural yields per unit area. In artificially illuminated plant factories, improving the efficiency of photosynthesis could significantly save energy and reduce production costs while maintaining the same output.

[0004] Modern facility agriculture requires artificial supplemental lighting to ensure continued production even on rainy days. The most commonly used light source is agricultural sodium lamps, which have high luminous efficiency and low equipment investment costs. They are generally used in scenarios where natural and artificial light are combined, using natural light when there is sufficient sunlight and agricultural sodium lamps for supplemental lighting when sunlight is insufficient. The use of LED light sources for plant supplemental lighting is also increasing. LED light sources can select a more efficient light spectrum, further saving electricity. LED plant supplemental lighting is also suitable for all-artificial lighting in plant factories or vertical farms.

[0005] 45% of sunlight's energy is photosynthetically active radiation, which can be used by plants during photosynthesis. The main reason for plants' low light utilization is that photosynthesis cannot continuously and efficiently absorb and utilize light energy. Photosynthesis consists of two interdependent reaction phases: the light reaction and the dark reaction. The light energy absorbed by the short light reaction requires the long dark reaction to convert it into organic matter. The light reaction is at least an order of magnitude faster than the dark reaction. Therefore, most of the continuous light is not utilized, but converted into fluorescence, photorespiration, and heat. This problem also exists in the use of artificial light for agricultural supplemental lighting, resulting in low supplemental lighting efficiency and high energy consumption.

[0006] Therefore, converting continuous sunlight or artificial light into intermittent pulsed light can improve the utilization rate of light energy for photosynthesis. While meeting the same supplementary lighting needs, it can save electricity and reduce the energy consumption cost of supplementary lighting. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for improving the utilization rate of photosynthetic light energy.

[0008] The device implemented is a scanning lighting device. The light beam emitted by sunlight or artificial light source passes through a moving reflector and / or lens to generate a moving light beam, which performs scanning lighting on the illuminated object. The illuminated object is a light-guiding device or a photosynthetic autotrophic organism. The illuminated object receives scanning pulse light illumination with alternating light and dark. The scanning pulse light duty cycle is 0<≤18%, and the scanning pulse light frequency is ≥390Hz.

[0009] The duty cycle of a scanning pulse light refers to the percentage of the light zone within the scanning illumination range at a given moment. The scanning illumination range refers to the range of the moving light beam. A moving light beam is also called a scanning beam. The light zone refers to the area of ​​the object being illuminated, while the dark zone refers to the area not illuminated at the same moment. At the same moment, the light zone plus the dark zone equals the scanning illumination range, and the object alternates between the light zone and the dark zone at different times. The scanning pulse light frequency refers to the number of times any point on the object is within the light zone in one second, or the number of times any point on the object receives illumination in one second.

[0010] Pulsed light planting lighting refers to the use of at least part of pulsed light to replace continuous light for lighting in agricultural planting and breeding. The applicant's long-term research has shown that the key to achieving a substantial increase in the utilization rate of photosynthetic light energy with pulsed light planting lighting is: under different pulsed light duty cycles, when the pulsed light frequency is too low, the light energy utilization rate is low. After the pulsed light frequency is higher than a certain value, the light energy utilization rate is increased close to the highest point, and enters a plateau period and remains stable. Under the condition that the pulsed light frequency is ≧390Hz, the pulsed light duty cycle is in the stage of rapid improvement of light energy utilization and the stage of stabilization at the plateau period at any value between 30%, 25%, 20%, 18%, 15%, 13%, 10%, 8%, 5%, 2% and above. When different duty cycles reach the platform stabilizer stage, the lower the duty cycle of the pulsed light, the higher the light energy utilization rate. A significant increase in light energy utilization means that under the premise of suitable temperature, air, and nutrients for planting, when the light source produces the same spectrum and the same instantaneous light intensity, the light energy utilization rate of plant photosynthesis under pulsed light illumination is increased by more than 100% compared to that under continuous light illumination.

[0011] Pulsed light for plant growth can be achieved in two ways: scanning pulses, or direct pulses emitted from a pulsed light source. While these two lighting methods and devices operate on a macroscopic level, at a microscopic level, scanning pulses and direct pulses are equivalent at the photosynthetic level, as long as the pulsed light waveform, intensity, spectrum, duty cycle, and frequency are consistent. Because the photosynthetic light systems, chloroplasts, and even plant cells of plants are tiny points, alternating light and dark illumination at a single point cannot distinguish between scanning pulses and direct pulses emitted directly from the light source.

[0012] The applicant's previously filed Chinese patents 2019112097994, 2023107549502, and 2023113067032 disclose devices that convert sunlight or artificial light into scanning illumination. These devices provide scanning illumination to objects within a certain range, with objects at fixed positions receiving alternating bright and dark scanning pulse light illumination. The present invention further discloses the duty cycle range and frequency range of the scanning pulse light and direct pulse light.

[0013] Pulsed light planting lighting that alternates between light and dark can be dark or ambient light. The ambient light is provided by natural light or other artificial light sources, and the average light intensity of the ambient light is ≤ 20% of the peak instantaneous light intensity of the pulse light.

[0014] The light source can be a gas discharge light source such as a high pressure sodium lamp, an agricultural sodium lamp, a metal halide lamp, an incandescent lamp, an LED lamp, an arc lamp, etc. The power supply mode of the light source is direct drive, constant current power supply, constant voltage power supply, rectifier, etc.

[0015] Preferably, the light source is an agricultural sodium lamp, a metal halide lamp or an LED lamp.

[0016] The light guide device can be a light guide plate or a fixed diffuse reflective mirror. The light entrance of the light guide plate or diffuse reflective mirror receives illumination from the light source, and the light exit or light exit surface provides diluted illumination to the plants or microalgae. Photoautotrophic organisms are capable of photosynthesis to synthesize organic matter, and include at least microalgae or plants.

[0017] Preferably, the scanning pulse light frequency is ≥470 Hz.

[0018] Preferably, the scanning pulse light frequency is ≥950 Hz.

[0019] Preferably, the scanning pulse light frequency is ≧2000 Hz.

[0020] Preferably, the scanning pulse light frequency is ≧10000 Hz.

[0021] At higher frequencies, the light energy utilization rate remains at a plateau, but the efficiency of the motor that achieves high-frequency motion decreases.

[0022] Preferably, 0<the scanning pulse light duty cycle≦13%.

[0023] Preferably, 0<the scanning pulse light duty cycle≦10%.

[0024] Preferably, 0<the scanning pulse light duty cycle≦5%.

[0025] A lower duty cycle, such as 2% or lower, is also effective in supplementing light to plants, or adjusting the plant photoperiod to promote flowering.

[0026] Preferably, the scanning illumination performed by the two or more scanning illumination devices on the same illuminated object may be synchronous or asynchronous.

[0027] The object to be illuminated obtains scanning pulse light illumination with the above duty cycle and frequency combination, which can be provided by more than two scanning illumination devices working in collaboration.

[0028] When two or more scanning lighting devices perform scanning lighting on the same object synchronously, the scanning pulse light frequency and scanning pulse light duty cycle obtained by the object remain unchanged, and the illumination intensity obtained by the object is the superposition of the illumination intensities provided by the two or more scanning lighting devices.

[0029] When two or more scanning devices perform scanning illumination on the same object in an asynchronous manner, there are at least three combinations.

[0030] One is that when the light beams of two or more scanning lighting devices partially overlap when scanning and illuminating the same object, the overlapping light beams provide the illuminated object with overlapping light intensity. The part of the light beams that are not overlapped but connected increases the duty cycle of the scanning pulse light, but the scanning pulse light frequency remains unchanged.

[0031] The second type is that the light beams of two or more scanning lighting devices are exactly connected when scanning and illuminating the same object. The scanning illumination of the same object by the two or more scanning light beams is neither superimposed nor separated. In this case, the light intensity obtained by the object remains unchanged, and the obtained scanning pulse light duty cycle is the sum of the scanning pulse light duty cycles provided by the two or more scanning lighting devices, and the scanning pulse light frequency remains unchanged.

[0032] The third situation is that when two or more scanning lighting devices perform scanning illumination on the same object, the light beams are separated from each other, the illumination intensity obtained by the object remains unchanged, the duty cycle of the obtained scanning pulse light is the sum of the duty cycles of the scanning pulse light provided by the two or more scanning lighting devices, and the scanning pulse light frequency is the sum of the scanning pulse light frequencies provided by the two or more scanning lighting devices.

[0033] The principles of the above three cases are the same as the waveform superposition principle.

[0034] For artificial light sources suitable for pulsed lighting, such as LED light sources, laser light sources, and gas discharge light sources with stroboscopic effects, pulsed lighting can be achieved directly through pulse power supply driving. The driving scheme of the pulse power supply can be a pulse circuit or a pulse width modulation (PWM) circuit. The technical solution is: a pulse lighting device, in which the artificial light source intermittently emits light under the drive of a pulse driving power supply to illuminate the illuminated object in an alternating light and dark manner. The illuminated object is a light-guiding device or a photosynthetic autotrophic organism. The illuminated object receives direct pulsed light illumination, with a direct pulse light duty cycle of 0 < ≦ 18%, and a direct pulse light frequency ≧ 390 Hz.

[0035] The duty cycle of direct pulse light refers to the proportion of time a light source is emitting light over a period of time. Objects in different areas of the illumination range are illuminated or darkened simultaneously. The frequency of direct pulse light is the number of times a light source emits light in one second.

[0036] Preferably, the direct pulse light frequency is ≥470 Hz.

[0037] Preferably, the direct pulse light frequency is ≥950 Hz.

[0038] Preferably, the direct pulse light frequency is ≧2000 Hz.

[0039] Preferably, the direct pulse light frequency is ≧10000 Hz.

[0040] Preferably, the direct pulse light frequency is ≥30kHz.

[0041] For artificial light sources driven by pulse emission, higher frequencies are more likely to cause waveform deformation and reduce luminous efficiency.

[0042] Preferably, 0<the direct pulse light duty cycle≦13%.

[0043] Preferably, 0<the direct pulse light duty cycle≦10%.

[0044] Preferably, 0<the direct pulse light duty cycle≦5%.

[0045] Preferably, 0<the direct pulse light duty cycle ≦2%.

[0046] A lower duty cycle, such as 2% or lower, is also effective in supplementing light to plants, or adjusting the plant photoperiod to promote flowering.

[0047] Preferably, the two or more light sources emit light under the drive of the pulse power supply, and the alternating light and dark illumination of the same illuminated object can be synchronous or asynchronous.

[0048] The direct pulse light illumination of the object with the above duty cycle and frequency combination can be provided by more than two pulse illumination devices working in cooperation.

[0049] When two or more light sources are driven by the driving power supply to emit light and perform alternating light and dark illumination on the same illuminated object synchronously, the frequency and duty cycle of the direct pulse light obtained by the illuminated object remain unchanged, and the light intensity obtained by the illuminated object is the superposition of the light intensities provided by the two or more pulse lighting devices.

[0050] When two or more light sources are driven by the pulse driving power supply to emit light and illuminate the same illuminated object in an alternating light and dark manner asynchronously, there are at least three combinations.

[0051] One is that when two light sources are driven by the pulse driving power supply to emit light, and the light emission time of the same illuminated object is partially overlapped when performing alternating light and dark illumination, the overlapping part of the time provides the illuminated object with illumination of overlapping light intensity, and the part of the light emission time that is not overlapped but connected increases the duty cycle of the direct pulse light, but the frequency of the direct pulse light remains unchanged.

[0052] The second type is that more than two light sources emit light under the drive of the pulse driving power supply, and the lighting time when performing alternating light and dark lighting on the same illuminated object just forms a relay. More than two light sources emit light under the drive of the pulse driving power supply, and the alternating light and dark lighting of the same illuminated object is neither superimposed nor separated. In this case, the light intensity obtained by the illuminated object remains unchanged, and the duty cycle of the direct pulse light obtained is the sum of the duty cycles of the direct pulse light provided by the two or more light sources when driven by the driving power supply, and the frequency of the direct pulse light remains unchanged.

[0053] The third situation is that more than two light sources emit light under the drive of the pulse driving power supply, and the lighting times are separated from each other when the same object is illuminated in alternating light and dark. The light intensity obtained by the object remains unchanged, and the duty cycle of the direct pulse light obtained is the sum of the duty cycles of the direct pulse light provided by the two or more light sources under the drive power supply, and the frequency of the direct pulse light is the sum of the frequencies of the direct pulse light provided by the two or more light sources under the drive power supply.

[0054] The principles of the above three cases are the same as the waveform superposition principle.

[0055] The technical problem solved by existing pulsed LED solutions for planting is to adjust the duty cycle of the pulsed light to achieve the desired effect of regulating the luminous power of the light source. This approach maintains the instantaneous luminous power while reducing the average luminous power. This technology is based on the principle of an LED breathing light. Its purpose is not to match the light and dark reactions of plant photosynthesis to improve the efficiency of photosynthetic light energy utilization. Therefore, it does not constitute a conflicting technical solution for this application.

[0056] The present invention also provides a scanning lighting device or a pulse lighting device, which is used in conjunction with agricultural breeding facilities to implement the lighting supplementary light device of any of the above methods.

[0057] The present invention also provides a method for cultivating microalgae or plants. In an agricultural cultivation facility, the microalgae or plants are provided with growth conditions such as nutrients, carbon dioxide, water, temperature and light to produce agricultural products. Light is the energy source for synthesizing organic matter through photosynthesis and is also a condition for plant light regulation. At least part of the light is provided by the above-mentioned scanning lighting device or pulse lighting device.

[0058] The method and device of the present invention are compatible with existing cultivation methods and existing agricultural setups that provide carbon dioxide, water, nutrients, and temperature to microalgae or plants. Photoautotrophic growth of microalgae or plants requires light, and the device of the present invention provides illumination, or at least a portion of the supplemental lighting, in existing cultivation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] FIG1 is a schematic diagram of a scanning lighting device composed of an LED light source and a reciprocating reflector in accordance with Example 1, illuminating a planar planting device.

[0060] FIG2 is a cross-sectional schematic diagram of a scanning lighting device composed of an agricultural sodium lamp light source and a rotating multi-faceted reflector in Example 2, illuminating a vertical cylindrical planting device. Example

[0061] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0062] Example 1 is an embodiment of the present invention of a scanning lighting device composed of an LED light source and a reciprocating reflector to illuminate a flat planting device. As shown in Figure 1, the substrate of the LED light source 11 is connected to the heat sink 40 to achieve heat dissipation. The light emitted by the LED light source 11 passes through the collimating lens 22 and is irradiated onto the reciprocating reflector 23 to form a scanning beam 00. The scanning beam 00 illuminates a local object 31 on the planting device 30. The object 31 is a plant that is planted on the cultivation device 30. The reciprocating reflector 23 is connected and driven by a motion device 50 to swing back and forth. The motion device 50 can be a galvanometer motor. When the reciprocating reflector 23 moves continuously, the scanning beam 00 performs multiple reciprocating scanning illuminations within the scanning irradiation range 03, and the object 31 within the scanning irradiation range 03 obtains scanning pulse light illumination. The area being irradiated by the scanning beam 00 is the light area 01, and the area in darkness is the dark area 02. The proportion of the light zone 01 within the scanning irradiation range 03 is the duty cycle of the scanning pulse light. As shown in the proportion in Figure 1, the duty cycle of the scanning pulse light is about 17%. Changing the light-emitting angle of the collimating lens 22 or changing the curvature of the reciprocating reflector 23 can change the width of the scanning light beam 00 and the proportion of the light zone, thereby changing the duty cycle of the scanning pulse light. The frequency of the scanning pulse light is twice the reciprocating frequency of the reciprocating reflector 23. For each reciprocating cycle, the scanning light beam 00 illuminates any point of the object 31 twice. When the reciprocating frequency of the reciprocating reflector 23 is 240Hz, the scanning pulse light frequency is 480Hz. The scanning pulse light frequency is proportional to the reciprocating frequency of the reciprocating reflector 23. Figure 1 is a schematic diagram, omitting devices such as the power supply, light-transmitting lampshade, and bracket.

[0063] Example 2 illustrates an embodiment of the present invention, using a scanning illumination device combining an agricultural sodium lamp light source and a rotating polygonal reflector to illuminate a vertical tubular planting device. As shown in Figure 2, light emitted from the agricultural sodium lamp light source 10 is reflected and converged by a rotating polygonal reflector 21 composed of ten rotationally symmetrically arranged concave reflectors into ten scanning beams 00, which illuminate an object 31 on the planting device 30. Object 31 is a plant, and the planting surface of the planting device 30 on which object 31 is located is a vertical tubular surface perpendicular to the paper. The scanning illumination device is located at the center of the tubular cross-section to ensure uniform illumination distance and intensity across the planting surface. The ten scanning beams illuminate the planting surface at equal intervals, creating ten alternating light zones and ten dark zones. As the rotating polygonal reflector 21 rotates clockwise about the agricultural sodium lamp light source 10, the ten scanning beams 00 also rotate clockwise, scanning the planting surface on which object 31 is located. The object 31 is illuminated by scanned pulsed light. The planting device 30 may contain a substrate cultivation device, a hydroponic device, or an aeroponic device, providing the plants with appropriate moisture and nutrients. In addition to the vertical tubular surface shown in the figure, the planting device may also be a vertical planting surface with a rectangular cross-section. The cross-section of the vertical planting surface may also be polygonal or hexagonal. Alternatively, the planting surface may be composed of multiple vertical planting racks with V-shaped or I-shaped cross-sections arranged opposite or in an alternating pattern. The 10 concave reflectors of the rotating polygonal reflector 21 are connected to the same motor shaft. For each clockwise or counterclockwise rotation, the same point on the object 31 is illuminated ten times by the scanning beam 00. When the motor speed is 4500 revolutions per minute, the resulting scanning pulse light frequency is 750 Hz. The scanning pulse light frequency is proportional to the motor speed, which is in turn proportional to the number of mirror surfaces of the rotating polygonal reflector 21. The scanning pulse light duty cycle, as shown in FIG2 , is approximately 18%. The scanning pulse light duty cycle is proportional to the number of mirror surfaces of the rotating polygonal reflector 21. In addition, the curvature of the rotating polygonal reflector 21 can change the width of the scanning beam 00 and the proportion of the light area, thereby changing the duty cycle of the scanning pulse light. Figure 2 is a schematic diagram, omitting the power supply, motor, transparent lampshade, bracket and other devices.

[0064] The above embodiments are only used to illustrate the design ideas and features of the present invention. Its purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. The protection scope of the present invention is not limited to the above embodiments. Those skilled in the art can implement a variety of technical solutions based on the combination of solutions of this application. All technical solutions with equivalent changes made based on the principles and design ideas disclosed by the present invention are within the protection scope of the present invention.

Claims

1. A method for improving the utilization rate of light energy in photosynthesis, wherein the device for achieving the method is a scanning lighting device, characterized in that: The light beam emitted by sunlight or artificial light source passes through a moving reflector and / or lens to generate a moving light beam, which performs scanning illumination on the illuminated object. The illuminated object is a light guide device or a photosynthetic autotrophic organism. The illuminated object receives scanning pulse light illumination with alternating light and dark. The scanning pulse light duty cycle is 0<≤18%, and the scanning pulse light frequency is ≥390Hz.

2. A method for improving the utilization efficiency of light and action light energy according to claim 1, characterized in that: The scanning pulse light frequency is ≥470 Hz.

3. A method for improving the utilization efficiency of photosynthetic light energy according to claim 1 or 2, characterized in that: 0<The scanning pulse light duty cycle ≦13%.

4. The method for improving the utilization efficiency of photosynthetic light energy according to claim 1 or 2, characterized in that: The scanning illumination performed by two or more scanning illumination devices on the same illuminated object may be synchronous or asynchronous.

5. The method for improving the utilization efficiency of photosynthetic light energy according to claim 3, wherein: The scanning illumination performed by two or more scanning illumination devices on the same illuminated object may be synchronous or asynchronous.

6. A scanning lighting device, characterized in that: A scanning lighting device is used in conjunction with agricultural breeding facilities to implement the method of any one of claims 1 to 5.

7. A method for cultivating microalgae or plants, wherein, in an agricultural cultivation facility, the microalgae or plants are provided with growth conditions such as nutrients, carbon dioxide, water, temperature, and light to produce agricultural products, wherein light is the energy source for photosynthesis of organic matter and also the condition for plant light regulation, characterized in that: At least part of the illumination is provided by a scanning illumination device as claimed in claim 6.

Images