Uniform tea baking device and method based on multi-wavelength laser array

Abstract

The invention discloses a tea leaf uniform baking device and method based on a multi-wavelength laser array. The device comprises a conveying belt used for bearing and conveying tea leaves, a laser emitting module and a control system. The laser emitting module comprises at least two groups of lasers with different wavelengths and optical fibers corresponding to the lasers, and light emitting ports of the optical fibers are arranged in an array manner, cover the width of a conveying belt, are mounted above the conveying belt in a crossing manner and are used for transmitting laser emitted by the lasers to tea leaves; the control system is electrically connected with the conveying belt and the laser emitting module and used for independently controlling starting and stopping of all lasers in the conveying belt and the laser emitting module. The tea leaf baking device can realize clean, non-contact, high-uniformity, accurate and controllable tea leaf baking.

Description

Technical Field

[0001] This invention belongs to the field of tea processing technology, and specifically relates to a tea uniform roasting device and method based on a multi-wavelength laser array. Background Technology

[0002] Tea roasting is a crucial step in the refining and processing of tea. Its main purpose is to effectively remove excess moisture from the tea leaves to facilitate storage, to deactivate residual enzymes through high temperatures to fix their quality, and to stimulate, transform, and fix the unique aroma and flavor of the tea leaves through heat. It is the core link in forming the final flavor and quality of the tea.

[0003] Currently, mainstream tea roasting techniques in the industry primarily utilize charcoal, electric heating elements, or hot air as heat sources. For example, Chinese utility model patent CN212987815U discloses a tea drying device, including a drying frame. Mounting blocks are fixedly installed around the center of the drying frame, and a placement frame is fixedly installed between the tops of the mounting blocks. A baffle is fixedly installed on the right side of the drying frame. An exhaust frame is fixedly installed at the upper part of the drying frame, and laser thermometers are fixedly installed around the bottom of the exhaust frame. The device activates the resistance heating mechanism and the electric fan mechanism via a control panel. The electric fan mechanism then delivers gas into the air pipe and into the resistance heating mechanism. As the gas passes through the resistance heating mechanism, it is heated and sent through the exhaust frame into the drying frame, where it comes into contact with the tea leaves placed on the upper part of the placement frame for drying. The gas inside the drying frame is absorbed by the electric fan mechanism through a connecting pipe and then circulated back into the air pipe.

[0004] While these traditional methods are widely used, they have revealed many inherent flaws in practice: environmental pollution and potential quality and safety hazards. Taking charcoal roasting as an example, the combustion process inevitably produces pollutants such as smoke and carbon dioxide, which does not conform to the development trend of green and clean production in the modern food industry. More importantly, the smoke or other odors produced by combustion are easily absorbed by the tea leaves, masking or even destroying their own aroma. Traditional roasting methods rely on heat conduction or convection, which inevitably creates a temperature gradient within the roasting space. This results in uneven heating, whether the tea leaves are piled up or laid out flat, with varying heat distribution between the interior and exterior, and between the center and the edges. This unevenness directly leads to poor consistency in the quality of the finished tea, seriously affecting the overall quality and commercial value of the product. Traditional equipment typically requires heating the entire oven cavity or a large amount of air before transferring the heat to the tea leaves. This results in a long energy transfer chain, significant heat loss, and low overall energy utilization. Furthermore, due to the system's high thermal inertia, the temperature control response is slow, making it difficult to accurately and quickly track and regulate the roasting temperature-time curve. This fails to meet the refined requirements of high-quality tea for roasting processes.

[0005] Therefore, there is an urgent need for a new tea roasting technology that can achieve clean, contactless, highly uniform, and precisely controllable results. Summary of the Invention

[0006] This invention provides a tea uniform roasting device and method based on a multi-wavelength laser array, aiming to solve the problems of environmental pollution, tea odor, uneven heating, high energy consumption and low control precision in the existing technology.

[0007] To solve the above-mentioned technical problems, the present invention proposes a tea uniform roasting device based on a multi-wavelength laser array, including a conveyor belt for carrying and transporting tea, a laser emitting module and a control system; The laser emitting module includes at least two sets of lasers of different wavelengths and optical fibers corresponding to the lasers. The output ports of the optical fibers are arranged in an array and cover the width of the conveyor belt, and are installed across the top of the conveyor belt to conduct the laser emitted by the lasers to the tea leaves. The control system is electrically connected to the conveyor belt and the laser emitting module, and is used to independently control the start and stop of each laser in the conveyor belt and the laser emitting module.

[0008] Preferably, the laser is a semiconductor laser with a wavelength of 1064nm and a semiconductor laser with a wavelength of 980nm.

[0009] Preferably, the conveyor belt is a metal mesh belt.

[0010] Preferably, the width of the conveyor belt is between 50 and 100 cm.

[0011] Preferably, the spacing between the light-emitting ports is 1cm to 10cm.

[0012] Preferably, each output port of the optical fiber is equipped with a collimating lens to form a circular light spot with a diameter of 1.5-10.5 cm.

[0013] Preferably, the optical fiber's output port is installed horizontally 20-40cm above the conveyor belt.

[0014] Preferably, the device further includes a housing, and the conveyor belt and the light output port are located inside the housing.

[0015] Preferably, the inner wall of the housing is a polished surface or a coated surface that enhances reflection.

[0016] Accordingly, the present invention also discloses a method for uniformly roasting tea leaves based on a multi-wavelength laser array, the method using the above-mentioned roasting apparatus, comprising the following steps: The control system controls the operation of the conveyor belt to transport tea leaves. The laser is activated to emit laser light towards the tea leaves for roasting; The control system synchronously controls the start and stop of each laser in the laser emitting module according to the position of the tea leaves on the conveyor belt, so that when the tea leaves enter the irradiation area corresponding to any laser, the corresponding laser is turned on; when the tea leaves leave the irradiation area corresponding to any laser, the corresponding laser is turned off, so as to ensure that different parts of the tea leaves receive laser irradiation time that is basically equal. The control system controls the degree of tea roasting by adjusting at least one of the following parameters: laser power, wavelength, laser on-time, and conveyor belt speed.

[0017] Compared with the prior art, the present invention has the following technical effects: 1. The roasting device proposed in this invention uses laser as a heat source and is a pure electric energy processing device. No combustion products are generated during the process, which fundamentally avoids pollutants such as smoke and harmful gases that may be caused by incomplete combustion of fuel, and also eliminates odor residue, thereby ensuring the original pure quality of tea to the greatest extent.

[0018] 2. The roasting apparatus proposed in this invention achieves synchronous scanning roasting by controlling the independent start and stop of each unit in the laser emission array through a control system. This ensures that different parts of each tea leaf on the conveyor belt receive precisely equal laser energy and irradiation time as they pass under the laser array, solving the problem of uneven heating caused by the different positions of the tea leaves within the roasting equipment in traditional roasting methods, and improving the consistency of the final product quality.

[0019] 3. The roasting apparatus proposed in this invention can respond precisely to laser power and on / off states within milliseconds. Combined with precise control of conveyor belt speed, this invention can accurately reproduce and execute extremely intricate and complex "roasting temperature-time" process curves. This high degree of controllability provides strong technical support for the personalized and customized processing of different types and grades of tea, and is especially suitable for high-end teas with stringent processing requirements.

[0020] 4. The roasting device proposed in this invention allows the laser energy to be directly and efficiently absorbed by the tea leaves and converted into heat energy. The energy is concentrated on the target material, greatly reducing heat loss to the surrounding environment. Compared with traditional roasting methods that require preheating the entire furnace or a large amount of hot air, the energy utilization rate of this invention is significantly improved, thereby achieving the goals of high efficiency, energy saving, and reduced production costs.

[0021] 5. The roasting apparatus proposed in this invention employs a multi-wavelength laser combination. Utilizing the physical property that different substances have varying absorption rates for specific wavelengths of laser light, it allows for the selective heating of specific components in tea leaves (such as moisture, tea polyphenols, and caffeine) by selecting or combining different wavelengths of laser light. This not only improves roasting efficiency and precision but also makes it possible to develop and create entirely new tea flavors by controlling changes in the internal chemical composition of the tea leaves. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the baking apparatus described in this invention; Figure 2 This is a schematic diagram of the laser emitting module described in an embodiment of the present invention; Figure 3 This is a schematic diagram of the optical output port array described in an embodiment of the present invention; Figure 4 This is a block diagram illustrating the control principle of the control system described in an embodiment of the present invention.

[0023] Reference numerals: 1. Conveyor belt; 2. Laser emitting module; 3. Control system; 4. Laser; 5. Optical fiber; 6. Tea leaves; 7. Collimating lens; 8. Housing; 9. Heat dissipation module. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present application and with reference to the accompanying drawings.

[0025] Example 1 This embodiment describes a tea uniform roasting device based on a multi-wavelength laser array. Please refer to [link / reference]. Figure 1 The roasting apparatus includes a conveyor belt 1 for carrying and transporting tea leaves, a laser emission module 2, and a control system 3.

[0026] like Figure 2 As shown, the laser emitting module 2 includes at least two sets of lasers 4 with different wavelengths and optical fibers 5 corresponding to the lasers 4. The output ports of the optical fibers 5 are arranged in an array and cover the width of the conveyor belt 1, spanning across the top of the conveyor belt 1, for transmitting the laser emitted by the lasers 4 to the tea leaves 6; the array of output ports is as follows: Figure 3 As shown.

[0027] The control system 3 is electrically connected to the conveyor belt 1 and the laser emitting module 2, and is used to independently control the start and stop of each laser 4 in the conveyor belt 1 and the laser emitting module 2.

[0028] In a preferred embodiment of the present invention, the laser 4 is a semiconductor laser with a wavelength of 1064nm and a semiconductor laser with a wavelength of 980nm.

[0029] However, those skilled in the art should understand that the present invention is not limited to the specific wavelength combination of 1064nm and 980nm. One of the core ideas of the present invention is to utilize the differences in the interaction between different wavelengths of laser light and different target components in tea (such as moisture, tea polyphenols, chlorophyll, caffeine, aromatic precursors, etc.) to achieve selective heating and precise process control. Therefore, in other embodiments, the wavelength of the laser 4 can be adjusted and selected according to the specific processing target and the type of tea. For example, other wavelengths with higher absorption efficiency for water molecules, such as lasers around 1450nm or 1940nm, can be selected to further improve dehydration efficiency.

[0030] For example, to better promote the transformation of substances within tea leaves during the roasting process to form unique aromas and flavors, specific wavelengths that can be preferentially absorbed by certain organic compounds (such as tea polyphenols and amino acids) can be selected. This may involve lasers in the near-infrared, mid-infrared, or even visible light bands. For instance, a carbon dioxide laser (wavelength approximately 10.6 μm, or 10600 nm) can be introduced, whose energy is readily and strongly absorbed by water and various organic compounds, and can be used for rapid fixation or aroma enhancement on the surface of tea leaves.

[0031] Furthermore, the laser emitting module 2 can include two or more sets of lasers with different wavelengths. For example, it can be a three-wavelength or four-wavelength combination system. The control system 3 can activate different wavelength laser combinations or operate simultaneously at different power ratios at different stages of baking according to a preset process curve. For example, in the early stage of baking, a wavelength with strong water absorption is mainly used for rapid drying; in the later stage of baking, another wavelength that promotes the formation of aromatic substances is switched or superimposed to achieve precise processing of multiple stages and objectives.

[0032] In a preferred embodiment of the present invention, the conveyor belt 1 is a metal mesh belt with a width between 50-100cm.

[0033] The choice of a metal mesh belt as the material for the conveyor mechanism is primarily based on the following considerations: First, metal possesses excellent high-temperature resistance, capable of withstanding the heat generated during laser roasting without damaging or releasing harmful substances. Second, the mesh structure offers excellent air permeability, crucial for tea roasting. When laser irradiation evaporates the internal moisture of the tea leaves, the resulting water vapor can not only escape from the top of the leaves but also quickly dissipate from below through the mesh openings of the metal belt, preventing moisture accumulation at the bottom of the leaves and thus significantly improving drying efficiency and uniformity. The width is set at 50-100cm to balance the efficiency of industrial production with the equipment's footprint and manufacturing costs.

[0034] To achieve uniform heating and coverage of the tea leaves 6 on the conveyor belt 1, this embodiment optimizes the design of the output port array of the optical fiber 5. Specifically, the spacing between adjacent output ports is set to 1cm to 10cm. Simultaneously, a collimating lens 7 is provided at each output port to shape the diverging laser beam emitted from the optical fiber, forming a circular light spot with a relatively uniform energy distribution and a diameter of 1.5cm to 10.5cm on the surface of the conveyor belt 1.

[0035] The diameter of the laser spot is set slightly larger than the spacing between the output ports, allowing adjacent circular laser spots to form a slight overlap on the surface of conveyor belt 1. This design effectively eliminates heating "blind spots" that may result from physical gaps between the ports and compensates for the uneven energy distribution of a single beam (especially a Gaussian beam), where the center energy is high and the edge energy is low, through the superposition of energy at the edge of the laser spot. By precisely controlling the overlap rate, it can be ensured that the laser energy density distribution received by the tea leaves tends to be a smooth straight line across the entire width perpendicular to the direction of movement of conveyor belt 1, thus fundamentally guaranteeing a high degree of uniformity in lateral heating, an advantage that is difficult to match with traditional heating methods. This range of spacing and laser spot diameter provides flexible design space for scenarios with different processing volumes and precision requirements.

[0036] In this embodiment, the optical fiber 5's output port array is mounted at a height of 20-40 cm above the conveyor belt 1. This height range provides the necessary working distance for the collimating lens 7 to expand and shape its emitted laser beam into a circular spot with a preset diameter (1.5-10.5 cm) on the surface of the conveyor belt 1, ensuring precise control over the spot size. This distance ensures a sufficient safety gap between the laser emitter and the tea leaves, preventing the tea leaves from accidentally tumbling or curling during transport and touching the delicate optical components. It also provides ample space for the moisture evaporated from the tea leaves to diffuse, preventing a high-humidity environment from forming in the processing area and thus affecting the roasting efficiency.

[0037] To further optimize energy utilization and ensure operational safety, the device preferably also includes a housing 8. The output port array of the conveyor belt 1 and the optical fiber 5 are both located inside the housing 8. As a key technical feature, the inner wall of the housing 8 is treated to have a highly reflective surface, for example, by finely mechanically polishing the stainless steel inner wall to form a mirror surface, or by depositing a highly reflective metal film (such as gold or silver) or a dielectric film for a specific laser wavelength on the inner wall surface using physical or chemical vapor deposition methods.

[0038] The purpose of chamber 8 is to ensure that laser beams not directly absorbed by the tea leaves, or reflected or transmitted from the tea leaf surface and metal mesh, are not lost due to absorption by the chamber walls. Instead, they are reflected again by the highly reflective inner walls and have the opportunity to be re-projected onto the tea leaves for absorption and utilization. This energy recycling mechanism significantly improves the overall energy efficiency of the device and reduces energy consumption. The laser beams reflected by the inner walls provide supplementary heating to the tea leaves from all directions through diffuse reflection, which helps improve the heating of areas that are difficult to cover by direct irradiation, such as the sides and bottom of the tea leaves, thereby further improving the uniformity of roasting at both macroscopic and microscopic levels. The enclosed chamber 8 completely isolates the high-power laser beam inside the equipment, acting as a laser safety shield and fundamentally protecting the personal safety of operators. At the same time, it also provides a stable, clean internal space for the roasting process, free from interference from external airflow, dust, and other environmental factors, ensuring the stability of the processing and the hygiene of the product.

[0039] In a specific embodiment of the present invention, the control system 3 is the core component for achieving precise and uniform roasting of tea leaves. Please refer to [link / reference needed]. Figure 4 Its structure and workflow are as follows: The control system 3 mainly includes a microprocessor unit, a laser drive circuit, a motor drive circuit, and a communication interface in terms of hardware.

[0040] The microprocessor unit is the brain of the entire control system. In this embodiment, STMicroelectronics' STM32 series, Field Programmable Gate Array (FPGA), or, for scenarios with lower cost requirements, the classic 51 microcontroller can be used. The microprocessor unit internally stores various expert process programs for different teas (such as Longjing, Biluochun, Tieguanyin, etc.) or different roasting levels (such as light roasting, full roasting, etc.). Each program is essentially a "roasting process curve" containing multiple key parameters, including at least the running speed of conveyor belt 1, the operating power of each laser 4, and the total roasting time.

[0041] For ease of operation, this device is equipped with a human-machine interface. Operators can directly select preset processes on this interface, such as the "Longjing Tea Light Roasting" mode. In addition, the microprocessor unit provides a communication interface (such as a serial port) that can be connected to an external computer via a data cable. This design greatly enhances the system's flexibility, allowing technicians to design, import, monitor and record data, or perform firmware upgrades on the equipment using host computer software.

[0042] Workflow details: Once the operator selects a baking process and starts the equipment, the microprocessor unit begins to execute the preset program.

[0043] The microprocessor unit first sends instructions to the motor drive circuit to precisely control the motor driving conveyor belt 1 to run at a set speed. In this embodiment, this speed can be steplessly adjusted within the range of 0.01 m / s to 0.5 m / s according to process requirements. The uniform and stable operation of the conveyor belt is the foundation for achieving uniform baking.

[0044] Synchronous control of the laser array: The core task of microprocessor unit 1 is to send precise control commands to the laser drive circuit. The laser drive circuit is responsible for converting the low-voltage logic signals from the microprocessor unit into the high-power stable current required to drive the semiconductor laser 4.

[0045] The control logic follows the principle of "open when tea leaves arrive, close when tea leaves leave." Since the speed v of conveyor belt 1 is known, and the physical position of each light-emitting port in the laser array is fixed, the microprocessor unit can accurately calculate the time required for any tea leaf on the conveyor belt to reach the area directly beneath each laser spot. Based on this, the microprocessor unit generates a precise timing sequence: when it calculates that the tea leaves are about to enter the irradiation area of ​​the first laser unit, it immediately sends a command to turn on that laser unit; when the tea leaves are about to leave the irradiation area, it immediately sends a command to turn it off. This process is performed sequentially and independently for each laser unit in the array.

[0046] In this way, no matter where the tea leaves are on the conveyor belt, every part of them receives the same total laser irradiation time as it passes under the entire laser emission array from beginning to end, thus fundamentally ensuring the ultimate uniformity of roasting.

[0047] In a specific example of the "light roasting" process for Longjing tea, the program might be set as follows: conveyor belt speed 0.1 m / s, all laser units operating at 50% of their rated power, and total roasting time (the time from when a single tea leaf enters the first laser spot to when it leaves the last) controlled between 5 and 30 minutes, the specific duration determined by the length of the laser array and the conveyor belt speed. The microprocessor unit will strictly adhere to these parameters to precisely control the entire roasting process to achieve optimal quality results.

[0048] Example 2 This embodiment is a method for uniformly roasting tea leaves based on a multi-wavelength laser array. The method uses the roasting apparatus described in Embodiment 1 and includes the following steps: The control system 3 controls the operation of the conveyor belt 1 to transport tea leaves 6. The laser 4 is turned on to emit a laser beam toward the tea leaves 6 for roasting.

[0049] Specifically, this can be expanded to the following steps S1-S5: S1: Spread the tea leaves 6 to be roasted evenly on the movable conveyor belt 1, which can be set inside a sealed roasting box 8. S2: Above the conveyor belt 1, at least two laser light output ports are arranged in parallel. The light output ports are connected to multiple independent and controllable lasers 4 through optical fibers 5. The laser wavelength emitted by the lasers 4 is located in the near-infrared band or the mid-infrared band, which can be efficiently absorbed by the moisture and organic matter in the tea leaves. S3: Start the conveyor belt 1 to run at a constant speed v; at the same time, start the corresponding laser 4; S4: The control system 3 controls the switching sequence of each laser 4 in the laser emitting module 2 according to the running speed v of the conveyor belt; specifically: when the tea leaves 6 move with the conveyor belt 1 to directly below the light output port of a certain laser, the laser is turned on and irradiates the tea leaves 6; when the tea leaves 6 move out of the irradiation area of ​​the laser, the unit is turned off; in this way, it is ensured that the laser energy and irradiation time received by each piece of tea leaves 6 on the conveyor belt 1 when passing below the light output port are basically the same; S5: During the roasting process, the roasting temperature and time of the tea are precisely controlled by adjusting the power density and wavelength combination of the laser and the running speed v of the conveyor belt, so as to adapt to the roasting process requirements of different types of tea (such as green tea, oolong tea, black tea, etc.).

[0050] The control system 3 synchronously controls the start and stop of each laser 4 in the laser emitting module 2 according to the position of the tea leaves 6 on the conveyor belt 1, so that when the tea leaves 6 enter the irradiation area corresponding to any laser 4, the corresponding laser 4 is turned on; when the tea leaves 6 leave the irradiation area corresponding to any laser 4, the corresponding laser 4 is turned off, so as to ensure that the laser irradiation time received by different parts of the tea leaves 6 is basically equal. The control system 3 controls the degree of tea roasting by adjusting at least one of the following parameters: laser power, wavelength, laser 4 on-time, and conveyor belt 1 speed.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A tea uniform roasting device based on a multi-wavelength laser array, comprising a conveyor belt (1) for carrying and transporting tea leaves, characterized in that, It also includes a laser emitting module (2) and a control system (3); The laser emitting module (2) includes at least two sets of lasers (4) with different wavelengths and optical fibers (5) corresponding to the lasers (4). The output ports of the optical fibers (5) are arranged in an array and cover the width of the conveyor belt (1), and are installed across the top of the conveyor belt (1) to conduct the laser emitted by the lasers (4) to the tea leaves (6). The control system (3) is electrically connected to the conveyor belt (1) and the laser emitting module (2) and is used to independently control the start and stop of each laser (4) in the conveyor belt (1) and the laser emitting module (2).

2. The apparatus according to claim 1, characterized in that, The laser (4) is a semiconductor laser with a wavelength of 1064nm and a semiconductor laser with a wavelength of 980nm.

3. The apparatus according to claim 1, characterized in that, The conveyor belt (1) is a metal mesh belt.

4. The apparatus according to claim 1 or 3, characterized in that, The width of the conveyor belt (1) is between 50 and 100 cm.

5. The apparatus according to claim 1, characterized in that, The spacing between the light-emitting ports is 1cm to 10cm.

6. The apparatus according to claim 1 or 5, characterized in that, Each output port of the optical fiber (5) is equipped with a collimating lens (7) to form a circular light spot with a diameter of 1.5-10.5 cm.

7. The apparatus according to claim 1, characterized in that, The optical fiber (5) has its output port mounted horizontally 20-40cm above the conveyor belt (1).

8. The apparatus according to claim 1, characterized in that, The device also includes a housing (8), and the conveyor belt (1) and the light output port are located inside the housing (8).

9. The apparatus according to claim 8, characterized in that, The inner wall of the box (8) is a polished surface or a coated surface to enhance reflection.

10. A method for uniformly roasting tea leaves based on a multi-wavelength laser array, characterized in that, The method uses the baking apparatus as described in claim 1 and includes the following steps: The control system (3) controls the operation of the conveyor belt (1) to transport tea leaves (6). The laser (4) is turned on to emit a laser beam toward the tea leaves (6) for roasting; The control system (3) synchronously controls the start and stop of each laser (4) in the laser emission module (2) according to the position of the tea leaves (6) on the conveyor belt (1), so that when the tea leaves (6) enter the irradiation area corresponding to any laser (4), the corresponding laser (4) is turned on; when the tea leaves (6) leave the irradiation area corresponding to any laser (4), the corresponding laser (4) is turned off, so as to ensure that the laser irradiation time received by different parts of the tea leaves (6) is basically equal. The control system (3) controls the degree of roasting of tea by adjusting at least one of the following parameters: the power of the laser, the wavelength, the turn-on time of the laser (4), and the speed of the conveyor belt (1).

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