CN202649111U - Plant foliage array LED infrared spectrum detector - Google Patents

Abstract

The utility model discloses a plant foliage array LED infrared spectrum detector based on a single chip microcomputer. The plant foliage array LED infrared spectrum detector mainly comprises an array light emitting diode circuit, a photoelectric conversion circuit, a temperature and humidity sensing circuit, a single chip microcomputer processing circuit, a communication interface, a data processing circuit, an upper computer data processing program and the like. The plant foliage array LED infrared spectrum detector can be used for measuring and recording the relative content, the moisture content, the NDVI (normalized differential vegetation index) and the like of chlorophyll a, chlorophyll b, xanthophyll and carotene of plants under different climatic environmental conditions (mainly including temperature and humidity) in real time, and can also be used for monitoring plant growth situations, the vegetation index and the influence of temperature, humidity and moisture on plant growth under various climatic conditions such as a temperate zone, cold zone and tropic in real time.

Description

Plant Leaf Array LED Infrared Spectrum Detector

technical field

The utility model relates to the field of biological detection instruments, in particular to a plant leaf array LED infrared spectrum detector for simple, accurate and rapid plant growth characteristics and vegetation index.

Background technique

As forestry researchers, they often need to conduct scientific investigations in the field to understand the local geography, climate, plant growth status, vegetation index and other information. The acquisition of these data has always been a difficult problem for forestry workers, because in the field environment, Various measuring equipments are inconvenient to carry, even if there are some specialized testing equipments, they either have a single function, which makes it necessary to bring various measuring equipments when going out for investigation; The analysis and processing does not meet the requirements of forestry informatization.

Utility model content

The purpose of the utility model is to provide a plant blade array LED infrared spectrum detector for rapid measurement of chlorophyll relative content, normalized vegetation index and leaf moisture under different climate environments, by measuring chlorophyll content, normalized vegetation index, The instrument which combines moisture content and temperature and humidity measurement in the same device overcomes the deficiencies in the traditional technology, thereby realizing the purpose of the utility model.

The technical problem solved by the utility model can be realized by adopting the following technical solutions:

Plant leaf array LED infrared spectrum detector, which includes:

A power module, the power module includes a lithium battery, a charging module connected to the lithium battery, and a battery boost circuit connected to the output terminal of the lithium battery;

A constant current source circuit, the two ends of which are respectively connected to the output end of the power module and the input end of the photodiode light-emitting circuit, for providing stable current to the photodiode light-emitting circuit;

A photodiode light-emitting circuit for emitting light of several wavelengths;

The blade clamping and measuring mechanism includes a blade clamping mechanism and a probe, and the blade clamping mechanism is facing the light-emitting part of the photodiode light-emitting circuit, and is used for fixing and measuring the blade;

The single-chip microcomputer control circuit is provided with a number of ports, which are respectively connected with a sensor circuit for detecting temperature and humidity, a liquid crystal display circuit for data display, a data storage circuit for data storage, and a time and date circuit for time recording. The undervoltage alarm circuit of the power module voltage is used for the computer of data transmission, processing and downloading;

The photoelectric conversion circuit is connected with the single-chip microcomputer control circuit, and is used for converting the light passing through the blade into a circuit signal and sending it to the single-chip microcomputer control circuit.

In one embodiment of the present invention, the wavelengths of light emitted by the photodiode light emitting circuit include 450nm, 490nm, 650nm, 680nm, 940nm and 1450nm.

In one embodiment of the present utility model, the blade clamping and measuring structure is provided with a Y-shaped optical fiber for reflecting the optical path and measuring the moisture content.

In one embodiment of the present utility model, the computer is provided with an RS232 communication interface.

The beneficial effect of the utility model is that it provides a plant growth characteristic detection device with strong battery life, multi-function, high intelligence, low cost, small volume and simple and convenient use, which has very important practical significance.

Description of drawings

Fig. 1 is a structural schematic diagram of the plant leaf array LED infrared spectrum detector.

Detailed ways

In order to make the technical means, creative features, goals and effects achieved by the utility model easy to understand, the utility model will be further elaborated below in conjunction with specific embodiments.

As shown in Figure 1, the plant leaf array LED infrared spectrum detector described in the utility model mainly comprises:

A power module, the power module includes a lithium battery 16, a charging module 17 connected to the lithium battery, and a battery boost circuit 14 connected to the output end of the lithium battery;

Among them, the TPS61030 chip of TI Company is selected as the battery boost circuit, which is a high-efficiency synchronous boost conversion chip with a conversion efficiency of up to 96%, an input voltage of 1.8-5.5V, and an output voltage option up to 5.5V; the lithium battery adopts aluminum-plastic soft packaging , safe and reliable, small thickness, light weight, large capacity (using 1200mAh), can be repeatedly charged and discharged, no need to replace the battery like a dry battery; the charging module uses the BQ24032 chip, the BQ24032 chip is a lithium battery dedicated power management integrated chip launched by TI , suitable for normal charging control, fast charging control, etc. of a group of lithium batteries. Its main feature is that it can reliably control the termination of charging, ensure the charging safety of lithium batteries, charge status indication, and provide high-efficiency power to the system while charging. ;

Constant current source circuit 1: using Infineon's light-emitting diode driver chip BCR402R, which can provide a stable current for the LED, and the LED driving current can be adjusted through an external adjustable resistor (20~60mA), so that the photodiode light-emitting circuit 2 emits light of constant intensity for measurement;

Photodiode light-emitting circuit 2, the wavelengths of the light-emitting diodes are 450nm (measurement of carotene), 490nm (measurement of lutein), 650nm (measurement of chlorophyll a), 680nm (measurement of chlorophyll b), 940nm, 1450nm (measurement of water);

Filter 18: a narrow-band interference filter is used, wherein the central wavelength of the red filter is 670nm, and the central wavelength of the near-infrared filter is 780nm;

Blade clamping and measuring structure 3: Made of aluminum alloy, light and strong. When measuring the chlorophyll content, put the leaves into the leaf clip; when measuring the water content, put the detector probe close to the leaves; when measuring the NDVI value, make the bottom of the detector parallel to the vegetation and the top point at the sunlight;

Photoelectric conversion circuit 4: use the special-purpose chip OPT301 device of Burr-Brown Company in the United States, which is a photoelectric integrated device integrating photodiode and current/voltage conversion amplifier. The current/voltage conversion amplifier is composed of a precision FET input operational amplifier and an on-chip metal film resistor;

Single-chip microcomputer control circuit 8: 8-bit single-chip microcomputer using AVR, ATmega128 is a single-chip microcomputer with the highest configuration of the 8-bit series single-chip microcomputer of ATMEL company, and it is widely used. The AVR microcontroller is embedded with high-quality Flash program memory, which is easy to erase and write, supports ISP and IAP, and is convenient for product debugging, development, production, and updating. The built-in long-life EEPROM can save key data for a long time to avoid loss when power is off. The large-capacity RAM on-chip can not only meet the needs of general occasions, but also more effectively support the use of high-level language to develop system programs, and can expand the external RAM like MCS-51 single-chip microcomputer. AVR Studio is an integrated environment assembly-level development and debugging software for ATMEL's AVR single-chip microcomputer, which is completely free. ATMEL AVR Studio integrated development environment (IDE), including AVR Assembler compiler, AVR Studio debugging function, download function and JTAG ICE emulation and other functions;

Undervoltage alarm circuit 10: The instrument uses a polymer lithium battery, but many modules in the instrument consume more power, such as a 4-line liquid crystal. Add this module, when the battery voltage drops, remind the user that the battery needs to be charged more. Two ways including buzzer sound and LCD12864 display reminder are adopted;

Data storage circuit 9: adopt AT series memory chip. Considering that the data storage capacity of the single-chip microcomputer is small, a memory chip 24LC64 is connected externally. The chip uses low-power CMOS technology to reduce power consumption. The chip has a 2-wire serial interface bus, compatible with I2C bus. The chip can be erased and written up to 1,000,000 times, the data can be stored for more than 200 years, the electrostatic protection voltage is greater than 4000V, and the working temperature is -40°C to 85°C.

Control button 12: realize data collection, deletion, display, calculation, storage and data display control, and the results can be seen through the LCD module;

Liquid crystal display circuit 11: JGD12864R Chinese character graphics dot matrix liquid crystal display module is adopted, and its screen is composed of 64 (rows) * 128 (columns) dot matrix, which can display 4 rows * 8 columns (32) Chinese characters or 128 * 16 dot matrix 64 full screen dot matrix graphics. Built-in 8192 Chinese characters (16X16 dot matrix), 128 characters (8X16 dot matrix) and 64X256 dot matrix display RAM (GDRAM);

Time and date circuit: In order to record the time and date at the same time as recording the measured value, it is convenient to analyze the data in the future, and the time and date module is added. The clock chip adopts an industrial-grade multi-function clock/calendar chip PCF8563 with extremely low power consumption and an I2C bus interface function launched by PHILIPS. Various alarm functions, timer functions, clock output functions and interrupt output functions of PCF8563 can complete various complex timing services, and even provide watchdog functions for single-chip microcomputers. The internal clock circuit, internal oscillation circuit, internal low voltage detection circuit (1.0V) and two-wire I2C bus communication mode not only make the peripheral circuit extremely simple, but also increase the reliability of the chip. PCF8563 is a clock chip with high cost performance. It has been widely used in product fields such as electric meters, water meters, gas meters, telephones, fax machines, portable instruments and battery-powered instruments. Adding the time and date module can conveniently record the time and date of the measurement, increase the practicability of the instrument, and is very convenient in actual use;

Temperature and humidity sensor circuit 6: Temperature and humidity integrated chip SHT×× series of Swiss Scnsirion company: it integrates the functions of temperature sensing, humidity sensing, signal conversion, A/D conversion and heater into one chip; provides two-wire digital Serial interface SCK and DATA, simple interface, support CRC transmission verification, high transmission reliability; after measurement and communication, it will automatically switch to low power consumption mode; high measurement accuracy, can provide temperature compensated humidity measurement value and high Mass dew point calculation function;

Computer and RS232 communication interface and download circuit 13: This module mainly realizes that the data measured outdoors is sent to the computer, and the stored data is analyzed and the corresponding curve is drawn through the LabVIEW host computer program.

The invention adopts the semiconductor luminous tube as the light emission source, the photoelectric sensor as the light receiving element, analyzes and processes the light intensity signal, obtains and compares it with the given one, and uses the comparison result to complete the relative chlorophyll content, moisture content and normalization of the analyzed leaf sample. The measurement of the NDVI value of the vegetation index and the measurement of the temperature and humidity of the environment is to use the temperature and humidity integrated sensor to collect the temperature and humidity, and directly process and read the value of the temperature and humidity through the single chip microcomputer, the system measurement is fast and accurate.

The device will be further described below.

The hardware is mainly composed of nine modules: core module, mainly including Atmega128 chip, reset, download interface, etc.; photoelectric conversion module, using the chip as OPT301 device; light-emitting circuit module: using the chip BCR402R as a constant current source for semiconductor light-emitting secondary dry Provide stable current; the power module is composed of polymer lithium battery and lithium battery charging management chip BQ24032; the data storage module uses the chip AT24C64, the size is 64KB; the temperature and humidity display module uses the SHT11 sensor chip; the clock display module uses the chip PCF8563; liquid crystal display module, the chip used is JGD12864R chip and undervoltage alarm circuit.

A fast method for measuring leaf chlorophyll content by photoelectric non-destructive testing method: chlorophyll absorption peaks are blue and red light regions, absorption troughs are in the green light region, and there is almost no absorption in the near-infrared region. Based on this, the red light region and near-infrared region are selected to measure chlorophyll. The specific process is to let the red light (peak wavelength at about 640nm and 650nm) and near-infrared light (peak at about 940nm) be emitted by the light-emitting diode. Chlorophyll a absorbs red light with a wavelength of 640nm, and chlorophyll b absorbs red light with a wavelength of 660nm, but does not absorb infrared light with a wavelength of 940nm. The emission and reception of infrared light with a wavelength of 940nm is mainly to eliminate the measurement of leaf thickness and other aspects. impact on the outcome. After the red light reaches the leaf, part of it is absorbed by the chlorophyll of the leaf, and the rest passes through the leaf and is converted into a corresponding electrical signal by the receiver, amplified by the amplifier, and then converted into a digital signal through the A/D conversion function of the single-chip microcomputer. The processor uses these digital signals to calculate the relative content of chlorophyll, which is expressed as the relative content unit of chlorophyll, displayed and stored automatically. The steps to calculate the relative content of chlorophyll are as follows:

In the standard state (no sample to be tested), the two light sources emit light sequentially and convert them into electrical signals to calculate the ratio of emitted light intensity.

After inserting the sample leaf, the two light sources emit light again, the transmitted light of the leaf is converted into an electrical signal, and the ratio of the transmitted light intensity is calculated.

Using the calculation results of the above two steps, use the following formula to calculate the relative content of chlorophyll a/b

$\mathrm{SPAD}={K\log }_{10}\left(\frac{{\mathrm{IR}}_t/{\mathrm{IR}}_0}{R_t/R_0}\right)$ (Formula 1)

Among them, K is a constant; IRt is the received 940nm infrared light intensity; IR0 is the emitted infrared light intensity; Rt is the received 640nm/660nm red light intensity; R0 is the emitted red light intensity.

The measurement method of lutein and carotene is similar to that of chlorophyll, only need to change the characteristic absorption wavelength, that is, the wavelength of the emitting diode. The characteristic absorption wavelength of lutein is 490nm, and the characteristic absorption wavelength of carotene is 450nm.

The water content of leaves is measured by the reflectance method: water has a reflection valley at 1450nm. When the water content of leaves increases, the reflection of incident light decreases, and the reflection on the reflection spectrum is that the valley will become deeper. When the water content of the leaves decreases, the absorption of water decreases and the reflection of incident light increases. The reflection on the reflection spectrum is that the trough will become shallower. The depth of the reflectance spectrum at 1450nm corresponds to the change of leaf moisture, and the regression model of spectral reflectance at 1450nm can be used to detect the leaf moisture content. When detecting reflected light, a Y-shaped light-guiding fiber is used, including an incident light port, a reflected light detection port, and a port for both illuminating and collecting reflected light. The incident end is connected to the light source (near-red light with a peak value of 1450nm), and the reflected light measurement end is connected to the photoelectric conversion device, which converts the reflected light through the photoelectric conversion device and outputs an electrical signal to the microcontroller, and obtains the final measurement result through processing. The steps to calculate leaf water content are as follows:

Align the whiteboard with the moisture measurement probe, press the moisture measurement button, and collect a reference spectrum.

Move the moisture measurement probe to the measured target, press the moisture measurement button, and the reflectance spectrum will be disabled.

Using the above two-step measurement, the spectral absorption depth value h can be measured, and it can be calculated

Moisture content (%)=K×h+C (Formula 2)

Among them, K and C are constants, which can be obtained by the method of linear regression in mathematical statistics.

The method of measuring the NDVI value of the normalized difference vegetation index: using sunlight as the light source, through 4 photoelectric converters with pre-filters, in the two characteristic bands of near-infrared and red light, respectively for the incident light of the sun and the reflected light of vegetation Carry out the measurement, measure the radiation intensity of the incident light of the sun and the reflected light of the vegetation in two bands, and then process it by the single-chip microcomputer to obtain the NDVI value. If the instrument measures the incident light signal in the red characteristic band as Esr, the vegetation reflected light signal in the corresponding band is Err; the incident light signal in the near infrared characteristic band is Esn, and the vegetation reflected light signal in the corresponding band is Ern, then:

$R_r=k_r\frac{{\mathrm{E.}}_{\mathrm{rr}}}{{\mathrm{E.}}_{\mathrm{sr}}};R_{\mathrm{no}}=k_{\mathrm{no}}\frac{{\mathrm{E.}}_{\mathrm{rn}}}{{\mathrm{E.}}_{\mathrm{sn}}}$ (Formula 3)

In the formula: kr and kn are proportional constants, which are determined by the optical system of the instrument and the characteristic parameters of the photoelectric converter. With Rr and Rn, the NDVI value can be calculated:

NDVI=( _Rn - _Rr )/( _Rn + _Rr )

Compared with the prior art, the present invention has the following advantages:

The LED light source circuit adopts a constant current source as the power supply, which ensures the constant light intensity of the light source, so that the subsequent measurement of the relative content of chlorophyll is accurate;

Light-guiding optical fiber is used for moisture measurement, and the power loss and attenuation of optical fiber are small, which ensures the accuracy of measurement.

Compared with the commonly used surface object spectrometer, the NDVI measurement equipment has simple structure, small weight, low cost, simple operation and more practicality.

Integrating chlorophyll, moisture, NDVI, temperature and humidity measurement into one, new and practical, easy to carry.

LabVIEW upper computer data processing program can draw curves of measured numbers, assist users in data analysis, simplify manual workload, and have a high degree of intelligence.

The basic principles and main features of the present utility model and the advantages of the present utility model have been shown and described above. Those skilled in the art should understand that the utility model is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions only illustrate the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model The new model also has various changes and improvements, and these changes and improvements all fall within the scope of the claimed utility model. The scope of protection required by the utility model is defined by the appended claims and their equivalents.

Claims (4)

1. The plant leaf array LED infrared spectrum detector is characterized in that it comprises: A power module, the power module includes a lithium battery, a charging module connected to the lithium battery, and a battery boost circuit connected to the output end of the lithium battery; A constant current source circuit, the two ends of which are respectively connected to the output end of the power module and the input end of the photodiode light-emitting circuit, for providing stable current to the photodiode light-emitting circuit; A photodiode light-emitting circuit for emitting light of several wavelengths; The blade clamping and measuring mechanism includes a blade clamping mechanism and a probe, and the blade clamping mechanism is facing the light-emitting part of the photodiode light-emitting circuit, and is used for fixing and measuring the blade; The single-chip microcomputer control circuit is provided with a number of ports, which are respectively connected with a sensor circuit for detecting temperature and humidity, a liquid crystal display circuit for data display, a data storage circuit for data storage, and a time and date circuit for time recording. The undervoltage alarm circuit of the power module voltage is used for the computer of data transmission, processing and downloading; The photoelectric conversion circuit is connected with the single-chip microcomputer control circuit, and is used for converting the light passing through the blade into a circuit signal and sending it to the single-chip microcomputer control circuit. 2. The plant leaf array LED infrared spectrum detector according to claim 1, wherein the wavelength of light emitted by the photodiode light-emitting circuit comprises 450nm, 490nm, 650nm, 680nm, 940nm and 1450nm. 3. The plant blade array LED infrared spectrum detector according to claim 1, characterized in that, the blade clamping and measuring structure is provided with a Y-shaped optical fiber for reflecting the optical path and measuring the moisture content. 4. The plant leaf array LED infrared spectrum detector according to claim 1, wherein the computer is provided with an RS232 communication interface.

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