CN101334359A - Portable plant nutrient ingredient damage-free measuring apparatus and method - Google Patents

Abstract

The invention discloses a portable lossless measuring device of plant nutrient components and a measuring method thereof; the measuring device comprises a monochromatic source, a photoelectric detector, a light source driving circuit, a signal conditioning circuit and a microcontroller system, and the monochromatic source and the photoelectric detector form an integral vane gripper that is respectively connected with the light source driving circuit and the signal conditioning circuit through electric cables, thus not only reducing light energy loss and raising signal-to-noise ratio, but also simplifying the measuring device and leading the sampling of the gripper to be flexible and convenient; the light source driving circuit mainly comprises a voltage regulating chip, a sampling resistance, a triode and an analog switch and realizes constant-current driving of the monochromatic source and programmed adjustment of current value, thus not only improving light source stability, but also effectively solving the saturation problem of the photoelectric detector, leading the photoelectric detector to work in the best detection range, increasing the signal-to-noise ratio and raising measuring precision; furthermore, the measuring device has additional measurement and deduction of dark noise in the measuring process, thus improving the measuring precision of the plant nutrient components.

Description

A kind of portable plant nutrient ingredient damage-free measuring apparatus and method

Technical field

The invention belongs to agriculture and forestry detection technique field, relate to the measurement of nitrogen and moisture in a kind of portable plant nutrient ingredient damage-free measuring apparatus and the method, particularly plant leaf blade.

Background technology

Nutrient content of plant is the important evidence of diagnosis of plant upgrowth situation and nutriment supply situation.The nutrient content of plant Non-Destructive Testing can be applicable to the evaluation of plant growing way, accurately water and fertilizer management, breed of variety and screening etc., and is significant for accurate agriculture and forestry.Nitrogen is providing important support for photosynthesis of plant and ecosystem yield-power, is a kind of important nutrient of plant, monitors the content of nitrogen in real time, can accurately apply fertilizer, and promotes the plant growth, helps reducing environmental pollution.Water is not only the plasmic important component of vegetable cell, and be the reactive material of plant intracellular metabolite process and plant solvent to absorption of nutrient ingredients and transportation, monitoring plant water regime promptly and accurately, significant to improving farm-forestry crop water management level and water use efficiency and conserve water resource.

That spectroscopy measurements plant leaf blade nutritional labeling has is harmless, quick, multicomponent detects simultaneously, simple operation and other advantages.Device to each biochemical parameter nondestructive measurement of plant leaf blade also has report at present, and owing to the numerous advantage of spectrographic technique, obtains people and more and more pay attention to.

Chinese invention patent CN1293379C discloses the system and method for a kind of portable Non-Destructive Testing field plant pigment, and this patent has proposed the measurement to chlorophyll concentration, and photoelectric detector saturation problem when adopting neutral reference to solve the measurement incident light.But the increase of neutral reference makes the structure of measurement mechanism and operation become complicated, and blade fixture and the fixing feasible sampling of the mode difficulty increase of casing.

Chinese invention patent CN1865926A, a kind of portable plant blade pigment pick-up unit is disclosed, measuring method to Chlorophylls and Carotenoids has been proposed, but the blade fixture of this device adopts the optical fiber connected mode, not only increased the complexity of device optical system, and optical fiber meeting loss part luminous energy, optical fiber fractures easily simultaneously, and operation is made troubles to device.

In addition and since in photoelectric detection system photodetector and electron device this after energising, have noises such as dark current, thermonoise, the dark noise in the measuring-signal is brought certain error to the measurement of plant component content.

Summary of the invention

The purpose of this invention is to provide a kind of portable plant nutrient ingredient damage-free measuring apparatus and method, problem at above-mentioned existence, the present invention has designed integrated blade fixture and program-controlled light source constant-current drive circuit, while has increased the measurement of dark noise and has reduced in measuring method, measurement mechanism has not only been simplified in these measures, make flexible operation simple, and improved measuring accuracy effectively.

The present invention is achieved in that

Portable plant nutrient ingredient damage-free measuring apparatus of the present invention comprises monochromatic source, photodetector, light source driving circuit, signal conditioning circuit and micro control system.

Be installed on to described monochromatic source and photoelectric probe position relative fixed the upper arm and the underarm inside of blade fixture, form integrated blade fixture, this integrated blade fixture directly is not fixed on the measurement mechanism main frame, but monochromatic source is linked to each other the hand-holdable independent operation of this integrated blade fixture respectively by cable with signal conditioning circuit with light source driving circuit with photodetector.

Described light source driving circuit can be realized the constant-current driving to monochromatic source.This light source driving circuit is realized the stable of drive current by the Voltage Feedback principle, and its circuit structure mainly comprises voltage stabilizing chip, sampling resistor, triode and analog switch.Voltage stabilizing chip with Voltage Feedback function feeds back by real-time voltage to the sampling resistor two ends, and the output voltage of corresponding adjusting voltage stabilizing chip utilizes the smooth output characteristics of triode simultaneously, has guaranteed the stable of output current.This light source driving circuit can also carry out program control selection to drive current at different measurement situations.Therefore the break-make of each passage of Digital Signals analog switch, each passage all connect a sampling resistor, and the resistance of these sampling resistors has nothing in common with each other, and realize program control adjusting to driving current value by the selection to different passages.

Described portable plant nutrient ingredient damage-free measuring apparatus comprises 3 monochromatic sources, and monochromatic source can be light emitting diode or laser diode.Output wavelength is respectively λ ₁=510～530nm, λ ₂=870～910nm and λ ₃=960～990nm.Wherein, λ ₁And λ ₃As measuring wavelength; λ ₂As reference wavelength.

Described photodetector can be photodiode, photoelectric cell or photomultiplier, can realize the detection to light in 400～1000nm scope.

Described signal conditioning circuit converts voltage signal (I/V conversion) to the current signal of photodetector, is met the analog voltage signal of A/D converter input range requirement.

Described micro control system mainly is made up of microcontroller, A/D converter, data memory module, supervisory circuit, serial communication circuit, clock circuit, LCD display, keyboard and power supply chip.Described microcontroller is the core devices of micro control system, and it has not only realized control, data processing to other functional module, and the control light source driving circuit realizes that light source is luminous in turn; A/D converter is converted to digital signal with analog voltage signal; Data memory module is used for the data and the result of storage of collected; Supervisory circuit is used for the supply voltage of microcontroller is monitored, and can realize the hand-reset function simultaneously; Serial communication circuit is realized the data transmission of this measurement mechanism and host computer; Clock circuit provides correct time for this measurement mechanism; LCD display is used for display result and prompting user operation; Keyboard is used for the selection of each function; Power supply chip provides stable voltage for this device.

Use above-mentioned measurement mechanism and carry out the measurement of plant leaf blade nutritional labeling, realize by following steps:

(1) opening power is kept closed integrated blade fixture, and the microprocessor controls A/D converter is gathered the analog voltage signal by signal conditioning circuit output, and the digital signal that obtains after the conversion is designated as dark noise magnitude of voltage V _DARK

(2) still make blade fixture be in closure state, 3 monochromatic sources of microprocessor controls are luminous in turn, and the direct irradiation photodetector is called reference light.Photodetector changes into electric signal with detected light signal, obtains analog voltage signal through signal conditioning circuit, after the A/D conversion, obtains 3 wavelength corresponding reference signal voltage value V respectively _R(λ ₁), V _R(λ ₂) and V _R(λ ₃);

(3) open integrated blade fixture, put tested blade, the anchor clamps that close, 3 monochromatic sources of microprocessor controls are luminous in turn, and the illumination that sees through blade is mapped on the photodetector, is called measuring light.Photodetector changes into electric signal with detected light signal, obtains analog voltage signal through signal conditioning circuit, after the A/D conversion, obtains the measurement signal voltages value V of 3 wavelength correspondences respectively _M(λ ₁), V _M(λ ₂) and V _M(λ ₃);

(4) calculate the content of plant leaf blade moisture and nitrogen according to following formula:

Different Nitrogen Concentration is C _N:

$C_N=b_{n0}+a_{n1}[\ln \left(\frac{V_M\left({\mathrm{\λ}}_1\right)-V_{\mathrm{DARK}}}{V_R\left({\mathrm{\λ}}_1\right)-V_{\mathrm{DARK}}}\right)-\ln \left(\frac{V_M\left({\mathrm{\λ}}_2\right)-V_{\mathrm{DARK}}}{V_R\left({\mathrm{\λ}}_2\right)-V_{\mathrm{DARK}}}\right)]$

Moisture concentration is C _W:

$C_W=b_{w0}+a_{w1}[\ln \left(\frac{V_M\left({\mathrm{\λ}}_3\right)-V_{\mathrm{DARK}}}{v_R\left({\mathrm{\λ}}_3\right)-V_{\mathrm{DARK}}}\right)-\ln \left(\frac{V_M\left({\mathrm{\λ}}_2\right)-V_{\mathrm{DARK}}}{V_R\left({\mathrm{\λ}}_2\right)-V_{\mathrm{DARK}}}\right)]$

B wherein _N0, a _N1, b _W0, a _W1Be coefficient.

The invention has the advantages that:

(1) blade fixture adopts the integrated design that light source and photodetector are integrated, anchor clamps are provided with device main frame separate type, anchor clamps directly are not fixed on the device main frame, but realize in the anchor clamps being connected respectively of light source driving circuit and signal conditioning circuit in the light source and photodetector and device main frame by cable, not only can reduce the loss of luminous energy, improve signal to noise ratio (S/N ratio), and simplified measurement mechanism effectively, make the anchor clamps sampling more flexible, be particularly suited for blade in particular cases such as small space or irregular space and measure.

(2) the light source constant-current drive circuit can be selected different current drives light sources, not only increased light source stability, and solved the saturated problem of photodetector effectively, photodetector is operated in the optimum detection scope, increase signal to noise ratio (S/N ratio), improved measuring accuracy.

(3) increased measurement in the measuring method of the present invention, from measuring-signal and reference signal, deducted the influence of dark noise when calculating nutritional labeling, improved measuring accuracy effectively dark noise.

Description of drawings

Fig. 1 is a measurement mechanism principle assumption diagram of the present invention;

Fig. 2 is integrated blade fixture structural representation;

Fig. 3 is the light source driving circuit schematic diagram;

Fig. 4 is the signal conditioning circuit schematic diagram.

Embodiment

Now in conjunction with the accompanying drawings, the embodiment of plant leaf blade nutritional labeling damage-free measuring apparatus of the present invention is done detailed introduction.

Plant leaf blade nutritional labeling damage-free measuring apparatus of the present invention mainly comprises following a few part: monochromatic source 1, photodetector 2, light source driving circuit 3, signal conditioning circuit 4 and micro control system 5.As shown in Figure 1, the monochromatic source 1 that is connected with light source driving circuit 3 of described micro control system 5 controls is taken turns luminous and received signal and is nursed one's health the analog voltage signal of circuit 4.This micro control system 5 mainly is made up of microcontroller 501, A/D converter 502, data memory module 503, supervisory circuit 504, serial communication circuit 505, clock circuit 506, LCD display 507, keyboard 508 and power supply chip 509.Can realize the functions such as data transmission, record acquisition time, demonstration as a result, function selecting and system reset between control, data acquisition, data processing, data storage, microcontroller 501 and the host computer to light source.Power supply chip 509 is by battery 510 power supplies, for whole damage-free measuring apparatus provides stable power voltage.

It is the single-chip microcomputer of MSP430F427 that described microcontroller 501 is selected model, and this single-chip microcomputer inside has the ADC16 module, can realize 16 A/D conversion, and A/D converter 502 is realized obtaining digital signal to characterizing the analog voltage signal collection of intensity signal; For the storage to a large amount of image data, damage-free measuring apparatus of the present invention has been expanded data memory module 503 to micro control system 5, and model is 24LC256, is used for the data and the data processed result of storage of collected.Supervisory circuit 504 chips are selected TPS3823-33, are used for the supply voltage of microcontroller 501 is monitored, and can realize hand-reset and watchdog function simultaneously.Serial communication circuit 505 chips are selected MAX232, realize the data transmission of microcontroller 501 in host computer and the micro control system 5.LCD display 507 is selected LCM12232, and the LCD MODULE of this model display is low in energy consumption, is connected with the general I/O interface of microcontroller 501, and LCD display 507 is used for the information of display result and prompting user operation.Described keyboard 508 is provided with 6 function selecting buttons, controls respectively dark noise voltage V _DARK, reference signal voltage V _RMeasurement, measurement signal voltages V _MMeasurement, display result and adjustment time.Owing to measure V _DARKAnd V _RThe time, blade fixture all is in closure state, so this device is realized V by a button _DARKAnd V _R Measurement.Clock circuit 506 chips are selected DS1302, and for micro control system 5 provides precise time, the backup battery of described clock circuit 506 chips adopts button cell CR2026.

Light source driving circuit 3 among Fig. 1, signal conditioning circuit 4 and control system 5 constitute the main frame of this measurement mechanism, and monochromatic source 1 and photodetector 2 constitute integrated blade fixture 6, and integrated blade fixture 6 and main frame are separated from each other, and link to each other by cable.Integrated blade fixture 6 is used for the leaf nutrition component content is measured, and the structure of integrated blade fixture as shown in Figure 2.Described monochromatic source 1 and photodetector 2 are installed in the upper arm 601 and underarm 602 inside of described integrated blade fixture 6 respectively, wherein monochromatic source 1 is connected with light source driving circuit 3 by cable 603, and photodetector 2 is connected with signal conditioning circuit 4 by cable 604.When measuring, integrated blade fixture 6 is not subjected to the position limit of measurement mechanism main frame, and operating personnel can hand the measurement that this integrated blade fixture 6 is realized plant leaf blade 7.

Monochromatic source 1 is selected light emitting diode (LED), and LED has stability and monochromaticity preferably, and LED full width at half maximum (FWHM) is 20～40nm usually, in the satisfied requirement to light source of plant parameter fields of measurement.LED is low in energy consumption, and running current is generally 20～50mA, is suitable for application portable, the powered battery instrument.3 LED wavelength that this device is selected are respectively λ ₁=510～530nm, λ ₂=870～910nm and λ ₃=960～990nm, wherein, λ ₁And λ ₃As measuring wavelength; λ ₂As reference wavelength.

Photodetector 2 is selected silicon photoelectric diode, and model is S1133-14, and the response wave length scope of this photodetector 2 is 320～1000nm, and dark current is 20pA.

As shown in Figure 3, described light source driving circuit 3 designs at damage-free measuring apparatus of the present invention, and its circuit structure mainly is made up of voltage stabilizing chip U3, triode Q1, analog switch U1, U2 and sampling resistor R1, R2, R3, R4.Voltage stabilizing chip U3 is superhigh precision, ultra-low noise, series-type voltage benchmark MAX6126 among the figure, and output voltage is 2.048 volts, and internal accuracy can reach 0.02%, constitutes constant-current circuit with triode Q1, realizes the constant-current driving to LED.The OUTF pin of voltage stabilizing chip U3 links to each other with the base stage of triode Q1, the OUTS pin links to each other with the emitter of triode Q1, the OUTS pin can be monitored the sampling resistor both end voltage in real time, feed back to U3 again, U3 regulates the output voltage of OUTF pin according to feedback, thereby the voltage at sampling resistor two ends is remained unchanged.Analog switch U1 (MAX4066) realizes that by Digital Signals 3 LED are luminous in turn.Analog switch U2 (ADG712) realizes the selection of drive current.The positive pole of 3 LED connects+voltage of 5V, and wavelength is λ ₁The negative pole of LED link to each other λ with the COM1 pin of U1 ₂And λ ₃LED links to each other with the COM3 pin with the COM2 pin of U1 respectively.The NO1 pin of U1, NO2 pin, NO3 pin link to each other with the collector of triode Q1.The IN1 pin of U1, IN2 pin, IN3 pin link to each other with pin P1.0, P1.1, the P1.2 of microcontroller 501 respectively, realize the control of 501 couples of analog switch U1 of microcontroller.Microcontroller 501 can be realized the break-make of led light source switch by control analog switch U1, and it is luminous in turn to control three LED.The end of sampling resistor R1, R2, R3 and R4 all links to each other with the emitter of Q1, and the other end links to each other with S1 pin, S2 pin, S3 pin and the S4 pin of U2 respectively, and D1 pin, D2 pin, D3 pin and D4 pin link to each other with ground.Pin S1 and D1 pin can be realized break-make, and pin S2 and D2 pin can be realized break-make, and S3 pin and D3 pin can be realized break-make, and S4 pin and D4 pin can be realized break-make.The IN1 pin of U2, IN2 pin, IN3 pin and IN4 pin link to each other with pin P1.3, P1.4, P1.5 and the P1.6 of microcontroller 501 respectively, realize the selection to each passage.By selecting each passage, can make different sampling resistor R1, R2, R3 and R4 be in conducting state, thus the size of current of control monochromatic source 1.The resistance of described sampling resistor R1, R2, R3 and R4 has nothing in common with each other.

Because the needs of damage-free measuring apparatus of the present invention need be measured dark noise magnitude of voltage V to the measurement of blade nitrogen and water _DARK, the reference signal voltage value V during LED direct irradiation photodetector 2 _RWith the measurement signal voltages value V that puts behind the blade _MFound through experiments, after the relative position of monochromatic source 1 and photodetector 2 is determined (is example with an example in the experimentation), when photodetector 2 directly detects the light time that LED sends, the V that photodetector 2 records _RCan reach 3～4V, V _DARKGenerally between 3～5mV, (can ignore) V _MBe 500mV to the maximum, minimum is 75mV.V _MSize very big relation is arranged with blade, when blade was relatively more yellow, the nitrogen that contains was fewer, V at this moment _MJust big, when blade is greener, illustrate that the nitrogen that contains is more relatively, V at this moment _MJust littler.From top data as can be seen, these three V parameter that will record _DARK, V _RAnd V _MDiffer bigger.Because 3 LED are to blade penetration capacity difference, and adopt identical current drives, these 3 LED light intensities are also inequality, this device photodetector 2 and signal conditioning circuit 4 employing+5V power supply, the maximum voltage that also can only collect about 4V, in order to make photodetector 2 detected signals remain on the optimum detection scope, so, need adopt different drive currents satisfy measurement requirement at 3 LED and the different measurement situations in this system.At this situation, light source driving circuit 3 adopts analog switch U2 (ADG712), selects by the break-make of exchanging economize on electricity resistance R1～R4, adopts different electric currents to drive to different LED.

Described light source driving circuit 3 has not only avoided because photodetector 2 saturated phenomenons that light source luminescent causes too by force, and makes the photodetector 2 detected light remain on its best sensing range by changing drive current, thereby measuring accuracy is improved.Adopt different current drives at Different Light when measuring the Different Nutrition composition, measure V _MShi Guangqiang a little less than, the drive current of the corresponding increase light source of break-make by regulating resistance R 1～R4 at this moment, light intensity can increase, detected like this Signal-to-Noise is improved.

Described signal conditioning circuit 4 mainly is made up of digital regulation resistance U5 (MAX5420), operational amplifier U6 (MAX4239), U7 (MAX4239) and U8 (MAX4239), as Fig. 4.D1 among the figure is a silicon photoelectric diode, the light signal that photodetector 2 receives converts electric current to, obtain voltage signal through the I/V change-over circuit then, voltage signal amplifies through operational amplifier U6, digital regulation resistance U5 and operational amplifier U7 are built into second amplifying circuit, U8 realizes voltage follower, is used to reduce the mutual interference mutually of digital circuit and mimic channel.The size of resistance R 5 has determined the detectability of signal conditioning circuit 4, and under the constant situation of irradiates light, the value of resistance R 5 is big more, and the voltage of I/V conversion is big more, and in like manner, the value of resistance R 5 is more little, and the voltage that I/V obtains is more little.Capacitor C 3 is used to eliminate noise, and resistance R 6 and capacitor C 4 realize low-pass filtering.The D0 pin of digital regulation resistance U5 links to each other with the P2.2 pin with the P2.1 of microcontroller 501 respectively with the D1 pin, and by the enlargement factor of the Digital Signals U5 of microcontroller 501 output, U5 can realize 1,2,4, the amplification of 8 four kind of multiple.

The supply voltage of described signal conditioning circuit 4 is+5V, the supply voltage of microcontroller 501 is 3.3V, whole damage-free measuring apparatus of the present invention is by 510 power supplies of 9V battery, use+5V and+two kinds of voltages of 3.3V, select corresponding power supply chip 509, voltage stabilizing chip REG1117A output is fixed+5V voltage, has the 1A driving force, voltage stabilizing chip TPS79533 output is fixed+3.3V voltage, has the driving force of 500mA.

In order to reduce the dark noise of photodetector in the damage-free measuring apparatus of the present invention 2 and each electron device as far as possible, carrying out gathering the influence V of dark noise earlier when the plant leaf blade nutritional labeling is measured to photodetector 2 _DARK, gather the output voltage values of reference light and measuring light correspondence then respectively, the corresponding output voltage values of reference light and measuring light deducts V respectively in the computation process in that nutritional labeling is carried out _DARKThereby, eliminated the influence of dark noise to measuring accuracy.

Use damage-free measuring apparatus of the present invention the plant leaf blade nutritional labeling is carried out nondestructive measurement, concrete measuring process is:

(1) opening power is kept closed integrated blade fixture 6, and the analog switch U1 in the microcontroller 501 control light source driving circuits 3 is in 3 led light sources to extinguish state.The analog voltage signal of microcontroller 501 control A/D converters 502 acquired signal modulate circuits 4 outputs is designated as dark noise magnitude of voltage V with the digital signal that obtains _DARK

(2) still make integrated blade fixture 6 be in closure state, the analog switch U1 in the microcontroller 501 control light source driving circuits 3 makes 3 led light sources luminous in turn, and direct irradiation photodetector 2 is called reference light.Gather the reference signal voltage value V of 3 led light source corresponding wavelength _R(λ ₁), V _R(λ ₂) and V _R(λ ₃).

Specific implementation is: at first, control analog switch U1 makes λ ₁LED is luminous, and other 2 LED extinguish, simultaneously, the 1st passage conducting of control U2, promptly sampling resistor R1 and U2 and triode Q1 constitute path, and other 3 resistance are in off-state, and sampling resistor R1 has at this moment determined the size of current of this light source driving circuit 3.

Then, control analog switch U1 makes λ ₂LED is luminous, and other 2 LED extinguish, simultaneously, the 2nd passage conducting of control U2, promptly sampling resistor R2 and U2 and triode Q1 constitute path, and other three resistance are in off-state, and sampling resistor R2 has at this moment determined the size of current of this light source driving circuit 3.Then, control λ ₃LED is luminous, and two other extinguishes, and the break-make situation of U2 remains unchanged.

(3) open integrated blade fixture 6, put measured leaf 7, the integrated blade fixture 6 that closes, 3 led light sources of microcontroller 501 controls are luminous in turn, and the illumination that sees through plant leaf blade 7 is mapped on the photodetector 2, is called measuring light.Gather the measurement signal voltages value V of 3 led light source corresponding wavelength _M(λ ₁), V _M(λ ₂) and V _M(λ ₃).

Specific implementation is: control U1 makes 3 led light sources luminous in turn, and micro control system 5 collects measurement signal voltages value V _M(λ ₁), V _M(λ ₂) and V _M(λ ₃).This process and previous step rapid (2) are basic identical, just the sampling resistor difference of each LED correspondence at this moment.λ ₁The corresponding sampling resistor R3 of LED, when promptly the LED of this wavelength is in luminance, sampling resistor R3 conducting; λ ₂And λ ₃The corresponding sampling resistor R4 of LED, when promptly the LED of these two wavelength is in luminance, sampling resistor R4 conducting.

After each measuring process was finished, microcontroller 501 control analog switch U1, U2 were in off-state.

(4) according to linear regression calculated with mathematical model plant leaf blade nutritional labeling concentration.

Because the existence of dark noise makes measuring-signal and reference signal have deviation, thereby can have influence on the plant nutrient ingredient measuring accuracy, so deducts the concentration that dark noise is found the solution nutritional labeling in the plant leaf blade among the present invention from measuring-signal and reference signal.The computing formula of nitrogen and moisture is as follows in the plant leaf blade:

Different Nitrogen Concentration is C _N:

$C_N=b_{n0}+a_{n1}[\ln \left(\frac{V_M\left({\mathrm{\λ}}_1\right)-V_{\mathrm{DARK}}}{V_R\left({\mathrm{\λ}}_1\right)-V_{\mathrm{DARK}}}\right)-\ln \left(\frac{V_M\left({\mathrm{\λ}}_2\right)-V_{\mathrm{DARK}}}{V_R\left({\mathrm{\λ}}_2\right)-V_{\mathrm{DARK}}}\right)]$

Moisture concentration is C _W:

$C_W=b_{w0}+a_{w1}[\ln \left(\frac{V_M\left({\mathrm{\λ}}_3\right)-V_{\mathrm{DARK}}}{v_R\left({\mathrm{\λ}}_3\right)-V_{\mathrm{DARK}}}\right)-\ln \left(\frac{V_M\left({\mathrm{\λ}}_2\right)-V_{\mathrm{DARK}}}{V_R\left({\mathrm{\λ}}_2\right)-V_{\mathrm{DARK}}}\right)]$

B wherein _N0, a _N1, b _W0, a _W1Be coefficient.

From last two formulas as can be seen, because when calculating nitrogen and moisture concentration, each reference signal and measuring-signal have all deducted dark noise, just having eliminated in the measurement mechanism photodetector and electron device dark noise therefore uses measuring method provided by the invention and measurement mechanism and can obtain accurate more plant leaf blade parameter concentration value the influence of measuring accuracy.

Claims (5)

1, a kind of portable plant nutrient ingredient damage-free measuring apparatus comprises monochromatic source (1), photodetector (2), light source driving circuit (3), signal conditioning circuit (4) and micro control system (5), it is characterized in that:

Described monochromatic source (1) is formed integrated blade fixture (6) with photodetector (2), wherein monochromatic source (1) and photodetector (2) are installed on the upper arm (601) and underarm (602) inside of integrated blade fixture (6) respectively, and monochromatic source (1) is connected with signal conditioning circuit (4) with light source driving circuit (3) by cable respectively with photodetector (2);

Described light source driving circuit (3) structure mainly comprises voltage stabilizing chip, sampling resistor, triode and analog switch; Voltage stabilizing chip, sampling resistor and triode constitute constant-current circuit, realize the constant-current driving to monochromatic source; Analog switch realizes that by Digital Signals monochromatic source takes turns luminous and by the selectivity break-make of sampling resistor being realized the program control adjusting of driving current value;

Described micro control system (5) is mainly by microcontroller (501), A/D converter (502), data memory module (503), supervisory circuit (504), serial communication circuit (505), clock circuit (506), LCD display (507), keyboard (508) and power supply chip (509) are formed, be used to realize the collection of data, data storage, the supply voltage monitoring, with functions such as the data transmission of host computer and demonstrations as a result, described microcontroller (501) is the core devices of micro control system (5), it has not only realized the control to other functional module, data processing, and control light source driving circuit (3) realizes that monochromatic source (1) is luminous in turn.

2, portable plant nutrient ingredient damage-free measuring apparatus according to claim 1 is characterized in that: described monochromatic source (1) is light emitting diode or laser diode.

3, portable plant nutrient ingredient damage-free measuring apparatus according to claim 1 is characterized in that: described photodetector (2) is photodiode, photoelectric cell or photomultiplier.

4, portable plant nutrient ingredient damage-free measuring apparatus according to claim 1 is characterized in that: described monochromatic source (1) comprises 3 LED monochromatic sources, and output wavelength is respectively λ ₁=510～530nm, λ ₂=870～910nm and λ ₃=960～990nm, wherein, λ ₁And λ ₃As measuring wavelength, λ ₂As reference wavelength.

5, application rights requires a kind of portable plant nutrient ingredient damage-free measuring method of 1 described measurement mechanism, it is characterized in that: may further comprise the steps:

(1) opening power is kept closed integrated blade fixture (6), and microcontroller (501) control A/D converter (502) is gathered the analog voltage signal by signal conditioning circuit (4) output, and the digital signal that obtains after the conversion is designated as dark noise magnitude of voltage V _DARK

(2) still make blade fixture be in closure state, microcontroller (501) 3 monochromatic sources of control (1) are luminous in turn, and direct irradiation photodetector (2) is called reference light; Photodetector (2) changes into electric signal with detected light signal, obtains analog voltage signal through signal conditioning circuit (4), after the A/D conversion, obtains 3 wavelength corresponding reference signal voltage value V respectively _R(λ ₁), V _R(λ ₂) and V _R(λ ₃);

(3) open integrated blade fixture (6), put tested blade (7), the anchor clamps that close, microcontroller (501) 3 monochromatic sources of control (1) are luminous in turn, and the illumination that sees through blade (7) is mapped on the photodetector (2), is called measuring light; Photodetector (2) changes into electric signal with detected light signal, obtains analog voltage signal through signal conditioning circuit (4), after the A/D conversion, obtains the measurement signal voltages value V of 3 wavelength correspondences respectively _M(λ ₁), V _M(λ ₂) and V _M(λ ₃);

(4) calculate the content of plant leaf blade moisture and nitrogen according to following formula:

Different Nitrogen Concentration is C _N:

$C_N=b_{n0}+a_{n1}[\ln \left(\frac{V_M\left({\mathrm{\λ}}_1\right)-V_{\mathrm{DARK}}}{V_R\left({\mathrm{\λ}}_1\right)-V_{\mathrm{DARK}}}\right)-\ln \left(\frac{V_M\left({\mathrm{\λ}}_2\right)-V_{\mathrm{DARK}}}{V_R\left({\mathrm{\λ}}_2\right)-V_{\mathrm{DARK}}}\right)]$

Moisture concentration is C _W:

$C_W=b_{w0}+a_{w1}[\ln \left(\frac{V_M\left({\mathrm{\λ}}_3\right)-V_{\mathrm{DARK}}}{V_R\left({\mathrm{\λ}}_3\right)-V_{\mathrm{DARK}}}\right)-\ln \left(\frac{V_M\left({\mathrm{\λ}}_2\right)-V_{\mathrm{DARK}}}{V_R\left({\mathrm{\λ}}_2\right)-V_{\mathrm{DARK}}}\right)]$

B wherein _N0, a _N1, b _W0, a _W1Be coefficient.

Images