Luminous intensity adjustment-based turbidity measurement method and system

Abstract

A luminous intensity adjustment-based turbidity measurement method and system. The turbidity measurement method comprises the steps: 1, by means of a transmitting circuit, a controller stimulates a multi-light-intensity LED to emit light, which is received by a photodiode after passing through a test solution and is then transmitted to the controller by means of a receiving circuit, and the controller processes data to obtain an S value; 2, by means of an I / O, the controller controls the luminous intensity of the multi-light-intensity LED so as to emit light of multiple light intensities, and two or more standard solutions are used to calibrate the light of multiple light intensities, thereby calibrating parameters for calculating the S value; and 3, a solution under test is tested and, during the testing process, the controller controls the multi-light-intensity LED to separately emit one of the light of multiple light intensities so as to measure the S value, compares the S value with the parameters calibrated in step 2, and adjusts the light intensity of the multi-light-intensity LED on the basis of a comparison result so as to measure the turbidity of the solution under test. The accuracy and stability of test results are improved.

Description

A turbidity testing method and system based on luminescence intensity adjustment Technical Field

[0001] This invention belongs to the field of turbidity testing technology, specifically relating to a turbidity testing method and system based on luminescence intensity adjustment. Background Technology

[0002] The 90-degree scattering method is a commonly used method for measuring the turbidity of solutions. This method is based on the scattering phenomenon described by the Lorentz-Boltzmann equation. It uses a photometer or spectrophotometer to measure the light intensity passing through the sample and the light intensity scattered by the sample at a 90-degree scattering direction, and calculates the turbidity of the sample based on the measurements. The scattering theorem used in this method is the Beer-Lambert Law. This theorem states that under the action of a plane wave with uniform radiation, the electro-optic response per unit length decreases exponentially with the length of the optical path, i.e., the classical Beer-Lambert law. In other words, light rays incident on particles suspended in a solution will undergo multiple scatterings, with some rays being scattered at 90-degree angles.

[0003] In this method, the measuring instrument calculates the ratio of the light intensity scattered at a 90-degree angle by solid particles in the suspension to the light intensity that passes through the sample but is not scattered. As the concentration of particles in the suspension increases, the intensity of scattered light also increases, and the ratio increases accordingly. Therefore, the magnitude of the ratio is directly proportional to the number of particles in the suspension. In practice, during measurement, a light source is introduced perpendicularly into the sample, and the sample is placed at a 90-degree scattering angle. A photometer or spectrophotometer measures the light intensity directly measured without passing through the sample, as well as the intensity of the light scattered at a 90-degree angle within the sample. Combining this with colorimetric calculations or photometric methods, the turbidity of the sample can be obtained. This method has high accuracy and is widely used in turbidity measurement in fields such as water, wastewater, food, medicine, and the environment.

[0004] However, existing turbidity testing equipment typically uses a fixed-intensity light source, which has limitations when measuring water samples with different turbidity levels. It cannot meet the special needs of high-turbidity or low-turbidity water samples, resulting in limited measurement accuracy and adaptability. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a turbidity testing method based on luminescence intensity adjustment, which improves the measurement accuracy and response speed, and also improves the accuracy and stability of the test results, in order to address the shortcomings of the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a turbidity testing method based on luminescence intensity adjustment, the method comprising the following steps:

[0007] Step 1: The controller excites LEDs of various light intensities to emit light through the transmitting circuit. After passing through the detection solution, the light is received by the photodiode and then transmitted to the controller through the receiving circuit. The controller processes the data to obtain the S value.

[0008] Step 2: The controller controls the luminous intensity of LEDs with multiple light intensities through I / O, emitting light of multiple intensities respectively, and uses two or more standard solutions to calibrate the light of multiple intensities, calibrating the parameters of S value calculated according to the Lambert-Beer formula y=kx+b;

[0009] Step 3: Test the solution to be tested. During the test, the controller controls the LEDs of multiple light intensities to emit one of the multiple light intensities, measures the S value, and compares the S value with the parameters calibrated in Step 2. Based on the comparison results, adjust the light intensity of the LEDs of multiple light intensities to test the turbidity of the solution to be tested.

[0010] The above-mentioned turbidity testing method based on luminous intensity adjustment includes a transmitting circuit comprising a DAC and a voltage-to-current conversion circuit, wherein the controller sequentially excites LEDs of multiple luminous intensities through the DAC and the voltage-to-current conversion circuit; the receiving circuit comprises a current-to-voltage conversion circuit and an AD collector, which is received by a photodiode and then transmitted to the controller sequentially through the current-to-voltage conversion circuit and the AD collector.

[0011] The turbidity testing method based on luminous intensity adjustment mentioned above includes low-intensity light, medium-intensity light and high-intensity light in steps two and three.

[0012] The above-mentioned turbidity testing method based on luminescence intensity adjustment is characterized in that: the specific method for calibrating low-intensity light, medium-intensity light, and high-intensity light using two standard solutions in step two, and determining the parameters for calculating the S value according to the Lambert-Beer formula y=kx+b, is as follows:

[0013] Step 201: Select two standard solutions with known turbidities of V1 and V2, where V1 < V2;

[0014] Step 202: Substitute V1 and V2 as values ​​of x into the Lambert-Beer formula y = kx + b to calculate the values ​​of k and b, where y represents the S value after signal processing. The parameter values ​​corresponding to the three intensities of light are then obtained as follows:

[0015] For low-intensity light, standard solution V1 corresponds to S11, k1, and b1; standard solution V2 corresponds to S12, k1, and b1.

[0016] For medium intensity light, standard solution V1 corresponds to S21, k2, and b2; standard solution V2 corresponds to S22, k2, and b2.

[0017] For high-intensity light, standard solution V1 corresponds to S31, k3, and b3; standard solution V2 corresponds to S32, k3, and b3.

[0018] The above-mentioned turbidity testing method based on luminous intensity adjustment involves step three, where the controller controls multiple LEDs to emit light of one of several intensities, measures the S-value, compares the S-value with the parameters calibrated in step two, and adjusts the light intensity of the multiple LEDs based on the comparison results. The specific method for testing the turbidity of the solution is as follows:

[0019] The controller controls multiple LEDs to emit medium-intensity light, and the measured S value is S23.

[0020] Compare S23 with S22;

[0021] When S23 > S22, it indicates that the turbidity of the solution to be tested is greater than that of the standard solution V2. The controller controls the LEDs of multiple light intensities to emit high-intensity light, retests the S value, and converts the S value into a turbidity value for display.

[0022] When S23 < S22, it indicates that the turbidity of the solution to be tested is less than that of the standard solution V2. The controller controls the LEDs of multiple light intensities to emit low-intensity light, retests the S value, and converts the S value into a turbidity value for display.

[0023] When S23 = S22, the controller does not adjust the level of the multi-level light intensity LED, but directly converts S23 into a turbidity value for display.

[0024] The present invention also discloses a turbidity testing system based on luminous intensity adjustment for implementing the above method, comprising a controller, a transmitting circuit connected to the controller and a multi-level luminous intensity LED connected to the transmitting circuit, a receiving circuit connected to the controller and a photodiode connected to the receiving circuit; the transmitting circuit includes a DAC and a voltage-to-current conversion circuit, and the receiving circuit includes a current-to-voltage conversion circuit and an AD acquisition unit.

[0025] The aforementioned turbidity testing system based on luminous intensity adjustment includes a voltage-to-current conversion circuit comprising an operational amplifier U1, a multiplexer analog switch U2, a multiplexer analog switch U3, a P-type transistor Q1, a P-type transistor Q2, and a P-type transistor Q3. The non-inverting input of operational amplifier U1 is connected to the power supply VCC via resistor R1 and grounded via resistor R2. The inverting input of operational amplifier U1 is connected to the multiplexer analog switch U3, and the output of operational amplifier U1 is connected to the multiplexer analog switch U2. Both multiplexer analog switches U2 and U3 are connected to the DAC of the controller. P-type transistors Q1 and Q3 are connected in parallel. After transistors Q2 and Q3, the sources of transistors Q1, Q2, and Q3 are connected to the inverting input of operational amplifier U1 via a multiplexer U3, and are simultaneously connected to multiple parallel resistors R6, R7, and R8. The drains of transistors Q1, Q2, and Q3 are connected to LEDs with varying light intensities. The gates of transistors Q1, Q2, and Q3 are connected to the output of operational amplifier U1 via a multiplexer U2, and are connected to the voltage VGOFF via resistors R3, R4, and R5, respectively.

[0026] The turbidity testing system based on luminous intensity adjustment described above is characterized in that the resistance values ​​of resistors R6, R7, and R8 are in the order R6>R7>R8.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. This invention improves measurement accuracy and response speed by dynamically adjusting the light source intensity to adapt to water samples with different turbidity levels, and also improves the accuracy and stability of test results.

[0029] 2. This invention can automatically adjust the intensity of the emitted light according to the turbidity value of the water sample, and can test not only low-turbidity water samples, but also high-turbidity water samples, thus improving the testing speed.

[0030] 3. This invention is not only applicable to laboratory environments, but also to on-site rapid testing and industrial process control, and has broad application prospects.

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0032] Figure 1 is a flowchart of the turbidity testing method based on luminescence intensity adjustment of the present invention;

[0033] Figure 2 is a schematic diagram of the turbidity testing system based on luminescence intensity adjustment according to the present invention;

[0034] Figure 3 is a circuit diagram of the voltage-current conversion circuit of the present invention. Detailed Implementation

[0035] Example 1

[0036] As shown in Figure 1, the turbidity testing method based on luminescence intensity adjustment in this embodiment includes the following steps:

[0037] Step 1: The controller excites LEDs of various light intensities through the transmitting circuit. After passing through the detection solution, the light is received by the photodiode and then transmitted to the controller through the receiving circuit. The controller processes the data to obtain the S value. The S value corresponds to the turbidity of the detection solution and can be converted into a turbidity value. The conversion method can be any existing conversion method.

[0038] Step 2: The controller controls the luminous intensity of LEDs with multiple light intensities through I / O, emitting light of multiple intensities respectively, and uses two or more standard solutions to calibrate the light of multiple intensities, calibrating the parameters of S value calculated according to the Lambert-Beer formula y=kx+b;

[0039] Step 3: Test the solution to be tested. During the test, the controller controls the LEDs of multiple light intensities to emit one of the multiple light intensities, measures the S value, and compares the S value with the parameters calibrated in Step 2. Based on the comparison results, adjust the light intensity of the LEDs of multiple light intensities to test the turbidity of the solution to be tested.

[0040] In this embodiment, the transmitting circuit includes a DAC and a voltage-to-current conversion circuit. The controller sequentially excites LEDs of multiple light intensities to emit light through the DAC and the voltage-to-current conversion circuit. The receiving circuit includes a current-to-voltage conversion circuit and an AD collector. The light is received by a photodiode and then transmitted to the controller sequentially through the current-to-voltage conversion circuit and the AD collector.

[0041] In this embodiment, the multi-intensity light mentioned in steps two and three includes low-intensity light, medium-intensity light, and high-intensity light.

[0042] In this embodiment, the specific method for calibrating low-intensity light, medium-intensity light, and high-intensity light using two standard solutions in step two, and determining the parameters for calculating the S value according to the Lambert-Beer formula y=kx+b, is as follows:

[0043] Step 201: Select two standard solutions with known turbidities of V1 and V2, where V1 < V2;

[0044] Step 202: Substitute V1 and V2 as values ​​of x into the Lambert-Beer formula y = kx + b to calculate the values ​​of k and b, where y represents the S value after signal processing. The parameter values ​​corresponding to the three intensities of light are then obtained as follows:

[0045] For low-intensity light, standard solution V1 corresponds to S11, k1, and b1; standard solution V2 corresponds to S12, k1, and b1.

[0046] For medium intensity light, standard solution V1 corresponds to S21, k2, and b2; standard solution V2 corresponds to S22, k2, and b2.

[0047] For high-intensity light, standard solution V1 corresponds to S31, k3, and b3; standard solution V2 corresponds to S32, k3, and b3.

[0048] In this embodiment, the controller in step three controls the LEDs of multiple light intensities to emit one of the multiple light intensities, measures the S value, compares the S value with the parameters calibrated in step two, and adjusts the light intensity of the LEDs of multiple light intensities based on the comparison results. The specific method for testing the turbidity of the solution to be tested is as follows:

[0049] The controller controls multiple LEDs to emit medium-intensity light, and the measured S value is S23.

[0050] Compare S23 with S22;

[0051] When S23 > S22, it indicates that the turbidity of the solution to be tested is greater than that of the standard solution V2. The controller controls the LEDs of multiple light intensities to emit high-intensity light, retests the S value, and converts the S value into a turbidity value for display.

[0052] When S23 < S22, it indicates that the turbidity of the solution to be tested is less than that of the standard solution V2. The controller controls the LEDs of multiple light intensities to emit low-intensity light, retests the S value, and converts the S value into a turbidity value for display.

[0053] When S23 = S22, the controller does not adjust the level of the multi-level light intensity LED, but directly converts S23 into a turbidity value for display.

[0054] Example 2

[0055] As shown in Figure 2, the turbidity testing system based on light intensity adjustment in this embodiment includes a controller, a transmitting circuit connected to the controller, a multi-level light intensity LED connected to the transmitting circuit, a receiving circuit connected to the controller, and a photodiode connected to the receiving circuit; the transmitting circuit includes a DAC and a voltage-to-current conversion circuit, and the receiving circuit includes a current-to-voltage conversion circuit and an AD acquisition unit.

[0056] As shown in Figure 3, in this embodiment, the voltage-to-current conversion circuit includes an operational amplifier U1, a multiplexer U2, a multiplexer U3, a P-type transistor Q1, a P-type transistor Q2, and a P-type transistor Q3. The non-inverting input terminal of the operational amplifier U1 is connected to the power supply VCC through a resistor R1 and grounded through a resistor R2. The inverting input terminal of the operational amplifier U1 is connected to the multiplexer U3, and the output terminal of the operational amplifier U1 is connected to the multiplexer U2. Both the multiplexer U2 and the multiplexer U3 are connected to the DAC of the controller. P-type transistors Q1 and Q3 are connected in parallel. After Q2 and P-type transistor Q3, the sources of P-type transistors Q1, Q2, and Q3 are connected to the inverting input of operational amplifier U1 via multiplexer U3, and are simultaneously connected to multiple parallel resistors R6, R7, and R8. The drains of P-type transistors Q1, Q2, and Q3 are connected to LEDs with varying light intensities. The gates of P-type transistors Q1, Q2, and Q3 are connected to the output of operational amplifier U1 via multiplexer U2, and are respectively connected to voltage VGOFF via resistors R3, R4, and R5.

[0057] In this embodiment, the resistance values ​​of resistors R6, R7, and R8 are in the order R6 > R7 > R8.

[0058] In practice, the controller uses Microchip's 16-bit microcontroller PIC24FJl28GA410. The integrated I / O ports and MOSFETs inside the microcontroller are used to form a switch to control the current of the LED, thereby realizing the on / off control of different LEDs. The integrated digital-to-analog converter (DAC) module inside the microcontroller chip outputs different voltages, and then the operational amplifier is used to convert the voltage into the LED's operating current, thereby realizing precise control of the LED's luminous intensity.

[0059] In practice, the end of resistor R1 connected to power supply VCC is grounded.

[0060] When multiplexer switches U2 and U3 are not in operation, all their channels are closed, resulting in zero current flowing through the LEDs of different brightness levels. Furthermore, since the gates of P-type transistors Q1, Q2, and Q3 are connected to the cutoff voltage VGOFF via resistors R3, R4, and R5 respectively, transistors Q1, Q2, and Q3 are ensured to be in the off state. Under the control of the controller, the i-th channel (where i ranges from 1 to 3) of multiplexer switches U2 and U3 is turned on, lowering the gate voltage of transistor Qi and causing it to turn on. This turn-on of transistor Qi selects the detection resistors R6, R7, and R8 connected to its source. The current flowing through the load, ILOAD, is equal to the reference voltage VREF divided by the detection resistors R6 (R7, R8).

[0061] Analog switch U3 is linked with analog switch U2 to prevent errors in current ILOAD when analog switch U2 malfunctions, thereby improving the stability and accuracy of the constant current source circuit.

[0062] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A turbidity testing method based on luminescence intensity adjustment, characterized in that, The method includes the following steps: Step 1: The controller excites LEDs of various light intensities to emit light through the transmitting circuit. After passing through the detection solution, the light is received by the photodiode and then transmitted to the controller through the receiving circuit. The controller processes the data to obtain the S value. Step 2: The controller controls the luminous intensity of LEDs with multiple light intensities through I / O, emitting light of multiple intensities respectively, and uses two or more standard solutions to calibrate the light of multiple intensities, calibrating the parameters of S value calculated according to the Lambert-Beer formula y=kx+b; Step 3: Test the solution to be tested. During the test, the controller controls the LEDs of multiple light intensities to emit one of the multiple light intensities, measures the S value, and compares the S value with the parameters calibrated in Step 2. Based on the comparison results, adjust the light intensity of the LEDs of multiple light intensities to test the turbidity of the solution to be tested.

2. The turbidity testing method based on luminescence intensity adjustment according to claim 1, characterized in that: The transmitting circuit includes a DAC and a voltage-to-current conversion circuit. The controller sequentially excites LEDs of multiple light intensities to emit light through the DAC and the voltage-to-current conversion circuit. The receiving circuit includes a current-to-voltage conversion circuit and an AD collector. The light is received by a photodiode and then transmitted to the controller sequentially through the current-to-voltage conversion circuit and the AD collector.

3. The turbidity testing method based on luminescence intensity adjustment according to claim 1, characterized in that: The multiple intensity levels of light mentioned in steps two and three include low-intensity light, medium-intensity light, and high-intensity light.

4. The turbidity testing method based on luminescence intensity adjustment according to claim 3, characterized in that: Step two describes the use of two standard solutions to calibrate low-intensity, medium-intensity, and high-intensity light, and the specific method for calculating the parameters of S based on the Lambert-Beer formula y=kx+b is as follows: Step 201: Select two standard solutions with known turbidities of V1 and V2, where V1 < V2; Step 202: Substitute V1 and V2 as values ​​of x into the Lambert-Beer formula y = kx + b to calculate the values ​​of k and b, where y represents the S value after signal processing. The parameter values ​​corresponding to the three intensities of light are then obtained as follows: For low-intensity light, standard solution V1 corresponds to S11, k1, and b1; standard solution V2 corresponds to S12, k1, and b1. For medium intensity light, standard solution V1 corresponds to S21, k2, and b2; standard solution V2 corresponds to S22, k2, and b2. For high-intensity light, standard solution V1 corresponds to S31, k3, and b3; standard solution V2 corresponds to S32, k3, and b3.

5. The turbidity testing method based on luminescence intensity adjustment according to claim 4, characterized in that: In step three, the controller controls the LEDs of various light intensities to emit one of the multiple light intensities, measures the S value, and compares the S value with the parameters calibrated in step two. Based on the comparison results, the light intensity of the LEDs of various light intensities is adjusted. The specific method for testing the turbidity of the solution to be tested is as follows: The controller controls multiple LEDs to emit medium-intensity light, and the measured S value is S23. Compare S23 with S22; When S23 > S22, it indicates that the turbidity of the solution to be tested is greater than that of the standard solution V2. The controller controls the LEDs of multiple light intensities to emit high-intensity light, retests the S value, and converts the S value into a turbidity value for display. When S23 < S22, it indicates that the turbidity of the solution to be tested is less than that of the standard solution V2. The controller controls the LEDs of multiple light intensities to emit low-intensity light, retests the S value, and converts the S value into a turbidity value for display. When S23 = S22, the controller does not adjust the level of the multi-level light intensity LED, but directly converts S23 into a turbidity value for display.

6. A turbidity testing system based on luminescence intensity adjustment that implements the method as described in claim 1, characterized in that: It includes a controller, a transmitting circuit connected to the controller and a multi-level LED connected to the transmitting circuit, a receiving circuit connected to the controller and a photodiode connected to the receiving circuit; the transmitting circuit includes a DAC and a voltage-to-current conversion circuit, and the receiving circuit includes a current-to-voltage conversion circuit and an AD acquisition unit.

7. The turbidity testing system based on luminescence intensity adjustment according to claim 6, characterized in that: The voltage-to-current conversion circuit includes an operational amplifier U1, a multiplexer U2, a multiplexer U3, a P-type transistor Q1, a P-type transistor Q2, and a P-type transistor Q3. The non-inverting input of operational amplifier U1 is connected to the power supply VCC through resistor R1 and grounded through resistor R2. The inverting input of operational amplifier U1 is connected to multiplexer U3, and the output of operational amplifier U1 is connected to multiplexer U2. Both multiplexer U2 and multiplexer U3 are connected to the DAC of the controller. P-type transistors Q1, Q2, and Q3 are connected in parallel. After transistor Q3, the sources of P-type transistors Q1, Q2, and Q3 are connected to the inverting input of operational amplifier U1 via analog multiplexer U3, and are also connected to multiple parallel resistors R6, R7, and R8. The drains of P-type transistors Q1, Q2, and Q3 are connected to LEDs with varying light intensities. The gates of P-type transistors Q1, Q2, and Q3 are connected to the output of operational amplifier U1 via analog multiplexer U2, and are connected to voltage VGOFF via resistors R3, R4, and R5, respectively.

8. The turbidity testing system based on luminescence intensity adjustment according to claim 7, characterized in that: The resistance values ​​of resistors R6, R7, and R8 are in the order R6 > R7 > R8.

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