Turbidity testing method and system based on luminous intensity adjustment

Abstract

The invention discloses a turbidity test method and system based on luminous intensity adjustment, and the method comprises the steps: 1, a controller excites a multi-level light intensity LED to emit light through a transmitting circuit, the light is received by a photodiode after passing through a detection solution, and then is transmitted to the controller through a receiving circuit, and the controller processes data to obtain an S value; 2, controlling the luminous intensity of the multi-level light intensity LED by a controller through I / O (Input / Output), respectively emitting multi-level intensity light, calibrating the multi-level intensity light by adopting two or more than two kinds of standard liquid, and calibrating a parameter for calculating an S value; and 3, detecting the solution to be detected, in the detection process, controlling the multi-gear light intensity LED to emit one of the multi-gear intensity light by the controller, measuring an S value, comparing the S value with the parameters calibrated in the step 2, adjusting the light intensity of the multi-gear light intensity LED according to a comparison result, and testing the turbidity of the solution to be detected. According to the invention, the accuracy and stability of test results are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of turbidity testing, and in particular relates to a turbidity testing method and system based on luminous intensity adjustment. Background Art

[0002] The 90-degree scattering method is a commonly used method for measuring the turbidity of a solution. This method is based on the scattering phenomenon described by the Lorentz-Boltzmann equation. This method uses a photometer or photometer to measure the intensity of light passing through the sample being measured and the intensity of light scattered by the sample in the 90-degree scattering direction, and calculates the turbidity of the sample based on the measured values. The scattering theorem used in this method is: The Beer-Lambert Law. This theorem stipulates that under the action of a uniformly radiated plane wave, the electro-optical response per unit length decreases as an exponential function of the optical path length, which is the classic Beer-Lambert law. In other words, light directed toward the grains suspended in the solution will be scattered multiple times, and some light will be scattered at an angle of 90 degrees.

[0003] When using this method, the measuring instrument measures the ratio of the light intensity scattered at a 90-degree angle by the solid particles in the suspension to the light intensity that passes through the sample without being scattered. As the concentration of the particles in the suspension increases, the intensity of the scattered light will also increase, and the ratio will increase. Therefore, the size of the ratio is proportional to the number of particles in the suspension. In practice, when measuring, a light source is introduced vertically into the sample, and the sample is placed at a scattering angle of 90 degrees. The light intensity directly measured without passing through the sample and the 90-degree scattered light intensity generated in the sample are measured by a photometer or photometer. The turbidity of the sample can be obtained by combining the colorimetric calculation method or the photometric method. This method has high accuracy and is widely used in turbidity measurement in the fields of water, sewage, food, medicine, and the environment.

[0004] However, the turbidity testing equipment in the prior art usually adopts a light source of fixed intensity, which has limitations when measuring water samples of different turbidity levels and 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 luminous intensity adjustment in view of the deficiencies in the above-mentioned prior art, which improves the measurement accuracy and response speed, and improves the accuracy and stability of the test results.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a turbidity testing method based on luminous intensity adjustment, the method comprising the following steps:

[0007] Step 1: The controller excites the multi-level light intensity LED through the transmitting circuit to emit light. After passing through the detection solution, it 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 the multi-level light intensity LED through the I / O, emits multi-level intensity light respectively, and uses two or more standard liquids to calibrate the multi-level intensity light, and calibrates the parameters of the S value calculated according to the Lambert-Beer formula y=kx+b;

[0009] Step three, the solution to be tested is tested, and during the testing process, the controller controls the multi-level light intensity LED to emit one of the multiple intensity levels of light, measures the S value, and compares the S value with the calibrated parameters in step two, adjusts the light intensity of the multi-level light intensity LED according to the comparison result, and tests the turbidity of the solution to be tested.

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

[0011] In the above-mentioned turbidity testing method based on luminous intensity adjustment, the multiple intensity levels of light in step 2 and step 3 include low intensity light, medium intensity light and high intensity light.

[0012] The above-mentioned turbidity test method based on luminous intensity adjustment is characterized in that: the two standard solutions described in step 2 are used to calibrate the low-intensity light, the medium-intensity light and the high-intensity light, and the specific method for calibrating the parameters for calculating the S value according to the Lambert-Beer formula y=kx+b is:

[0013] Step 201, selecting two standard solutions with known turbidities V1 and V2, V1<V2;

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

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

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

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

[0018] In the above-mentioned turbidity test method based on luminous intensity adjustment, the controller in step 3 controls the multi-level light intensity LED to emit one of the multi-level intensity lights respectively, measures the S value, and compares the S value with the calibrated parameter in step 2, adjusts the light intensity of the multi-level light intensity LED according to the comparison result, and tests the turbidity of the solution to be tested in the specific method as follows:

[0019] The controller controls the multi-level light intensity LED to emit medium-level intensity light, and the measured S value is S23;

[0020] Compare S23 with S22;

[0021] When S23>S22, it means that the turbidity of the solution to be tested is greater than that of the standard solution V2, and the controller controls the multi-level light intensity LEDs to emit high-level intensity light respectively, retests the S value, and converts the S value into a turbidity value for display;

[0022] When S23<S22, it means that the turbidity of the solution to be tested is less than that of the standard solution V2, and the controller controls the multi-level light intensity LEDs to emit low-level intensity light respectively, 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 gear position of the multi-gear light intensity LED, and 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 realizing the above method, comprising a controller, a transmitting circuit connected to the controller and a multi-level light intensity LED connected to the transmitting circuit, and a receiving circuit connected to the controller and a photodiode connected to the receiving circuit; the transmitting circuit comprises a DAC and a voltage-current conversion circuit, and the receiving circuit comprises a current-voltage conversion circuit and an AD collector.

[0025] The above-mentioned turbidity test system based on luminous intensity adjustment, the voltage-current conversion circuit includes an operational amplifier U1, a multi-way analog switch U2, a multi-way analog switch U3, a P-type transistor Q1, a P-type transistor Q2 and a P-type transistor Q3, the non-phase input terminal of the operational amplifier U1 is connected to the power supply VCC through a resistor R1, and is grounded through a resistor R2; the inverting input terminal of the operational amplifier U1 is connected to the multi-way analog switch U3, the output terminal of the operational amplifier U1 is connected to the multi-way analog switch U2, and the multi-way analog switch U2 and the multi-way analog switch U3 are both connected to the DAC of the controller; the P-type transistors Q1, P-type After the transistor Q2 and the P-type transistor Q3, the sources of the P-type transistor Q1, the P-type transistor Q2 and the P-type transistor Q3 are connected to the inverting input terminal of the operational amplifier U1 through the multi-way analog switch U3, and are simultaneously connected to multiple parallel resistors R6, resistor R7 and resistor R8 with the multi-way analog switch U3; the drains of the P-type transistor Q1, the P-type transistor Q2 and the P-type transistor Q3 are connected to the multi-level light intensity LED, and the gates of the P-type transistor Q1, the P-type transistor Q2 and the P-type transistor Q3 are connected to the output terminal of the operational amplifier U1 through the multi-way analog switch U2, and are connected to the voltage VGOFF through the resistor R3, the resistor R4 and the resistor R5 respectively.

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

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

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

[0029] 2. The present invention can automatically adjust the intensity of the light according to the turbidity value of the test water sample, so it can test not only low turbidity water samples but also high turbidity water samples, thereby improving the test speed.

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

[0031] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0033] Figure 2The system principle diagram of the turbidity testing system based on luminous intensity adjustment of the present invention;

[0034] Figure 3 The circuit diagram of the voltage-current conversion circuit of the present invention is shown in FIG. DETAILED DESCRIPTION

[0035] Example 1

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

[0037] Step 1: The controller excites the multi-level light intensity LED to emit light through the transmitting circuit. After passing through the detection solution, it 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 the conversion method in the prior art.

[0038] Step 2: The controller controls the luminous intensity of the multi-level light intensity LED through the I / O, emits multi-level intensity light respectively, and uses two or more standard liquids to calibrate the multi-level intensity light, and calibrates the parameters of the S value calculated according to the Lambert-Beer formula y=kx+b;

[0039] Step three, the solution to be tested is tested, and during the testing process, the controller controls the multi-level light intensity LED to emit one of the multiple intensity levels of light, measures the S value, and compares the S value with the calibrated parameters in step two, adjusts the light intensity of the multi-level light intensity LED according to the comparison result, and tests the turbidity of the solution to be tested.

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

[0041] In this embodiment, the multiple levels of intensity light in step 2 and step 3 include low-level intensity light, medium-level intensity light and high-level intensity light.

[0042] In this embodiment, the two standard solutions described in step 2 are used to calibrate the low-intensity light, the medium-intensity light and the high-intensity light. The specific method for calibrating the parameters for calculating the S value according to the Lambert-Beer formula y=kx+b is:

[0043] Step 201, selecting two standard solutions with known turbidities V1 and V2, V1<V2;

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

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

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

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

[0048] In this embodiment, the controller in step 3 controls the multi-level light intensity LED to emit one of the multi-level intensity lights respectively, measures the S value, and compares the S value with the parameter calibrated in step 2, adjusts the light intensity of the multi-level light intensity LED according to the comparison result, and tests the turbidity of the solution to be tested in the following specific method:

[0049] The controller controls the multi-level light intensity LED to emit medium-level intensity light, and the measured S value is S23;

[0050] Compare S23 with S22;

[0051] When S23>S22, it means that the turbidity of the solution to be tested is greater than that of the standard solution V2, and the controller controls the multi-level light intensity LEDs to emit high-level intensity light respectively, retests the S value, and converts the S value into a turbidity value for display;

[0052] When S23<S22, it means that the turbidity of the solution to be tested is less than that of the standard solution V2, and the controller controls the multi-level light intensity LEDs to emit low-level intensity light respectively, 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 gear position of the multi-gear light intensity LED, and directly converts S23 into a turbidity value for display.

[0054] Example 2

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

[0056] like Figure 3As shown, in this embodiment, the voltage-current conversion circuit includes an operational amplifier U1, a multi-way analog switch U2, a multi-way analog switch U3, a P-type transistor Q1, a P-type transistor Q2 and a P-type transistor Q3. The non-phase input terminal of the operational amplifier U1 is connected to the power supply VCC through a resistor R1 and is grounded through a resistor R2; the inverting input terminal of the operational amplifier U1 is connected to the multi-way analog switch U3, the output terminal of the operational amplifier U1 is connected to the multi-way analog switch U2, and the multi-way analog switch U2 and the multi-way analog switch U3 are both connected to the DAC of the controller; the P-type transistor Q1, the P-type transistor Q2 are connected in parallel After connecting the P-type transistor Q1, the P-type transistor Q2 and the P-type transistor Q3, the sources of the P-type transistor Q1, the P-type transistor Q2 and the P-type transistor Q3 are connected to the inverting input terminal of the operational amplifier U1 through the multi-way analog switch U3, and are simultaneously connected to multiple parallel resistors R6, R7 and R8 with the multi-way analog switch U3; the drains of the P-type transistor Q1, the P-type transistor Q2 and the P-type transistor Q3 are connected to the multi-level light intensity LED, and the gates of the P-type transistor Q1, the P-type transistor Q2 and the P-type transistor Q3 are connected to the output terminal of the operational amplifier U1 through the multi-way analog switch U2, and are connected to the voltage VGOFF through the resistor R3, the resistor R4 and the resistor R5 respectively.

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

[0058] In the specific implementation, the controller adopts Microchip's 16-bit microcontroller PIC24FJl28GA410, and utilizes the integrated I / O port and MOS tube inside the microcontroller to form a switch that controls the on and off current of the LED lamp, thereby realizing the on and off control of different LEDs; utilizes the digital-to-analog converter (DAC) module integrated inside the microcontroller chip to output different voltages, and then uses an operational amplifier to convert the voltage into the working current of the LED, thereby realizing precise control of the LED luminous intensity.

[0059] In a specific implementation, one end of the resistor R1 connected to the power source VCC is grounded.

[0060] When the multi-way analog switch U2 and the multi-way analog switch U3 are not working, all its channels are in the closed state. At this time, the current flowing through the multi-level light intensity LED is 0, and because the gates of the P-type transistor Q1, the P-type transistor Q2 and the P-type transistor Q3 are connected to the cut-off voltage VGOFF through the resistors R3, R4 and R5 respectively, the transistors Q1, Q2 and Q3 are ensured to be in the cut-off state; under the control of the controller, the i-th channel (the value of i is 1 to 3) in the multi-way analog switch U2 and the multi-way analog switch U3 is turned on, the gate voltage of the transistor Qi is lowered to turn on the transistor Qi, so that the detection resistors R6, R7 and R8 connected to the source of the transistor Qi are selected by the turning on of the transistor Qi, and the current ILOAD flowing through the load = the reference voltage VREF / the detection resistor R6 (R7, R8).

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

[0062] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A turbidity testing method based on luminous intensity adjustment, characterized in that: The method comprises the following steps: Step 1: The controller excites the multi-level light intensity LED through the transmitting circuit to emit light. After passing through the detection solution, it 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 the multi-level light intensity LED through the I / O, emits multi-level intensity light respectively, and uses two or more standard liquids to calibrate the multi-level intensity light, and calibrates the parameters of the S value calculated according to the Lambert-Beer formula y=kx+b; Step three, the solution to be tested is tested, and during the testing process, the controller controls the multi-level light intensity LED to emit one of the multiple intensity levels of light, measures the S value, and compares the S value with the calibrated parameters in step two, adjusts the light intensity of the multi-level light intensity LED according to the comparison result, and tests the turbidity of the solution to be tested.

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

3. A turbidity testing method based on luminous intensity adjustment according to claim 1, characterized in that: The multiple levels of intensity light in step 2 and step 3 include low-level intensity light, medium-level intensity light and high-level intensity light.

4. The turbidity testing method based on luminous intensity adjustment according to claim 3, characterized in that: The specific method of using two standard solutions to calibrate low-intensity light, medium-intensity light and high-intensity light in step 2 to calibrate the parameters for calculating the S value according to the Lambert-Beer formula y=kx+b is as follows: Step 201, selecting two standard solutions with known turbidities V1 and V2, V1<V2; Step 202: Substitute V1 and V2 as the values ​​of x into the Lambert-Beer formula y=kx+b to calculate the k and b values, where y represents the S value collected after signal processing; the parameter values ​​corresponding to the three intensities of light are obtained as follows: For low intensity light, standard solution V1 corresponds to S11, k1, b1; standard solution V2 corresponds to S12, k1, b1; For medium intensity light, standard solution V1 corresponds to S21, k2, b2; standard solution V2 corresponds to S22, k2, b2; For high-intensity light, standard liquid V1 corresponds to S31, k3, b3; standard liquid V2 corresponds to S32, k3, b3.

5. A turbidity testing method based on luminous intensity adjustment according to claim 4, characterized in that: In step 3, the controller controls the multi-level light intensity LED to emit one of the multi-level intensity lights, measures the S value, and compares the S value with the parameter calibrated in step 2. The light intensity of the multi-level light intensity LED is adjusted according to the comparison result. The specific method for testing the turbidity of the solution to be tested is: The controller controls the multi-level light intensity LED to emit medium-level intensity light, and the measured S value is S23; Compare S23 with S22; When S23>S22, it means that the turbidity of the solution to be tested is greater than that of the standard solution V2, and the controller controls the multi-level light intensity LEDs to emit high-level intensity light respectively, retests the S value, and converts the S value into a turbidity value for display; When S23<S22, it means that the turbidity of the solution to be tested is less than that of the standard solution V2, and the controller controls the multi-level light intensity LEDs to emit low-level intensity light respectively, retests the S value, and converts the S value into a turbidity value for display; When S23=S22, the controller does not adjust the gear position of the multi-gear light intensity LED, and directly converts S23 into a turbidity value for display.

6. A turbidity testing system based on luminous intensity adjustment for implementing the method as claimed in claim 1, characterized in that: It includes a controller, a transmitting circuit connected to the controller and a multi-level light intensity LED connected to the transmitting circuit, as well as a receiving circuit connected to the controller and a photodiode connected to the receiving circuit; the transmitting circuit includes a DAC and a voltage-current conversion circuit, and the receiving circuit includes a current-voltage conversion circuit and an AD collector.

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

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

Images