Method for controlling optical signals in black carbon analysis

Abstract

The invention relates to a photoelectric detection technology, and particularly provides an optical signal control method in black carbon analysis, which comprises the following steps: (S1) lifting a first pipeline, moving a blank paper tape to the lower side of the first pipeline, and pressing the blank paper tape by the first pipeline; (S2) different light sources emit measuring light at different times, the measuring light passes through a first sampling area, a second sampling area and a reference area on the blank paper tape, and the plurality of detection units respectively output transmission light signals; (S3) control parameters of the detection unit are adjusted, so that the transmission light signals are located in the target range, and the control parameters comprise the integrating capacitance and the integrating time; (S4) gas to be detected enters the first pipeline, black carbon in the gas is enriched in the first sampling area and the second sampling area, and the enrichment rates are different; and (S5) the analysis unit obtains the black carbon concentration in the gas to be detected according to the output values of the plurality of detection units. The method has the advantages of high precision and the like and is applied to environmental protection monitoring.

Description

Technical Field

[0001] The invention relates to photoelectric detection technology, and in particular to a method for controlling optical signals in black carbon analysis. Background Art

[0002] In the black carbon analyzer project, the light attenuation method is needed to determine the range of black carbon concentration.

[0003] In order to ensure the stability of the black carbon concentration value, it is required that the light intensity sampling value should not be too large or too small after changing the paper. In addition, it is necessary to collect the light signals of 7 bands through the same sampling circuit.

[0004] like Figure 1 As shown in the figure, the photodiode has different receiving efficiencies for light signals of different wavelengths. According to the manual, the conversion energy of 330nm light and 950nm light differs by about 3 times. In order to ensure the same range of sampling values, different processing logic needs to be specified for the control and signal acquisition of each band of LED lights.

[0005] In order to solve the above problems, the solution in the prior art is: after the LED light is turned on, the signal is collected through the photodiode, and after passing through the resistor, a voltage signal is generated for sampling and analysis to obtain the sampled value. The small signal can be collected by setting the acquisition gear. The disadvantage of this solution is that 1. It is necessary to design and configure hardware circuits, which increases complexity and cost.

[0006] 2. The adjustment efficiency is low. Summary of the invention

[0007] In order to solve the deficiencies in the above-mentioned prior art solutions, the present invention provides a method for controlling optical signals in black carbon analysis.

[0008] The objective of the present invention is achieved through the following technical solutions: A method for controlling optical signals in black carbon analysis comprises the following steps: (S1) lifting the first pipe, the blank paper tape moves to the lower side of the first pipe, and the first pipe presses the blank paper tape; (S2) Different light sources L i The measuring light is emitted in different time periods, and the measuring light passes through the first sampling area, the second sampling area and the reference area on the blank paper tape, and the multiple detection units respectively output the transmission light signal A passing through the first sampling area. 1i , the transmitted light signal A passing through the second sampling area 2i , the transmitted light signal A passing through the reference area 3i ; i=1,2···N, N is an integer greater than 2; (S3) adjusting the control parameters of the detection unit so that the transmitted light signal A1i , A 2i and A 3i are respectively within a target range, and the control parameters include an integral capacitance and an integral time; (S4) the gas to be tested enters the first pipeline, and the black carbon in the gas is enriched in the first sampling area and the second sampling area at different enrichment rates; (S5) The analyzing unit obtains the black carbon concentration in the gas to be tested according to the output values ​​of the plurality of detecting units.

[0009] Compared with the prior art, the present invention has the following beneficial effects: 1. Using the current integration scheme, the current signal generated by the photodetector is directly input into the AD chip without passing through the resistor, thus avoiding the influence of the resistor value fluctuation on the sampling value; 2. According to the range of the transmitted light intensity signal, the adaptive configuration of the integral capacitor is realized, so that the sampling values ​​of light signals of different bands are controlled in the same range, which increases the service life of the light source and improves the stability of the product; 3. Add the function of fine-tuning the integral time to avoid the problem of too large or too small light force due to different light transmittance of the paper tape; 4. The signal channel and reference channel are sampled simultaneously to reduce the impact of LED signal fluctuations on the sampling results and improve the stability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The disclosure of the present invention will become easier to understand with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only used to illustrate the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. In the drawings: Figure 1 It is a schematic diagram of the relationship between the photodiode receiving efficiency and the light wavelength according to the prior art; Figure 2 is a flow chart of a method for controlling optical signals in black carbon analysis according to the present invention; Figure 3 Schematic diagram of the structure of the black carbon analyzer according to the present invention. DETAILED DESCRIPTION

[0011] Figure 1-Figure 3 The following description describes optional specific embodiments of the present invention to teach those skilled in the art how to implement and reproduce the present invention. In order to teach the technical solution of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art will understand that variations or replacements derived from these specific embodiments will be within the scope of the present invention. Those skilled in the art will understand that the following features can be combined in various ways to form multiple variations of the present invention. Thus, the present invention is not limited to the following optional specific embodiments, but is only limited by the claims and their equivalents.

[0012] Example 1.

[0013] A method for controlling optical signals in black carbon analysis according to an embodiment of the present invention, such as Figure 2 As shown, the following steps are included: (S1) Figure 3 As shown, the first pipe 11 is lifted, the blank paper tape 21 moves to the lower side of the first pipe 11, and the first pipe 11 presses the blank paper tape 21; (S2) Different light sources L i The measuring light is emitted at 31 seconds in time, and the measuring light passes through the first sampling area 22, the second sampling area 23 and the reference area 24 on the blank paper tape 21, and the plurality of detection units 41-43 respectively output the transmission light signal A passing through the first sampling area 22. 1i , the transmitted light signal A passing through the second sampling area 23 2i , the transmitted light signal A passing through the reference region 24 3i ; i=1,2···N, N is an integer greater than 2; (S3) adjusting the control parameters of the detection unit so that the transmitted light signal A 1i , A 2i and A 3i are respectively within a target range, and the control parameters include an integral capacitance and an integral time; (S4) The gas to be tested enters the first pipeline 11, and the black carbon in the gas is enriched in the first sampling area 22 and the second sampling area 23, and the enrichment rates are different; (S5) The analyzing unit obtains the black carbon concentration in the gas to be tested according to the output values ​​of the plurality of detecting units.

[0014] In order to improve the efficiency and accuracy of the adjustment, further, in step (S3), according to the transmitted light signal A 1i , A 2i and A 3i Difference from target range, select adjustment method: Determine the transmitted light signal A 1i , A 2i and A 3i Whether the difference from the target range exceeds the threshold; If it is less than the threshold, adjust the integration time; If it is not less than the threshold, calculate the target range and the current light source L i The corresponding transmitted light signal A 1i , A 2i and A 3i The ratio of The target integral capacitance is obtained based on the basic integral capacitance and the ratio, and the basic integral capacitance corresponds to the target range. The quotient of the basic integral capacitance and the ratio is used as the target integral capacitance. Finding one of two selectable integral capacitors adjacent to the target integral capacitor with a smaller deviation, wherein the selectable capacitors are a plurality of discrete capacitance values; Will be combined with the current light source L i The corresponding integral capacitor is adjusted to the one with the smaller deviation.

[0015] In order to improve adaptability, further, if the target integral capacitance is less than the minimum value of the selectable integral capacitance, it is adjusted to the minimum selectable integral capacitance and the integral time is increased.

[0016] In order to improve the accuracy of black carbon detection results, further, in step (S5), A 1i / A 3i and A 2i / A 3i , and then calculate the black carbon concentration.

[0017] Example 2.

[0018] Application example of the method for controlling optical signals in black carbon analysis according to embodiment 1 of the present invention In this application example, Figure 2 As shown, the method comprises the following steps: (S1) Figure 3 As shown, the first pipe 11 is lifted, and the blank paper tape 21 moves to the lower side of the first pipe 11 , and the first pipe 11 presses the blank paper tape 21 , so that the blank paper tape 21 is clamped between the first pipe 11 and the second pipe 12 .

[0019] (S2) 7 LED light sources L i The measuring light was emitted at 31 minutes in time, and the wavelengths were 330nm, 470nm, 520nm, 590nm, 660nm, 880nm and 950nm.

[0020] The measuring light passes through the first sampling area 22, the second sampling area 23 and the reference area 24 on the blank paper tape 21, and the three detection units 41-43 simultaneously collect the transmitted light signal, thereby outputting the transmitted light signal A passing through the first sampling area 22 and the reference light signal A respectively. 1i , the transmitted light signal A passing through the second sampling area 23 2i , the transmitted light signal A passing through the reference region 24 3i ; i=1,2···7.

[0021]

[0022] (S3) adjusting the control parameters of the detection unit so that the transmitted light signal A 1i , A 2i and A 3i are respectively within the target range, and the control parameters include integration capacitance and integration time.

[0023] The detection unit includes a photodiode and a control chip. The control chip is used to adjust the integration capacitor and the integration time. The selectable capacitor of the control chip is a plurality of discrete capacitance values, such as 3PF, 12.5PF, 25PF, 37.5PF, 50PF, 62.5PF, 75PF and 87.5PF. For the same charge output by the photodiode, the smaller the integration capacitor, the larger the output transmitted light signal. The influence of each selectable capacitor on the size of the transmitted light signal is greater than the integration time. Therefore, the adjustment of the integration capacitor is used as a coarse adjustment, and the adjustment of the integration time is used as a fine adjustment.

[0024] The specific adjustment method of the control parameters is as follows: Determine the transmitted light signal A 1i , A 2i and A 3i Whether the difference with the target range exceeds the threshold. The target range is set between 500000 and 900000, and the threshold is 200000. The transmitted light signal corresponding to light source L6 is within the target range, and the corresponding integral capacitor is used as the basic integral capacitor, which is 87.5PF.

[0025] If it is less than the threshold, adjust the integration time. If the difference between the transmitted light signal corresponding to light source L7 and the target range is small, only adjust the integration time.

[0026] If it is not less than the threshold, it means that the difference is large and it is not possible to adjust only the integration time. The integration capacitor must be adjusted. Calculate the target range and the current light source L i The corresponding transmitted light signal A 1i , A 2i and A 3i ratio.

[0027] For example, the transmitted light signal corresponding to L1 needs to adjust the integral capacitor so that the ratio is close to or exceeds 100.

[0028] The transmitted light signal corresponding to L2 must adjust the integral capacitor so that the ratio is greater than or close to 2.

[0029] The quotient of the basic integrating capacitance and the ratio is used as the target integrating capacitance.

[0030] For example, for the transmitted light signal corresponding to the light source L1, the target integration capacitance is less than 0.875PF, but the minimum selectable integration capacitance is 3PF, so 3PF is selected and the integration time is increased.

[0031] The transmitted light signal corresponding to the light source L2 needs to adjust the integral capacitor, and the ratio is close to 43PF.

[0032] The one of two selectable integrating capacitors adjacent to the target integrating capacitor and having a smaller deviation is found.

[0033] For example, for light source L2, select 37.5PF.

[0034] Will be combined with the current light source L i The corresponding integral capacitor is adjusted to the smaller deviation so that the collected transmission light signal A 1i , A 2i and A 3i Within target range.

[0035]

[0036] (S4) Under the suction of the pump 51, the gas to be tested passes through the first pipeline 11 and the second pipeline 12 in sequence, and the black carbon in the gas is enriched in the first sampling area 22 and the second sampling area 23. The flow rates through the first sampling area 22 and the second sampling area 23 are different, and the rates of black carbon enrichment are different.

[0037] (S5) The analyzing unit obtains the black carbon concentration in the gas to be tested according to the output values ​​of the plurality of detecting units.

[0038] Use A 1i / A 3i and A 2i / A 3i Used as the basic parameter for calculating black carbon concentration, this method eliminates the error caused by light source fluctuations at different time points.

Claims

1. A method for controlling light signals in black carbon analysis, comprising the following steps: (S1) lifting the first pipe, the blank paper tape moves to the lower side of the first pipe, and the first pipe presses the blank paper tape; (S2) Different light sources L i The measuring light is emitted in different time periods, and the measuring light passes through the first sampling area, the second sampling area and the reference area on the blank paper tape, and the multiple detection units respectively output the transmission light signal A passing through the first sampling area. 1i , the transmitted light signal A passing through the second sampling area 2i , the transmitted light signal A passing through the reference area 3i ; i=1,2···N, N is an integer greater than 2; (S3) adjusting the control parameters of the detection unit so that the transmitted light signal A 1i , A 2i and A 3i are respectively within a target range, and the control parameters include an integral capacitance and an integral time; (S4) the gas to be tested enters the first pipeline, and the black carbon in the gas is enriched in the first sampling area and the second sampling area at different enrichment rates; (S5) The analyzing unit obtains the black carbon concentration in the gas to be tested according to the output values ​​of the plurality of detecting units.

2. The method for controlling optical signals in black carbon analysis according to claim 1, characterized in that: In step (S3), according to the transmitted light signal A 1i , A 2i and A 3i Difference from target range, select adjustment method: Determine the transmitted light signal A 1i , A 2i and A 3i Whether the difference from the target range exceeds the threshold; If it is less than the threshold, adjust the integration time; If it is not less than the threshold, calculate the target range and the current light source L i The corresponding transmitted light signal A 1i , A 2i and A 3i The ratio of Obtaining a target integral capacitance according to a basic integral capacitance and the ratio, the basic integral capacitance corresponding to the target range; Finding the one with the smaller deviation among two selectable integrating capacitors adjacent to the target integrating capacitor; Will be combined with the current light source L i The corresponding integral capacitor is adjusted to the one with the smaller deviation.

3. The method for controlling optical signals in black carbon analysis according to claim 1, characterized in that: If the target integral capacitance is less than the minimum selectable integral capacitance, the integral capacitance is adjusted to the minimum selectable integral capacitance and the integral time is increased.

4. The method for controlling optical signals in black carbon analysis according to claim 2, characterized in that: The quotient of the basic integral capacitance and the ratio is used as the target integral capacitance.

5. The method for controlling optical signals in black carbon analysis according to claim 2, characterized in that: The selectable capacitance is a discrete plurality of capacitance values.

6. The method for controlling optical signals in black carbon analysis according to claim 1, characterized in that: The light source is LED with different output wavelengths.

7. The method for controlling optical signals in black carbon analysis according to claim 1, characterized in that: In step (S5), obtain A 1i / A 3i and A 2i / A 3i , and then calculate the black carbon concentration.

Images