Device and method for automatically adjusting light resistance detection light intensity

Abstract

The invention relates to the technical field of fluid detection, and discloses a device and a method for automatically adjusting light intensity of light resistance detection, and the device comprises an overflow channel valve block, a light source device, a light source driving circuit, a DAC circuit, a photoelectric receiver, an I / U conversion circuit, an ADC sampling circuit, a detection circuit assembly and an automatic regulation and control device. The method comprises the following steps: setting the lowest voltage and the highest voltage of the light source device; the fluid can stably pass through the flow passage; the DC voltage output by the DAC is changed from low to high; measuring and storing light source voltages at two ends of the light source device and corresponding photovoltages; stopping until the light source voltage reaches the highest working voltage of the light source device; obtaining an optimal light source voltage interval; the direct current voltage output by the DAC enables the light source voltage and the photovoltage to be in the optimal photoelectric conversion efficiency state; and the particle concentration value in the fluid is detected. According to the invention, the optimal light intensity state for generating the particle pulse is obtained by automatically adjusting the light resistance detection light intensity.

Description

Technical Field

[0001] The present invention relates to the technical field of fluid detection, and in particular, to a device and method for automatically adjusting the light intensity for light resistance detection. Background Art

[0002] In the on-line detection method of fluid particulate matter, the light resistance method is simple and practical and is most widely used. The light resistance detection principle is to use the transmission or blocking effect of light to identify and quantify tiny particles in a liquid. When a liquid containing insoluble microparticles flows through a narrow detection channel, a beam of incident light perpendicular to the liquid flow direction passes through the channel. These microparticles will partially block or scatter the light, resulting in a decrease in the light intensity received by the photoelectric receiver, thereby generating a pulse proportional to the cross-sectional area of the microparticles. Through precise circuit processing, the change of this signal is converted into quantifiable data, and accurate measurement of the number and size of microparticles can be achieved.

[0003] To implement the light resistance detection principle, existing light resistance detection devices such as Figure 1 shown mainly consist of an over-flow channel valve block, a DAC circuit, a proportional gain circuit, a light source drive circuit, a light source device, a photoelectric receiver, an I / U conversion circuit, and a detection circuit. The over-flow channel of the over-flow channel valve block is used to pass the fluid. There is an incident window for the light source on one side of the over-flow channel pipe wall, and a receiving window for the photoelectric receiver on the other side. The light source device and the photoelectric receiver are symmetrically installed on both sides of the over-flow channel pipe wall. The emission light power of the light source device is controlled by the light source drive circuit. Adjusting the DC voltage input of the proportional gain circuit can adjust the light source drive circuit, and the DC voltage of the proportional gain circuit is given by the DAC circuit. After the light source emits light, a uniform and stable detection light field is formed inside the flow channel. The light source penetrates the flow channel and forms a light-shielding particle pulse on the target surface of the photoelectric receiver. The detection circuit statistically identifies the particle pulse, converts it into a particle concentration value, and in fact, both the light source device and the photoelectric receiver are conditioned by the detection circuit.

[0004] In actual detection, different light field intensities of the light resistance detection device have different effects on the generation of particulate matter pulses. On the one hand, the light field intensity needs to be kept constant and consistent. On the other hand, the most ideal light intensity state for generating particle pulses needs to be determined according to the performance of the optoelectronic device. Currently, the determination of the light field intensity of the light resistance detection device is mainly subjectively judged by manually observing the pulse generation effect of the oscilloscope. This method relies solely on personal experience values as the judgment, which not only seriously lacks scientific basis, but also requires manual repeated evaluation to re-determine the most ideal light intensity state for generating particle pulses once the design parameters of the light resistance detection device change. Therefore, if the light intensity for light resistance detection can be automatically adjusted to obtain the most ideal light intensity state for generating particle pulses, the time and difficulty of device adjustment during each measurement will be reduced. Summary of the Invention

[0005] To overcome the deficiencies of the prior art, the object of the present invention is to automatically determine the optimal detection light field by obtaining the optoelectronic effect.

[0006] The present invention provides a device for automatically adjusting the light intensity for photoresist detection, comprising the following components: an over-channel valve block, a light source device, a light source drive circuit, a DAC circuit, a photoelectric receiver, an I / U conversion circuit, an ADC sampling circuit, a detection circuit assembly, and an automatic control device; specifically:

[0007] The over-channel of the over-channel valve block is used for passing fluid. On one side of the over-channel pipe wall, there is an incident window for the light source, and a light source device is installed at the incident window. On the symmetric other side, there is a receiving window, and a photoelectric receiver is installed at the receiving window;

[0008] The light source device provides an incident light source, which is installed at the incident window of the flow channel pipe wall. The luminous power is adjusted by adjusting the working current of the light source device, and the working current of the light source device is controlled by the light source drive circuit;

[0009] The light source drive circuit is used to drive the light source device and adjust the luminous power of the light source device according to the DC voltage given by the DAC circuit;

[0010] The DAC circuit is used to output a DC voltage according to the voltage control signal received from the automatic control device;

[0011] The photoelectric receiver is used to receive the light shielding pulse of the particles through the incident window and convert the received light into a photocurrent;

[0012] The I / U conversion circuit is used to convert the photocurrent into a photovoltage, and the photovoltage is the particle pulse voltage signal;

[0013] The ADC sampling circuit is used to sample the photovoltage and send the sample to the detection circuit;

[0014] The detection circuit is used to detect the particle concentration value in the fluid, and the detection circuit obtains the particle concentration value in the fluid according to the sample;

[0015] The automatic control device is used to automatically adjust the voltage across the light source device, and includes a voltage measurement component, a voltage control component, a voltage storage component, and an optimal interval detection component; specifically:

[0016] The voltage control component controls the DC voltage output by the DAC circuit by outputting a voltage control signal, thereby adjusting the light source voltage across the light source device; the voltage control component first sets the DC voltage to the lowest voltage at which the light source device operates through the voltage control signal, and then gradually increases the light source voltage to the highest voltage at which the light source device operates through the voltage control signal. After that, according to the optimal light source voltage range returned by the optimal range detection component, the optimal voltage control signal corresponding to the optimal light source voltage range is queried from the voltage storage component, and the voltage control component outputs the optimal voltage control signal to control the light source voltage, so that the light source voltage is within the optimal light source voltage range;

[0017] The voltage measuring device is used to measure the light source voltage across the light source device and the light voltage after conversion by the corresponding I / U conversion circuit;

[0018] The voltage storage component is used to store the output signal of the voltage control component and the light source voltage and light voltage measured by the corresponding voltage measuring device;

[0019] The optimal range detection component obtains the optimal light source voltage range at the optimal photoelectric conversion efficiency based on the light source voltage and the light voltage, and sends it to the voltage control component.

[0020] Preferably, the optimal range detection component obtains the optimal light source voltage range at the optimal photoelectric conversion efficiency based on the light source voltage and the light voltage, and the determination method of the optimal light source voltage range is as follows:

[0021] First, establish a photoelectric conversion curve based on the light source voltage and the corresponding light voltage stored in the voltage storage component. According to the minimum value of the light source voltage as the lowest voltage U min1 at which the source device operates, and the maximum value of the light source voltage as the maximum voltage U max1 at which the source device operates, divide [U min1 ,U max1 into N intervals;

[0022] The light source voltage range of the a-th interval among the N intervals is [U ax1 ,U ax2 . According to the photoelectric conversion curve, the corresponding light voltage [U ay1 ,U ay2 can be obtained; therefore, the endpoints at both ends of the a-th interval are (U ax1 ,U ay1 ) and (U ax2 ,U ay2 );

[0023] According to the endpoints at both ends of the a-th interval, the linear expression of the a-th interval is y = A a x + B a ,A ais the slope of the linear expression for the a-th interval, and B a is the intercept of the linear expression for the a-th interval;

[0024] Obtain the cumulative deviation value of the a-th interval based on the optoelectronic conversion curve and the linear expression of the a-th interval;

[0025] Calculate the cumulative deviation values of N intervals respectively, and select the interval with the smallest cumulative deviation value as the optimal light source voltage interval.

[0026] Preferably, the dividing [U min1 , U max1 into N intervals is specifically as follows: The N intervals can be evenly divided into N intervals within [U min1 , U max1 , or can be partitioned starting from U min1 according to the specified interval size until U max1 .

[0027] Preferably, the obtaining the cumulative deviation value of the a-th interval based on the optoelectronic conversion curve and the linear expression of the a-th interval is specifically as follows:

[0028] Evenly take M points for the a-th interval within the light source voltage [U ax1 , U ax2 . For the i-th point, the corresponding light voltage on the optoelectronic conversion curve is U ai , and the light voltage obtained according to the linear expression is y ai . The cumulative deviation value of the a-th interval is:

[0029]

[0030] Preferably, the N intervals start from U min1 , with each interval being 100 mV until U max1 ; when calculating the cumulative deviation value of the a-th interval, take one point every 1 mV.

[0031] Preferably, the light source drive circuit includes a composite amplifier tube and a proportional gain circuit, specifically as follows:

[0032] The emitter of the composite amplifier tube provides the working current for the light source device to adjust the light emission power; the base voltage of the composite amplifier tube is controlled by the proportional gain circuit; the proportional gain circuit is implemented by a low-offset operational amplifier, and the circuit amplifies the input DC voltage and uses it as the base voltage of the composite amplifier tube; the DC voltage of the proportional gain circuit is given by the DAC circuit; adjusting the DC voltage input of the proportional gain circuit can achieve the effect of adjusting the emitter current of the composite amplifier tube, and the emission light power of the light source device also changes accordingly.

[0033] Preferably, the light source device is a laser diode or a light-emitting diode, and the optical receiver is a photodiode.

[0034] Preferably, the optical voltage is a particle pulse voltage signal.

[0035] The present invention also discloses a method for automatically adjusting the light intensity for photoresist detection, which includes the following steps:

[0036] Step 1, set the minimum voltage and the maximum voltage at which the light source device operates through the voltage measuring component of the automatic control device;

[0037] Step 2, let the fluid pass stably through the flow channel of the flow channel valve block;

[0038] Step 3, the voltage control component of the automatic control device sends a voltage control signal to change the DC voltage output by the DAC from low to high according to the minimum voltage at which the light source device operates; at the same time, the voltage measuring device of the automatic control device measures the light source voltage across the light source device and the corresponding optical voltage, and stores the voltage control signal and the corresponding light source voltage and optical voltage into the voltage storage component;

[0039] Step 4, when the light source voltage reaches the maximum voltage at which the light source device operates, the voltage control component of the automatic control device stops changing the DC voltage output by the DAC;

[0040] Step 5, the optimal interval detection component of the automatic control device obtains the optimal light source voltage interval at the optimal photoelectric conversion efficiency according to the light source voltage and the optical voltage stored in the voltage storage component, and sends it to the voltage control component;

[0041] Step 6, the voltage control component searches for the corresponding optimal voltage control signal from the voltage storage component according to the optimal light source voltage interval, and the voltage control component inputs the optimal voltage control signal into the DAC, so that the light source voltage and the optical voltage are in the optimal state of photoelectric conversion efficiency;

[0042] Step 7, the detection circuit detects the particle concentration value in the fluid.

[0043] Preferably, Step 7 further includes:

[0044] During the detection process, the voltage measuring device of the automatic control device continuously measures the light source voltage across the light source device. When the light source voltage is lower than the optimal light source voltage interval, the voltage measuring device sends a voltage increasing signal to the voltage control component, and the voltage control component adjusts the voltage control signal to increase the DC voltage output by the DAC. When the light source voltage is higher than the optimal light source voltage interval, the voltage measuring device sends a voltage decreasing signal to the voltage control component, and the voltage control component adjusts the voltage control signal to decrease the DC voltage output by the DAC.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] 1. An automatic control device and a voltage measuring device are additionally installed in the existing photoresist detection device of the present invention. Without changing the structure of the existing photoresist detection device, the method is simple and has strong implementation feasibility, with good general applicability and technical application value.

[0047] 2. The device proposed by the present invention can automatically adjust the light intensity of photoresist detection to obtain the most ideal light intensity state for generating particle pulses, reducing the time for device adjustment during each measurement.

[0048] 3. The present invention uses a quantitative method to obtain the most ideal light intensity for generating particle pulses. Based on science, it does not rely on personal experience values and has good repeatability and indication accuracy guarantee. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a schematic diagram of the principle of the existing photoresist detection device;

[0050] Figure 2 is a schematic diagram of the principle of the device for automatically adjusting the light intensity of photoresist detection of the present invention;

[0051] Figure 3 is a schematic diagram of the driving circuit of the light source device of the present invention;

[0052] Figure 4 is a schematic diagram of the photoelectric receiver and I / U conversion circuit of the present invention;

[0053] Figure 5 is the fitting curve of the working voltage of the laser diode - the photoelectric conversion voltage of the photodiode in the first example of the present invention;

[0054] Figure 6 is the cumulative deviation change curve in the first example of the present invention;

[0055] Figure 7 is the fitting curve of the working voltage of the laser diode - the photoelectric conversion voltage of the photodiode in the second example of the present invention;

[0056] Figure 8 is the cumulative deviation change curve in the second example of the present invention;

[0057] Figure 9 is the fitting curve of the working voltage of the laser diode - the photoelectric conversion voltage of the photodiode in the third example of the present invention;

[0058] Figure 10 is the cumulative deviation change curve in the third example of the present invention;

[0059] Figure 11It is the fitting curve of the laser diode operating voltage - photodiode photoelectric conversion voltage in the fourth example of the present invention;

[0060] Figure 12 It is the cumulative deviation change curve in the fourth example of the present invention. Detailed implementation manners

[0061] To better understand the technical solution of the present invention, the following combines the drawings and embodiments to further describe the detailed implementation manners of the present invention in detail. The same reference numerals in the drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the drawings, the drawings do not have to be drawn to scale unless otherwise specified.

[0062] The present invention is a device for automatically adjusting the light intensity for photoresist detection. A voltage measuring device and an automatic control device are added to the existing photoresist detection device, such as Figure 2 shown, and specifically includes the following parts: an over - flow channel valve block 1, a light source device 2, a light source driving circuit 3, a DAC circuit 4, a photoelectric receiver 5, an I / U conversion circuit 6, an ADC sampling circuit 7, a detection circuit assembly 8, and an automatic control device 9. The following is a detailed description:

[0063] The over - flow channel of the over - flow channel valve block 1 is used for passing fluid. There is an incident window for the light source on one side of the over - flow channel pipe wall. A light source device is installed at the incident window, and on the symmetric other side, there is a receiving window, and a photoelectric receiver is installed at the receiving window.

[0064] The light source device 2 provides an incident light source and is installed at the incident window of the flow channel pipe wall. The luminous power can be adjusted by adjusting the working current of the light source device, and the working current of the light source device is controlled by the light source driving circuit.

[0065] The light source driving circuit 3 is used to drive the light source device. As Figure 3 shown, the emitter of the composite amplifier tube provides sufficient working current for the light source device to adjust the luminous power. The base voltage of the composite amplifier tube is controlled by a proportional gain circuit. The proportional gain circuit is implemented by a low - offset operational amplifier. The circuit amplifies the input DC voltage and uses it as the base voltage of the composite amplifier tube. By adjusting the DC voltage input of the proportional gain circuit, the emitter current of the composite amplifier tube can be adjusted, and the emitted light power of the light source device also changes accordingly. When the DC voltage of the proportional gain circuit increases, the light power of the light source device increases, and vice versa. The DC voltage of the proportional gain circuit is given by the DAC circuit.

[0066] The DAC (digital - to - analog conversion circuit) circuit 4 is used to output a DC voltage according to the voltage control signal received from the automatic control device.

[0067] The photoelectric receiver 5 is used to receive the light-shielding pulses of the particles through the incident window and convert the received light into photocurrent. The photoelectric receiver is mainly implemented by a photodiode, as Figure 4 shown. The photoelectric receiver is installed at the incident window of the flow channel pipe wall, and the photocurrent is input to the I / U (current / voltage) conversion circuit.

[0068] The I / U (current / voltage) conversion circuit 6 is used to convert the photocurrent into a photovoltage, and the photovoltage is the particle pulse voltage signal. As Figure 4 shown, the I / U conversion circuit consists of an operational amplifier and integral resistance and capacitance. The particle pulse voltage signal obtained by the I / U conversion circuit is input to the ADC (analog-to-digital conversion) sampling circuit.

[0069] The ADC (analog-to-digital conversion) sampling circuit 7 is used to sample the particle pulse voltage signal and send the sampling to the detection circuit.

[0070] The detection circuit 8 is used to detect the particle concentration value in the fluid, and the detection circuit obtains the particle concentration value in the fluid according to the sampling.

[0071] The automatic regulation device 9 is used to automatically adjust the voltage across the light source device, including a voltage measurement component 91, a voltage control component 92, a voltage storage component 93, and an optimal interval detection component 94. Under different light field intensities, the pulse amplitudes generated by the particles are different. It is necessary to determine an optimal light field intensity for particle detection. At this light field intensity, the pulse amplitude generated by the particles is the largest. Therefore, the automatic regulation device first needs to determine the optimal photoelectric state for particle pulse photoelectric conversion, and at the same time, it also needs to maintain and adjust the stability of the detected photovoltage, so that the particle pulse photoelectric conversion has a suitable and constant light field.

[0072] The voltage control component controls the DC voltage output by the DAC circuit through the output voltage control signal, thereby adjusting the light source voltage across the light source device. The voltage control component first sets the DC voltage to the lowest voltage for the light source device to work through the voltage control signal, and then gradually increases the light source voltage to the highest voltage for the light source device to work through the voltage control signal. Then, according to the optimal light source voltage interval returned by the optimal interval detection component, it queries the optimal voltage control signal corresponding to the optimal light source voltage interval from the voltage storage component, and the voltage control component outputs the optimal voltage control signal to control the light source voltage, so that the light source voltage is within the optimal light source voltage interval.

[0073] The voltage measurement device is used to measure the light source voltage across the light source device and the photovoltage after conversion by the corresponding I / U conversion circuit.

[0074] The voltage storage component is used to store the output signal of the voltage control component and the light source voltage and photovoltage measured by the corresponding voltage measurement device.

[0075] The optimal interval detection component obtains the optimal light source voltage interval when the optimal photoelectric conversion efficiency of photoelectric conversion is obtained based on the light source voltage and the optical voltage, and sends it to the voltage control component. The determination method of the optimal light source voltage interval is as follows:

[0076] First, establish a photoelectric conversion curve based on the light source voltage and the corresponding optical voltage stored in the voltage storage component. Usually, the light source voltage is selected as the X-axis and the optical voltage is selected as the Y-axis. The minimum value of the light source voltage is the lowest voltage U at which the source device operates min1 , and the maximum value of the light source voltage is the maximum voltage U at which the source device operates max1 . Divide [U min1 , U max1 into N intervals. The N intervals can be evenly divided into N intervals in [U min1 , U max1 , or can be partitioned starting from U min1 according to the specified interval size until U max1 . At this time, the last interval may be different in size from other intervals. In this embodiment, considering that the interval interval cannot take too large a value, it is therefore adopted that starting from U min1 , each interval is 100 mV until U max1 . The deviation cumulative value needs to be calculated for each subsequent interval.

[0077] The light source voltage range of the a-th interval among the N intervals is [U ax1 , U ax2 . According to the photoelectric conversion curve, the corresponding optical voltage [U ay1 , U ay2 can be obtained; therefore, the endpoints at both ends of the a-th interval are (U ax1 , U ay1 ) and (U ax2 , U ay2 ).

[0078] The linear expression of the a-th interval is obtained according to the endpoints at both ends of the a-th interval as y = A a x + B a , where A a is the slope of the linear expression of the a-th interval, and B a is the intercept of the linear expression of the a-th interval.

[0079] The deviation cumulative value of the a-th interval is obtained according to the photoelectric conversion curve and the linear expression of the a-th interval. Specifically: For the a-th interval, M points are evenly taken in the light source voltage [U ax1 , U ax2 . In this embodiment, it is preferably taken one point every 1 mV. For the i-th point, the corresponding optical voltage on the photoelectric conversion curve is U ai, the photocurrent obtained according to the straight-line expression is y ai , the cumulative deviation value of the a-th interval is:

[0080]

[0081] Calculate the cumulative deviation values of N intervals respectively. The smaller the cumulative deviation value of an interval, the better the linearity of the current interval; conversely, the larger the value, the worse the linearity. The interval with the smallest cumulative deviation value is the optimal optical field state for photoelectric conversion, with the best photoelectric conversion efficiency. The light source voltage interval where the interval with the smallest cumulative deviation value is located is called the optimal light source voltage interval.

[0082] The present invention provides a method for automatically adjusting the light intensity for photoresistance detection, and the specific method is as follows:

[0083] Step 1, set the minimum voltage and the maximum voltage at which the light source device operates through the voltage measurement component of the automatic control device.

[0084] Step 2, let the fluid pass stably through the flow channel of the flow channel valve block.

[0085] Step 3, the voltage control component of the automatic control device sends a voltage control signal to change the DC voltage output by the DAC from low to high according to the minimum voltage at which the light source device operates; at the same time, the voltage measurement device of the automatic control device measures the light source voltage across the light source device and the corresponding photocurrent, and stores the voltage control signal and the corresponding light source voltage and photocurrent in the voltage storage component.

[0086] Step 4, when the light source voltage reaches the maximum voltage at which the light source device operates, the voltage control component of the automatic control device stops changing the DC voltage output by the DAC.

[0087] Step 5, the optimal interval detection component of the automatic control device obtains the optimal light source voltage interval at the best photoelectric conversion efficiency for photoelectric conversion according to the light source voltage and photocurrent stored in the voltage storage component, and sends it to the voltage control component.

[0088] Step 6, the voltage control component searches for the corresponding optimal voltage control signal from the voltage storage component according to the optimal light source voltage interval, and the voltage control component inputs the optimal voltage control signal into the DAC, so that the light source voltage and photocurrent are in the state with the best photoelectric conversion efficiency.

[0089] Step 7: The detection circuit detects the particle concentration value in the fluid. During the detection process, the voltage measuring device of the automatic regulation device continuously measures the light source voltage across the light source device. When the light source voltage is lower than the optimal light source voltage range, the voltage measuring device sends a signal to increase the voltage to the voltage control component, and the voltage control component adjusts the voltage control signal to increase the DC voltage output by the DAC. When the light source voltage is higher than the optimal light source voltage range, the voltage measuring device sends a signal to decrease the voltage to the voltage control component, and the voltage control component adjusts the voltage control signal to decrease the DC voltage output by the DAC, so that the light source voltage and the optical voltage are always in the state with the best photoelectric conversion efficiency.

[0090] According to the present invention, different devices for automatically adjusting the light intensity detected by the photoresist are used for testing. In the following examples, the default interval is from U min1 starting with every 100 mV as an interval until U max1 , and in each interval, a point is taken every 1 mV to calculate the cumulative deviation of the interval; it is ensured that the same interval and deviation accumulation are used in each example to obtain different optimal light source voltage ranges, specifically as follows:

[0091] Example 1: The device for automatically adjusting the light intensity detected by the photoresist is a brand-new device. Its light source device is a low-power laser diode, and the photoelectric receiver is a photodiode with a target area of 1.2 mm 2 . The fitting curve of the operating voltage of the laser diode - the photoelectric conversion voltage of the photodiode is as Figure 5 shown. The corresponding cumulative deviation change curve is as Figure 6 shown. It can be seen from Figure 6 that as the incident light intensity increases, the linearity of its optical voltage change curve gradually increases, and at the same time, the photoelectric conversion curve has excellent monotonicity, that is, when detecting the photoresist particle pulse, the greater the light intensity, the better the effect of generating the particle pulse. Therefore, when using this device for automatically adjusting the light intensity detected by the photoresist, the device for automatically adjusting the light intensity detected by the photoresist will adjust the voltage of the laser diode to the maximum operating voltage.

[0092] Example 2: The light source device of the device for automatically adjusting the light intensity detected by the photoresist is a low-power LED (light-emitting diode), and the photoelectric receiver is a photodiode with a target area of 2.3 mm 2 . The fitting curve of the operating voltage of the LED - the photoelectric conversion voltage of the photodiode is as Figure 7 shown. The corresponding cumulative deviation change curve is as Figure 8 shown. It can be seen from Figure 8 that the entire cumulative deviation change curve does not have monotonicity. By analyzing the photoelectric conversion curve, it is obtained that when a = 180, the linear deviation is the smallest. Therefore, the light source voltage range of the 180th interval is used as the optimal light field intensity.

[0093] Example 3: The light source device of the device for automatically adjusting the light intensity for photoresist detection is a laser diode, and the photoelectric receiver is a photodiode with a target area of 2.3 mm 2 . The fitting curve of the operating voltage of the laser diode - the photoelectric conversion voltage of the photodiode is as shown in Figure 9 . The corresponding cumulative deviation change curve is as shown in Figure 10 . It can be seen from Figure 10 that the entire cumulative deviation change curve is not monotonic. By analyzing the photoelectric conversion curve, when a = 467, the linear deviation is the smallest. Therefore, the light source voltage range in the 467th interval is used as the optimal light field intensity.

[0094] Example 4: The device for automatically adjusting the light intensity for photoresist detection is a device that has been used for a certain period of time. Its light source device is also a low-power laser diode, and the photoelectric receiver is a photodiode with a target area of 1.2 mm 2 . The fitting curve of the operating voltage of the light source device - the photoelectric conversion voltage of the photodiode is as shown in Figure 11 . The corresponding cumulative deviation change curve is as shown in Figure 12 . It can be seen from Figure 12 that the entire cumulative deviation change curve is not monotonic. By analyzing the photoelectric conversion curve, when a = 569, the linear deviation is the smallest. Therefore, the light source voltage range in the 569th interval is used as the optimal light field intensity.

[0095] Finally, it should be noted that the above-described embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for automatically adjusting light resistance to detect light intensity, characterized in that: It includes the following components: The flow channel valve block, light source device, light source driving circuit, DAC circuit, photoelectric receiver, I / U conversion circuit, ADC sampling circuit, detection circuit and automatic control device; specifically: The flow passage of the flow passage valve block is used for passing fluid, and an incident window of a light source is provided on one side of the flow passage pipe wall, and a light source device is installed at the incident window, and a receiving window is provided on the other symmetrical side, and a photoelectric receiver is installed at the receiving window; The light source device provides an incident light source and is installed at an incident window on the wall of the flow channel. The luminous power is adjusted by adjusting the working current of the light source device, and the working current of the light source device is controlled by the light source driving circuit; The light source driving circuit is used to drive the light source device and adjust the light power of the light source device according to the DC voltage given by the DAC circuit; The DAC circuit is used to output a DC voltage according to a voltage control signal received from the automatic control device; The photoelectric receiver is used to receive the light-shielding pulse of the particle through the incident window and convert the received light into photocurrent; The I / U conversion circuit is used to convert the photocurrent into a photovoltage, which is a particle pulse voltage signal; The ADC sampling circuit is used to sample the photovoltage and send the sample to the detection circuit; The detection circuit is used to detect the particle concentration value in the fluid, and the detection circuit obtains the particle concentration value in the fluid according to sampling; The automatic control device is used to automatically adjust the voltage across the light source device, including a voltage measuring component, a voltage control component, a voltage storage component and an optimal interval detection component; specifically: The voltage control component controls the DC voltage output by the DAC circuit by outputting a voltage control signal, thereby adjusting the light source voltage at both ends of the light source device; the voltage control component first sets the DC voltage to the minimum voltage that makes the light source device work through the voltage control signal, and then gradually increases the light source voltage to the maximum voltage that the light source device works through the voltage control signal, and then queries the optimal voltage control signal corresponding to the optimal light source voltage interval from the voltage storage component according to the optimal light source voltage interval returned by the optimal interval detection component, and the voltage control component outputs the optimal voltage control signal to control the light source voltage, so that the light source voltage is in the optimal light source voltage interval; The voltage measuring device is used to measure the light source voltage at both ends of the light source device and the light voltage converted by the corresponding I / U conversion circuit; The voltage storage component is used to store the output signal of the voltage control component and the light source voltage and light voltage measured by the corresponding voltage measuring device; The optimal interval detection component obtains the optimal light source voltage interval when the photoelectric conversion efficiency is optimal according to the light source voltage and the photovoltage, and sends it to the voltage control component.

2. The device for automatically adjusting light resistance to detect light intensity according to claim 1, characterized in that: The optimal interval detection component obtains the optimal light source voltage interval when the photoelectric conversion efficiency is optimal according to the light source voltage and the photovoltage. The optimal light source voltage interval is determined as follows: First, a photoelectric conversion curve is established based on the light source voltage stored in the voltage storage component and the corresponding photovoltage. The minimum value of the light source voltage is the minimum voltage U of the source device. min1 , the maximum value of the light source voltage is the maximum voltage U of the source device max1 , will [U min1 , U max1 ] is divided into N intervals; The light source voltage range of the ath interval among N intervals is [U ax1 , U ax2 ], according to the photoelectric conversion curve, the corresponding photovoltage [U ay1 , U ay2 ]; therefore, the endpoints of the ath interval are (U ax1 , U ay1 ) and (U ax2 , U ay2 ); The straight line expression of the ath interval is y=A according to the endpoints of the ath interval. a x+B a , A a is the slope of the straight line expression of the ath interval, B a is the intercept of the ath interval straight line expression; The accumulated deviation value of the a-th interval is obtained according to the photoelectric conversion curve and the straight line expression of the a-th interval; The accumulated deviation values ​​of N intervals are calculated respectively, and the interval with the smallest accumulated deviation value is selected as the optimal light source voltage interval.

3. The device for automatically adjusting light resistance to detect light intensity according to claim 2, characterized in that: The min1 , U max1 ] is divided into N intervals, specifically: N intervals can be in [U min1 , U max1 ] is evenly divided into N intervals, or it can be divided into min1 Start partitioning according to the specified interval size until U max1 .

4. The device for automatically adjusting light resistance to detect light intensity according to claim 2, characterized in that: The cumulative deviation value of the a-th interval is obtained according to the photoelectric conversion curve and the straight line expression of the a-th interval, specifically: For the ath interval, the light source voltage [U ax1 , U ax2 ] uniformly select M points, for the i-th point, the corresponding photovoltage on the photoelectric conversion curve is U ai , the photovoltage obtained according to the linear expression is y ai , the cumulative deviation of the ath interval is:

5. The device for automatically adjusting light resistance to detect light intensity according to claim 2, characterized in that: The N intervals are taken from U min1 At the beginning, each 100mV is a section until U max1 ; When calculating the cumulative deviation value of the ath interval, one point is taken at every 1 mV interval.

6. The device for automatically adjusting light resistance to detect light intensity according to claim 1, characterized in that: The light source driving circuit includes a composite amplifier tube and a proportional gain circuit, specifically: The emitter of the composite amplifier tube provides working current for the light source device to adjust the luminous power; the base voltage of the composite amplifier tube is controlled by a proportional gain circuit; the proportional gain circuit is implemented by a low offset operational amplifier, and the circuit amplifies the input DC voltage as the base voltage of the composite amplifier tube; the DC voltage of the proportional gain circuit is given through a DAC circuit; adjusting the DC voltage input of the proportional gain circuit can achieve the effect of adjusting the emitter current of the composite amplifier tube, and the emitted light power of the light source device also changes accordingly.

7. The device for automatically adjusting light resistance to detect light intensity according to claim 1, characterized in that: The light source device is a laser diode or a light emitting diode, and the photoelectric receiver is a photodiode.

8. The device for automatically adjusting light resistance to detect light intensity according to claim 1, characterized in that: The photovoltage is a particle pulse voltage signal.

9. A method for using the device for automatically adjusting light resistance to detect light intensity as claimed in any one of claims 1 to 8, characterized in that: It includes the following steps: Step 1: Setting the minimum voltage and maximum voltage of the light source device by means of a voltage measuring component of an automatic control device; Step 2, allowing the fluid to stably pass through the flow passage of the flow passage valve block; Step 3: The voltage control component of the automatic control device sends a voltage control signal to change the DC voltage output by the DAC from low to high according to the minimum voltage of the light source device; at the same time, the voltage measuring device of the automatic control device measures the light source voltage and the corresponding photovoltage at both ends of the light source device, and stores the voltage control signal and the corresponding light source voltage and photovoltage in the voltage storage component; Step 4: When the light source voltage reaches the maximum operating voltage of the light source device, the voltage control component of the automatic control device stops changing the DC voltage output by the DAC; Step 5, the optimal interval detection component of the automatic control device obtains the optimal light source voltage interval when the photoelectric conversion efficiency is optimal according to the light source voltage and the photovoltage stored in the voltage storage component, and sends it to the voltage control component; Step 6: The voltage control component searches for the corresponding optimal voltage control signal from the voltage storage component according to the optimal light source voltage interval, and the voltage control component uses the optimal voltage control signal to input into the DAC, so that the light source voltage and the photovoltage are in the optimal state of photoelectric conversion efficiency; Step seven: the detection circuit detects the particle concentration value in the fluid.

10. The method of the device for automatically adjusting light resistance to detect light intensity according to claim 9, characterized in that: The step seven also includes: During the detection process, the voltage measuring device of the automatic control device continuously measures the light source voltage at both ends of the light source device. When the light source voltage is lower than the optimal light source voltage range, the voltage measuring device sends a voltage increase signal to the voltage control component, and the voltage control component adjusts the voltage control signal to increase the DC voltage output by the DAC. When the light source voltage is higher than the optimal light source voltage range, the voltage measuring device sends a voltage decrease signal to the voltage control component, and the voltage control component adjusts the voltage control signal to reduce the DC voltage output by the DAC.

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