Processing circuit of particle counter with test interface and particle counter

Abstract

The utility model discloses a particle counter processing circuit with a test interface and a particle counter, and relates to the field of particle counting, and the particle counter processing circuit comprises a signal amplification circuit and a signal acquisition processing circuit; the signal acquisition and processing circuit comprises a plurality of signal acquisition and processing sub-circuits; the signal acquisition and processing sub-circuit comprises a filter circuit, an operational amplifier circuit and a clamping circuit; the signal amplification circuit can receive a photocurrent signal output by the particle counting sensor, convert and amplify the photocurrent signal by different multiples to obtain a plurality of voltage pulse signals, and output the voltage pulse signals to the corresponding signal acquisition and processing sub-circuits; the filter circuit is used for filtering clutters in the process of receiving the voltage pulse signal; the operational amplifier circuit is used for performing operational amplifier processing on the filtered voltage pulse signal to obtain a particle signal; the clamping circuit is used for clamping the range of the output particle signals. Therefore, the signal acquisition and processing circuit can improve the resolution and definition of the particle signal and ensure that the particle signal meets the requirements of measurement and calibration.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of particle counter, especially a kind of processing circuit of particle counter with test interface and particle counter. BACKGROUND

[0002] Particle counter is a kind of instrument based on the principle of light scattering, for detecting and measuring the concentration of particles in air or liquid. But in actual life, particle counter may exist certain error when leaving factory, and with the increase of use time, sensor, electronic component etc. of particle counter can appear aging, drift etc., thereby affecting the accuracy of measurement result. Therefore, particle counter needs to be measured and calibrated, to ensure that it can provide accurate particle concentration and particle size distribution data in actual use.

[0003] In order to avoid the influence of internal noise and interference of equipment on calibration process, particle signal needs to be separately led out for identification. In prior art, voltage pulse signal for comparison counting output by signal amplification circuit is directly led out for measurement and calibration, without additional processing, which can lead to inaccurate measurement and calibration result due to reasons such as noise in particle signal, insufficient accuracy of particle signal and the like.

[0004] Therefore, how to output particle signal meeting the requirement of measurement and calibration is a problem to be solved at present. UTILITY MODEL CONTENT

[0005] Therefore, the purpose of the utility model is to provide a kind of processing circuit of particle counter with test interface, for outputting particle signal meeting the requirement of measurement and calibration. The specific scheme is as follows:

[0006] In order to solve the above technical problem, the present application provides a kind of processing circuit of particle counter with test interface, comprising: signal amplification circuit, signal acquisition processing circuit;Wherein, the signal acquisition processing circuit contains one or more signal acquisition processing subcircuit;The signal acquisition processing subcircuit includes filter circuit, operational amplifier circuit and clamping circuit;

[0007] The input end of the signal amplification circuit is connected with particle counting sensor, for receiving the photocurrent signal corresponding to particle size output by the particle counting sensor;The output end of the signal amplification circuit is connected with the input end of corresponding signal acquisition processing subcircuit, for converting and amplifying different multiples to obtain a plurality of voltage pulse signals, and outputting the voltage pulse signal to corresponding signal acquisition processing subcircuit;

[0008] The input end of the filter circuit is the input end of the signal acquisition and processing sub-circuit, the output end of the filter circuit is connected with the input end of the operational amplifier circuit, and is used for filtering the noise in the process of receiving the voltage pulse signal;

[0009] The output end of the operational amplifier circuit is connected with the test interface as the output end of the signal acquisition and processing sub-circuit, and is used for operational amplifier processing of the filtered voltage pulse signal to obtain a particle signal.

[0010] The clamping circuit is connected with the output end of the signal acquisition and processing sub-circuit, and is used for clamping the range of the particle signal output by the signal acquisition and processing sub-circuit.

[0011] As an optional solution, in the processing circuit of the particle counter with a test interface, the signal acquisition and processing sub-circuit further comprises a first resistor; wherein the first resistor is a 0 ohm resistor.

[0012] The first end of the first resistor is connected with the output end of the operational amplifier circuit; and the second end of the first resistor is connected with the test interface as the output end of the signal acquisition and processing sub-circuit.

[0013] As an optional solution, in the processing circuit of the particle counter with a test interface, the operational amplifier circuit comprises any one or a combination of several of a voltage follower circuit, a non-inverting amplifier circuit and an inverting amplifier circuit.

[0014] As an optional solution, in the processing circuit of the particle counter with a test interface, the operational amplifier circuit comprises a second resistor, a third resistor, a first capacitor and a first operational amplifier.

[0015] The non-inverting input end of the first operational amplifier is the input end of the operational amplifier circuit.

[0016] The inverting input end of the first operational amplifier, the second end of the second resistor and the first end of the third resistor are connected; the second end of the third resistor is connected with the output end of the first operational amplifier, and the common end thereof is the output end of the operational amplifier circuit.

[0017] The first capacitor is connected with the third resistor in parallel; and the first end of the second resistor is grounded.

[0018] As an optional solution, in the processing circuit of the particle counter with a test interface, the clamping circuit comprises a first diode and a second diode.

[0019] The first diode and the second diode are connected in series, and the common end thereof is connected with the second end of the first resistor.

[0020] The cathode of the first diode is connected with a power supply, and the anode of the second diode is grounded.

[0021] As an optional solution, in the processing circuit of the particle counter with a test interface, the filter circuit comprises a fourth resistor and a second capacitor.

[0022] The first end of the second capacitor serves as an input end of the filter circuit, and the first end of the fourth resistor serves as an output end of the filter circuit, both of which are connected with a non-inverting input end of the first operational amplifier.

[0023] The second end of the fourth resistor and the second end of the second capacitor are grounded.

[0024] As an optional solution, in the processing circuit of the particle counter with a test interface, the signal acquisition and processing sub-circuit further comprises a fifth resistor, and the fifth resistor is a 0-ohm resistor.

[0025] The first end of the fifth resistor serves as an input end of the signal acquisition and processing sub-circuit, and the second end of the fifth resistor is connected with an input end of the filter circuit.

[0026] As an optional solution, in the processing circuit of the particle counter with a test interface, the signal amplification circuit comprises a signal conversion circuit and a plurality of signal amplification sub-circuits.

[0027] The input end of the signal conversion circuit serves as an input end of the signal amplification circuit, and the output end of the signal conversion circuit is connected with an input end of the signal amplification sub-circuit, for converting and amplifying the photoelectric current signal into a first voltage pulse signal.

[0028] The output end of the signal amplification sub-circuit is connected with an input end of the corresponding signal acquisition and processing sub-circuit, for amplifying the first voltage pulse signal according to a set amplification ratio to obtain the voltage pulse signal.

[0029] As an optional solution, in the processing circuit of the particle counter with a test interface, the test interface is an SMA interface.

[0030] To solve the above technical problems, the application further provides a particle counter comprising the particle counting sensor and the processing circuit of the particle counter with a test interface.

[0031] The processing circuit of the particle counter with a test interface provided by the application comprises a signal amplification circuit and a signal acquisition processing circuit, wherein the signal acquisition processing circuit comprises one or more signal acquisition processing sub-circuits, the particle counting sensor outputs a photoelectric current signal corresponding to the particle size to the signal amplification circuit, the signal amplification circuit converts the photoelectric current signal and amplifies it according to different amplification rates to obtain a plurality of voltage pulse signals, the signal acquisition processing sub-circuit comprises a filter circuit, an operational amplifier circuit and a clamping circuit, the output end thereof is connected with a test device, and is used for acquiring the corresponding voltage pulse signal and performing operational amplifier processing on the voltage pulse signal to obtain a particle signal, so as to meet the requirements of test calibration. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can also be obtained according to the provided drawings without creative labor.

[0033] Figure 1 A circuit connection diagram of a particle counter provided by the embodiment of the present application;

[0034] Figure 2 A circuit diagram of a specific signal acquisition processing sub-circuit provided by the embodiment of the present application;

[0035] Figure 3 A circuit diagram of a specific signal acquisition processing sub-circuit provided by the embodiment of the present application;

[0036] Figure 4A circuit connection diagram of a particle counter with a comparison circuit is provided for an embodiment of the present application.

[0037] The reference signs are as follows: 10 is a particle counting sensor, 20 is a signal amplification circuit, 30 is a signal acquisition processing circuit, 21 is a signal conversion circuit, 22 is a signal amplification sub-circuit, 31 is a signal acquisition processing sub-circuit, 311 is an operational amplifier circuit, 312 is a clamping circuit, and 313 is a filter circuit. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0039] The core of the present application is to provide a processing circuit of a particle counter with a test interface and a particle counter.

[0040] In order for those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0041] A particle counter is an instrument based on the principle of light scattering, used for detecting and measuring the concentration of particles in air or liquid. However, in actual life, there may be certain errors in the particle counter when it is shipped, and with the increase of use time, the sensor, electronic components and other components of the particle counter may age, drift and other problems, thereby affecting the accuracy of the measurement results. Therefore, it is necessary to measure and calibrate the particle counter to ensure that it can provide accurate particle concentration and particle size distribution data in actual use.

[0042] In order to avoid the influence of internal noise and interference of the equipment on the calibration process, the particle signal needs to be separately led out for identification. In the prior art, the voltage pulse signal output by the signal amplification circuit 20 for comparison counting is directly led out for measurement and calibration without additional processing, which may result in inaccurate measurement and calibration results due to the existence of noise in the particle signal, insufficient accuracy of the particle signal and other reasons.

[0043] Therefore, how to output a particle signal that meets the measurement and calibration requirements is a problem that needs to be solved at present.

[0044] In order to solve the above problems, the present application provides a particle counter with a test interface. Figure 1 , 2The utility model discloses a kind of processing circuit of particle counter with test interface, comprising: signal amplification circuit 20, signal acquisition processing circuit 30;Wherein, signal acquisition processing circuit 30 contains multiple signal acquisition processing subcircuit 31;Signal acquisition processing subcircuit 31 includes filter circuit 313, operational amplifier circuit 311 and clamping circuit 312;

[0045] The input end of the signal amplification circuit 20 is connected with the particle counting sensor 10, for receiving the photocurrent signal corresponding to the particle size output by the particle counting sensor 10; the output end of the signal amplification circuit 20 is connected with the input end of the corresponding signal acquisition processing subcircuit 31, for converting and amplifying the photocurrent signal to obtain multiple voltage pulse signals, and outputting the voltage pulse signals to the corresponding signal acquisition processing subcircuit 31; but it can be understood that, Figure 2 The above merely illustrates a specific embodiment, and does not represent only this embodiment.

[0046] The input end of the filter circuit 313 serves as the input end of the signal acquisition processing subcircuit 31, and the output end of the filter circuit 313 is connected with the input end of the operational amplifier circuit 311, for filtering the noise in the process of receiving the voltage pulse signal; but it can be understood that the filter circuit 313 can be any circuit capable of realizing the filtering function, Figure 1 The above merely illustrates a specific embodiment, and does not represent only this embodiment.

[0047] The output end of the operational amplifier circuit 311 serves as the output end of the signal acquisition processing subcircuit 31 and is connected with the test interface, for performing operational amplifier processing on the filtered voltage pulse signal to obtain the particle signal; but it can be understood that the operational amplifier circuit 311 can be any circuit capable of performing operational amplifier processing on the voltage pulse signal, Figure 1 The above merely illustrates a specific embodiment, and does not represent only this embodiment.

[0048] The clamping circuit 312 is connected with the output end of the signal acquisition processing subcircuit 31, for clamping the range of the particle signal output by the signal acquisition processing subcircuit 31. But it can be understood that the clamping circuit 312 can be any circuit capable of realizing the clamping function, Figure 1 The above merely illustrates a specific embodiment, and does not represent only this embodiment.

[0049] In this embodiment, the particle counting sensor 10 as the core component of the particle counter can detect particles in the gas or liquid to be measured and convert the particle size signal into a measurable photocurrent signal. In a specific embodiment, the particle counting sensor 10 can convert the scattered light generated by the interaction between the light beam emitted by the laser and the particles in the gas or liquid to be measured into a photocurrent signal based on the light scattering principle. In another specific embodiment, the particle counting sensor 10 can also collect the charged particles generated by ionizing gas molecules to form a current signal based on the ionization effect principle. Here, no specific limitation is made.

[0050] It can be understood that the photocurrent signal output by the particle counting sensor 10 is generally in the order of milliamperes or even microamperes or even lower, which is very weak and difficult to be directly used for measurement calibration or comparison counting. Therefore, the photocurrent signal needs to be output to the signal amplification circuit 20.

[0051] It should be noted that compared with measurement calibration, the particle counter has relatively lower requirements for the particle signal used for comparison counting. Therefore, after the photocurrent signal output by the counting sensor is converted and amplified by the signal amplification circuit 20, the generated multiple groups of voltage pulse signals can be directly used for comparison counting of the particle counter.

[0052] In this embodiment, the photocurrent signal input to the signal amplification circuit 20 by the particle counting sensor 10 is a current signal, while comparison counting and measurement calibration generally require voltage signals for processing and analysis. Therefore, in some cases, the signal amplification circuit 20 also needs to include a signal conversion circuit 21, which includes a transimpedance amplifier and an operational amplifier, and can convert and amplify the current signal into a voltage signal.

[0053] It should be noted that the resolution and clarity of the particle signal required by the measurement calibration are very strict, and the voltage pulse signal output by the signal amplification circuit 20 may only meet the requirements of comparison counting. Therefore, a signal acquisition and processing circuit 30 can be added between the signal amplifier and the test equipment to obtain the particle signal as the final signal output to the test equipment after the voltage pulse signal is processed again.

[0054] In this embodiment, since the signal amplification circuit 20 outputs multiple groups of voltage pulse signals, and different groups of voltage pulse signals are obtained by different set amplification rates, the signal acquisition and processing circuit 30 needs to be divided into multiple signal acquisition and processing sub-circuits 31 corresponding to the voltage pulse signals output by the signal amplification sub-circuit which needs to be processed again, and the received voltage pulse signals are processed respectively. It can be understood that the specific structure of the signal acquisition and processing sub-circuit 31 depends on the gap between the resolution and clarity of the corresponding voltage pulse signal and the requirement of the measurement calibration.

[0055] In this embodiment, the signal acquisition and processing sub-circuit 31 includes an operational amplifier circuit 311, a filter circuit 313 and a clamping circuit 312. The operational amplifier circuit 311 can perform operational amplification processing on the voltage pulse signal to meet the resolution requirement of the measurement calibration. The filter circuit 313 can filter the noise in the process of receiving the voltage pulse signal to meet the definition requirement of the measurement calibration. The clamping circuit 312 can limit the range of the particle signal finally input to the test equipment, and limit the output voltage within the limit range of the clamping circuit 312. Since the voltage pulse signal input to different signal acquisition and processing sub-circuits 31 is the photocurrent signal amplified by different set magnifications, the particle signal range most suitable for the set magnification needs to be selected and input to the test equipment to ensure the accuracy of the measurement calibration result. The operational amplifier circuit can include one or a combination of a voltage follower circuit, a non-inverting amplifier circuit and an inverting amplifier circuit, and the operational amplification processing can be amplification, reduction or following, etc.

[0056] In a specific case, as shown in Figure 2 FIG. 2 is a circuit diagram of a specific signal acquisition and processing sub-circuit 31. The operational amplifier circuit 311 is composed of a second resistor R2, a third resistor R3, a first capacitor C1 and a first operational amplifier U1. RX_OUT1 is the output terminal of the first operational amplifier U1, which is connected to the test interface via a first resistor R1. The filter circuit 313 is composed of a second capacitor C2 and a fourth resistor R4. The clamping circuit 312 is composed of a first diode D1 and a second diode D2. The power supply VCC_10 is used to provide the voltage level of one clamping in the clamping circuit 312. RX_IN2 is the input terminal of the signal acquisition and processing sub-circuit 31. The output terminal of the signal acquisition and processing sub-circuit 31 is connected to pin 5 of U70, and U70 is an SMA interface.

[0057] It can be understood that if the voltage pulse signal output by the signal amplification circuit 20 has met the requirement of the measurement calibration, as shown in Figure 3 FIG. 3, the signal acquisition and processing sub-circuit 31 can only have a sixth resistor R6. RX_IN3 is the input terminal of the signal acquisition and processing sub-circuit 31, which is connected to the output terminal of the signal amplification circuit 20. At this time, the voltage pulse signal is output to the test interface via the sixth resistor R6, and the voltage pulse signal is directly used for measurement calibration. The sixth resistor R6 is a 0-ohm resistor. In the figure, U72 is an SMA interface.

[0058] It should be noted that the voltage pulse signal output by the signal amplification circuit 20 can be directly input to the comparison circuit for comparison counting. As shown in Figure 4 FIG. 4, the comparison circuit includes a plurality of comparison sub-circuits. The input terminals of the comparison sub-circuits are respectively connected to the output terminals of the corresponding signal amplification sub-circuits 22, for receiving the voltage pulse signal output by the signal amplification sub-circuit 22 to perform comparison counting and output a counting signal.

[0059] In the embodiment, the multiple voltage pulse signals output by the signal amplification circuit 20 are output to different comparison sub-circuits respectively. Since the voltage pulse signals output by the signal amplification circuit 20 are converted and amplified to meet the resolution requirement of comparison counting, the comparison sub-circuits can directly perform comparison counting after receiving the voltage pulse signals. Generally, there is a comparison threshold in one comparison sub-circuit, and the voltage pulse signal output by the signal amplification sub-circuit 22 is compared with the comparison threshold in the comparison sub-circuit connected thereto. If the condition is met, it is preliminarily determined that the particle in the particle size range corresponding to the comparison sub-circuit, and a counting signal is output, so as to realize accurate classification and counting of particles of different particle sizes.

[0060] As can be seen from the above, the photoelectric current signal of the particle output by the particle counting sensor 10 can be output as multiple voltage pulse signals with a set amplification ratio through the signal amplification circuit 20, and the voltage pulse signals are output to the corresponding signal acquisition and processing sub-circuit 31. In the signal amplification circuit 20, the photoelectric current signal can be amplified with a suitable amplification ratio, and the amplification ratios of different voltage pulse signals output are different, so that the resolution of the signal is improved. However, the resolution and accuracy of the voltage pulse signals output at this time may not meet the requirement of measurement calibration. After the voltage pulse signal output by the signal amplification sub-circuit 22 is input to the corresponding signal acquisition and processing sub-circuit 31, the filter circuit 313 can filter out the interference signal in the process of receiving the voltage pulse signal, so as to meet the requirement of measurement calibration on the accuracy of the particle signal. The operational amplifier circuit 311 can perform secondary operation on the voltage pulse signal, so as to meet the requirement of measurement calibration on the resolution of the particle signal. The clamping circuit 312 clamps the range of the particle signal output by the signal acquisition and processing sub-circuit 31, that is, it can ensure that the output particle signal meets the range requirement of measurement calibration, and can also avoid the situation that the particle signal output is too high and the test equipment needs to measure a larger range of signal, that is, the performance requirement of the test equipment can be reduced. Therefore, the signal acquisition and processing circuit 30 can ensure that the output particle signal meets the requirement of measurement calibration.

[0061] In order to facilitate measurement calibration, the utility model discloses a kind of processing circuit of particle counter with test interface, relative to last embodiment, the technical scheme of this embodiment is further described and optimized.Specifically:

[0062] The signal acquisition and processing sub-circuit 31 further comprises a first resistor R1.

[0063] The first end of the first resistor R1 is connected with the output end of the operational amplifier circuit 311. The second end of the first resistor R1 is connected with the test interface as the output end of the signal acquisition and processing sub-circuit 31.

[0064] In the embodiment, the first resistor R1 is a 0 ohm resistor which can be used to lead the particle signal to be tested, and the 0 ohm resistor can be used as a temporary connection or disconnection means, and the connection mode of the circuit can be quickly changed by welding or removing the 0 ohm resistor. When only a part of the particle diameter particle signal needs to be measured and calibrated, the 0 ohm resistor can be removed to switch the particle signal range input to the test device.

[0065] As can be seen from the above, because the 0 ohm resistor can be used as a temporary connection or disconnection means, the first resistor R1 is arranged between the output end of the signal acquisition processing sub-circuit 31 and the test interface, and the particle signal range input to the test device can be switched by a simple operation, and the first resistor R1 can also lead the particle signal to be tested, so that the measurement and calibration are more convenient.

[0066] In order to perform appropriate operational amplification processing on the voltage pulse signal to meet the measurement and calibration requirements, the utility model discloses a specific processing circuit of particle counter with test interface, and relative to the previous embodiment, the technical scheme is further explained and optimized. Specifically:

[0067] The operational amplifier circuit includes any one or combination of the voltage follower circuit, the non-inverting amplifier circuit and the inverting amplifier circuit.

[0068] In the embodiment, the operational amplifier circuit 311 can select any one or combination of the voltage follower circuit, the non-inverting amplifier circuit and the inverting amplifier circuit according to the actual situation of the voltage pulse signal. When the resolution of the voltage pulse signal does not meet the measurement and calibration requirements, different magnifications of the non-inverting amplifier circuit and the inverting amplifier circuit are selected as the operational amplifier circuit 311 according to specific scaling requirements. When it is required to ensure that the input voltage is equal to the output voltage, the voltage follower circuit needs to be selected as the operational amplifier circuit 311.

[0069] Therefore, any one or combination of the voltage follower circuit, the non-inverting amplifier circuit and the inverting amplifier circuit with different magnifications is selected as the operational amplifier circuit 311 based on specific conditions, so that appropriate operational amplification processing can be performed on the voltage pulse signal to meet the measurement and calibration requirements.

[0070] In order to perform secondary operational amplification on the voltage pulse signal, the utility model discloses a specific processing circuit of particle counter with test interface, and relative to the previous embodiment, the technical scheme is further explained and optimized. Specifically:

[0071] The operational amplifier circuit 311 includes a second resistor R2, a third resistor R3, a first capacitor C1 and a first operational amplifier U1.

[0072] The non-inverting input end of the first operational amplifier U1 is used as the input end of the operational amplifier circuit 311.

[0073] The inverting input terminal of the first operational amplifier U1, the second terminal of the second resistor R2 and the first terminal of the third resistor R3 are connected; the second terminal of the third resistor R3 is connected with the output terminal of the first operational amplifier U1, and the common terminal is as the output terminal of the operational amplifier circuit 311;

[0074] The first capacitor C1 is connected with the third resistor R3 in parallel; and the first terminal of the second resistor R2 is grounded.

[0075] In the application, the operational amplifier circuit 311 adopts an operational amplifier to realize the secondary amplification of the voltage pulse signal, wherein the size of the second resistor R2 and the third resistor R3 can be set to adjust the amplification multiple of the operational amplifier circuit 311, wherein the first operational amplifier U1 and the third resistor R3 form a negative feedback loop, the second resistor R2 in the operational amplifier circuit 311 has a voltage dividing effect with one end grounded, and the amplification multiple of the amplifier can be adjusted by changing the ratio of the second resistor R2 and the third resistor R3. In addition, the first capacitor C1 and the third resistor R3 are connected in parallel to form a direct current isolation circuit for isolating direct current voltage. With the increase of the signal frequency, the capacitive reactance of the first capacitor C1 gradually decreases, realizing the bypass effect of the high-frequency signal, reducing the effect of the high-frequency signal in the negative feedback loop, improving the amplification function of the first operational amplifier U1 to the high-frequency signal, and widening the bandwidth of the first operational amplifier U1.

[0076] As can be seen from the above, the operational amplifier circuit 311 comprises the first operational amplifier U1, and based on the basic function of the first operational amplifier U1 to amplify the input signal, the secondary operational amplifier can realize the amplification, reduction and following of the voltage pulse signal, and the amplification multiple is determined by the size of the second resistor R2 and the third resistor R3. The low-pass filter circuit formed by the first capacitor C1 and the third resistor R3 can ensure the normal operation of the first operational amplifier U1 and widen the bandwidth of the first operational amplifier U1. Therefore, the operational amplifier circuit 311 can realize the secondary operational amplifier of the voltage pulse signal.

[0077] In order to limit the particle signal range output by the signal acquisition and processing sub-circuit 31, the utility model discloses a kind of processing circuit of particle counter with test interface, relative to last embodiment, this embodiment is further described and optimized to technical solution. Specifically:

[0078] The clamping circuit 312 includes: the first diode D1 and the second diode D2.

[0079] The first diode D1 and the second diode D2 are connected in series, and the common terminal is connected with the second terminal of the first resistor R1.

[0080] The cathode of the first diode D1 is connected with the power supply; and the anode of the second diode D2 is grounded.

[0081] In the embodiment, when the output voltage of the signal acquisition and processing sub-circuit 31 continuously rises until exceeding the sum of the power supply voltage and the conduction voltage of the first diode D1, the first diode D1 is turned on, the voltage difference between the two ends of the first diode D1 is quickly stabilized and maintained near the conduction voltage of the first diode D1, so that the output voltage of the signal acquisition and processing sub-circuit 31 cannot continue to rise, and the upper limit clamping is realized; when the output voltage of the signal acquisition and processing sub-circuit 31 continuously decreases until exceeding the sum of the ground voltage and the conduction voltage of the second diode D2, the second diode D2 is turned on, the voltage difference between the two ends of the second diode D2 is quickly stabilized and maintained near the conduction voltage of the second diode D2, so that the output voltage of the signal acquisition and processing sub-circuit 31 cannot continue to decrease, and the lower limit clamping is realized.

[0082] Generally, the particle counter counts the particles of the particle size standard and above the particle size standard as the particle size standard, for example, the particle count of the 0.3-micron particle size standard is for the particles with a particle size of 0.3 microns or more, or counts the particles with a particle size between two particle size standards as a low particle size standard, for example, when the adjacent particle size standards are 0.3 microns and 0.5 microns, the particle count of the 0.3-micron particle size standard is for the particles with a particle size of 0.3 microns to less than 0.5 microns, so that the size of the output particle signal is limited under the premise that the test equipment meets the calibration particle signal, and the range of the test equipment for calibration and identification also does not need to be too large.

[0083] As can be seen from the above, based on the unidirectional conduction of the first diode D1 and the second diode D2, and the characteristic that the voltage difference between the two ends of the diode is maintained near the conduction voltage after the diode is turned on, the upper limit clamping and the lower limit clamping of the output voltage of the signal acquisition and processing sub-circuit 31 can be realized, so that the particle signal range output by the signal acquisition and processing sub-circuit 31 can be limited through the clamping circuit 312.

[0084] In order to improve the accuracy of the particle signal, the utility model discloses a kind of specific particle counter processing circuit with test interface, relative to last embodiment, this embodiment is further described and optimized to technical solution. Specifically:

[0085] The filter circuit 313 includes a fourth resistor R4 and a second capacitor C2.

[0086] The first end of the second capacitor C2 is connected to the non-inverting input terminal of the first operational amplifier U1 as the input terminal of the filter circuit 313, and the first end of the fourth resistor R4 is connected to the output terminal of the filter circuit 313.

[0087] The second end of the fourth resistor R4 and the second end of the second capacitor C2 are grounded.

[0088] In the embodiment, the second capacitor C2 and the fourth resistor R4 can form an RC filter circuit. Since the capacitive reactance of the capacitor is inversely proportional to the signal frequency, when the voltage pulse signal input into the signal acquisition processing sub-circuit 31 is a low-frequency signal, the second capacitor C2 is equivalent to an open circuit, and most of the voltage pulse signal passes through the fourth resistor R4 and is output from the filter circuit 313. For a high-frequency signal, the capacitive reactance of the second capacitor C2 decreases rapidly, so most of the high-frequency signal flows to the ground through the second capacitor C2, thereby realizing bypassing and attenuating the high-frequency signal.

[0089] As can be seen from the above, the second capacitor C2 and the fourth resistor R4 form an RC filter circuit 313. Due to the characteristic that the capacitive reactance of the second capacitor C2 is inversely proportional to the signal frequency, most of the high-frequency signal is bypassed and attenuated, thereby realizing suppression of the high-frequency signal. Therefore, the accuracy of the particle signal can be improved by the filter circuit 313.

[0090] In order to ensure the accuracy of the measurement calibration, the utility model discloses a kind of specific particle counter processing circuit with test interface, relative to last embodiment, the technical solution of this embodiment is further described and optimized.Specifically:

[0091] The signal acquisition processing sub-circuit 31 further comprises a fifth resistor R5.

[0092] The first end of the fifth resistor R5 is connected to the input end of the signal acquisition processing sub-circuit 31, and the second end of the fifth resistor R5 is connected to the input end of the filter circuit 313.

[0093] In the embodiment, the signal acquisition processing sub-circuit 31 is not directly connected to the output end of the signal amplification circuit 20, but a 0-ohm resistor is arranged at the connection. This is because there may be mutual interference between different circuit modules. The 0-ohm resistor can be used as a simple isolation means to isolate the signal acquisition processing sub-circuit 31 from the signal amplification circuit 20, thereby avoiding interference with the particle signal output to the test equipment and ensuring the accuracy of the measurement calibration result. In addition, the fifth resistor R5 as a 0-ohm resistor can also be used to lead the voltage pulse signal to be processed again.

[0094] It can be understood that the 0-ohm resistor in the present application is not a resistor with an ohmic value of 0. Generally, a 0-ohm resistor has a certain resistance value, for example, a resistance value less than 100 ohms, such as 30 ohms or 50 ohms. The resistance value is not specifically limited according to the circuit requirements.

[0095] As can be seen from the above, the fifth resistor R5 is arranged between the output end of the signal amplification circuit 20 and the input end of the signal acquisition processing sub-circuit 31. The isolation effect of the 0-ohm resistor can be utilized to avoid signal interference between the signal amplification circuit 20 and the signal acquisition processing sub-circuit 31.

[0096] In order to generate a plurality of different magnification amplified voltage pulse signals, the utility model discloses a kind of specific processing circuit of particle counter with test interface, relative to last embodiment, the technical solution of this embodiment is further described and optimized.Specifically:

[0097] Signal amplification circuit 20 includes: signal conversion circuit 21 and multiple signal amplification sub-circuit 22;

[0098] The input end of signal conversion circuit 21 is as the input end of signal amplification circuit 20, and the output end of signal conversion circuit 21 is connected with the input end of signal amplification sub-circuit 22, for converting and amplifying photoelectric current signal as first voltage pulse signal;

[0099] The output end of signal amplification sub-circuit 22 is connected with the input end of corresponding signal acquisition processing sub-circuit 31, for amplifying first voltage pulse signal according to set magnification, and obtains voltage pulse signal.

[0100] In the embodiment, signal conversion circuit 21 includes transimpedance amplifier, operational amplifier, if particle count sensor 10 output is photoelectric current signal, cannot be directly used for measurement calibration and comparison count, signal conversion circuit 21 can convert the photoelectric current signal into signal that can be analyzed and identified.For example, when particle count sensor 10 output is photoelectric current signal is current signal, signal conversion circuit 21 can convert photoelectric current signal into voltage pulse signal.

[0101] It can be understood that signal amplification circuit 20 can convert and amplify the above-mentioned photoelectric current signal according to different amplification rates to obtain multiple groups of voltage pulse signals, so signal amplification circuit 20 can include multiple signal amplification sub-circuits 22, each signal amplification sub-circuit 22 has different amplification rates, to ensure that the signals of each particle size standard particle of particle counter can be effectively amplified and transmitted, to avoid signal distortion or uneven frequency response problems. Among them, one signal amplification sub-circuit 22 can include one or more cascaded operational amplifiers, and each signal amplification sub-circuit 22 can also share operational amplifier.

[0102] In a specific embodiment, signal amplification circuit 20 can include multiple single-stage amplification circuits with different set magnifications, each single-stage amplification circuit is a signal amplification sub-circuit 22, which can include one or more operational amplifiers, and the single-stage amplification circuits are independent of each other and are connected with the output end of particle count sensor 10, so that signal amplification circuit 20 can output multiple voltage pulse signals with different amplification rates.

[0103] In another specific embodiment, the signal amplification circuit 20 can be composed of multiple single-stage amplification circuits connected in series, and the amplification factor is gradually increased through multi-stage amplification, so that the output voltage pulse signal of the multiple single-stage amplification circuits with appropriate amplification factor can be selected according to the demand of the amplification factor, so as to realize the multi-ratio amplification of the photoelectric current signal.

[0104] It can be understood that there may be noise in the process of outputting the photoelectric current signal, and therefore the signal amplification sub-circuit 22 can also include a filter for smoothing the output voltage pulse signal and improving the stability of the particle counter.

[0105] As can be seen from the above, the signal conversion circuit 21 can convert and amplify the photoelectric current signal, different signal amplification sub-circuits 22 have different set ratios, and therefore the signal amplification circuit 20 can output voltage pulse signals of different amplification ratios that can be used for measurement calibration and comparison counting.

[0106] In order to ensure stable signal transmission between the output end of the signal acquisition and processing circuit 30 and the test equipment, the utility model embodiment discloses a specific particle counter processing circuit with a test interface, which is further described and optimized compared with the previous embodiment. Specifically:

[0107] The test interface is an SMA interface.

[0108] In the embodiment, the test interface can be an SMA interface. The SMA interface can support a wide frequency range, usually up to 18GHz or higher, and some high-performance models can even reach 26.5GHz, which is suitable for transmission of various high-frequency signals and can meet the needs of different high-frequency application scenarios such as wireless networks, satellite communications, radar measurement, etc. In addition, the SMA interface adopts a metal shell and an internal shielding structure, which can effectively prevent external interference signals from affecting the stability and reliability of signal transmission, thereby ensuring the accuracy of test data. As the most common and widely used radio frequency interface standard, the size, specification and electrical performance of the SMA interface are clearly defined, and products produced by different manufacturers that meet the SMA standard have good interchangeability and compatibility, making it convenient for users to select and replace equipment and accessories.

[0109] As can be seen from the above, due to the characteristics of the SMA interface such as wide frequency range and internal shielding structure, the connection between the signal acquisition and processing circuit 30 and the test equipment and the stable signal transmission can be ensured.

[0110] Finally, the embodiment provides a particle counter comprising the above-mentioned particle counter processing circuit with a test interface.

[0111] The above description of disclosed embodiments enables one of ordinary skill in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A processing circuit of a particle counter with a test interface, characterized in that The application relates to a signal amplification circuit and a signal acquisition processing circuit. The signal acquisition processing circuit comprises one or more signal acquisition processing sub-circuits, and the signal acquisition processing sub-circuit comprises a filter circuit, an operational amplifier circuit and a clamping circuit. The input end of the signal amplification circuit is connected with a particle counting sensor, used for receiving a photocurrent signal corresponding to the particle size output by the particle counting sensor; the output end of the signal amplification circuit is connected with the input end of the corresponding signal acquisition processing sub-circuit, used for converting and amplifying the photocurrent signal to obtain multiple voltage pulse signals, and outputting the voltage pulse signals to the corresponding signal acquisition processing sub-circuit; The input end of the filter circuit is used as the input end of the signal acquisition processing sub-circuit, the output end of the filter circuit is connected with the input end of the operational amplifier circuit, and the filter circuit is used for filtering the voltage pulse signal during the receiving process; The output end of the operational amplifier circuit is used as the output end of the signal acquisition processing sub-circuit and is connected with a test interface, used for performing operational amplifier processing on the filtered voltage pulse signal to obtain a particle signal; The clamping circuit is connected with the output end of the signal acquisition processing sub-circuit, used for clamping the range of the particle signal output by the signal acquisition processing sub-circuit.

2. The processing circuit of a particle counter with test interface according to claim 1, characterized in that, The signal acquisition processing sub-circuit further comprises a first resistor, wherein the first resistor is a 0-ohm resistor; The first end of the first resistor is connected with the output end of the operational amplifier circuit, and the second end of the first resistor is used as the output end of the signal acquisition processing sub-circuit and is connected with a test interface.

3. The processing circuit of a particle counter with test interface according to claim 1, characterized in that, The operational amplifier circuit comprises any one or a combination of several of a voltage follower circuit, a non-inverting amplifier circuit and an inverting amplifier circuit.

4. The processing circuit of a particle counter with test interface of claim 1, wherein, The operational amplifier circuit comprises a second resistor, a third resistor, a first capacitor and a first operational amplifier; The non-inverting input end of the first operational amplifier is used as the input end of the operational amplifier circuit; The inverting input end of the first operational amplifier, the second end of the second resistor and the first end of the third resistor are connected; the second end of the third resistor is connected with the output end of the first operational amplifier, and the common end is used as the output end of the operational amplifier circuit; The first capacitor is connected with the third resistor in parallel, and the first end of the second resistor is grounded.

5. The particle counter with test interface processing circuit of claim 1, wherein, The clamping circuit comprises a first diode and a second diode; The first diode and the second diode are connected in series, and the common end is connected with the second end of the first resistor; The cathode of the first diode is connected with a power supply, and the anode of the second diode is grounded.

6. The processing circuit of a particle counter with test interface according to claim 4, characterized in that, The filter circuit comprises a fourth resistor and a second capacitor; The first end of the second capacitor is used as the input end of the filter circuit, and the first end of the fourth resistor is used as the output end of the filter circuit, and both are connected with the non-inverting input end of the first operational amplifier; The second end of the fourth resistor and the second end of the second capacitor are grounded.

7. The particle counter with test interface processing circuit of claim 1, wherein, The signal acquisition processing sub-circuit further comprises a fifth resistor, and the fifth resistor is a 0-ohm resistor; The first end of the fifth resistor is used as the input end of the signal acquisition processing sub-circuit, and the second end of the fifth resistor is connected with the input end of the filter circuit.

8. The processing circuit of a particle counter with test interface according to any one of claims 1 to 7, characterized in that, The signal amplification circuit comprises a signal conversion circuit and a plurality of signal amplification sub-circuits; An input end of the signal conversion circuit serves as an input end of the signal amplification circuit, and an output end of the signal conversion circuit is connected with an input end of the signal amplification sub-circuit, for converting and amplifying the photoelectric current signal into a first voltage pulse signal; An output end of the signal amplification sub-circuit is connected with an input end of the corresponding signal acquisition and processing sub-circuit, for amplifying the first voltage pulse signal according to a set amplification ratio, to obtain the voltage pulse signal.

9. The particle counter with test interface processing circuit of claim 1, wherein, The test interface is an SMA interface.

10. A particle counter, characterized by, A processing circuit of the particle counter with the test interface according to any one of claims 1 to 9 and the particle counting sensor.

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