Photoelectric signal circuit for detecting particulate matters in air

Abstract

The utility model relates to a photoelectric signal circuit for detecting air particulate matters, which comprises a photoelectric tube D4 and an operational amplifier U3A, the positive electrode of the photoelectric tube D4 is connected to the in-phase input end of the operational amplifier U3A, the negative electrode of the photoelectric tube D4 is connected to the inverting input end of the operational amplifier U3A, a capacitor C28 and a resistor R26 which are connected in parallel are bridged between the inverting input end and the output end of the operational amplifier U3A, and the capacitor C28 and the resistor R26 are connected in parallel. The output end of the operational amplifier U3A is further connected with a resistor R41 and a capacitor C44 which are connected in series and grounded, a resistor R33 is further externally connected between the positive electrode of the phototube D4 and the in-phase input end of the operational amplifier U3A, a resistor R39 and a capacitor C38 are further connected in parallel, and the resistor R39 and the capacitor C38 are connected in series. And the concentration or the diameter of the particulate matter can be obtained by processing the photoelectric signal.

Description

Technical Field

[0001] The utility model relates to the technical field of particulate matter detection, in particular to a photoelectric signal circuit for detecting air particulate matter. Background Art

[0002] Particulate matter, also known as dust, refers to various solid or liquid particles uniformly dispersed in an aerosol system. The main methods for measuring particulate matter in the air are: 1. Gravimetric method, 2. Concentration specification table comparison method, 3. Particle counting method, 4. Light scattering method, 5. Photometric determination method, etc. At present, no stable photoelectric signal circuit detection method has been proposed. Content of the Utility Model

[0003] Objective of the utility model: In order to overcome the defects of the prior art, the utility model provides a photoelectric signal circuit for detecting air particulate matter. By processing the photoelectric signal, the concentration or diameter of the particulate matter can be obtained.

[0004] Technical solution of the utility model: A photoelectric signal circuit for detecting air particulate matter includes a phototube D4 and an operational amplifier U3A. The positive electrode of the phototube D4 is connected to the non-inverting input terminal of the operational amplifier U3A, and the negative electrode of the phototube D4 is connected to the inverting input terminal of the operational amplifier U3A. A capacitor C28 and a resistor R26 connected in parallel are connected across the inverting input terminal and the output terminal of the operational amplifier U3A. The output terminal of the operational amplifier U3A is also connected to a series-connected resistor R41 and capacitor C44 and grounded. An external resistor R33 is also connected between the positive electrode of the phototube D4 and the non-inverting input terminal of the operational amplifier U3A, and a resistor R39 and a capacitor C38 are also connected in parallel. The resistor R39 and the capacitor C38 are connected in series.

[0005] Preferably, the output voltage of the operational amplifier U3A is also connected to the non-inverting input terminal of the operational amplifier U3B through a capacitor C34. A capacitor C29 and a resistor R30 connected in parallel are connected across the inverting input terminal and the output terminal of the operational amplifier U3B. The inverting input terminal of the operational amplifier U3B is also grounded through a resistor R28. The output terminal of the operational amplifier U3B is also connected to a series-connected resistor R31 and capacitor C35 and grounded. An external resistor R29 is also connected between the capacitor C4 and the non-inverting input terminal of the operational amplifier U3B, and a resistor R36 and a capacitor C37 are also connected in parallel. The resistor R36 and the capacitor C37 are connected in series.

[0006] Preferably, the models of the operational amplifiers U3A and U3B are RS722XM.

[0007] Preferably, the model of the phototube D4 is SFH 2200 A01.

[0008] By processing the optoelectronic signals, the concentration and diameter of the particulate matter are obtained. The circuit design has high precision, fast response, and good stability. Description of the Drawings

[0009] Figure 1 It is the circuit diagram of the specific embodiment of the present invention. Detailed Embodiment

[0010] Next, the technical solutions in this embodiment will be clearly and completely described in conjunction with the drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0011] As Figure 1 shown, an optoelectronic signal circuit for detecting airborne particulate matter of the present invention includes a phototube D4, operational amplifiers U3A and U3B. The positive electrode of the phototube D4 is connected to the non-inverting input terminal of the operational amplifier U3A, and the negative electrode of the phototube D4 is connected to the inverting input terminal of the operational amplifier U3A. A capacitor C28 and a resistor R26 connected in parallel are connected across the inverting input terminal and the output terminal of the operational amplifier U3A. The output terminal of the operational amplifier U3A is also connected to a series-connected resistor R41 and capacitor C44 and grounded. A resistor R33 is also externally connected between the positive electrode of the phototube D4 and the non-inverting input terminal of the operational amplifier U3A, and a resistor R39 and a capacitor C38 are also connected in parallel. The resistor R39 and the capacitor C38 are connected in series.

[0012] The output voltage of the operational amplifier U3A is also connected to the non-inverting input terminal of the operational amplifier U3B through a capacitor C34. A capacitor C29 and a resistor R30 connected in parallel are connected across the inverting input terminal and the output terminal of the operational amplifier U3B. The inverting input terminal of the operational amplifier U3B is also grounded through a resistor R28. The output terminal of the operational amplifier U3B is also connected to a series-connected resistor R31 and capacitor C35 and grounded. A resistor R29 is also externally connected between the capacitor C4 and the non-inverting input terminal of the operational amplifier U3B, and a resistor R36 and a capacitor C37 are also connected in parallel. The resistor R36 and the capacitor C37 are connected in series.

[0013] Specifically, the models of the operational amplifiers U3A and U3B are RS722XM.

[0014] Specifically, the model of the phototube D4 is SFH 2200 A01.

[0015] The principle of the present invention is:

[0016] Particulate matter enters through the air duct. When passing through the detection port, the scattered light irradiates on the phototube D4, generating a photocurrent, and this photocurrent can be used as an impact current. The amplitude of the impact current is related to the concentration of particulate matter, the sensitivity of the phototube, etc. If factors such as the flow rate of the solidified particulate matter and the output slew rate of the operational amplifier are fixed, the time width of the impact current is positively correlated with the diameter of the particulate matter. Thus, by collecting the width of the impact current, the diameter of the particulate matter can be discriminated; it can also be used as a reference for particle concentration through circuit processing and calculation.

Claims

1. An optoelectronic signal circuit for detecting airborne particulate matter, characterized in that: It includes a phototube D4 and an operational amplifier U3A. The positive pole of the phototube D4 is connected to the non-inverting input terminal of the operational amplifier U3A, and the negative pole of the phototube D4 is connected to the inverting input terminal of the operational amplifier U3A. A capacitor C28 and a resistor R26 in parallel are connected across the inverting input terminal and the output terminal of the operational amplifier U3A. The output terminal of the operational amplifier U3A is also connected to a series-connected resistor R41 and capacitor C44 and grounded. Between the positive pole of the phototube D4 and the non-inverting input terminal of the operational amplifier U3A, there is also an externally connected resistor R33, and a resistor R39 and a capacitor C38 are also connected in parallel. The resistor R39 and the capacitor C38 are connected in series.

2. The optoelectronic signal circuit for detecting airborne particulate matter according to claim 1, wherein: The output voltage of the operational amplifier U3A is also connected to the non-inverting input terminal of the operational amplifier U3B through a capacitor C34. A capacitor C29 and a resistor R30 in parallel are connected across the inverting input terminal and the output terminal of the operational amplifier U3B. The inverting input terminal of the operational amplifier U3B is also grounded through a resistor R28. The output terminal of the operational amplifier U3B is also connected to a series-connected resistor R31 and capacitor C35 and grounded. Between the capacitor C4 and the non-inverting input terminal of the operational amplifier U3B, there is also an externally connected resistor R29, and a resistor R36 and a capacitor C37 are also connected in parallel. The resistor R36 and the capacitor C37 are connected in series.

3. The optoelectronic signal circuit for detecting airborne particulate matter according to claim 2, wherein: The models of the operational amplifiers U3A and U3B are RS722XM.

4. The optoelectronic signal circuit for detecting airborne particulate matter according to claim 1 or 2, characterized in that: The model of the phototube D4 is SFH 2200 A01.

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