阅读说明：本技术 一种微弱脉冲信号放大电路和微尘探测器 (Weak pulse signal amplifying circuit and micro-dust detector ) 是由 李兴冀 杨剑群 董尚利 吕钢 于 2020-07-28 设计创作，主要内容包括：本发明涉及放大电路技术领域,提供一种微弱脉冲信号放大电路和微尘探测器,包括输入电容、冲击传感器、电荷灵敏前置放大子电路和电荷灵敏后置放大子电路,输入电容和冲击传感器各自与电荷灵敏前置放大子电路的输入端电连接,电荷灵敏后置放大子电路与电荷灵敏前置放大子电路级联组成电荷灵敏放大子电路,成倍提高了电荷灵敏放大子电路的放大倍率,提升了电荷灵敏放大子电路的信号放大能力,在冲击传感器处于空闲状态下,利用输入电容,测试电荷灵敏放大子电路与冲击传感器适配,在冲击传感器处于探测状态下,输入电容防止输出微弱电荷脉冲信号至电荷灵敏放大子电路的性能,以免输入电容对冲击传感器产生信号干扰。(The invention relates to the technical field of amplifying circuits, and provides a weak pulse signal amplifying circuit and a dust detector, which comprise an input capacitor, an impact sensor, a charge sensitive pre-amplifying sub-circuit and a charge sensitive post-amplifying sub-circuit, wherein the input capacitor and the impact sensor are respectively electrically connected with the input end of the charge sensitive pre-amplifying sub-circuit, the charge sensitive post-amplifying sub-circuit and the charge sensitive pre-amplifying sub-circuit are cascaded to form the charge sensitive amplifying sub-circuit, the amplification factor of the charge sensitive amplifying sub-circuit is increased in multiples, the signal amplification capability of the charge sensitive amplifying sub-circuit is improved, the input capacitor is utilized to test the adaptation of the charge sensitive amplifying sub-circuit and the impact sensor when the impact sensor is in an idle state, and the input capacitor prevents the output of a weak charge pulse signal to the charge sensitive amplifying sub-circuit when the impact sensor is in a detection state, so as to avoid the input capacitance from generating signal interference on the impact sensor.)

1. The weak pulse signal amplification circuit is characterized by comprising an input capacitor (1), an impact sensor (2), a charge sensitive pre-amplification sub-circuit (3) and a charge sensitive post-amplification sub-circuit (4), wherein the input capacitor (1) and the impact sensor (2) are respectively and electrically connected with the input end of the charge sensitive pre-amplification sub-circuit (3), and the output end of the charge sensitive pre-amplification sub-circuit (3) is electrically connected with the input end of the charge sensitive post-amplification sub-circuit (4);

the input capacitor (1) is used for receiving an alternating current pulse signal, converting the alternating current pulse signal into a weak charge pulse signal and outputting the weak charge pulse signal to the input end of the charge sensitive pre-amplifier sub-circuit (3) when the impact sensor (2) is in a first idle state, wherein the first idle state is a state when the impact sensor (2) is not impacted by dust particles;

the input capacitor (1) is further configured to maintain a second idle state when the impact sensor (2) is in a detection state, the second idle state being suitable for the input capacitor (1) to prevent the weak charge pulse signal from being output to the charge-sensitive pre-amplifier sub-circuit (3).

2. Weak pulse signal amplification circuit according to claim 1, characterized in that the capacitance of the input capacitor (1) is close to or equal to the capacitance of the impact sensor (2).

3. The weak pulse signal amplifying circuit according to claim 2, wherein the impact sensor (2) is an ionization type sensor having a capacitance of 2 picofarads or more and 200 picofarads or less.

4. The weak pulse signal amplifying circuit according to claim 3, wherein the ionization type sensor comprises a deflection electrode mesh (21), a coated electrode plate (22), a first insulating layer (23), a second insulating layer (24) and a protective layer (25);

the deflection electrode net (21) and the first insulating layer (23) are oppositely arranged in parallel and form a discharge space, the coated electrode plate (22) is clamped between the first insulating layer (23) and the second insulating layer (24), and the second insulating layer (24) is attached to the protective layer (25);

the deflection electrode net (21) is grounded, and the coated electrode plate (22) is electrically connected with the input end of the charge sensitive preamplifier sub-circuit (3).

5. The weak pulse signal amplifying circuit according to claim 4, wherein the plated electrode plate (22) comprises a metal plated film (221) and a tipped metal substrate (222), the metal plated film (221) covers the tipped metal substrate (222), the thickness of the metal plated film (221) is greater than or equal to 0.01 μm and less than or equal to 0.1 μm, and the area of the tipped metal substrate (222) is greater than or equal to 4 cm and less than or equal to 150 cm.

6. The faint pulse signal amplification circuit of claim 1, wherein the charge sensitive preamplifier sub-circuit (3) comprises a junction field effect transistor (31), a first operational amplifier (32), a first direct current regulator (33), a first feedback capacitor (34), a first feedback resistor (35), a current limiting resistor (36), and a decoupling capacitor (37);

the grid electrode of the junction field effect tube (31) is set as the input end of the charge sensitive pre-amplification sub-circuit (3), the drain electrode of the junction field effect tube (31) is electrically connected with the inverting input end of the first operational amplifier (32), and the source electrode of the junction field effect tube (31) is electrically connected with the non-inverting input end of the first operational amplifier (32);

the non-inverting input end of the first operational amplifier (32) is grounded, the positive end of the first operational amplifier (32) is electrically connected with the positive end of the first direct current voltage stabilizer (33), the negative end of the first operational amplifier (32) is electrically connected with the negative end of the first direct current voltage stabilizer (33), and the output end of the first operational amplifier (32) is electrically connected with the grid electrode of the junction field effect transistor (31) through the first feedback capacitor (34) and the first feedback resistor (35) which are connected in parallel;

one end of the current limiting resistor (36) is electrically connected with the output end of the first operational amplifier (32), the other end of the current limiting resistor (36) is grounded through the decoupling capacitor (37), a common end between the current limiting resistor (36) and the decoupling capacitor (37) is a first resistance-capacitance coupling end, and the first resistance-capacitance coupling end is set as the output end of the charge sensitive preamplifier sub-circuit (3).

7. The weak pulse signal amplifying circuit according to claim 6, wherein the decoupling capacitor (37) and the current limiting resistor (36) form a low pass filter branch, and a passband cutoff frequency of the low pass filter branch is greater than or equal to 200Hz and less than or equal to 10 MHz.

8. The faint pulse signal amplification circuit of claims 1 to 7, wherein the charge-sensitive post-amplification sub-circuit (4) comprises a second operational amplifier (41), a second direct current voltage regulator (42), a second feedback capacitor (43), and a second feedback resistor (44);

the inverting input end of the second operational amplifier (41) is set as the input end of the charge-sensitive post-amplification sub-circuit (4), the non-inverting input end of the second operational amplifier (41) is grounded, the positive end of the second operational amplifier (41) is electrically connected with the positive end of the second direct current voltage stabilizer (42), the negative end of the second operational amplifier (41) is electrically connected with the negative end of the second direct current voltage stabilizer (42), and the output end of the second operational amplifier (41) is electrically connected with the inverting input end of the second operational amplifier (41) through the second feedback capacitor (43) and the second feedback resistor (44) after being connected in parallel.

9. The faint pulse signal amplification circuit of claim 8, wherein the charge-sensitive post-amplification sub-circuit (4) comprises a coupling capacitor (45), a ground resistor (46), a third operational amplifier (47), a third dc regulator (48), a third feedback capacitor (49), and a third feedback resistor (410);

one end of the coupling capacitor (45) is electrically connected with the output end of the second operational amplifier (41), the other end of the coupling capacitor (45) is grounded through the grounding resistor (46), a common end between the coupling capacitor (45) and the grounding resistor (46) is a second resistance-capacitance coupling end, and the second resistance-capacitance coupling end is electrically connected with the inverting input end of the third operational amplifier (47);

the non-inverting input end of the third operational amplifier (47) is grounded, the positive end of the third operational amplifier (47) is electrically connected with the positive end of the third direct current voltage stabilizer (48), the negative end of the third operational amplifier (47) is electrically connected with the negative end of the third direct current voltage stabilizer (48), and the output end of the third operational amplifier (47) is electrically connected with the inverting input end of the third operational amplifier (47) through the third feedback capacitor (49) and the third feedback resistor (410) which are connected in parallel.

10. The weak pulse signal amplifying circuit according to claim 9, wherein the ground resistor (46) and the coupling capacitor (45) form a high-pass filtering branch, and a passband cutoff frequency of the high-pass filtering branch is greater than or equal to 200Hz and less than or equal to 10 MHz.

11. A mote detector comprising a weak pulse signal amplifying circuit according to claims 1-10.

Technical Field

The invention relates to the technical field of amplifying circuits, in particular to a weak pulse signal amplifying circuit and a dust detector.

Background

An existing dust particle detector generally includes a weak pulse signal discharge circuit, and referring to fig. 1, a weak pulse signal discharge circuit is shown, which includes an impact sensor and a charge sensitive pre-amplification sub-circuit, the charge sensitive pre-amplification sub-circuit is directly electrically connected to the impact sensor, the impact sensor is impacted by micron-sized solid particles at a high speed (for brief description, the micron-sized solid particles are referred to as dust particles), a weak charge pulse signal is generated, and the weak charge pulse signal is output to the charge sensitive pre-amplification sub-circuit (for brief description, the weak charge pulse signal output from the impact sensor is referred to as a first charge signal), and the charge sensitive pre-amplification sub-circuit amplifies the first charge signal, thereby improving the detection accuracy of the dust particles.

However, in the above weak pulse signal discharge circuit, the amplification factor of the charge-sensitive pre-amplifier sub-circuit is limited, which limits the signal amplification capability, and thus, limits the performance of the dust detector for detecting dust particles.

Disclosure of Invention

The invention provides a weak pulse signal amplification circuit and an impact sensor, aiming at the problem that the signal amplification capacity of a weak pulse signal discharge circuit in the prior art is limited due to the amplification factor of a charge sensitive preamplification sub-circuit.

The invention provides a weak pulse signal amplifying circuit, which comprises an input capacitor, an impact sensor and a charge sensitive pre-amplification sub-circuit, wherein the input capacitor and the impact sensor are respectively and electrically connected with the input end of the charge sensitive pre-amplification sub-circuit;

the input capacitor is used for receiving an alternating current pulse signal, converting the alternating current pulse signal into a weak charge pulse signal and outputting the weak charge pulse signal to the input end of the charge sensitive pre-amplification sub-circuit when the impact sensor is in a first idle state, wherein the first idle state is a state when the impact sensor is not impacted by micro-dust;

the input capacitor is further configured to maintain a second idle state when the impact sensor is in a detection state, the second idle state being suitable for the input capacitor to prevent the weak charge pulse signal from being output to the charge-sensitive pre-amplifier sub-circuit.

The beneficial effects of the above technical scheme are: the input capacitor and the impact sensor are respectively and directly coupled with the input end of the charge sensitive pre-amplification sub-circuit, so that the impact sensor is prevented from being coupled with the charge sensitive pre-amplification sub-circuit through the input capacitor, and the input capacitor is prevented from working along with the impact sensor.

Compared with the charge sensitive amplifying sub-circuit with single-stage attribute, the amplification factor of the charge sensitive amplifying sub-circuit is increased in multiples, and the signal amplification capability of the charge sensitive amplifying sub-circuit is improved.

When the impact sensor is in an idle state, the input capacitor has the performance of receiving an alternating current pulse signal, converting the alternating current pulse signal into a weak charge pulse signal and outputting the weak charge pulse signal to the charge sensitive pre-amplification sub-circuit (for brief description, the weak charge pulse signal output from the input capacitor is called as a second charge signal), and the performance of the charge sensitive amplification sub-circuit with the grading property is tested through the second charge signal.

When the impact sensor is in a detection state, the input capacitor has the performance of preventing a weak charge pulse signal from being output to the charge sensitive pre-amplification sub-circuit, so that the input capacitor does not generate signal interference on the impact sensor, the impact sensor directly outputs a first charge signal to the input end of the charge sensitive pre-amplification sub-circuit, the charge sensitive amplification sub-circuit with the grading property amplifies the first charge signal, and the reliability of the weak pulse signal amplification circuit is improved.

On the basis of the technical scheme, the invention further improves the following steps.

Optionally, the capacitance of the input capacitor is close to or equal to the capacitance of the shock sensor.

The beneficial effects of the above technical scheme are: the capacitance difference between the input capacitor and the impact sensor is smaller, compared with the fact that the capacitance difference between the input capacitor and the impact sensor is obvious, the detection state of the impact sensor is simulated more accurately through the input capacitor, noise of the second charge signal is reduced, the signal-to-noise ratio of the second charge signal is improved, and the accuracy of testing performance indexes such as the working point and the amplification factor of the charge sensitive pre-amplification sub-circuit is improved.

Optionally, the impact sensor is an ionization sensor having a capacitance greater than or equal to 2 picofarads and less than or equal to 200 picofarads.

The beneficial effects of the above technical scheme are: the capacitance of the ionization type sensor is prevented from exceeding the range of 2 picofarads to 200 picofarads, so that the performance of the charge sensitive pre-amplification sub-circuit is better adapted to the ionization type sensor, and the reliability of the direct coupling work of the ionization type sensor and the charge sensitive pre-amplification sub-circuit is ensured.

Optionally, the ionization type sensor comprises a deflection electrode mesh, a coated electrode plate, a first insulating layer, a second insulating layer and a protective layer;

the deflection electrode net and the first insulating layer are oppositely arranged in parallel to form a discharge space, the coated electrode plate is clamped between the first insulating layer and the second insulating layer, and the second insulating layer is attached to the protective layer;

the deflection electrode net is grounded, and the coated electrode plate is electrically connected with the input end of the charge sensitive preamplifier sub-circuit.

The beneficial effects of the above technical scheme are: the first insulating layer prevents local arc light from being formed in the discharge space, the coated electrode plate is located in an insulating interlayer formed by the first insulating layer and the second insulating layer, external electric field interference can be restrained for the coated electrode plate, damage prevention protection is provided for the second insulating layer through the protective layer, and the service life of the ionization type sensor can be prolonged.

Optionally, the coated electrode plate includes a metal coating and a tipped metal substrate, the metal coating covers the tipped metal substrate, the thickness of the metal coating is greater than or equal to 0.01 micrometer and less than or equal to 0.1 micrometer, and the area of the tipped metal substrate is greater than or equal to 4 square centimeters and less than or equal to 150 square centimeters.

The beneficial effects of the above technical scheme are: the metal coating has good conductive uniformity and high density, no tip is arranged on the tip-removed metal substrate, tip discharge is prevented from being caused, a first charge signal is enhanced on the coated electrode plate, the thickness of the metal coating is prevented from exceeding the range of 0.01-0.1 micrometer, the requirements of the metal coating on easy forming and thinning are effectively balanced, the area of the tip-removed metal substrate is prevented from exceeding the range of 4-150 square centimeters, the tip-removed metal substrate is more beneficial to miniaturization, materials are saved, and the cost is reduced.

Optionally, the charge-sensitive preamplifier sub-circuit includes a junction field effect transistor, a first operational amplifier, a first dc voltage regulator, a first feedback capacitor, a first feedback resistor, a current-limiting resistor, and a decoupling capacitor;

the grid electrode of the junction field effect transistor is set as the input end of the charge sensitive preamplifier sub-circuit, the drain electrode of the junction field effect transistor is electrically connected with the inverting input end of the first operational amplifier, and the source electrode of the junction field effect transistor is electrically connected with the non-inverting input end of the first operational amplifier;

the non-inverting input end of the first operational amplifier is grounded, the positive end of the first operational amplifier is electrically connected with the positive end of the first direct current voltage stabilizer, the negative end of the first operational amplifier is electrically connected with the negative end of the first direct current voltage stabilizer, and the output end of the first operational amplifier is electrically connected with the grid electrode of the junction field effect transistor through the first feedback capacitor and the first feedback resistor which are connected in parallel;

one end of the current limiting resistor is electrically connected with the output end of the first operational amplifier, the other end of the current limiting resistor is grounded through the decoupling capacitor, a common end between the current limiting resistor and the decoupling capacitor is a first resistance-capacitance coupling end, and the first resistance-capacitance coupling end is set as the output end of the charge sensitive preamplifier sub-circuit.

The beneficial effects of the above technical scheme are: the junction field effect transistor and the first operational amplifier form a cascade amplification network, the voltage of a negative electrode end is reduced for the first operational amplifier through the first direct current voltage stabilizer, the voltage of the first operational amplifier is lower than the voltage of a positive electrode end, the situation that a pre-amplification sub-circuit is in a normal working point is guaranteed, the first feedback capacitor and the first feedback resistor form a first feedback network, high-frequency gain and amplification factor limitation are reduced for the cascade amplification network through the first feedback network, high-frequency interference is restrained, oscillation is prevented, and compared with the situation that the first feedback network is connected in parallel to an inverting input end and an output end of the first operational amplifier, the utilization rate of the first feedback network is improved.

Optionally, the decoupling capacitor and the current limiting resistor form a low-pass filtering branch, and a passband cutoff frequency of the low-pass filtering branch is greater than or equal to 200Hz and less than or equal to 10 MHz.

The beneficial effects of the above technical scheme are: the passband cut-off frequency of the low-pass filtering branch circuit is prevented from exceeding the range of 200Hz to 10MHz, after the first operational amplifier, the suppression performance is enhanced aiming at high-frequency signals with the frequency higher than the passband cut-off frequency of the low-pass filtering branch circuit, the anti-high-frequency signal interference capability of the charge sensitive pre-amplification sub-circuit is promoted, the signal amplification capability of the charge sensitive pre-amplification sub-circuit is promoted, and therefore the performance of the charge sensitive pre-amplification sub-circuit is better adapted to the ionization type sensor.

Optionally, the charge-sensitive post-amplification sub-circuit includes a second operational amplifier, a second dc voltage regulator, a second feedback capacitor, and a second feedback resistor;

the inverting input end of the second operational amplifier is set as the input end of the charge sensitive post-amplification sub-circuit, the non-inverting input end of the second operational amplifier is grounded, the positive end of the second operational amplifier is electrically connected with the positive end of the second direct current voltage stabilizer, the negative end of the second operational amplifier is electrically connected with the negative end of the second direct current voltage stabilizer, and the output end of the second operational amplifier is electrically connected with the inverting input end of the second operational amplifier through the second feedback capacitor and the second feedback resistor after being connected in parallel.

The beneficial effects of the above technical scheme are: the voltage of the negative end of the second operational amplifier is reduced for the second operational amplifier through the second direct current voltage stabilizer, the voltage of the negative end of the second operational amplifier is lower than that of the positive end, the charge-sensitive post-amplification sub-circuit is guaranteed to be at a normal working point, the second feedback capacitor and the second feedback resistor form a second feedback network, high-frequency gain and amplification factor limitation are reduced for the second operational amplifier through the second feedback network, high-frequency interference is restrained, oscillation is prevented, and the stability of the charge-sensitive post-amplification sub-circuit is favorably improved.

Optionally, the charge-sensitive post-amplifier sub-circuit includes a coupling capacitor, a ground resistor, a third operational amplifier, a third dc voltage stabilizer, a third feedback capacitor, and a third feedback resistor;

one end of the coupling capacitor is electrically connected with the output end of the second operational amplifier, the other end of the coupling capacitor is grounded through the grounding resistor, a common end between the coupling capacitor and the grounding resistor is a second resistance-capacitance coupling end, and the second resistance-capacitance coupling end is electrically connected with the inverting input end of the third operational amplifier;

the non-inverting input end of the third operational amplifier is grounded, the positive end of the third operational amplifier is electrically connected with the positive end of the third direct current voltage stabilizer, the negative end of the third operational amplifier is electrically connected with the negative end of the third direct current voltage stabilizer, and the output end of the third operational amplifier is electrically connected with the inverting input end of the third operational amplifier through the third feedback capacitor and the third feedback resistor which are connected in parallel.

The beneficial effects of the above technical scheme are: the second operational amplifier and the third operational amplifier are coupled through the coupling capacitor, so that a direct-current signal is blocked between the second operational amplifier and the third operational amplifier by the coupling capacitor, filtering is performed between the second operational amplifier and the third operational amplifier through a high-pass filtering branch circuit formed by the coupling capacitor and the grounding resistor, the utilization rate of the coupling capacitor is improved, and the electric connection mode among the coupling capacitor, the grounding resistor and the third operational amplifier is simplified by utilizing the second resistance-capacitance coupling end.

The voltage of the negative end of the third operational amplifier is reduced for the third operational amplifier through the third direct current voltage stabilizer, the voltage of the negative end of the third operational amplifier is lower than that of the positive end, the charge-sensitive post-amplification sub-circuit is guaranteed to be at a normal working point, the third feedback capacitor and the third feedback resistor form a third feedback network, high-frequency gain and amplification factor limitation are reduced for the third operational amplifier through the third feedback network, high-frequency interference is restrained, oscillation is prevented, and the stability and the signal amplification capacity of the charge-sensitive post-amplification sub-circuit are improved.

Optionally, the ground resistor and the coupling capacitor form a high-pass filtering branch, and a passband cutoff frequency of the high-pass filtering branch is greater than or equal to 200Hz and less than or equal to 10 MHz.

The beneficial effects of the above technical scheme are: the passband cut-off frequency of the high-pass filtering branch circuit is prevented from exceeding the range of 200Hz to 10MHz, the suppression performance is enhanced aiming at low-frequency signals with lower frequency than the passband cut-off frequency of the high-pass filtering branch circuit between the second operational amplifier and the third operational amplifier, the low-frequency signal interference resistance of the charge sensitive post-amplification sub-circuit is improved, the signal amplification capability of the charge sensitive post-amplification sub-circuit is improved, and therefore the good performance of the charge sensitive post-amplification sub-circuit is favorably adapted to the ionization type sensor.

A second aspect of the invention provides a mote detector comprising a weak pulse signal amplification circuit as described in the first aspect.

The beneficial effects of the above technical scheme are: in the weak pulse signal amplifying circuit, an input capacitor and an impact sensor are respectively and directly coupled with the input end of the charge sensitive pre-amplification sub-circuit, so that the impact sensor is prevented from being coupled with the charge sensitive pre-amplification sub-circuit through the input capacitor, and the input capacitor is prevented from working along with the impact sensor.

Compared with the charge sensitive amplifying sub-circuit with single-stage attribute, the amplification factor of the charge sensitive amplifying sub-circuit is increased in multiples, the signal amplification capacity of the charge sensitive amplifying sub-circuit is improved, and the space range of the micro dust detector for detecting the micro dust is expanded on the basis of ensuring the detection precision.

When the impact sensor is in an idle state, the input capacitor has the performance of receiving an alternating-current pulse signal, converting the alternating-current pulse signal into a weak charge pulse signal and outputting the weak charge pulse signal to the charge sensitive pre-amplification sub-circuit, and the performance of the charge sensitive amplification sub-circuit with the grading property is tested through the second charge signal.

When the impact sensor is in a detection state, the input capacitor has the performance of preventing a weak charge pulse signal from being output to the charge sensitive pre-amplification sub-circuit, so that the input capacitor does not generate signal interference on the impact sensor, the impact sensor directly outputs a first charge signal to the input end of the charge sensitive pre-amplification sub-circuit, the charge sensitive amplification sub-circuit with the grading property amplifies the first charge signal, and the reliability of the weak pulse signal amplification circuit is improved.

Drawings

FIG. 1 is a schematic diagram of a weak pulse signal discharging circuit in the prior art;

fig. 2 is a schematic diagram of a weak pulse signal amplifying circuit according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an ionization type sensor according to an embodiment of the present invention;

FIG. 4 is a schematic cross-sectional view of a coated electrode plate according to an embodiment of the present invention;

FIG. 5 is a waveform diagram illustrating a first charge signal according to an embodiment of the present invention;

fig. 6 is a diagram illustrating the relationship between the electrical signal output from the charge-sensitive post-amplifier sub-circuit and the mass and velocity of the mote according to an embodiment of the present invention.

Description of reference numerals:

1-an input capacitor, 2-an impact sensor, 3-a charge sensitive pre-amplification sub-circuit and 4-a charge sensitive post-amplification sub-circuit;

21-deflection electrode mesh, 22-coated electrode plate, 23-first insulating layer, 24-second insulating layer, 25-protective layer, 221-metal coating, 222-tippling metal substrate;

31-junction field effect transistor, 32-first operational amplifier, 33-first direct current voltage stabilizer, 34-first feedback capacitor, 35-first feedback resistor, 36-current limiting resistor, 37-decoupling capacitor;

41-a second operational amplifier, 42-a second direct current voltage stabilizer, 43-a second feedback capacitor, 44-a second feedback resistor, 45-a coupling capacitor, 46-a ground resistor, 47-a third operational amplifier, 48-a third direct current voltage stabilizer, 49-a third feedback capacitor and 410-a third feedback resistor.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Referring to fig. 2, a weak pulse signal amplifying circuit according to an embodiment of the present invention is shown, and includes an input capacitor 1, an impact sensor 2, and a charge sensitive pre-amplification sub-circuit 3, where one end of the input capacitor 1 and one end of the impact sensor 2 are respectively and directly electrically connected to an input terminal of the charge sensitive pre-amplification sub-circuit 3, and the other end of the impact sensor 2 is grounded, so that the impact sensor 2 is prevented from being coupled to the charge sensitive pre-amplification sub-circuit 3 through the input capacitor 1, and the input capacitor 1 is prevented from working along with the impact sensor 2.

Compared with the charge sensitive amplifying sub-circuit with single-stage attribute, the amplification factor of the charge sensitive amplifying sub-circuit is increased by times, the signal amplification capability of the charge sensitive amplifying sub-circuit is improved, and the space range of detecting the dust particles is expanded on the basis of ensuring the detection precision by the dust particle detector.

Optionally, the other end of the input capacitor 1 and the output end of the charge-sensitive pre-amplification sub-circuit 3 may be electrically connected to a controller, respectively, when the impact sensor 2 is in a first idle state, the controller outputs an ac pulse signal to the input capacitor 1, under the action of the ac pulse signal, the input capacitor 1 enters a working state, the working state is suitable for the input capacitor 1 to receive the ac pulse signal, convert the ac pulse signal into a second charge signal and output the second charge signal to the input end of the charge-sensitive pre-amplification sub-circuit 3, the performance of the charge-sensitive amplification sub-circuit with the hierarchical property is tested by the second charge signal, on the basis of preventing the impact sensor 2 from generating signal interference on the input capacitor 1, it is convenient to predict that the charge-sensitive amplification sub-circuit with the hierarchical property is matched with the impact sensor 2, the working independence of the input capacitor 1 and the reliability of the weak pulse signal amplification circuit are improved.

When the impact sensor 2 enters a detection state from a first idle state, the controller stops outputting the alternating current pulse signal to the input capacitor 1, so that the input capacitor 1 enters a second idle state from a working state, the impact sensor 2 directly outputs a first charge signal to the input end of the charge sensitive pre-amplification sub-circuit 3, the charge sensitive amplification sub-circuit with the grading property amplifies the first charge signal, and the reliability of the weak pulse signal amplification circuit is improved.

It should be noted that the first idle state is a state when the impact sensor 2 is not impacted by the dust particles, the detection state is a state when the impact sensor 2 generates a first charge signal and outputs the first charge signal to the charge-sensitive pre-amplifier sub-circuit 3 under the impact of the dust particles, the second idle state is a state when the input capacitor 1 prevents outputting a second charge signal to the charge-sensitive pre-amplifier sub-circuit 3, and the working state is a state when the input capacitor 1 generates a second charge signal and outputs the second charge signal to the charge-sensitive pre-amplifier sub-circuit 3 under the action of the ac pulse signal.

Optionally, the capacitance of the input capacitor 1 is close to or equal to the capacitance of the impact sensor 2, so that it is ensured that the difference between the capacitance of the input capacitor 1 and the capacitance of the impact sensor 2 is smaller, and compared with the case that the difference between the capacitance of the input capacitor 1 and the capacitance of the impact sensor 2 is obvious, the detection state of the impact sensor 2 is simulated more accurately through the input capacitor 1, so that the noise of the second charge signal is reduced, the signal-to-noise ratio of the second charge signal is improved, and the accuracy of testing the performance indexes such as the operating point and the amplification factor of the charge-sensitive pre-amplification sub-circuit 3 is improved.

Optionally, the impact sensor 2 is an ionization type sensor, the capacitance of the ionization type sensor is greater than or equal to 2 picofarads and less than or equal to 200 picofarads, the capacitance of the ionization type sensor is prevented from exceeding the range of 2 picofarads to 200 picofarads, and the performance of the charge-sensitive preamplifier sub-circuit 3 is better adapted to the ionization type sensor, so as to ensure the reliability of the direct coupling operation of the ionization type sensor and the charge-sensitive preamplifier sub-circuit 3, for example, the capacitance of the ionization type sensor is 2 picofarads or 6 picofarads or 200 picofarads.

Taking the capacitance of the ionization type sensor as 6 picofarads for example, the capacitance of the input capacitor 1 is equal to 5.3 picofarads or 6.2 picofarads, indicating that the capacitance of the input capacitor 1 is close to the capacitance of the ionization type sensor.

Alternatively, referring to fig. 3, an ionization type sensor according to an embodiment of the present invention is shown, where the ionization type sensor includes a deflection electrode mesh 21, a coated electrode plate 22, a first insulating layer 23, a second insulating layer 24, and a protective layer 25, the deflection electrode mesh 21 is disposed opposite to the first insulating layer 23 in parallel and forms a discharge space, the coated electrode plate 22 is sandwiched between the first insulating layer 23 and the second insulating layer 24, the second insulating layer 24 is attached to the protective layer 25, for example, the deflection electrode mesh 21 is a nickel mesh plate, the permeability of the nickel mesh plate is 80%, so that the fine dust in a high-speed motion state enters the discharge space from the nickel mesh plate, and the capacitance of the coated electrode plate 22 is equal to 5 picofarads.

The first insulating layer 23 prevents the formation of local arc light in the discharge space, the coated electrode plate 22 is located in the insulating interlayer formed by the first insulating layer 23 and the second insulating layer 24, which helps to suppress external electric field interference for the coated electrode plate 22, and the protective layer 25 provides damage-proof protection for the second insulating layer 24, which helps to prolong the service life of the ionization type sensor.

The deflection electrode network 21 is grounded, the coated electrode plate 22 is electrically connected with the input end of the charge-sensitive preamplifier circuit 3, for example, one end of the deflection electrode network 21 is electrically connected with one end of an alternating current power supply, the other end of the deflection electrode network 21 is grounded, one end of the coated electrode plate 22 is electrically connected with the other end of the alternating current power supply, and the other end of the coated electrode plate 22 and one end of the input capacitor 1 are connected in parallel at the input end of the charge-sensitive preamplifier circuit.

Alternatively, the negative electrode of the dc power supply is electrically connected to the deflection electrode grid 21, the positive electrode of the dc power supply is electrically connected to the coated electrode plate 22, and in the process of applying a dc high voltage to the deflection electrode grid 21 and the coated electrode plate 22 by the dc power supply, the fine dust in a high-speed motion state enters the discharge space from the deflection electrode grid 21, and plasma is generated in the discharge space, so that a first charge signal is formed on the deflection electrode grid 21 and the coated electrode plate 22.

Optionally, referring to fig. 4, which illustrates a coated electrode plate 22 according to an embodiment of the present invention, the coated electrode plate 22 includes a metal coating 221 and a tipped-off metal substrate 222, the metal coating 221 covers the tipped-off metal substrate 222, the metal coating 221 has good conductivity uniformity and high density, no tip is formed on the tipped-off metal substrate 222, and tip discharge is prevented from being induced, for example, the metal coating 221 is made of a metal material with high density, such as tungsten, gold, platinum, iridium, or rhodium, and the like, and the amount of charge generated by the metal coating 221 increases with the density, and the metal coating with high density is formed outside the tipped-off metal substrate 222, which is helpful for enhancing the first charge signal on the coated electrode plate 22.

The thickness of the metal plating film 221 is greater than or equal to 0.01 micrometers and less than or equal to 0.1 micrometers, so that the thickness of the metal plating film 221 is prevented from exceeding the range of 0.01 micrometers to 0.1 micrometers, the requirements of the metal plating film 221 on easy forming and thinning are effectively balanced, materials are saved, and the cost is reduced, for example, the thickness of the metal plating film 221 is 0.01 micrometers or 0.05 micrometers or 0.1 micrometers.

Taking the thickness of the metal plating film 221 as 0.01 as an example, the mass range of the metal plating film manufactured by the electrostatic fine dust acceleration device is 10^-15g<m<10^-10g range and speed range of 1km/s<v<Iron powder in the range of 50km/s, which is input to an ionization sensor as fine dust, and m is 1.1 × 10^-11g and v ═ 8.2km/s of fine dust, see fig. 5, showing first charge signals output from the deflection electrode grid 21 and the coated electrode plate 22, respectively, of an embodiment of the present invention, wherein the curve near 0.22 represents the first charge signal from the deflection electrode grid 21 and the curve near 0.00 represents the first charge signal from the coated electrode plate 22.

The area of the truncated metal substrate 222 is greater than or equal to 4 square centimeters and less than or equal to 150 square centimeters, so that the area of the truncated metal substrate 222 is prevented from exceeding the range of 4 square centimeters to 150 square centimeters, the miniaturization of the truncated metal substrate 222 is facilitated, the material saving is facilitated, and the cost is reduced.

Optionally, the charge-sensitive preamplifier circuit 3 includes a jfet 31, a first operational amplifier 32, a first dc regulator 33, a first feedback capacitor 34, a first feedback resistor 35, a current limiting resistor 36, and a decoupling capacitor 37, a gate of the jfet 31 is set as an input terminal of the charge-sensitive preamplifier circuit 3, the gate of the jfet 31 is electrically connected to the input capacitor 1 and the impact sensor 2, respectively, a drain of the jfet 31 is electrically connected to an inverting input terminal of the first operational amplifier 32, and a source of the jfet 31 is electrically connected to a non-inverting input terminal of the first operational amplifier 32, for example, the jfet 31 is IF3601, and the first operational amplifier 32 is a 250.

The non-inverting input terminal of the first operational amplifier 32 is grounded, the positive terminal of the first operational amplifier 32 is electrically connected to the positive terminal of the first dc regulator 33, the negative terminal of the first operational amplifier 32 is electrically connected to the negative terminal of the first dc regulator 33, the output terminal of the first operational amplifier 32 is electrically connected to the gate of the jfet 31 through the first feedback capacitor 34 and the first feedback resistor 35 connected in parallel, for example, the capacitance of the first feedback capacitor 34 is 0.25 picofarad, and the resistance of the first feedback resistor 35 is 1G ohm.

The junction field effect transistor 31 has the characteristics of small driving power, high response speed, high working frequency and the like, and is beneficial to reducing signal noise, the junction field effect transistor 31 and the first operational amplifier 32 form a cascade amplification network, the voltage of the negative end is reduced for the first operational amplifier 32 through the first direct current voltage stabilizer 33, so that the voltage of the first operational amplifier 32 is lower than that of the positive end, the pre-amplification sub-circuit is ensured to be at a normal working point, the first feedback capacitor 34 and the first feedback resistor 35 form a first feedback network, high-frequency gain and amplification factor limitation are reduced for the cascade amplification network through the first feedback network, high-frequency interference is inhibited, and oscillation is prevented.

One end of the current limiting resistor 36 is electrically connected with the output end of the first operational amplifier 32, the other end of the current limiting resistor 36 is grounded through the decoupling capacitor 37, the common end between the current limiting resistor 36 and the decoupling capacitor 37 is a first resistance-capacitance coupling end, and the first resistance-capacitance coupling end is set as the output end of the charge sensitive preamplifier sub-circuit 3.

Optionally, the decoupling capacitor 37 and the current limiting resistor 36 constitute a low-pass filtering branch, a passband cutoff frequency of the low-pass filtering branch is greater than or equal to 200Hz and less than or equal to 10MHz, the passband cutoff frequency of the low-pass filtering branch is prevented from exceeding the range of 200Hz to 10MHz, after the first operational amplifier 32, the suppression performance is enhanced for a high-frequency signal with a frequency higher than the passband cutoff frequency of the low-pass filtering branch, which is helpful for improving the high-frequency signal interference resistance of the charge-sensitive preamplifier sub-circuit 3 and improving the signal amplification capability of the charge-sensitive preamplifier sub-circuit 3, thereby facilitating better performance of the charge-sensitive preamplifier sub-circuit 3 to be adapted to the ionization type sensor, for example, the passband cutoff frequency of the low-pass filtering branch is in the range of 500Hz to 2 MHz.

The input end of the charge-sensitive post-amplification sub-circuit 4 is electrically connected with the first resistance-capacitance coupling end, the first operational amplifier 32 and the charge-sensitive post-amplification sub-circuit 4 are coupled through the current-limiting resistor 36, so that the current-limiting resistor 36 limits current between the first operational amplifier 32 and the charge-sensitive post-amplification sub-circuit 4, and the low-frequency filtering branch circuit formed by the current-limiting resistor 36 and the decoupling capacitor 37 filters between the first operational amplifier 32 and the charge-sensitive post-amplification sub-circuit 4, thereby improving the utilization rate of the current-limiting resistor 36, and simplifying the electrical connection mode among the current-limiting resistor 36, the decoupling capacitor 37 and the charge-sensitive post-amplification sub-circuit 4 by using the first resistance-capacitance coupling end.

Optionally, the charge-sensitive post-amplification sub-circuit 4 includes a second operational amplifier 41, a second dc regulator 42, a second feedback capacitor 43, and a second feedback resistor 44, an inverting input terminal of the second operational amplifier 41 is set as an input terminal of the charge-sensitive post-amplification sub-circuit 4, a non-inverting input terminal of the second operational amplifier 41 is grounded, a positive terminal of the second operational amplifier 41 is electrically connected to a positive terminal of the second dc regulator 42, a negative terminal of the second operational amplifier 41 is electrically connected to a negative terminal of the second dc regulator 42, and an output terminal of the second operational amplifier 41 is electrically connected to the inverting input terminal of the second operational amplifier 41 through the second feedback capacitor 43 and the second feedback resistor 44 which are connected in parallel.

The voltage of the negative end of the second operational amplifier 41 is reduced through the second direct current voltage stabilizer 42, so that the voltage of the negative end of the second operational amplifier 41 is lower than the voltage of the positive end, the charge-sensitive post-amplification sub-circuit 4 is ensured to be at a normal working point, the second feedback capacitor 43 and the second feedback resistor 44 form a second feedback network, the high-frequency gain and the amplification limiting factor are reduced for the second operational amplifier 41 through the second feedback network, the high-frequency interference is inhibited, the oscillation is prevented, and the stability of the charge-sensitive post-amplification sub-circuit 4 is improved.

Optionally, the model of the second operational amplifier 41 is the same as the model of the first operational amplifier 32, the model of the second dc regulator 42 is the same as the model of the first dc regulator 33, the capacitance of the second feedback capacitor 43 is equal to the capacitance of the first feedback capacitor 34, and the resistance of the second feedback resistor 44 is equal to the resistance of the first feedback resistor 35.

Optionally, the charge-sensitive post-amplifier sub-circuit 4 includes a coupling capacitor 45, a ground resistor 46, a third operational amplifier 47, a third dc regulator 48, a third feedback capacitor 49, and a third feedback resistor 410, one end of the coupling capacitor 45 is electrically connected to the output end of the second operational amplifier 41, the other end of the coupling capacitor 45 is grounded through the ground resistor 46, a common end between the coupling capacitor 45 and the ground resistor 46 is a second rc coupling end, and the second rc coupling end is electrically connected to the inverting input end of the third operational amplifier 47.

The second operational amplifier 41 and the third operational amplifier 47 are coupled through the coupling capacitor 45, so that the coupling capacitor 45 blocks direct current signals between the second operational amplifier 41 and the third operational amplifier 47, and filtering is performed between the second operational amplifier 41 and the third operational amplifier 47 through a high-pass filtering branch circuit formed by the coupling capacitor 45 and the grounding resistor 46, so that the utilization rate of the coupling capacitor 45 is improved, and the electric connection mode among the coupling capacitor 45, the grounding resistor 46 and the third operational amplifier 47 is simplified by utilizing the second resistance-capacitance coupling end.

The non-inverting input terminal of the third operational amplifier 47 is grounded, the positive terminal of the third operational amplifier 47 is electrically connected to the positive terminal of the third dc voltage stabilizer 48, the negative terminal of the third operational amplifier 47 is electrically connected to the negative terminal of the third dc voltage stabilizer 48, and the output terminal of the third operational amplifier 47 is electrically connected to the inverting input terminal of the third operational amplifier 47 through the third feedback capacitor 49 and the third feedback resistor 410 which are connected in parallel.

The voltage of the negative end of the third operational amplifier 47 is reduced by the third direct current voltage stabilizer 48, so that the voltage of the negative end of the third operational amplifier 47 is lower than that of the positive end, the charge-sensitive post-amplification sub-circuit 4 is ensured to be at a normal working point, the third feedback capacitor 49 and the third feedback resistor 410 form a third feedback network, the third feedback network is used for reducing high-frequency gain and limiting amplification factor for the third operational amplifier 47, high-frequency interference is inhibited, oscillation is prevented, and the stability and the signal amplification capability of the charge-sensitive post-amplification sub-circuit 4 are improved.

Optionally, the capacitance of the coupling capacitor 45 is equal to that of the decoupling capacitor 37, the resistance of the ground resistor 46 is equal to that of the current limiting resistor 36, the model of the third operational amplifier 47 is equal to that of the first operational amplifier 32, the model of the third dc regulator 48 is equal to that of the first dc regulator 33, the capacitance of the third feedback capacitor 49 is equal to that of the first feedback capacitor 34, and the resistance of the third feedback resistor 410 is equal to that of the first feedback resistor 35.

Optionally, the ground resistor 46 and the coupling capacitor 45 form a high-pass filter branch, the passband cutoff frequency of the high-pass filter branch is greater than or equal to 200Hz and less than or equal to 10MHz, the passband cutoff frequency of the high-pass filter branch is prevented from exceeding the range of 200Hz to 10MHz, between the second operational amplifier 41 and the third operational amplifier 47, the suppression performance is enhanced for the low-frequency signal with a frequency lower than the passband cutoff frequency of the high-pass filtering branch, the anti-low-frequency signal interference capability of the charge-sensitive post-amplification sub-circuit 4 is improved, the signal amplification capability of the charge-sensitive post-amplification sub-circuit 4 is improved, thereby, the good performance of the charge sensitive post-amplification sub-circuit 4 is facilitated to be adapted to the ionization type sensor, for example, the passband cutoff frequency of the high-pass filtering branch is the same as the passband cutoff frequency of the low-pass filtering branch, and the passband cutoff frequency of the high-pass filtering branch is equal to 500Hz or 1MHz or 2 MHz.

Referring to FIG. 6, there is shown an embodiment of the present invention between the electrical signal output from the charge sensitive post-amplifier sub-circuit 4 and the mass and velocity of the moteThe relationship between the electrical signal and the mass and velocity of the mote can be expressed as: q ═ α × m × v^βWhere Q represents the total charge amount of the aforementioned electric signal, α represents a first coefficient, m represents the mass of the fine dust, v represents the velocity of the fine dust, and β represents a second coefficient.

The invention also provides a dust particle detector which comprises a metal shell and a weak pulse signal amplification circuit board, wherein the metal shell is hollow, the weak pulse signal amplification circuit board is fixed in the metal shell, the metal shell expands the damage prevention capability and the electromagnetic shielding capability of the weak pulse signal amplification circuit board, and is beneficial to prolonging the service life and the electromagnetic shielding performance of the dust particle detector, for example, the metal shell is an aluminum alloy cylinder or an iron box.

The weak pulse signal amplifying circuit board comprises a metal circuit board and the weak pulse signal amplifying circuit, wherein the weak pulse signal amplifying circuit is in multiple paths, the multiple paths of weak pulse signal amplifying circuits are integrated on the metal circuit board, any two paths of weak pulse signal amplifying circuits are in an isolated state, compared with the mode that one path of weak pulse signal amplifying circuit is integrated on the PCB circuit board, the multiple paths of weak pulse signal amplifying circuits are isolated through the metal circuit board, the space utilization rate of the metal circuit board is improved, the performances of electromagnetic shielding, signal amplification, heat dissipation and the like of the weak pulse signal amplifying circuit board are improved, the space range of detecting the micro dust is expanded on the basis of ensuring the detection precision by the micro dust detector, for example, the metal circuit board is made of any one of aluminum, titanium alloy, copper and stainless steel, and the weak pulse signal amplifying circuit is 14 paths, the 14 weak pulse signal amplification circuits are arranged on the metal circuit board in a rectangular shape with 2 rows and 7 columns, or the weak pulse signal amplification circuits are 16, and the 16 weak pulse signal amplification circuits are arranged on the metal circuit board in a square shape with 4 rows and 4 columns.

Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and such changes and modifications will fall within the scope of the present invention.