CN213241407U - Fire detector - Google Patents
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- CN213241407U CN213241407U CN202022220481.0U CN202022220481U CN213241407U CN 213241407 U CN213241407 U CN 213241407U CN 202022220481 U CN202022220481 U CN 202022220481U CN 213241407 U CN213241407 U CN 213241407U
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- 238000006243 chemical reaction Methods 0.000 claims abstract description 42
- 230000003321 amplification Effects 0.000 claims abstract description 26
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 26
- 239000003990 capacitor Substances 0.000 claims description 67
- 239000000835 fiber Substances 0.000 claims description 21
- 230000003287 optical effect Effects 0.000 claims description 15
- 239000013307 optical fiber Substances 0.000 claims description 2
- 238000010586 diagram Methods 0.000 description 4
- 238000001914 filtration Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000007850 degeneration Effects 0.000 description 2
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000005693 optoelectronics Effects 0.000 description 1
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Abstract
The utility model provides a fire detector, through setting up two fortune preamplification circuit, the two-channel differential formula input that the input end adopted makes the unstable error signal in the input signal offset through the difference, has strengthened the stability of system; the pre-amplification circuit is arranged in the double operational amplifier pre-amplification circuit, so that the voltage output by the photoelectric conversion circuit is amplified on one hand, and the dynamic error of the pre-amplification circuit caused by the unmatched circuit resistance is eliminated by adjusting the reference voltage on the other hand; the RC filter circuit filters high-frequency interference signals existing in the output signals of the differential preamplifier circuit by arranging the RC filter circuit and the low-pass filter in the filter circuit, so that the input impedance of the circuit is improved; the low pass filter further filters out high frequency signals in the circuit.
Description
Technical Field
The utility model relates to an electric fire alarm system technical field especially relates to a fire detector.
Background
In order to effectively prevent electrical fire and achieve the purpose of detecting and alarming the electrical fire, people begin to develop various detectors to monitor the fire according to the signal characteristics of the electrical fire, currently, the fiber grating sensor is mainly used for detecting the electrical fire, the optical signal collected by the fiber grating sensor needs to be demodulated and then converted into an electrical signal through a photoelectric conversion circuit, because the current signal converted by the photoelectric conversion circuit is very small, and the influence of various noises is added, therefore, to improve the detection accuracy of the whole system, the amplifying circuit and the filter circuit are indispensable parts in the signal processing stage, wherein, the amplifying circuit in the existing fiber grating sensor usually adopts a differential pre-amplifying circuit, since the circuit has a high requirement for resistance matching, unnecessary dynamic errors are introduced in the case of resistance mismatch.
Therefore, in order to solve the above problem, the utility model provides a fire detector, through optimizing the structure of differential formula preamplifier circuit, eliminates the dynamic error that the resistance mismatch arouses.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model provides a fire detector, through optimizing the structure of differential formula preamplifier circuit, eliminate the dynamic error that the resistance mismatch arouses.
The technical scheme of the utility model is realized like this: the utility model provides a fire detector, which comprises a fiber grating sensor, a photoelectric conversion circuit, a CPU, a filter circuit and a double operational amplifier pre-amplifying circuit, wherein the double operational amplifier pre-amplifying circuit comprises a reference voltage, a pre-amplifying circuit and a differential pre-amplifying circuit;
the optical signal output by the fiber bragg grating sensor is transmitted to the input end of the photoelectric conversion circuit, is detected by the photoelectric conversion circuit and converts the optical signal into an electric signal, the output end of the photoelectric conversion circuit is respectively electrically connected with the first input end of the preamplifier circuit and the first input end of the differential preamplifier circuit, the reference voltage is respectively electrically connected with the second input end of the preamplifier circuit and the second input end of the differential preamplifier circuit, the output end of the preamplifier circuit is electrically connected with the second input end of the differential preamplifier circuit, the output end of the differential preamplifier circuit is electrically connected with the input end of the filter circuit, and the output end of the filter circuit is electrically connected with the analog input end of the CPU.
On the basis of the above technical solution, it is preferable that the photoelectric conversion circuit includes a photodiode D100, a resistor R6, a resistor R7, capacitors C30-C32, and a third operational amplifier CA 3130;
the anode of the photodiode D100 is grounded, the cathode of the photodiode D100 is electrically connected to the inverting input terminal of the third operational amplifier CA3130, one end of the capacitor C30 and one end of the resistor R6 are both grounded, the other end of the capacitor C30 and the other end of the resistor R6 are respectively electrically connected to the non-inverting input terminal of the third operational amplifier CA3130, the output terminal of the third operational amplifier CA3130 is respectively electrically connected to the first input terminal of the preamplifier circuit and the first input terminal of the differential preamplifier circuit through the capacitor C32, the resistor R7 is connected in parallel between the output terminal of the third operational amplifier CA3130 and the inverting input terminal thereof, and the capacitor C31 is connected in parallel to both ends of the resistor R7.
On the basis of the above technical solution, preferably, the pre-amplifier circuit includes a resistor R1, a resistor R2, a resistor R4, and a first operational amplifier LM 358;
the output end of the photoelectric conversion circuit is electrically connected with the non-inverting input end of the first operational amplifier LM358, the reference voltage is electrically connected with one end of the resistor R1, the other end of the resistor R1 is electrically connected with the inverting input end of the first operational amplifier LM358 and the second input end of the differential type preamplifier circuit respectively, the output end of the first operational amplifier LM358 is electrically connected with the second input end of the differential type preamplifier circuit through the resistor R4, and the resistor R2 is connected between the output end of the first operational amplifier LM358 and the inverting input end of the first operational amplifier LM358 in parallel.
Still further preferably, the differential pre-amplifier circuit comprises a resistor R3, a resistor R5, a capacitor C20 and a second operational amplifier LM 358;
the output end of the first operational amplifier LM358 is electrically connected with the inverting input end of the second operational amplifier LM358 through a resistor R4, the other end of the resistor R1 is electrically connected with the inverting input end of the second operational amplifier LM358 through a resistor R3, the output end of the photoelectric conversion circuit is electrically connected with the non-inverting input end of the second operational amplifier LM358, the output end of the second operational amplifier LM358 is electrically connected with the input end of the filter circuit, a capacitor C20 is connected between the output end and the inverting input end of the second operational amplifier LM358 in parallel, and a resistor R5 is connected at two ends of a capacitor C20 in parallel.
On the basis of the above technical solution, preferably, the filter circuit includes an RC filter circuit and a low-pass filter;
the output end of the differential preamplification circuit is electrically connected with the input end of the low-pass filter through the RC filter circuit, and the output end of the low-pass filter is electrically connected with the analog input end of the CPU.
Still further preferably, the RC filter circuit includes a resistor R22, a resistor R23, a capacitor C15 and a capacitor C16;
the output end of the differential preamplifier circuit is electrically connected with one end of a resistor R22, the other end of the resistor R22 is electrically connected with one end of a resistor R23 and one end of a capacitor C15 respectively, the other end of the capacitor C15 is electrically connected with the output end of the low-pass filter, the other end of the resistor R23 is electrically connected with the input end of the low-pass filter and one end of a capacitor C16 respectively, and the other end of the capacitor C16 is grounded.
Still further preferably, the low pass filter includes a fourth operational amplifier CA3130, a resistor R24, and a capacitor C17;
the other end of the resistor R23 is electrically connected to the non-inverting input terminal of the fourth operational amplifier CA3130, the output terminal of the fourth operational amplifier CA3130 is electrically connected to the analog input terminal of the CPU and the other end of the capacitor C15, the capacitor C17 is connected in parallel between the output terminal of the fourth operational amplifier CA3130 and the inverting input terminal thereof, and the resistor R24 is connected in parallel to both ends of the capacitor C17.
The utility model discloses a fire detector has following beneficial effect for prior art:
(1) by arranging the double operational amplifier preamplification circuits and adopting double-channel differential input at the input end, unstable error signals in input signals are offset by difference values, so that the stability of the system is enhanced;
(2) the pre-amplification circuit is arranged in the double operational amplifier pre-amplification circuit, so that the voltage output by the photoelectric conversion circuit is amplified on one hand, and the dynamic error of the pre-amplification circuit caused by the unmatched circuit resistance is eliminated by adjusting the reference voltage on the other hand;
(3) the differential preamplification circuit is arranged in the double operational preamplification circuit, so that unstable error signals existing in the electric signals output by the fiber bragg grating sensor and the preamplification circuit are offset by difference;
(4) the RC filter circuit filters high-frequency interference signals existing in the output signals of the differential preamplifier circuit by arranging the RC filter circuit and the low-pass filter in the filter circuit, so that the input impedance of the circuit is improved; the low pass filter further filters out high frequency signals in the circuit.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a system diagram of a fire detector according to the present invention;
fig. 2 is a circuit diagram of a photoelectric conversion circuit in a fire detector according to the present invention;
fig. 3 is a circuit diagram of a dual-operational pre-amplifier circuit in a fire detector according to the present invention;
fig. 4 is a circuit diagram of a filter circuit in a fire detector according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work all belong to the protection scope of the present invention.
As shown in fig. 1, the fire detector of the present invention includes a fiber grating sensor, a photoelectric conversion circuit, a CPU, a filter circuit, and a dual operational amplifier preamplifier circuit.
And the fiber grating sensor detects the temperature of the electronic equipment or the electric line and outputs an optical signal to the photoelectric conversion circuit. And the optical signal output by the fiber bragg grating sensor is transmitted to the input end of the photoelectric conversion circuit. In this embodiment, the improvement of the internal structure of the fiber grating sensor is not involved, and therefore, the internal structure of the fiber grating sensor will not be described in detail herein. The type of the fiber grating sensor is not limited in this embodiment, and the BGK-FBG4500S is preferably used.
And the photoelectric conversion circuit detects the optical signal output by the fiber bragg grating sensor and converts the optical signal into an electric signal. The input end of the photoelectric conversion circuit receives an optical signal output by the fiber bragg grating sensor and converts the optical signal into an electrical signal, and the output end of the photoelectric conversion circuit is electrically connected with the double-operational amplifier preamplifier circuit.
Preferably, in the present embodiment, as shown in fig. 2, the photoelectric conversion circuit includes a photodiode D100, a resistor R6, a resistor R7, capacitors C30-C32, and a third operational amplifier CA 3130; the anode of the photodiode D100 is grounded, the cathode of the photodiode D100 is electrically connected to the inverting input terminal of the third operational amplifier CA3130, one end of the capacitor C30 and one end of the resistor R6 are both grounded, the other end of the capacitor C30 and the other end of the resistor R6 are respectively electrically connected to the non-inverting input terminal of the third operational amplifier CA3130, the output terminal of the third operational amplifier CA3130 is respectively electrically connected to the first input terminal of the preamplifier circuit and the first input terminal of the differential preamplifier circuit through the capacitor C32, the resistor R7 is connected in parallel between the output terminal of the third operational amplifier CA3130 and the inverting input terminal thereof, and the capacitor C31 is connected in parallel to both ends of the resistor R7. As shown in fig. 2, V1 represents the electrical signal output by the optoelectronic conversion circuit; u3 denotes a third operational amplifier CA 3130.
The photodiode D100 receives an optical signal output by the grating optical fiber sensor and converts the optical signal into a current signal; the resistor R6 and the capacitor C30 form an RC filter circuit, and the resistor R6 is used for preventing the zero drift of the third operational amplifier CA 3130; the capacitor C30 is used for filtering high-frequency and high-voltage interference signals; the resistor R7 is a negative feedback resistor and is used for generating voltage drop; the capacitor C31 is a compensation capacitor and is used for compensating the phase difference of the input signals; the capacitor C32 is a coupling capacitor and is used for isolating direct current; the photodiode D100 receives the optical signal output from the fiber bragg grating sensor and converts the optical signal into a current signal, and the converted current signal is output to the resistor R7 to form a voltage drop and is amplified by the third operational amplifier CA3130 to output a voltage signal.
The double-operational amplifier pre-amplifying circuit amplifies an electric signal output by the photoelectric conversion circuit, and the input end adopts double-channel differential input, so that an unstable error signal in an input signal is offset by a difference value, and the stability of the system is enhanced. Preferably, in this embodiment, the dual-operational pre-amplifier circuit includes a reference voltage, a pre-amplifier circuit, and a differential pre-amplifier circuit. One path of the electric signal converted and output by the photoelectric conversion circuit is input to the preamplification circuit, and the other path of the electric signal is input to the differential preamplification circuit; one path of the reference voltage is input to the pre-amplification circuit, and the other path of the reference voltage is input to the differential pre-amplification circuit.
The reference voltage is a bias input of the preamplifier circuit. In the present embodiment, as shown in fig. 2, Vr represents a reference voltage; in this embodiment, the reference voltage is an adjustable voltage.
The pre-amplification circuit is used for amplifying the voltage output by the photoelectric conversion circuit on the one hand; on the other hand, when the resistors in the circuit are not matched, the pre-amplification circuit generates an output error, the output error is only related to the electric signal output by the photoelectric conversion circuit and the reference voltage, and the electric signal output by the photoelectric conversion circuit is constant, so that the dynamic error of the pre-amplification circuit caused by the mismatch of the resistors of the circuit is eliminated by adjusting the value of the reference voltage. The first input end of the preamplifier circuit is electrically connected with the output end of the photoelectric conversion circuit, the second input end of the preamplifier circuit is electrically connected with the reference voltage, and the output end of the preamplifier circuit is electrically connected with the second input end of the differential preamplifier circuit.
Preferably, in this embodiment, as shown in fig. 3, the pre-amplifier circuit includes a resistor R1, a resistor R2, a resistor R4, and a first operational amplifier LM 358; the non-inverting input end of the first operational amplifier LM358 is electrically connected with the output end of the photoelectric conversion circuit, the reference voltage is electrically connected with one end of the resistor R1, the other end of the resistor R1 is electrically connected with the inverting input end of the first operational amplifier LM358 and the second input end of the differential type preamplifier circuit respectively, the output end of the first operational amplifier LM358 is electrically connected with the second input end of the differential type preamplifier circuit through the resistor R4, and the resistor R2 is connected between the output end of the first operational amplifier LM358 and the inverting input end of the first operational amplifier LM358 in parallel. As shown in fig. 3, U1 correspondingly represents the first operational amplifier LM 358; the non-inverting input end of the first operational amplifier LM358 corresponds to the first input end of the pre-amplifier circuit; the inverting input terminal of the first operational amplifier LM358 corresponds to the second input terminal of the preamplifier circuit, and the output terminal of the first operational amplifier LM358 corresponds to the output terminal of the preamplifier circuit.
The reference voltage is input to the inverting input end of the first operational amplifier LM358 through a resistor R1, and the resistor R1 is a load resistor and prevents the first operational amplifier LM358 from being broken down; the resistor R2 is a degeneration resistor for reducing the nonlinear distortion and offset voltage of the first operational amplifier LM 358; the first operational amplifier LM358 is a differential amplifier, when the resistors in the circuit are not matched, the first operational amplifier LM358 can generate an output error, the output error is only related to the electric signal output by the photoelectric conversion circuit and the reference voltage, the electric signal output by the photoelectric conversion circuit is constant, and the dynamic error of the electric signal output by the first operational amplifier LM358 caused by the mismatch of the resistors of the circuit is eliminated by adjusting the value of the reference voltage input to the inverting input end of the first operational amplifier LM 358; the resistor R4 is a voltage drop resistor, and the output end of the first operational amplifier LM358 outputs an electric signal to form a voltage drop output voltage through the resistor R4.
The differential pre-amplification circuit is used for amplifying the voltage output by the pre-amplification circuit; on the other hand, the unstable error signal in the input signal is cancelled by the difference. The first input end of the differential preamplifier circuit is electrically connected with the output end of the photoelectric conversion circuit, the second input end of the differential preamplifier circuit is respectively electrically connected with the output end of the preamplifier circuit and the reference voltage, and the output end of the differential preamplifier circuit is electrically connected with the input end of the filter circuit.
Preferably, in this embodiment, as shown in fig. 3, the differential pre-amplifier circuit includes a resistor R3, a resistor R5, a capacitor C20, and a second operational amplifier LM 358; the inverting input end of the second operational amplifier LM358 is electrically connected with the output end of the first operational amplifier LM358 through a resistor R4, the inverting input end of the second operational amplifier LM358 is electrically connected with the other end of the resistor R1 through a resistor R3, the non-inverting input end of the second operational amplifier LM358 is electrically connected with the output end of the photoelectric conversion circuit, the output end of the second operational amplifier LM358 is electrically connected with the input end of the filter circuit, a capacitor C20 is connected between the output end of the second operational amplifier LM358 and the inverting input end of the second operational amplifier LM358 in parallel, and a resistor R5 is connected at two ends of a capacitor C20 in parallel. As shown in fig. 3, U2 correspondingly represents the second operational amplifier LM 358; vout1 represents the voltage signal output by the differential pre-amplification circuit; the non-inverting input end of the second operational amplifier LM358 corresponds to the first input end of the differential preamplifier circuit; the inverting input terminal of the second operational amplifier LM358 corresponds to the second input terminal of the differential preamplifier, and the output terminal of the second operational amplifier LM358 corresponds to the output terminal of the differential preamplifier.
The reference voltage is input to the inverting input end of the second operational amplifier LM358 through the resistor R3, and the resistor R3 is a load resistor and prevents the second operational amplifier LM358 from being broken down; the resistor R5 is a degeneration resistor for reducing the nonlinear distortion and offset voltage of the second operational amplifier LM 358; the capacitor C20 is a filter capacitor for filtering out interference signals in the circuit.
And the filter circuit filters high-frequency interference signals in the circuit. The input end of the filter circuit is electrically connected with the output end of the differential preamplification circuit, and the output end of the filter circuit is electrically connected with the analog input end of the CPU. Preferably, in this embodiment, the filter circuit includes an RC filter circuit and a low-pass filter; the output end of the differential preamplification circuit is electrically connected with the input end of the low-pass filter through the RC filter circuit, and the output end of the low-pass filter is electrically connected with the analog input end of the CPU.
And the RC filter circuit is used for filtering high-frequency interference signals existing in the output signals of the differential pre-amplification circuit and improving the input impedance of the circuit. Preferably, in this embodiment, as shown in fig. 4, the RC filter circuit includes a resistor R22, a resistor R23, a capacitor C15, and a capacitor C16; one end of the resistor R22 is electrically connected with the output end of the differential preamplifier circuit, the other end of the resistor R22 is electrically connected with one end of the resistor R23 and one end of the capacitor C15 respectively, the other end of the capacitor C15 is electrically connected with the output end of the low-pass filter, the other end of the resistor R23 is electrically connected with the input end of the low-pass filter and one end of the capacitor C16 respectively, and the other end of the capacitor C16 is grounded. The resistor R22, the capacitor C15, the resistor R23 and the capacitor C16 form two groups of RC filter circuits, so that the output voltage is reduced at a higher speed in a high frequency band, high-frequency interference signals in the circuit are effectively filtered, and the input impedance of the circuit is improved.
And the low-pass filter is used for amplifying the voltage signal output by the RC filter circuit and further filtering the high-frequency signal. Preferably, in the present embodiment, as shown in fig. 4, the low pass filter includes a fourth operational amplifier CA3130, a resistor R24, and a capacitor C17; the other end of the resistor R23 is electrically connected to the non-inverting input terminal of the fourth operational amplifier CA3130, the output terminal of the fourth operational amplifier CA3130 is electrically connected to the analog input terminal of the CPU and the other end of the capacitor C15, the capacitor C17 is connected in parallel between the output terminal of the fourth operational amplifier CA3130 and the inverting input terminal thereof, and the resistor R24 is connected in parallel to both ends of the capacitor C17. As shown in fig. 4, U4 corresponds to the fourth operational amplifier CA3130, and Vout2 represents the voltage signal filtered by the low-pass filter.
Wherein, the resistor R24 is a negative feedback resistor; the capacitor C17 is a negative feedback capacitor; a low-pass filter for rapidly attenuating the amplitude-frequency characteristic of the fourth operational amplifier CA3130 at high frequencies; meanwhile, the capacitor C17 filters high-frequency signals in the circuit; the fourth operational amplifier CA3130 is configured to amplify the RC filter circuit output voltage signal.
And the CPU processes and calculates the electric signal output by the filter circuit. The analog input end of the CPU is electrically connected with the output end of the filter circuit. In this embodiment, the improvement of the internal structure of the CPU is not involved, and therefore, the internal structure of the CPU will not be described here. The present embodiment does not limit the type of the CPU, and preferably, AT89C51 is used.
The utility model discloses a theory of operation is: the fiber bragg grating sensor collects the temperature of an electric circuit, outputs an optical signal to the photoelectric conversion circuit to be converted into an electric signal, the electric signal is divided into two paths, one path of the electric signal is output to the pre-amplification circuit, the pre-amplification circuit eliminates dynamic errors caused by circuit resistance mismatching by adjusting the voltage value of the reference voltage on one hand, and amplifies the electric signal output by the photoelectric conversion circuit and outputs the electric signal to the differential pre-amplification circuit on the other hand; and the other path of the signal is input into a differential pre-amplification circuit, the differential pre-amplification circuit enables unstable error signals existing in the electric signal output by the fiber grating sensor and the electric signal output by the pre-amplification circuit to be counteracted through a difference value, and the counteracted signal is input into a CPU for processing and calculation after a high-frequency interference signal is filtered by an RC filter circuit and a low-pass filter.
The beneficial effect of this embodiment does: by arranging the double operational amplifier preamplification circuits and adopting double-channel differential input at the input end, unstable error signals in input signals are offset by difference values, so that the stability of the system is enhanced;
the pre-amplification circuit is arranged in the double operational amplifier pre-amplification circuit, so that the voltage output by the photoelectric conversion circuit is amplified on one hand, and the dynamic error of the pre-amplification circuit caused by the unmatched circuit resistance is eliminated by adjusting the reference voltage on the other hand;
the differential preamplification circuit is arranged in the double operational preamplification circuit, so that unstable error signals existing in the electric signals output by the fiber bragg grating sensor and the preamplification circuit are offset by difference;
the RC filter circuit filters high-frequency interference signals existing in the output signals of the differential preamplifier circuit by arranging the RC filter circuit and the low-pass filter in the filter circuit, so that the input impedance of the circuit is improved; the low pass filter further filters out high frequency signals in the circuit.
The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. The utility model provides a fire detector, its includes fiber grating sensor, photoelectric conversion circuit, CPU, filter circuit, two fortune preamplifiers circuit, its characterized in that: the dual-operational amplifier preamplifier circuit comprises a reference voltage, a preamplifier circuit and a differential preamplifier circuit;
the optical fiber grating sensor comprises a fiber grating sensor, a differential preamplifier circuit, a filter circuit, a photoelectric conversion circuit, a reference voltage and a reference voltage, wherein an optical signal output by the fiber grating sensor is transmitted to the input end of the photoelectric conversion circuit, is detected by the photoelectric conversion circuit and is converted into an electric signal, the output end of the photoelectric conversion circuit is electrically connected with the first input end of the preamplifier circuit and the first input end of the differential preamplifier circuit respectively, the reference voltage is electrically connected with the second input end of the preamplifier circuit and the second input end of the differential preamplifier circuit respectively, the output end of the preamplifier circuit is electrically connected with the second input end of the differential preamplifier circuit, the output end of the differential preamplifier circuit is electrically connected with the input end of the filter circuit, and the output end of the filter circuit is electrically connected with the analog input end of the CPU.
2. A fire detector as claimed in claim 1, characterised in that: the photoelectric conversion circuit comprises a photodiode D100, a resistor R6, a resistor R7, capacitors C30-C32 and a third operational amplifier CA 3130;
the positive electrode of the photodiode D100 is grounded, the negative electrode of the photodiode D100 is electrically connected to the inverting input terminal of the third operational amplifier CA3130, one end of the capacitor C30 and one end of the resistor R6 are both grounded, the other end of the capacitor C30 and the other end of the resistor R6 are respectively electrically connected to the non-inverting input terminal of the third operational amplifier CA3130, the output terminal of the third operational amplifier CA3130 is respectively electrically connected to the first input terminal of the preamplifier circuit and the first input terminal of the differential preamplifier circuit through the capacitor C32, the resistor R7 is connected in parallel between the output terminal of the third operational amplifier CA3130 and the inverting input terminal thereof, and the capacitor C31 is connected in parallel to both ends of the resistor R7.
3. A fire detector as claimed in claim 1, characterised in that: the pre-amplification circuit comprises a resistor R1, a resistor R2, a resistor R4 and a first operational amplifier LM 358;
the output end of the photoelectric conversion circuit is electrically connected with the non-inverting input end of the first operational amplifier LM358, the reference voltage is electrically connected with one end of the resistor R1, the other end of the resistor R1 is electrically connected with the inverting input end of the first operational amplifier LM358 and the second input end of the differential type preamplifier circuit respectively, the output end of the first operational amplifier LM358 is electrically connected with the second input end of the differential type preamplifier circuit through the resistor R4, and the resistor R2 is connected between the output end of the first operational amplifier LM358 and the inverting input end of the first operational amplifier LM358 in parallel.
4. A fire detector as claimed in claim 3, characterised in that: the differential pre-amplification circuit comprises a resistor R3, a resistor R5, a capacitor C20 and a second operational amplifier LM 358;
the output end of the first operational amplifier LM358 is electrically connected with the inverting input end of the second operational amplifier LM358 through a resistor R4, the other end of the resistor R1 is electrically connected with the inverting input end of the second operational amplifier LM358 through a resistor R3, the output end of the photoelectric conversion circuit is electrically connected with the non-inverting input end of the second operational amplifier LM358, the output end of the second operational amplifier LM358 is electrically connected with the input end of the filter circuit, a capacitor C20 is connected between the output end and the inverting input end of the second operational amplifier LM358 in parallel, and a resistor R5 is connected at two ends of a capacitor C20 in parallel.
5. A fire detector as claimed in claim 1, characterised in that: the filter circuit comprises an RC filter circuit and a low-pass filter;
the output end of the differential preamplification circuit is electrically connected with the input end of the low-pass filter through the RC filter circuit, and the output end of the low-pass filter is electrically connected with the analog input end of the CPU.
6. A fire detector as claimed in claim 5, characterised in that: the RC filter circuit comprises a resistor R22, a resistor R23, a capacitor C15 and a capacitor C16;
the output end of the differential preamplifier circuit is electrically connected with one end of a resistor R22, the other end of the resistor R22 is electrically connected with one end of a resistor R23 and one end of a capacitor C15 respectively, the other end of the capacitor C15 is electrically connected with the output end of the low-pass filter, the other end of the resistor R23 is electrically connected with the input end of the low-pass filter and one end of a capacitor C16 respectively, and the other end of the capacitor C16 is grounded.
7. A fire detector as claimed in claim 6, characterised in that: the low pass filter comprises a fourth operational amplifier CA3130, a resistor R24 and a capacitor C17;
the other end of the resistor R23 is electrically connected to the non-inverting input terminal of the fourth operational amplifier CA3130, the output terminal of the fourth operational amplifier CA3130 is electrically connected to the analog input terminal of the CPU and the other end of the capacitor C15, the capacitor C17 is connected in parallel between the output terminal of the fourth operational amplifier CA3130 and the inverting input terminal thereof, and the resistor R24 is connected in parallel to both ends of the capacitor C17.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022220481.0U CN213241407U (en) | 2020-09-30 | 2020-09-30 | Fire detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022220481.0U CN213241407U (en) | 2020-09-30 | 2020-09-30 | Fire detector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN213241407U true CN213241407U (en) | 2021-05-18 |
Family
ID=75878002
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202022220481.0U Expired - Fee Related CN213241407U (en) | 2020-09-30 | 2020-09-30 | Fire detector |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN213241407U (en) |
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2020
- 2020-09-30 CN CN202022220481.0U patent/CN213241407U/en not_active Expired - Fee Related
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Granted publication date: 20210518 |