Ordinary fire alarm detection circuit, ordinary fire automatic alarm controller and ordinary fire automatic alarm system

Abstract

The invention relates to the technical field of fire alarm detection, and provides an ordinary fire alarm detection circuit, an ordinary automatic fire alarm controller and an ordinary automatic fire alarm system, and a two-bus detection loop comprises a first switch unit, a sampling unit, a fire alarm detector, a second switch unit and a terminal resistor; one end of the first switch unit is connected with a power input end and a control signal input end, the other end of the first switch unit is connected with one end of the sampling unit and one end of the fire alarm detector, the other end of the sampling unit outputs sampling signals, and the other end of the fire alarm detector is connected with one end of the second switch unit. The other end of the second switch unit is connected to a power supply input end and a control signal input end; the terminal resistor is connected in parallel with the fire detector; the first switch unit and the second switch unit are in mutual exclusion conduction so as to control the two-bus detection loop to enter a fire inspection state or a line inspection state; the problem that fire alarm or line fault cannot be distinguished due to excessive terminals can be effectively solved, and the detection effect is good.

Description

Technical Field

[0001] The present invention relates to the technical field of fire detection, and more specifically to a common fire detection circuit, a common fire automatic alarm controller and a system. Background Art

[0002] The automatic fire alarm system is generally divided into intelligent automatic fire alarm system and ordinary automatic fire alarm system. The ordinary automatic fire alarm system is also the traditional automatic fire alarm system. In the ordinary automatic fire alarm system, the fire detection circuit is the most critical and indispensable part of the whole system, which carries the alarm detection task of all fire detectors in the system. The fire detection circuit refers to the detection circuit connected to the two buses, generally also called the "zone" circuit. Multiple terminals are mounted on this bus. This bus can identify the alarm status of the terminal and the line fault status, such as open circuit, short circuit, etc. In an ordinary automatic fire alarm controller, the basic unit elements are roughly fixed, but the fire detection circuit is an exception, because different fire protection layout places determine the number of fire detection circuits required. In the circuit implementation scheme, in the existing fire detection circuit, the detection line and the fire alarm output are both in the same direction. When more and more terminals are connected, the fire alarm pull current becomes larger and larger, resulting in its threshold close to the short circuit threshold and unable to distinguish between the fire alarm output and the line fault status, and the detection result is not accurate enough. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a common fire detection circuit, a common fire automatic alarm controller and a system in view of the above-mentioned defects of the prior art.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] On the one hand, the present invention provides a common fire detection circuit, including a two-bus detection circuit, wherein the two-bus detection circuit includes a first switch unit, a sampling unit, a fire detector, a second switch unit and a terminal resistor; one end of the first switch unit is connected to a power input terminal and a control signal input terminal, the other end of the first switch unit is respectively connected to one end of the sampling unit and the fire detector, the other end of the sampling unit outputs a sampling signal, the other end of the fire detector is connected to one end of the second switch unit, and the other end of the second switch unit is connected to the power input terminal and the control signal input terminal; the terminal resistor is connected in parallel with the fire detector; the first switch unit and the second switch unit are mutually exclusive turned on to control the two-bus detection circuit to enter a fire inspection state or a line inspection state.

[0006] In some embodiments, when the first switch unit is turned off, the second switch unit is turned on, and the two-bus detection circuit enters a fire alarm inspection state; when the first switch unit is turned on, the second switch unit is turned off, and the two-bus detection circuit enters a line detection state.

[0007] In some embodiments, the first switch unit includes a first triode, a second triode, a first diode, a first resistor, a second resistor, a third resistor and a fourth resistor; the emitter of the first triode is respectively connected to the power input terminal and one end of the first resistor, the other end of the first resistor is connected to one end of the second resistor, and the other end of the second resistor is connected to the collector of the second triode; the base of the second triode is connected to one end of the third resistor, and the other end of the third resistor is connected to the control signal input terminal; the emitter of the second triode is grounded; the base of the first triode is connected between the first resistor and the second resistor; the collector of the first triode is connected to the positive electrode of the first diode, the negative electrode of the first diode is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the sampling unit.

[0008] In some embodiments, the sampling unit includes a third transistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a second diode and a third diode; one end of the fifth resistor and the cathode of the second diode are both connected to the other end of the fourth resistor, and the other end of the fifth resistor and the emitter of the third transistor are both grounded; the anode of the second diode is respectively connected to the cathode of the third diode and one end of the sixth resistor, the anode of the third diode is connected to the control signal input end, and the other end of the sixth resistor is connected to the base of the third transistor; the collector of the third transistor is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the eighth resistor, and the other end of the eighth resistor is respectively connected to the other end of the fourth resistor and one end of the fire detector.

[0009] In some embodiments, the sampling unit further includes a first capacitor and a first TVS tube, and the first capacitor and the first TVS tube are connected in parallel at one end of the fire detector and connected to a protective ground.

[0010] In some embodiments, the fifth resistor is a sampling resistor; and the second diode is a voltage regulator diode.

[0011] In some embodiments, the second switch unit includes a fourth transistor, a fifth transistor, a sixth transistor, a seventh transistor, a fuse, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor and a fourteenth resistor; the emitter of the fourth transistor is respectively connected to one end of the fuse and the ninth resistor, the other end of the fuse is connected to the power input terminal, the other end of the ninth resistor is connected to one end of the tenth resistor, the other end of the tenth resistor is connected to the collector of the sixth transistor, and the base of the fourth transistor is connected between the ninth resistor and the tenth resistor; the sixth transistor The base of the fourth transistor is respectively connected to the collector of the eleventh resistor and the seventh transistor, the base of the seventh transistor is connected to one end of the twelfth resistor, and the other end of the twelfth resistor is connected to the control signal input terminal; the collector of the fourth transistor is respectively connected to the collector of the fifth transistor and the other end of the fire detector, the base of the fifth transistor is connected to one end of the thirteenth resistor, and the other end of the thirteenth resistor is connected to the control signal input terminal; the emitter of the fifth transistor is connected to one end of the fourteenth resistor, and the other end of the fourteenth resistor and the emitters of the sixth and seventh transistors are all grounded.

[0012] In some embodiments, the second switch unit further includes a second capacitor and a second TVS tube, and the second capacitor and the second TVS tube are connected in parallel to the other end of the fire detector and connected to the protective ground.

[0013] On the other hand, the present invention also provides a common type automatic fire alarm controller, comprising a common type fire alarm detection circuit as described in any one of the above items.

[0014] On the other hand, the present invention also provides a common type automatic fire alarm system, comprising the common type automatic fire alarm controller as described above.

[0015] The beneficial effects of the present invention are as follows: different from the prior art, in the ordinary fire detection circuit of the present invention, one end of the first switch unit is connected to the power input end and the control signal input end, the other end of the first switch unit is respectively connected to one end of the sampling unit and the fire detector, the other end of the sampling unit outputs a sampling signal, the other end of the fire detector is connected to one end of the second switch unit, and the other end of the second switch unit is connected to the power input end and the control signal input end; the terminal resistor is connected in parallel with the fire detector; the first switch unit and the second switch unit are mutually exclusive turned on to control the two-bus detection loop to enter the fire inspection state or the line inspection state; thereby respectively realizing the detection of fire alarm output and line fault, which can effectively solve the problem of being unable to distinguish whether it is a fire alarm or a line fault when too many terminals are connected, the detection effect is better, and the detection result is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1It is a principle block diagram of a common fire detection circuit in Embodiment 1 of the present invention;

[0017] Figure 2 is a circuit layout diagram of a common fire detection circuit in Embodiment 1 of the present invention;

[0018] Figure 3 This is a working diagram of a common fire detection circuit in Embodiment 1 of the present invention;

[0019] The names and serial numbers in the figure are: first switch unit-1; sampling unit-2; fire detector-3; second switch unit-4; terminal resistor-5; first switch control module-41; second switch control module-42. DETAILED DESCRIPTION

[0020] The terms "first", "second", "third" and "fourth" etc. in the specification and claims of the present invention and the drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, products or devices.

[0021] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0022] "Multiple" means two or more. "And / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the related objects are in an "or" relationship.

[0023] Moreover, the terms "up, down, front, back, left, right, upper end, lower end" etc. indicating directions are all based on the posture and position of the device or equipment described in this solution during normal use.

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be described clearly and completely in combination with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are partial embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0025] Embodiment 1: The embodiment of the present invention provides a common fire detection circuit, such as Figure 1 As shown in, the ordinary fire detection circuit includes a two-bus detection circuit, which includes a first switch unit 1, a sampling unit 2, a fire detector 3, a second switch unit 4 and a terminal resistor 5; one end of the first switch unit 1 is connected to a power input terminal and a control signal input terminal, the other end of the first switch unit 1 is respectively connected to one end of the sampling unit 2 and the fire detector 3, the other end of the sampling unit 2 outputs a sampling signal, the other end of the fire detector 3 is connected to one end of the second switch unit 4, and the other end of the second switch unit 4 is connected to the power input terminal and the control signal input terminal; the terminal resistor 5 is connected in parallel with the fire detector 3; the first switch unit 1 and the second switch unit 4 are mutually exclusive to control the two-bus detection circuit to enter a fire inspection state or a line inspection state.

[0026] Specifically, in this embodiment, when the first switch circuit 1 is turned off, the second switch circuit 4 is turned on, and the two-bus detection circuit enters the fire alarm inspection state. The fire detection circuit in the fire alarm inspection state is shown by arrow A. When the first switch circuit 1 is turned on, the second switch circuit 4 is turned off, and the two-bus detection circuit enters the line detection state. The line detection circuit in the line detection state is shown by arrow B. Thus, the detection of the fire alarm output and the line fault is realized respectively, which can effectively solve the problem of being unable to distinguish whether it is a fire alarm or a line fault when too many terminals are connected, and the detection effect is better.

[0027] The circuit layout of the first switch unit 1 is as follows: Figure 2As shown in, the first switch unit 1 includes a first triode Q1, a second triode Q2, a first diode D2, a first resistor R36, a second resistor R39, a third resistor R42 and a fourth resistor R35; the emitter of the first triode Q1 is connected to the power input terminal and one end of the first resistor R36 respectively, the other end of the first resistor R36 is connected to one end of the second resistor R39, and the other end of the second resistor R39 is connected to the collector of the second triode Q2; the base of the second triode Q2 is connected to one end of the third resistor R42, and the other end of the third resistor R42 is connected to the control signal input terminal; the emitter of the second triode Q2 is grounded; the base of the first triode Q1 is connected between the first resistor R36 and the second resistor R39; the collector of the first triode Q1 is connected to the positive electrode of the first diode D2, the negative electrode of the first diode D2 is connected to one end of the fourth resistor R35, and the other end of the fourth resistor R35 is connected to the sampling unit 2.

[0028] The circuit layout of the sampling unit 2 is as follows: Figure 2 As shown in , the sampling unit 2 includes a third transistor Q3, a fifth resistor R40, a sixth resistor R43, a seventh resistor R41, an eighth resistor R37, a second diode ZD1 and a third diode D4; one end of the fifth resistor R40 and the cathode of the second diode ZD1 are both connected to the other end of the fourth resistor R35, and the other end of the fifth resistor R40 and the emitter of the third transistor Q3 are both grounded; the anode of the second diode ZD1 is respectively connected to the cathode of the third diode D4 and one end of the sixth resistor R43, the anode of the third diode D4 is connected to the control signal input end, and the other end of the sixth resistor R43 is connected to the base of the third transistor Q3; the collector of the third transistor Q3 is connected to one end of the seventh resistor R41, the other end of the seventh resistor R41 is connected to one end of the eighth resistor R37, and the other end of the eighth resistor R37 is respectively connected to the other end of the fourth resistor R35 and one end of the fire detector 3. Specifically, the fifth resistor R40 is a sampling resistor, and the resistance value of the sampling resistor is 750Ω. The second diode ZD1 is a voltage stabilizing diode.

[0029] Under normal circumstances, the fire detection circuit is an external output unit, and factors such as port protection and line protection are considered during design. The existing fire detection circuit not only uses high-cost devices such as varistors and gas discharge tubes in the external part of the port, but also has a series of short-circuit protection units, which further increases the cost. In particular, in the identification of short circuit, open circuit and fire alarm, the solution adopted is to use comparators to distinguish the states. The cost of comparators is also relatively high. For a single-channel fire detection circuit, the cost difference may not be obvious enough, but when more fire detection circuits are required, the cost difference will become more significant.

[0030] Therefore, further, the sampling unit 2 further includes a first capacitor C21 and a first transient voltage zener diode TVS1, and the first capacitor C21 and the first transient voltage zener diode TVS1 are connected in parallel at one end of the fire detector 3 and connected to the protective ground. In this embodiment, large-volume and high-cost devices such as varistors and discharge tubes are removed from the port and replaced with small-volume and low-cost first capacitors C21 and first transient voltage zener diodes TVS1. By using a transient voltage zener diode, the interference level is filtered, so that the EMC performance with the same effect can be achieved by using very few protective devices, effectively reducing the design and manufacturing costs.

[0031] The circuit layout of the second switch unit 4 is as follows: Figure 2 As shown in, the second switch unit 4 includes a fourth transistor Q4, a fifth transistor Q5, a sixth transistor Q6, a seventh transistor Q7, a fuse F2, a ninth resistor R46, a tenth resistor R47, an eleventh resistor R48, a twelfth resistor R53, a thirteenth resistor R49 and a fourteenth resistor R51; the emitter of the fourth transistor Q4 is connected to one end of the fuse F2 and the ninth resistor R46 respectively, the other end of the fuse F2 is connected to the power input end, the other end of the ninth resistor R46 is connected to one end of the tenth resistor R47, the other end of the tenth resistor R47 is connected to the collector of the sixth transistor Q6, and the base of the fourth transistor Q4 is connected between the ninth resistor R46 and the tenth resistor R47 The base of the sixth triode Q6 is connected to the collector of the eleventh resistor R48 and the seventh triode Q7 respectively, the base of the seventh triode Q7 is connected to one end of the twelfth resistor R53, and the other end of the twelfth resistor R53 is connected to the control signal input terminal; the collector of the fourth triode Q4 is connected to the collector of the fifth triode Q5 and the other end of the fire detector 3 respectively, the base of the fifth triode Q5 is connected to one end of the thirteenth resistor R49, and the other end of the thirteenth resistor R49 is connected to the control signal input terminal; the emitter of the fifth triode Q5 is connected to one end of the fourteenth resistor R51, and the other end of the fourteenth resistor R51 and the emitters of the sixth triode Q6 and the seventh triode Q7 are all grounded.

[0032] The fourth transistor Q4, the sixth transistor Q6, the seventh transistor Q7, the fuse F2, the ninth resistor R46, the tenth resistor R47, the eleventh resistor R48 and the twelfth resistor R53 constitute the first switch control module 41 in the second switch unit 4, which is used to realize power input and control signal input. The fifth transistor Q5, the thirteenth resistor R49 and the fourteenth resistor R51 constitute the second switch control module 42 in the second switch unit 4, which is used to realize control signal input and form a line detection return path in the line detection state.

[0033] Furthermore, the second switch unit 4 also includes a second capacitor C25 and a second transient voltage regulator diode TVS2, which are connected in parallel to the other end of the fire detector 3 and connected to the protection ground, and the second capacitor C25 and the second transient voltage regulator diode TVS2 with small volume and low cost are used to replace large volume and high cost components such as varistors and discharge tubes. By reducing the components used in the circuit, the component cost of the overall circuit is reduced, and the components used in this embodiment are smaller in volume, so that the volume of the manufactured circuit board can also be smaller, which effectively reduces the design and manufacturing cost of the circuit board.

[0034] In this embodiment, the terminal resistor 5 is a diode, which needs to be terminated between the positive and negative electrodes of the two buses. Figure 1 When diodes are used properly as resistors, more flexibility and selectivity can be provided for circuit design.

[0035] The following describes the principle of realizing fire alarm output and line fault detection in its specific implementation in combination with the circuit layout of the aforementioned common fire alarm detection circuit:

[0036] In this embodiment, the fire alarm output and line fault detection are time-division multiplexed. A complete working cycle is divided into a fire alarm inspection state and a line inspection state. For the specific work flow, please refer to Figure 3 .pass Figure 2 The ZONE-_CTRL signal shown in the figure realizes the mutually exclusive conduction of the first transistor Q1 and the fourth transistor Q4, thereby realizing the distinction between the fire alarm inspection state and the line inspection state. Among them, when ZONE-_CTRL is low, the fourth transistor Q4 is turned on, the first transistor Q1 is turned off, and the fire alarm inspection state is entered; when ZONE-_CTRL is high, the fourth transistor Q4 is turned off, the first transistor Q1 is turned on, and the line inspection state is entered.

[0037] The fire alarm judgment logic is as follows:

[0038] In the fire alarm inspection state, since the fourth transistor Q4 is turned on, the 24V voltage passes through the fourth transistor Q4, and then flows back to the system ground through the terminal via the sampling resistor. If the terminal does not report a fire alarm, the pull current is small, and the voltage across the sampling resistor is low, which means that the sampling value is low; conversely, when the terminal pulls a large current after the alarm, the voltage across the sampling resistor is high, and it is considered that a fire alarm has occurred after reaching the corresponding threshold. It can be understood that the terminal here refers to the fire detector 3.

[0039] The fault judgment logic is as follows:

[0040] In the line detection state, since the first transistor Q1 is turned on and the fifth transistor Q5 is turned on at the same time, the 24V voltage flows back to the system ground through the first transistor Q1 and the parallel path of the first diode D2, the fifth transistor Q5 and the sampling resistor. If the external line is not short-circuited at this time, the sampling value is the sum of the conduction voltage drop of the fifth transistor Q5 and the conduction voltage drop of the terminal resistor 5. If the external line is short-circuited at this time, the sampling value is the conduction voltage drop of the fifth transistor Q5. If the external line is open at this time, the sampling value is the voltage divided value of the fourth resistor R35 and the sampling resistor to 24V. Different fault states can be distinguished according to the different thresholds collected.

[0041] This embodiment has obvious advantages in the short circuit protection of the unit scheme. It does not need to add an additional short circuit protection unit to achieve the purpose of not damaging the device in the event of a short circuit. Whether it is a short circuit in the line detection process or in the fire alarm output process, the unit will not be damaged. The reason is that in the line detection stage, the line detection current is limited by the fourth resistor R35. Whether it is short-circuited or not, it can only output a few mA to ten mA at most, and the current magnitude is very small. For the fire alarm output stage, whether it is short-circuited or not, it can only output tens of mA at most, so the cost of short-circuit protection can be reduced.

[0042] Embodiment 2: The embodiment of the present invention further provides a general fire automatic alarm controller, including the general fire detection circuit provided in the above embodiment 1. If the cost of the general fire detection circuit is reduced, the manufacturing cost of the general fire automatic alarm controller can also be reduced, which helps to improve its market competitiveness. For the description of the general fire detection circuit, please refer to embodiment 1.

[0043] Embodiment 3: The embodiment of the present invention further provides a general fire automatic alarm system, including the general fire automatic alarm controller provided in Embodiment 2. The structure and model of the general fire automatic alarm controller shall be subject to actual application, and this embodiment does not make any specific limitation.

[0044] It should be understood that, for ordinary technical workers in the field, improvements or changes can be made based on the above description, and all these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A common fire detection circuit, comprising a two-bus detection circuit, characterized in that: The two-bus detection circuit includes a first switch unit, a sampling unit, a fire detector, a second switch unit and a terminal resistor; one end of the first switch unit is connected to a power input terminal and a control signal input terminal, the other end of the first switch unit is respectively connected to one end of the sampling unit and the fire detector, the other end of the sampling unit outputs a sampling signal, the other end of the fire detector is connected to one end of the second switch unit, and the other end of the second switch unit is connected to the power input terminal and the control signal input terminal; the terminal resistor is connected in parallel with the fire detector; the first switch unit and the second switch unit are mutually exclusive turned on to control the two-bus detection circuit to enter a fire inspection state or a line inspection state.

2. The common fire detection circuit according to claim 1, characterized in that: When the first switch unit is turned off, the second switch unit is turned on, and the two-bus detection circuit enters a fire alarm inspection state; when the first switch unit is turned on, the second switch unit is turned off, and the two-bus detection circuit enters a line detection state.

3. The common fire detection circuit according to claim 1, characterized in that: The first switch unit includes a first triode, a second triode, a first diode, a first resistor, a second resistor, a third resistor and a fourth resistor; the emitter of the first triode is respectively connected to the power input terminal and one end of the first resistor, the other end of the first resistor is connected to one end of the second resistor, and the other end of the second resistor is connected to the collector of the second triode; the base of the second triode is connected to one end of the third resistor, and the other end of the third resistor is connected to the control signal input terminal; the emitter of the second triode is grounded; the base of the first triode is connected between the first resistor and the second resistor; the collector of the first triode is connected to the positive electrode of the first diode, the negative electrode of the first diode is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the sampling unit.

4. The common fire detection circuit according to claim 3 is characterized in that: The sampling unit includes a third triode, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a second diode and a third diode; one end of the fifth resistor and the cathode of the second diode are both connected to the other end of the fourth resistor, and the other end of the fifth resistor and the emitter of the third triode are both grounded; the anode of the second diode is respectively connected to the cathode of the third diode and one end of the sixth resistor, the anode of the third diode is connected to the control signal input end, and the other end of the sixth resistor is connected to the base of the third triode; the collector of the third triode is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the eighth resistor, and the other end of the eighth resistor is respectively connected to the other end of the fourth resistor and one end of the fire detector.

5. The common fire detection circuit according to claim 4, characterized in that: The sampling unit further includes a first capacitor and a first TVS tube, wherein the first capacitor and the first TVS tube are connected in parallel at one end of the fire detector and connected to a protective ground.

6. The common fire detection circuit according to claim 4 or 5, characterized in that: The fifth resistor is a sampling resistor; the second diode is a voltage regulator diode.

7. The common fire detection circuit according to claim 1, characterized in that: The second switch unit includes a fourth transistor, a fifth transistor, a sixth transistor, a seventh transistor, a fuse, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor and a fourteenth resistor; the emitter of the fourth transistor is connected to one end of the fuse and the ninth resistor respectively, the other end of the fuse is connected to the power input terminal, the other end of the ninth resistor is connected to one end of the tenth resistor, the other end of the tenth resistor is connected to the collector of the sixth transistor, the base of the fourth transistor is connected between the ninth resistor and the tenth resistor; the base of the sixth transistor is connected to the ninth resistor and the tenth resistor respectively. The first transistor and the second transistor are connected to the collector of the eleventh resistor and the seventh transistor respectively, the base of the seventh transistor is connected to one end of the twelfth resistor, and the other end of the twelfth resistor is connected to the control signal input terminal; the collector of the fourth transistor is connected to the collector of the fifth transistor and the other end of the fire detector respectively, the base of the fifth transistor is connected to one end of the thirteenth resistor, and the other end of the thirteenth resistor is connected to the control signal input terminal; the emitter of the fifth transistor is connected to one end of the fourteenth resistor, and the other end of the fourteenth resistor and the emitters of the sixth and seventh transistors are all grounded.

8. The common fire detection circuit according to claim 7, characterized in that: The second switch unit further includes a second capacitor and a second TVS tube, and the second capacitor and the second TVS tube are connected in parallel to the other end of the fire detector and connected to the protective ground.

9. A common type of automatic fire alarm controller, characterized in that: The invention comprises a common fire detection circuit as described in any one of claims 1 to 8.

10. A common automatic fire alarm system, characterized in that: Including the common type automatic fire alarm controller as described in claim 9.

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