Light warning device connection line detection circuit of fire sound and light alarm
By designing a detection circuit for the light warning device connection line in the fire alarm, the status of the connection line can be monitored in real time and fault information can be reported. This solves the problem that the connection line is prone to breakage and cannot be detected in time in the existing technology, thus improving the reliability and maintenance efficiency of the fire alarm.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- QINGDAO DINGXIN COMM & FIRE FIGHTING SAFETY CO LTD
- Filing Date
- 2025-07-07
- Publication Date
- 2026-07-28
AI Technical Summary
The existing fire alarm light warning device connection wires are only physically fixed, lacking real-time monitoring and fault feedback mechanisms. This makes the connection wires prone to breakage due to environmental vibration or aging, making it impossible to detect and report faults in a timely manner, thus affecting evacuation safety.
A detection circuit for the connection line of a light warning device was designed. The connection line status is detected in real time through an AD sampling port and a voltage divider structure. Combined with a temperature detection circuit, the circuit can monitor the continuity of the connection line and the ambient temperature, and report fault information to the main control unit.
It enables real-time status monitoring of the connection lines, improves the reliability of detection and timely reporting of fault information, ensures the normal operation of fire alarms in extreme environments, and simplifies the maintenance process.
Smart Images
Figure CN224569594U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of alarm device technology, specifically to a detection circuit for the connection line of a fire alarm's light warning device. Background Technology
[0002] Fire alarm systems, particularly audible and visual alarms, are crucial on-site indicator devices within fire alarm systems. They guide personnel to quickly identify danger zones and evacuate during a fire by emitting strong audible alarm signals and high-frequency flashing visual warning signals. The visual warning device, as a core functional module of the audible and visual alarm, is typically connected to the alarm body via a dedicated cable; the reliability of this connection directly impacts the effectiveness of the fire alarm system.
[0003] In existing technologies, the connection wires of light warning devices mainly rely on physical fixing methods (such as socket clips, terminal crimping, etc.) to connect to the main body. However, such mechanical fixing methods have the following significant drawbacks: First, during long-term use, the connection wires are prone to poor contact or even open circuits due to environmental vibration, external pulling force, or material aging. However, traditional solutions only reinforce the physical structure and lack a real-time monitoring mechanism for the continuity status of the connection wires. Second, hidden open circuits (such as partial breakage of the wire core or oxidation of the contact point) are difficult to detect by visual inspection or simple checks, which may cause the light warning device to fail during a fire, seriously threatening the safety of personnel evacuation. Third, existing fire alarm devices do not have a connection wire status feedback interface. When the connection wire is abnormally disconnected, it is impossible to report fault information to the fire alarm linkage controller in the fire linkage control center, making it difficult for maintenance personnel to troubleshoot and repair in a timely manner.
[0004] In summary, the connection reliability of the light warning device of the existing fire alarm is only ensured by physical fixing. It lacks an effective continuity detection and fault feedback mechanism, which cannot meet the high reliability requirements of fire protection equipment for monitoring the status of key functional modules. Summary of the Invention
[0005] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a detection circuit for the connection line of the light warning device of a fire sound and light alarm, which can determine whether the connection line is normal or disconnected based on different sampling voltage states.
[0006] The technical solution of this utility model is as follows:
[0007] A detection circuit for the light warning device connection line of a fire alarm includes a power supply circuit for the light warning device, which is also connected to a temperature detection circuit. The power supply circuit for the light warning device includes a DC power supply Vdd, the output of which is connected to the first terminal of a first capacitor C1. The first terminal of the first capacitor C1 is also connected in parallel with the anode of a diode VD1 and the anode of a first light-emitting diode HL1. The second terminal of the first capacitor C1 is grounded. The cathode of the first light-emitting diode HL1 is connected in series with the anode of a second light-emitting diode HL2, and the cathode of the second light-emitting diode HL2 is connected in series with the anode of a third light-emitting diode HL3. The entire series connection is connected in parallel with the anode of diode VD1 and the first terminal of inductor L1. The cathode of diode VD1 is connected in parallel with the second terminal of inductor L1 and the source of MOSFET VM1. The gate of MOSFET VM1 is electrically connected to the first terminal of a first resistor R1 and the control port IO. The second terminal of the first resistor R1 is grounded, and the drain of MOSFET VM1 is grounded.
[0008] Preferably, the temperature detection circuit includes a thermistor RT1, the first terminal of the thermistor RT1 is connected to the power supply voltage through a fourth resistor R4, the second terminal of the thermistor RT1 is grounded, and the thermistor RT1 is connected in parallel with a third capacitor C3.
[0009] Preferably, the connection node between the thermistor RT1 and the fourth resistor R4 is configured with a temperature sampling port AD_TEP to obtain the voltage divider signal of that node.
[0010] Preferably, the cathode of the third LED HL3 is electrically connected to the first end of the inductor L1 and the first end of the second resistor R2, respectively. The second end of the second resistor R2 is electrically connected to the first end of the third resistor R3, the first end of the second capacitor C2, and the AD sampling port AD_CH, respectively.
[0011] Preferably, the second terminal of the third resistor R3 and the second terminal of the second capacitor C2 are grounded together.
[0012] Preferably, the DC power supply Vdd is powered by a 24V DC input.
[0013] Preferably, the first light-emitting diode HL1, the second light-emitting diode HL2, and the third light-emitting diode HL3 are all light-emitting diodes, and the forward voltage drop of the three is the same.
[0014] Preferably, the MOS transistor VM1 is an N-channel enhancement-mode MOS field-effect transistor, and its gate is grounded through the first resistor R1 to form a pull-down bias circuit.
[0015] Preferably, the AD sampling port AD_CH is used to acquire the voltage signal of the voltage divider node between the second resistor R2 and the third resistor R3.
[0016] Preferably, the third capacitor C3 is a filter capacitor, which is connected in parallel with the thermistor RT1 to stabilize the output signal of the temperature detection circuit.
[0017] Compared with the prior art, this utility model has the following advantages:
[0018] 1. Real-time detection of connection continuity: By setting an AD sampling port AD_CH in the power supply circuit of the light warning device, combined with the voltage divider structure of the second resistor R2 and the third resistor R3, the voltage signal of the connection detection circuit can be accurately obtained. When the connection is normally connected, the circuit is conducting, forming a stable voltage divider (the voltage value is (U-3VF)×R3 / (R2+R3), where U is the 24V supply voltage and VF is the forward voltage drop of a single LED); when the connection is disconnected, there is no current in the circuit, resulting in a zero sampling voltage at AD_CH. By observing the voltage difference between the two states, the continuity of the connection can be quickly determined, solving the problem that existing technologies rely solely on physical fixation and cannot detect hidden open circuits.
[0019] 2. Improve the reliability of detection in extreme environments: By adding a temperature detection circuit (including thermistor RT1, fourth resistor R4 and temperature sampling port AD_TEP), the ambient temperature signal can be obtained in real time.
[0020] 3. Simple circuit structure and strong compatibility: The detection module (AD_CH sampling circuit) and the temperature compensation module (AD_TEP sampling circuit) are both based on the original power supply circuit of the light warning device. Only a small number of resistors, capacitors and sampling ports need to be added. There is no need to modify the core light-emitting function circuit (HL1, HL2, HL3 series structure) of the light warning device. This design not only ensures the original performance of the light warning device, but also provides a low-cost and easy-to-implement technical solution for the upgrade and transformation of existing fire sound and light alarms.
[0021] 4. Supports fault information reporting and improves system maintenance efficiency: The detection result (high level / low level) of the AD_CH port can be directly output to the main control unit of the fire alarm, and the main control unit can report the fault information of "open circuit of light warning device connection line" to the fire alarm linkage controller of the fire linkage control center. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 This is a schematic diagram of the circuit structure principle of this utility model.
[0024] Figure 2 This is a schematic diagram of the power supply circuit for the light warning device of this utility model.
[0025] Figure 3 This is the schematic diagram of the temperature detection circuit of this utility model. Detailed Implementation
[0026] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.
[0027] Example
[0028] like Figure 1 As shown, a detection circuit for the light warning device connection line of a fire alarm includes a power supply circuit for the light warning device, and the power supply circuit for the light warning device is also connected to a temperature detection circuit, such as... Figure 2 As shown, the power supply circuit of the light warning device includes a DC power supply V. dd DC power supply V dd Connect the first capacitor C1. The first terminal of the first capacitor C1 is connected in parallel with the first terminal of the diode VD1 and the first terminal of the first LED HL1. The second terminal of the first capacitor C1 is grounded. The first LED HL1, the second LED HL2, and the third LED HL3 are connected in series and then connected in parallel with the first terminal of the diode VD1 and the first terminal of the inductor L1. The second terminal of the diode VD1 is connected in parallel with the second terminal of the inductor L1 and the source of the MOSFET VM1. The gate of VM1 is connected in parallel with the first terminal of the first resistor R1 and the control port IO. The second terminal of the first resistor R1 is grounded. The drain of the MOSFET VM1 is grounded.
[0029] like Figure 3 As shown, the temperature detection circuit includes a thermistor RT1. The first terminal of the thermistor RT1 is connected to the power supply voltage, the second terminal of the thermistor RT1 is grounded, the thermistor RT1 is connected in parallel with the third capacitor C3, and a fourth resistor R4 is provided between the thermistor RT1 and the power supply voltage.
[0030] A temperature sampling port AD_TEP is provided between the thermistor RT1 and the fourth resistor R4.
[0031] The second terminal of the third LED HL3 is connected in parallel to the first terminal of the inductor L1 and the first terminal of the second resistor R2. The second terminal of the second resistor R2 is also connected in parallel to the first terminal of the third resistor R3, the first terminal of the second capacitor C2, and the AD sampling port AD_CH.
[0032] The second terminal of the third resistor R3 is connected to the second terminal of the second capacitor C2 and simultaneously grounded.
[0033] The DC power supply Vdd is powered by a 24V DC input.
[0034] The first LED HL1, the second LED HL2, and the third LED HL3 are all light-emitting diodes, and their forward voltage drops are the same.
[0035] The MOS transistor VM1 is an N-channel enhancement-mode MOS field-effect transistor. Its gate is grounded through the first resistor R1, forming a pull-down bias circuit.
[0036] The AD sampling port AD_CH is used to acquire the voltage signal of the voltage divider node between the second resistor R2 and the third resistor R3.
[0037] The third capacitor, C3, is a filter capacitor connected in parallel with the thermistor RT1 to stabilize the output signal of the temperature detection circuit.
[0038] Work process description:
[0039] 1. Normal working status
[0040] When the light warning device connection is properly connected, the main control unit outputs a high level (≥4V) through the control port IO, turning on the MOSFET VM1 and forming the power supply circuit: 24V power supply → C1 → VD1 → L1 → LED string (HL1-HL2-HL3) → R2 → R3 → ground. At this time, the LED string emits light normally. Sampling through the AD_CH port yields the voltage across the first terminal of resistor R3. According to the voltage divider principle of a series circuit, the voltage across the first terminal of resistor R3 is:
[0041]
[0042] Where VF is the forward voltage drop when a single LED is conducting, substituting the parameters (VF=2.2V, R2=10kΩ, R3=2kΩ), the voltage across the first terminal of resistor R3 is calculated to be 2.9V.
[0043] ;
[0044] When the main control unit detects that the AD_CH voltage is ≥2.5V, it determines that the connection line is in normal condition.
[0045] 2. Connection cable disconnected.
[0046] When the connecting wires break due to aging, pulling, or other reasons, the LED string circuit is open, no current flows through R2 and R3, and the voltage at the AD_CH port drops to 0V (equipotential with ground). Sampling through the AD_CH port yields the voltage at the first terminal of resistor R3, which is 0V.
[0047] The voltage levels detected by the AD_CH sampling port are different when the connection is normal and when it is disconnected, thus the status of the connection can be effectively determined.
[0048] 3. Temperature compensation process
[0049] When the ambient temperature changes, the resistance of the thermistor RT1 changes. The voltage across the first terminal of the thermistor RT1 can be obtained through the AD_TEP port. The current ambient temperature can be obtained by comparing the resistance of resistor R4 with the resistance-temperature curve of the thermistor. Based on the relationship curve between the forward voltage drop VF of the LED and temperature, the forward voltage drop VF of the LED can be compensated, thereby ensuring the reliability of the detection circuit under extreme ambient temperatures.
[0050] The detection circuit in this embodiment can accurately identify the continuity of the connection line: when normally connected, the error between the AD_CH voltage and the theoretical calculation value is ≤ ±0.1V, and when disconnected, the AD_CH voltage is stable at 0V; the temperature compensation function enables the adjustment accuracy of the detection threshold with temperature changes to reach ±0.05V, effectively avoiding the interference of ambient temperature on the detection results.
[0051] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, it is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the present invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope of the claims.
Claims
1. A detection circuit for the connection line of the light warning device in a fire alarm, comprising a power supply circuit for the light warning device, characterized in that, The power supply circuit for the light warning device is also connected to a temperature detection circuit. The power supply circuit for the light warning device includes a DC power supply Vdd, the output of which is connected to the first terminal of a first capacitor C1. The first terminal of the first capacitor C1 is also connected in parallel with the anode of diode VD1 and the anode of the first light-emitting diode HL1. The second terminal of the first capacitor C1 is grounded. The cathode of the first light-emitting diode HL1 is connected in series with the anode of the second light-emitting diode HL2. The cathode of the second light-emitting diode HL2 is connected in series with the anode of the third light-emitting diode HL3. The entire series connection is connected in parallel with the anode of diode VD1 and the first terminal of inductor L1. The cathode of diode VD1 is connected in parallel with the second terminal of inductor L1 and the source of MOSFET VM1. The gate of MOSFET VM1 is electrically connected to the first terminal of first resistor R1 and the control port IO. The second terminal of first resistor R1 is grounded. The drain of MOSFET VM1 is grounded.
2. The detection circuit for the light warning device connection line of the fire alarm as described in claim 1, characterized in that, The temperature detection circuit includes a thermistor RT1. The first terminal of the thermistor RT1 is connected to the power supply voltage through a fourth resistor R4, the second terminal of the thermistor RT1 is grounded, and the thermistor RT1 is connected in parallel with a third capacitor C3.
3. The detection circuit for the light warning device connection line of the fire alarm as described in claim 2, characterized in that, The connection node between the thermistor RT1 and the fourth resistor R4 is equipped with a temperature sampling port AD_TEP to obtain the voltage divider signal of the node.
4. The detection circuit for the light warning device connection line of the fire alarm as described in claim 1, characterized in that, The cathode of the third LED HL3 is electrically connected to the first end of the inductor L1 and the first end of the second resistor R2, respectively. The second end of the second resistor R2 is electrically connected to the first end of the third resistor R3, the first end of the second capacitor C2, and the AD sampling port AD_CH, respectively.
5. The detection circuit for the light warning device connection line of the fire alarm as described in claim 4, characterized in that, The second terminal of the third resistor R3 and the second terminal of the second capacitor C2 are both grounded.
6. The detection circuit for the light warning device connection line of the fire alarm as described in claim 1, characterized in that, The DC power supply V dd It uses a 24V DC input power supply.
7. The detection circuit for the light warning device connection line of the fire audible and visual alarm as described in claim 1, characterized in that, The first LED HL1, the second LED HL2, and the third LED HL3 are all light-emitting diodes, and their forward voltage drops are the same.
8. The detection circuit for the light warning device connection line of the fire alarm as described in claim 1, characterized in that, The MOS transistor VM1 is an N-channel enhancement-mode MOS field-effect transistor, and its gate is grounded through the first resistor R1 to form a pull-down bias circuit.
9. The detection circuit for the light warning device connection line of the fire alarm as described in claim 4, characterized in that, The AD sampling port AD_CH is used to acquire the voltage signal of the voltage divider node between the second resistor R2 and the third resistor R3.
10. The detection circuit for the light warning device connection line of the fire audible and visual alarm as described in claim 2, characterized in that, The third capacitor C3 is a filter capacitor, which is connected in parallel with the thermistor RT1 to stabilize the output signal of the temperature detection circuit.