Light source fault detection circuit for emergency lighting lamp

Abstract

The utility model relates to a light source fault detection circuit for an emergency lighting lamp, which belongs to the technical field of light source fault detection and comprises a constant current driving module, a fly-wheel diode VD1, light emitting diodes HL1 and HL2, an inductor L1 and a light source fault detection module consisting of a plurality of resistors and a plurality of capacitors. The resistor is connected in parallel with the light source cathode to limit voltage and avoid slight lighting of the lamp bead; the resistance value of the resistor is configured to reduce the influence of the leakage current, the MCU collects the positive and negative electrode partial voltage and performs difference calculation, the short circuit, open circuit and normal state of the light source are accurately judged, the parallel capacitor realizes signal filtering, and the power supply adaptation improves the system stability.

Description

Technical Field

[0001] The utility model belongs to the technical field of light source fault detection circuits, and in particular relates to a light source fault detection circuit for emergency lighting fixtures. Background Art

[0002] Fire emergency lighting plays a vital role in ensuring safe evacuation and rescue in fire emergencies. While existing fire emergency lighting light source fault detection technologies include light source fault detection, overheat protection, and self-recovery functions, they still struggle to accurately distinguish between short circuits, open circuits, and normal light source states, hindering fault diagnosis accuracy. This is because some detection circuits fail to fully account for the dimly lit state of the light source in non-emergency situations, leading to misleading detection.

[0003] Prior art publication number CN206743613U describes a light source fault detection and overheat protection circuit for fire emergency lighting fixtures. The circuit includes a light source, a light source fault detection circuit, a temperature detection overheat protection circuit, and a light source fault recovery circuit. The light source is a light-emitting diode (LED). The fault detection circuit consists of resistors, the overheat protection circuit includes a control transistor, a driver transistor, and several resistors, and the recovery circuit includes a resettable fuse and resistors. However, this circuit cannot accurately distinguish between short circuits, open circuits, and normal light source conditions. Furthermore, it fails to fully account for the dimming of the lamp in non-emergency situations, compromising the accuracy of fault detection and making misjudgments more likely. Utility Model Content

[0004] The technical problem solved by the utility model is to overcome the defects in the prior art and provide a light source fault detection circuit for emergency lighting fixtures.

[0005] The technical solutions adopted in this utility model are as follows:

[0006] The light source fault detection circuit for emergency lighting fixtures described in the present invention includes a driving module, a detection module and a control module, wherein the driving module is a constant current driving module, the detection module includes a freewheeling diode VD1, a light emitting diode unit, an inductor L1, a first resistance unit and a first capacitance unit, and the control module is an MCU control module; the driving module, the detection module and the control module are electrically connected in sequence; wherein the first resistance unit includes resistors R1, R2, R3, R4 and R5 connected in series in sequence, and the resistors R1 and R5 are grounded; the resistor R3 is connected in parallel with the light emitting diode unit and is used to clamp the voltage across the light source to a range that is insufficient to emit light in a non-emergency state; the first capacitance unit includes capacitors C1 and C2, wherein capacitor C1 is connected in parallel with resistor R1, and capacitor C2 is connected in parallel with resistor R5 to form an RC filtering circuit; the pins of the MCU control module are respectively connected to the node between resistors R1 and R2 and the node between resistors R4 and R5, and the judgment of whether the light source is short-circuited, open-circuited or in a normal state is realized through voltage divider difference calculation.

[0007] The light-emitting diode unit includes a light-emitting diode HL1 and a light-emitting diode HL2 connected in series. The cathode of the light-emitting diode HL2 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to the anode of the freewheeling diode VD1, and the cathode of the freewheeling diode VD1 is connected to the anode of the light-emitting diode HL1, forming an inductive discharge freewheeling circuit when the drive module is turned off.

[0008] The detection module also includes a DC power supply VCC, the output end of which is respectively connected to the cathode of the freewheeling diode VD1, the anode of the light-emitting diode HL1, one end of the resistor R2 and one end of the resistor R3 to provide stable power supply for the detection module.

[0009] The drive module includes a constant current drive chip, a second resistance unit and a second capacitance unit; the model of the constant current drive chip is OC5038, the second resistance unit includes resistors R6, R7 and R8, the second capacitance unit includes capacitors C3 and C4, pin 1 of the constant current drive chip is grounded, pin 4 is connected to the node between the freewheeling diode VD1 and the inductor L1, pin 5 is connected to resistor R7, pin 6 is connected to resistor R6, pin 7 is connected to capacitor C4, and pin 8 is connected to capacitor C3 and resistor R8; the other ends of resistors R6, R7, capacitors C3 and C4 are all grounded, and the other end of resistor R8 is connected to the DC power supply VCC.

[0010] The MCU control module includes an MCU control chip and a third capacitor unit. The model of the MCU control chip is CS2172BLO. The third capacitor unit includes capacitors C5, C6, C7 and C8. Pin 6 of the MCU control chip is connected to capacitor C7, pin 7 is connected to the DC power supply VCC and capacitor C6, pin 8 is connected to the DC power supply VCC, pin 9 is grounded, and pin 15 is connected between resistor R1 and resistor R2. Capacitor C5 is connected between pins 9 and 12, capacitor C8 is connected between pins 9 and 13, and capacitors C6 and C7 are both grounded.

[0011] The power supply VCC adopts a 36V DC power supply, and the resistance values of the resistors R1, R2, R3, R4 and R5 are 1MΩ, 12MΩ, 36KΩ, 120KΩ and 10KΩ respectively.

[0012] The light source body formed by the series connection of the light emitting diode HL1 and the light emitting diode HL2, together with the freewheeling diode VD1 and the inductor L1, constitutes a discharge circuit when the driving module is turned off, thereby maintaining the continuity of the inductor current.

[0013] The constant current driver chip has built-in logic circuits and MOS tubes, and switches the working state through the level signal of pin 3.

[0014] The utility model has the following beneficial effects:

[0015] 1. By connecting the resistor R2 in parallel with the negative electrode of the light source, the voltage across the lamp beads is effectively clamped to a range that is insufficient to emit light, eliminating the phenomenon of the lamp beads being slightly bright in non-emergency states.

[0016] 2. Use the microcontroller unit MCU to collect the positive voltage U of the light source IO2 and negative electrode partial voltage U IO1 , through difference calculation, it can accurately distinguish the normal conduction, short circuit and open circuit states of the light source, and improve the accuracy of fault judgment.

[0017] 3. The capacitor and resistor are connected in parallel to form a filter circuit, which effectively suppresses circuit noise interference, ensures the stability of the voltage signal, and further reduces the probability of misjudgment.

[0018] 4. Use 36V power adapter drive module to optimize circuit power consumption and compatibility to ensure efficient operation of the emergency lighting system.

[0019] 5. By reasonably configuring the resistance value, the impact of the freewheeling diode leakage current on the detection voltage can be significantly reduced, avoiding misjudgment problems caused by excessive leakage current. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the electrical connection system diagram of the utility model;

[0021] Figure 2 This is the overall circuit schematic diagram of the utility model;

[0022] Figure 3 This is the circuit schematic diagram of the detection module;

[0023] Figure 4 This is the schematic diagram of the driving module circuit;

[0024] Figure 5 This is the control module circuit schematic. DETAILED DESCRIPTION

[0025] like Figures 1 to 5 As shown, the light source fault detection circuit for emergency lighting fixtures described in the present invention includes a driving module, a detection module and a control module, the driving module is a constant current driving module, the detection module includes a freewheeling diode VD1, a light emitting diode unit, an inductor L1, a first resistance unit and a first capacitance unit, and the control module is an MCU control module; the driving module, the detection module and the control module are electrically connected in sequence; wherein the first resistance unit includes resistors R1, R2, R3, R4 and R5 connected in series in sequence, and the resistors R1 and R5 are grounded; the resistor R3 is connected in parallel with the light emitting diode unit to clamp the voltage across the light source to a range that is insufficient to emit light in a non-emergency state; the first capacitance unit includes capacitors C1 and C2, wherein the capacitor C1 is connected in parallel with the resistor R1, and the capacitor C2 is connected in parallel with the resistor R5 to form an RC filter circuit; the pins of the MCU control module are respectively connected to the node between the resistor R1 and the resistor R2 and the node between the resistor R4 and the resistor R5, and the judgment of the short circuit, open circuit and normal state of the light source is realized through the voltage divider difference calculation.

[0026] The light-emitting diode unit includes a light-emitting diode HL1 and a light-emitting diode HL2 connected in series. The cathode of the light-emitting diode HL2 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to the anode of the freewheeling diode VD1, and the cathode of the freewheeling diode VD1 is connected to the anode of the light-emitting diode HL1, forming an inductive discharge freewheeling circuit when the drive module is turned off.

[0027] The detection module also includes a DC power supply VCC, the output end of which is respectively connected to the cathode of the freewheeling diode VD1, the anode of the light-emitting diode HL1, one end of the resistor R2 and one end of the resistor R3 to provide stable power supply for the detection module.

[0028] The drive module includes a constant current drive chip, a second resistance unit and a second capacitance unit; the model of the constant current drive chip is OC5038, the second resistance unit includes resistors R6, R7 and R8, the second capacitance unit includes capacitors C3 and C4, pin 1 of the constant current drive chip is grounded, pin 4 is connected to the node between the freewheeling diode VD1 and the inductor L1, pin 5 is connected to resistor R7, pin 6 is connected to resistor R6, pin 7 is connected to capacitor C4, and pin 8 is connected to capacitor C3 and resistor R8; the other ends of resistors R6, R7, capacitors C3 and C4 are all grounded, and the other end of resistor R8 is connected to the DC power supply VCC.

[0029] The MCU control module includes an MCU control chip and a third capacitor unit. The model of the MCU control chip is CS2172BLO. The third capacitor unit includes capacitors C5, C6, C7 and C8. Pin 6 of the MCU control chip is connected to capacitor C7, pin 7 is connected to the DC power supply VCC and capacitor C6, pin 8 is connected to the DC power supply VCC, pin 9 is grounded, and pin 15 is connected between resistor R1 and resistor R2. Capacitor C5 is connected between pins 9 and 12, capacitor C8 is connected between pins 9 and 13, and capacitors C6 and C7 are both grounded.

[0030] The power supply VCC adopts a 36V DC power supply, and the resistance values of the resistors R1, R2, R3, R4 and R5 are 1MΩ, 12MΩ, 36KΩ, 120KΩ and 10KΩ respectively.

[0031] The light source body formed by the series connection of the light emitting diode HL1 and the light emitting diode HL2, together with the freewheeling diode VD1 and the inductor L1, constitutes a discharge circuit when the driving module is turned off, thereby maintaining the continuity of the inductor current.

[0032] The constant current driver chip has built-in logic circuits and MOS tubes, and switches the working state through the level signal of pin 3.

[0033] Specifically, the constant current driver chip has built-in logic circuitry and MOS transistors. When pin 3 of the constant current driver chip is set high, the constant current driver chip enters a constant current state, at which point the built-in logic circuit controls the on / off state of the built-in MOS transistor. When the built-in MOS transistor is in the on state, the input voltage of 36V flows through the light-emitting diode, inductor L1, the built-in MOS transistor, resistors R6, and R7, charging the inductor L1. The current flowing through inductor L1 gradually increases with charging time. When the voltage drop across resistors R6 and R7 reaches the current detection threshold voltage, the built-in MOS transistor is turned off. When the built-in MOS transistor is in the off state, the inductor L1 discharges through a loop formed by the light-emitting diode, freewheeling diode VD1, and inductor L1 itself. After a fixed off time, the built-in MOS transistor returns to the on state and repeats the on / off cycle. In the event of a fault, pin 3 of the constant current driver chip is set low, and the constant current driver chip stops outputting.

[0034] Specifically, when performing fault detection on the light source of emergency lighting fixtures, first determine the acquisition voltage U of the light source. IO2 The light source is the light emitting diode HL1 and the light emitting diode HL2 connected in series.

[0035] Specifically, when the light source is normally turned on and not bright, according to the resistance values of resistors R3, R4 and R5 and the current I on resistor R3 R3 Determine the leakage current I of the freewheeling diode VD1 VD1漏 , by the leakage current I VD1漏 and the current I on resistor R3 R3 The voltage U on port IO1 at this time can be calculated IO1 .

[0036] Specifically, when the light source is normally turned on and lit, determine the voltage drop U of the lamp bead. 降 , calculate the power supply VCC voltage and the voltage drop U of the lamp bead 降 The difference between the two values is calculated, and then the ratio of the resistance R5 to the sum of the resistances R4 and R5 is calculated. The product of the difference and the ratio can be used to calculate the voltage U on the port IO1 at this time. IO1 .

[0037] Specifically, when the light source is short-circuited, the voltage U on the port IO1 at this time can be calculated by multiplying the power supply VCC voltage by the ratio of the resistor R5 to the sum of the resistance values of the resistors R4 and R5. IO1 .

[0038] Specifically, when the light source is disconnected, the leakage current I VD1漏 The voltage U on port IO1 at this time is calculated by adding the resistance value of resistor R5. IO1 .

[0039] Specifically, by changing the voltage U on port IO2 IO2 The voltage U on port IO1 IO1 By performing a difference operation, the thresholds of when the light source is disconnected, open, and normal can be determined based on the operation results, thereby achieving the purpose of light source fault detection.

[0040] Specifically, the power supply VCC adopts a 36V DC power supply, the resistance values of the resistors R1, R2, R3, R4 and R5 are 1MΩ, 12MΩ, 36KΩ, 120KΩ and 10KΩ respectively, and the collected voltage U of the positive electrode of the light source is IO2 for:

[0041]

[0042] During the actual test, the collected voltage U of the positive electrode of the light source IO2 is 2.769V.

[0043] Specifically, when the light source is normally turned on but does not light up, it is caused by:

[0044]

[0045] If the leakage current is 10μA, the current on R3 is 209μA, U IO1 The voltage is 2.19V. In the actual test process, at room temperature, when the light source is normally turned on and not lit, the lamp bead does not have a slight bright phenomenon. IO1 is 2.167V. Under high temperature, when the light source is normally turned on and not lit, the lamp bead does not have a slight bright phenomenon. IO1 is 2.186V.

[0046] Specifically, when the light source is normally lit, if the voltage drop of the lamp bead is 11V, the voltage of IO1 is:

[0047]

[0048] During the actual test, when the light source is normally turned on and lit, U IO1 It is 1.907V.

[0049] Specifically, when the light source is short-circuited, the voltage of IO1 is:

[0050]

[0051] During the actual test, when the light source is short-circuited, U IO1 is 2.769V.

[0052] Specifically, when the light source is disconnected, the voltage of IO1 is:

[0053]

[0054] During the actual test, at room temperature, when the light source is disconnected, U IO1 The measured value deviates from the theoretical value because the actual test process takes into account the situation when the leakage current of the freewheeling diode is large under high temperature conditions. Under high temperature, when the light source is disconnected, U IO1 is 64.1mV.

[0055] By performing a difference calculation on IO2 and IO1, we can obtain the threshold values for when the light source is open, short-circuited, and normal. The above high-temperature conditions were simulated by blowing a hot air gun on the position of the freewheeling diode VD1. Obviously, there is a deviation between the theoretical calculated value and the output value during the actual test. This is because the preset value has a deviation between the theoretical calculation and the actual test, which is a normal phenomenon. The main purpose of this technical solution is to detect and judge light source faults. Therefore, both the theoretical calculated value and the actual test value are explanations for light source fault detection and judgment.

[0056] Specifically, the resistance network configuration of the detection module includes a series resistance chain consisting of resistor R1, resistor R2, resistor R3, resistor R4 and resistor R5. Both ends of the series resistance chain are grounded, that is, resistor R1 and resistor R5 are grounded, and then resistor R3 is connected in parallel with the light source LED HL1 and the light source diode HL2 to clamp the light source voltage below 2.5V to eliminate dim brightness.

[0057] Specifically, two voltage division sampling points U are set IO1 and U IO2 , U IO1 The voltage at the node between resistors R4 and R5 is the voltage at the negative electrode of the light source, U IO2 The voltage taken from the node between resistors R1 and R2 is the positive voltage of the light source.

[0058] Specifically, capacitor C1 is connected in parallel with resistor R1 , and capacitor C2 is connected in parallel with capacitor R5 , forming an RC filter to effectively suppress noise interference.

[0059] Specifically, setting the resistor R2 to 12MΩ can significantly reduce the leakage current I of the freewheeling diode VD1. VD1漏 The impact on partial pressure.

Claims

1. A light source fault detection circuit for emergency lighting fixtures, comprising a drive module, a detection module and a control module, characterized in that: The driving module is a constant current driving module, the detection module includes a freewheeling diode VD1, a light-emitting diode unit, an inductor L1, a first resistor unit and a first capacitor unit, and the control module is an MCU control module; the driving module, the detection module and the control module are electrically connected in sequence; wherein, the first resistor unit includes resistors R1, R2, R3, R4 and R5 connected in series in sequence, and resistors R1 and R5 are grounded; the resistor R3 is connected in parallel with the light-emitting diode unit to clamp the voltage across the light source to a range that is insufficient to emit light in a non-emergency state; the first capacitor unit includes capacitors C1 and C2, wherein capacitor C1 is connected in parallel with resistor R1, and capacitor C2 is connected in parallel with resistor R5 to form an RC filter circuit; the pins of the MCU control module are respectively connected to the node between resistor R1 and resistor R2 and the node between resistor R4 and resistor R5, and the judgment of whether the light source is short-circuited, open-circuited or in normal state is realized through voltage divider difference calculation.

2. The light source fault detection circuit for emergency lighting fixtures according to claim 1, characterized in that: The light-emitting diode unit includes a light-emitting diode HL1 and a light-emitting diode HL2 connected in series, the cathode of the light-emitting diode HL2 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to the anode of the freewheeling diode VD1, and the cathode of the freewheeling diode VD1 is connected to the anode of the light-emitting diode HL1, forming an inductive discharge freewheeling circuit when the drive module is turned off.

3. The light source fault detection circuit for emergency lighting fixtures according to claim 1, characterized in that: The detection module further includes a DC power supply VCC, the output end of which is respectively connected to the cathode of the freewheeling diode VD1, the anode of the light-emitting diode HL1, one end of the resistor R2 and one end of the resistor R3 to provide stable power supply for the detection module.

4. The light source fault detection circuit for emergency lighting fixtures according to claim 3, characterized in that: The drive module includes a constant current drive chip, a second resistance unit and a second capacitance unit; the model of the constant current drive chip is OC5038, the second resistance unit includes resistors R6, R7 and R8, the second capacitance unit includes capacitors C3 and C4, pin 1 of the constant current drive chip is grounded, pin 4 is connected to the node between the freewheeling diode VD1 and the inductor L1, pin 5 is connected to resistor R7, pin 6 is connected to resistor R6, pin 7 is connected to capacitor C4, and pin 8 is connected to capacitor C3 and resistor R8; the other ends of the resistors R6, R7, capacitors C3 and C4 are all grounded, and the other end of the resistor R8 is connected to the DC power supply VCC.

5. The light source fault detection circuit for emergency lighting fixtures according to claim 3, characterized in that: The MCU control module includes an MCU control chip and a third capacitor unit. The model of the MCU control chip is CS2172BLO. The third capacitor unit includes capacitors C5, C6, C7 and C8. Pin 6 of the MCU control chip is connected to capacitor C7, pin 7 is connected to the DC power supply VCC and capacitor C6, pin 8 is connected to the DC power supply VCC, pin 9 is grounded, and pin 15 is connected between resistor R1 and resistor R2. The capacitor C5 is connected between pin 9 and pin 12, the capacitor C8 is connected between pin 9 and pin 13, and the capacitor C6 and capacitor C7 are both grounded.

6. The light source fault detection circuit for emergency lighting fixtures according to claim 4, characterized in that: The power supply VCC adopts a 36V DC power supply, and the resistance values of the resistors R1, R2, R3, R4 and R5 are 1MΩ, 12MΩ, 36KΩ, 120KΩ and 10KΩ respectively.

7. The light source fault detection circuit for emergency lighting fixtures according to claim 2, characterized in that: The light source body formed by the series connection of the light emitting diode HL1 and the light emitting diode HL2, together with the freewheeling diode VD1 and the inductor L1, constitutes a discharge circuit when the driving module is turned off, thereby maintaining the continuity of the inductor current.

8. The light source fault detection circuit for emergency lighting fixtures according to claim 4, characterized in that: The constant current driver chip has built-in logic circuits and MOS tubes, and switches the working state through the level signal of pin 3.

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