Emergency lighting control circuit and emergency lighting system

Abstract

The invention discloses an emergency lighting control circuit and an emergency lighting system, the emergency lighting control circuit comprises an impedance detection circuit and a dimming control circuit, and the impedance detection circuit generates an impedance detection signal; the dimming control circuit is connected with the impedance detection circuit, when the impedance detection circuit outputs a first impedance detection signal representing a low impedance state and the lighting load works in a non-dimming mode, the brightness of the lighting load is first brightness, and if the dimming control circuit obtains a high-low impedance switching signal for N times within a first preset time, the brightness of the lighting load is second brightness; the dimming control circuit controls the lighting load to work in a dimming mode, the brightness of the lighting load is weakened or enhanced from first brightness according to a set rate, N is a positive integer, and timing is started when the impedance detection circuit outputs a second impedance detection signal representing a high impedance state in first preset time. Through the arrangement, the lighting load can be provided with more brightness gears, and the brightness of the lighting load can be conveniently adjusted.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to an emergency lighting control circuit and an emergency lighting system. Background Art

[0002] As emergency lighting is used more and more widely, and even used as conventional lighting in some occasions, the brightness of emergency lighting is required to adapt to different environments.

[0003] like Figure 1 As shown, in the prior art, the number of high / low impedance state switching of the L / N terminal of the emergency lighting control circuit is usually detected, and the output brightness of the emergency lighting system is adjusted according to the number of switching. A common adjustment method is that the number of switching is negatively correlated with the output brightness, such as detecting one switch, the brightness is 100%; detecting two switches, the brightness is 50%; detecting three switches, the brightness is 25%; detecting four switches, the brightness returns to 100% and enters a cycle according to the above rules.

[0004] It can be seen that the existing emergency lighting brightness adjustment means can only set a limited number of brightness levels. If there are too many levels, it is very inconvenient for users. Therefore, it is urgent to provide an emergency lighting control circuit that can have more brightness levels to adapt to different environments and is more convenient for users to operate. Summary of the invention

[0005] In order to solve the deficiencies of the prior art, an object of the present invention is to provide an emergency lighting control circuit and an emergency lighting system to solve the problem of complex brightness level adjustment of lighting loads in the prior art.

[0006] To achieve the above objectives, this application adopts the following technical solutions:

[0007] In a first aspect, the present application provides an emergency lighting control circuit, wherein an AC input voltage supplies power to a lighting load through a power supply device, and the emergency lighting control circuit controls a battery to supply power to the lighting load, comprising:

[0008] An impedance detection circuit, the impedance detection circuit is used to detect the impedance state between the high and low potential ends of the AC input to generate an impedance detection signal;

[0009] A dimming control circuit, the dimming control circuit is connected to the impedance detection circuit, when the impedance detection circuit outputs a first impedance detection signal representing a low impedance state, and the lighting load operates in a non-dimming mode, the current brightness of the lighting load is recorded as a first brightness, if the dimming control circuit obtains N high-low impedance switching signals within a first preset time, the dimming control circuit controls the lighting load to operate in the dimming mode, and the brightness of the lighting load is reduced or increased from the first brightness at a set rate, wherein N is a positive integer, and the first preset time starts from when the impedance detection circuit outputs a second impedance detection signal representing a high impedance state.

[0010] Further, after the lighting load enters the dimming mode, when the first brightness is reduced to the lowest brightness at a set rate, the lowest brightness is recorded as the second brightness; or, when the first brightness is increased to the highest brightness at a set rate, the highest brightness is recorded as the second brightness.

[0011] Furthermore, in the dimming mode, when the dimming control circuit obtains the high and low impedance switching signals N times within the second preset time, the dimming control circuit controls the lighting load to operate in the non-dimming mode, and the lighting load is maintained at a third brightness, which is any brightness in the process of decreasing or increasing from the first brightness to the second brightness at a set rate.

[0012] Furthermore, the impedance detection circuit obtains a voltage input signal and compares the voltage input signal with a reference threshold voltage to output an impedance detection signal. When the voltage input signal is greater than the reference threshold voltage, a first impedance detection signal is output; when the voltage input signal is less than or equal to the reference threshold voltage, a second impedance detection signal is output.

[0013] Furthermore, the dimming control circuit includes:

[0014] A first timing circuit is connected to the output end of the impedance detection circuit. In a non-dimming mode, the first timing circuit starts timing when receiving the second impedance detection signal, wherein the first timing circuit is configured to output a trigger signal within a first preset time;

[0015] The second timing circuit is connected to the output end of the impedance detection circuit. In the dimming mode, the second timing circuit starts timing when receiving the second impedance detection signal, wherein the second timing circuit is configured to output a locking signal within a second preset time.

[0016] Furthermore, the dimming control circuit includes:

[0017] A reference voltage generating circuit is connected to the first timing circuit and the second timing circuit respectively. The reference voltage generating circuit outputs a variable reference threshold voltage when acquiring a trigger signal. The reference voltage generating circuit outputs a fixed reference threshold voltage when acquiring a locking signal.

[0018] The current control circuit is connected to the output end of the reference voltage generating circuit and controls the current flowing through the lighting load according to the reference threshold voltage.

[0019] Furthermore, the dimming control circuit also includes a logic circuit, which receives the trigger signal and the lock signal to generate a control signal for controlling the reference voltage generating circuit.

[0020] Furthermore, the reference voltage generating circuit comprises:

[0021] The counter starts counting when receiving a trigger signal and generates a corresponding counting signal according to the number of bits of the counter. The counter stops counting when receiving a locking signal and outputs a fixed counting signal.

[0022] A DAC module receives a counting signal and generates a corresponding reference threshold voltage according to the counting signal;

[0023] The first selection circuit receives a control signal and outputs a reference threshold voltage to the current control circuit according to the control signal.

[0024] Furthermore, the dimming control circuit includes:

[0025] a second selection circuit, wherein two input ends of the second selection circuit receive an impedance detection signal and a low-level signal respectively, an output end of the second selection circuit and an output end of the first timing circuit are connected to a logic circuit, and the first timing circuit can shield the impedance detection signal before obtaining a high-low impedance switching signal, so that the counter cannot receive a trigger signal;

[0026] The third selection circuit, the two input ends of the third selection circuit receive the impedance detection signal and the low-level signal respectively, the output end of the third selection circuit and the output end of the second timing circuit are connected to the logic circuit, and the second timer can shield the impedance detection signal in the non-dimming mode, so that the counter cannot receive the locking signal.

[0027] Furthermore, the power supply device also includes a high-voltage isolation circuit, which is connected between the AC input terminal and the battery, and is used to isolate the AC input terminal and the battery when an AC input voltage exists.

[0028] In a second aspect, the present application further provides an emergency lighting system, which comprises any one of the emergency lighting control circuits in the first aspect.

[0029] Compared with the prior art, the present invention detects the impedance detection result of the emergency lighting control circuit through the impedance detection circuit, and the dimming control circuit continuously obtains two different impedance detection results within the first preset time to control the lighting load to work in the dimming mode, and the brightness of the lighting load can be continuously increased or decreased, thereby increasing the number of brightness gears of the lighting load, and the lighting load can be made to work in the dimming mode through a single switching action of the switch module, so that it is more convenient to adjust the brightness of the lighting load. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a circuit structure diagram of a dimming circuit in an emergency lighting system in the prior art;

[0031] Figure 2 This is a circuit block diagram of the emergency lighting system in the implementation manner of this application;

[0032] Figure 3 is a circuit structure diagram of an impedance detection circuit in an embodiment of the present application;

[0033] Figure 4 is a circuit block diagram of a dimming control circuit in an embodiment of the present application;

[0034] Figure 5 is a circuit block diagram of a reference voltage generating circuit in an embodiment of the present application;

[0035] Figure 6 This is a circuit structure diagram of an emergency lighting control circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the specific implementation manner of the present application will be clearly and completely described below in conjunction with the drawings in the implementation manner of the present application.

[0037] like Figure 2 As shown, the present application provides an emergency lighting control circuit 10, which can be used in an emergency lighting system 100, and the AC input voltage supplies power to the lighting load 30 through the power supply device 20. The power supply device 20 here includes a voltage conversion circuit 21 and a battery 22, and the voltage conversion circuit 21 receives the AC input voltage to supply power to the lighting load 30. The voltage conversion circuit 21 takes an AC / DC converter as an example, and when there is an AC input voltage, the AC / DC converter converts the AC input voltage into a DC voltage to supply power to the lighting load 30. When there is no AC output voltage, the lighting load 30 is powered by the battery.

[0038] As an implementation mode, the emergency lighting control circuit 10 includes:

[0039] The impedance detection circuit 11 is connected to at least one input terminal of the AC input voltage to detect the impedance state between the two terminals of the AC input to generate an impedance detection signal. The emergency lighting system 100 includes a switch module connected between the two terminals of the AC input voltage. If a high impedance state is detected between the two terminals of the AC input, the switch module is determined to be disconnected; if a low impedance state is detected between the two terminals of the AC input, the switch module is determined to be turned on.

[0040] The dimming control circuit 12 is connected to the output end of the impedance detection circuit 11, so that the dimming control circuit 12 can obtain the impedance detection signal output by the impedance detection circuit 11 and control the brightness of the lighting load 30 according to the impedance detection signal.

[0041] When the lighting load 30 works in the non-dimming mode, the current brightness of the lighting load is recorded as the first brightness. At this time, if the dimming control circuit 12 obtains N high-low impedance switching signals within the first preset time, that is, the switch module performs N switching actions within the first preset time, the dimming control circuit 12 controls the lighting load 30 to work in the dimming mode. At this time, the brightness of the lighting load 30 decreases or increases from the first brightness according to the set rate. It should be noted that N is a positive integer, and the first preset time starts from when the impedance detection circuit outputs the second impedance detection signal representing the high impedance state.

[0042] When the lighting load 30 works in the dimming mode, the brightness of the lighting load 30 decreases or increases between the first brightness and the second brightness at a set rate. For example, after entering the dimming mode, when the lighting load 30 decreases from the first brightness to the lowest brightness at a set rate, the lowest brightness is recorded as the second brightness; or, when the lighting load 30 increases from the first brightness to the highest brightness at a set rate, the highest brightness is recorded as the second brightness.

[0043] In the dimming mode, if the dimming control circuit 12 obtains N high-low impedance switching signals within the second preset time, that is, the switch module performs N switching actions within the second preset time, the dimming control circuit 12 controls the lighting load 30 to operate in the non-dimming mode, and the lighting load 30 is maintained at a third brightness, which is any brightness in the process of decreasing or increasing from the first brightness to the second brightness at a set rate; wherein the second preset time starts from when the impedance detection circuit outputs a second impedance detection signal representing a high impedance state.

[0044] Through the above settings, the operation steps of adjusting the brightness of the lighting load 30 are simplified. When the brightness of the lighting load 30 needs to be adjusted, the switch module performs N switching actions within the first preset time, so that the dimming control circuit 12 obtains N high-low impedance switching signals within the first preset time, and the brightness of the lighting load 30 decreases or increases between the first brightness and the second brightness at a set rate. When the brightness of the lighting load 30 reaches the brightness required by the user, the switch module performs N switching actions within the second preset time, so that the dimming control circuit 12 obtains N high-low impedance switching signals within the second preset time, and the brightness of the lighting load 30 can be maintained at the third brightness required by the user. Compared with the prior art, the lighting load 30 under the control of the emergency lighting control circuit 10 has a larger brightness adjustment range.

[0045] Specifically, the impedance detection circuit 11 obtains a voltage input signal according to at least one input terminal of the connected AC input, and compares the voltage input signal with a reference threshold voltage Vref1 to obtain an impedance detection signal.

[0046] like Figure 3 As shown, the impedance detection circuit 11 includes a resistor R1, a resistor R2 and a comparator U1. The equivalent resistance Rd between the two input terminals of the AC input is detected by the impedance detection circuit 11. The impedance detection circuit 11 is connected to any one of the neutral terminal VN and the live terminal VL of the AC input to obtain a voltage input signal. The comparator U1 compares the voltage input signal with a reference threshold voltage Vref1. When the voltage of the voltage input signal is greater than the reference threshold voltage Vref1, the comparator U1 outputs a first impedance detection signal representing a low impedance state, and the switch module is closed at this time; when the voltage of the voltage input signal is less than the reference threshold voltage Vref1, the comparator U1 outputs a second impedance detection signal representing a high impedance state, and the switch module is disconnected at this time.

[0047] like Figure 4 As shown, the dimming control circuit 12 includes a first timing circuit 121 and a second timing circuit 122. The first timing circuit 121 and the second timing circuit 122 are connected to the output end of the impedance detection circuit 11 and receive an impedance detection signal representing an impedance state.

[0048] Taking the impedance detection circuit 11 obtaining a high-low impedance switching signal once as an example, when the lighting load 30 works in the non-dimming mode, the lighting load 30 is at the first brightness, and when the first timing circuit 121 receives the second detection signal, it starts timing. At this time, the switch module is disconnected, and the lighting load 30 stops working. When the first timing circuit 121 obtains the first detection signal within the first preset time, it stops timing and outputs a trigger signal T1. At this time, the lighting load 30 works in the dimming mode, and the brightness of the lighting load 30 decreases or increases between the first brightness and the second brightness at a set rate.

[0049] When the lighting load 30 works in the dimming mode, the second timing circuit 122 starts timing when it receives the second impedance detection signal. At this time, the switch module is disconnected and the lighting load 30 stops working. When the second timing circuit 122 obtains the first impedance detection signal within the second preset time, it stops timing and outputs a lock signal T2. At this time, the lighting load 30 works in the non-dimming mode, and the brightness of the lighting load 30 is maintained at the third brightness required by the user.

[0050] like Figure 4 and Figure 5 As shown, as an implementation, the dimming control circuit 12 further includes:

[0051] The reference voltage generating circuit 123 is connected to the first timing circuit 121 and the second timing circuit 122 respectively. When the reference voltage generating circuit 123 obtains the trigger signal T1, the reference voltage generating circuit 123 outputs a variable reference threshold voltage. When the reference voltage generating circuit 123 obtains the locking signal T2, the reference threshold voltage is outputted. The reference threshold voltage is weakened or enhanced at a set rate. By weakening or enhancing the reference threshold voltage, the brightness of the lighting load 30 can be adjusted between the first brightness and the second brightness.

[0052] The current control circuit 124 is connected to the output end of the reference voltage generating circuit 123 , and the current control circuit 124 controls the current flowing through the lighting load 30 according to the reference threshold voltage.

[0053] The logic circuit 125 is connected to the first timing circuit 121 and the second timing circuit 122 respectively, so as to receive the trigger signal T1 and the locking signal T2, and generate a control signal for controlling the reference voltage generating circuit 123 according to the trigger signal T1 or the locking signal T2. The logic circuit 125 is also connected to the impedance detection circuit 11 to determine whether the trigger signal T1 and the locking signal T2 are valid, that is, when the impedance detection signal reaches the falling edge, the first timing circuit 121 or the second timing circuit 122 starts timing, and the first timing circuit 121 outputs the trigger signal T1 when obtaining the first impedance detection signal within the first preset time, or the second timing circuit 122 outputs the locking signal T2 when obtaining the first impedance detection signal within the second preset time.

[0054] Specifically, the reference voltage generating circuit 123 includes a counter 1231 , which is connected to the output terminals of the first timing circuit 121 and the second timing circuit 122 , respectively, to receive the trigger signal T1 sent by the first timing circuit 121 or the locking signal T2 sent by the second timing circuit 122 .

[0055] When the counter 1231 receives the trigger signal T1 , it starts counting and generates a counting signal.

[0056] Exemplarily, the counter 1231 is an 8-bit counter, one end of the counter 1231 is connected to the output of the clock circuit, and the counter 1231 starts counting when it receives a trigger signal T1.

[0057] Optionally, the counter 1231 is configured as a down counter, the output end of the counter 1231 is set from 1 to 0 starting from the low bit, and outputs a counting signal corresponding to its bit number. When the counter 1231 receives the locking signal T2, it stops counting and outputs the current counting signal.

[0058] Optionally, the counter 1231 is configured as an adding counter, and the output end of the counter 1231 is set from 0 to 1 starting from the low bit, and outputs a counting signal corresponding to the number of bits.

[0059] DAC module 1232, DAC module 1232 is connected to counter 1231, DAC module 1232 receives the counting signal sent by counter 1231, and generates a corresponding reference threshold voltage according to the counting signal. When DAC module 1232 receives the locking signal T2, it stops counting, and at this time, DAC module 1232 outputs a fixed reference threshold voltage.

[0060] The first selection circuit 1233 receives the reference threshold voltage output by the DAC module 1232. The first selection circuit 1233 is connected to the logic circuit 125. In the non-dimming mode, if the first timing circuit 121 obtains the impedance switching signal N times within the first preset time, the logic circuit 125 generates a control signal according to the trigger signal sent by the first timing circuit 121, and the first selection circuit 1233 outputs the reference threshold voltage to the current control circuit 124 according to the control signal.

[0061] Alternatively, in the dimming mode, if the second timing circuit 122 obtains N impedance switching signals within the second preset time, the logic circuit 125 generates a control signal according to the locking signal sent by the second timing circuit 122, and the first selection circuit 1233 outputs the reference threshold voltage to the current control circuit 124 according to the control signal.

[0062] Exemplarily, if the first timing circuit 121 does not obtain an impedance switching signal within a first preset time, and the second timing circuit 122 does not obtain an impedance switching signal within a second preset time, the first selection circuit 1233 outputs a fixed threshold voltage Vref2 to ensure that the lighting load 30 maintains a fixed brightness.

[0063] Through the above settings, the reference voltage generating circuit 123 can control the counter 1231 to start or stop based on the trigger signal T1 or the lock signal T2, so as to output the corresponding reference threshold voltage. Since the emergency lighting control circuit 10 is suitable for the lighting load 30 driven by the battery 22, in the absence of AC input, the emergency lighting system 100 needs to detect the impedance state of the circuit when it is turned on or off, and the first timing circuit 121 and the second timing circuit 122 perform corresponding timing actions according to the impedance detection signal, thereby controlling the lighting load 30 to switch between the dimming mode and the non-dimming mode, thereby simplifying the circuit structure.

[0064] like Figure 6 As shown, specifically, the current control circuit 124 includes a switch tube S1, an operational amplifier U2 and a sampling circuit 1241. The first end of the switch tube S1 is connected to the battery 22, the second end is connected to the lighting load 30, and the output end of the operational amplifier U2 is connected to the control end of the switch tube S1. The current flowing through the switch tube S1 is controlled to adjust the brightness of the lighting load 30. The non-inverting input end of the operational amplifier U2 is connected to the first selection circuit 1233, and the reverse input end of the operational amplifier U2 is connected to the sampling circuit 1241. The sampling circuit 1241 is connected to the second end of the switch tube S1 to sample and characterize the current flowing through the switch tube S1, wherein the sampling circuit 1241 includes at least one sampling resistor.

[0065] In the example of the present application, the logic circuit 125 includes:

[0066] The first AND gate circuit 1241 and the first trigger 1242, the two input terminals of the first AND gate circuit 1241 are respectively connected to the first timing circuit 121 and the impedance detection circuit 11, so as to determine whether the first timing circuit 121 outputs a valid trigger signal. Taking the first trigger 1242 as an RS trigger as an example, the set terminal of the first trigger 1242 is connected to the output terminal of the first AND gate circuit 1241.

[0067] The second AND gate circuit 1243 and the second trigger 1244, the two input terminals of the second AND gate circuit 1243 are respectively connected to the second timing circuit 122 and the impedance detection circuit 11, so as to determine whether the second timing circuit 122 outputs a valid trigger signal. Taking the second trigger 1244 as an RS trigger as an example, the set terminal of the second trigger 1244 is connected to the output terminal of the second AND gate circuit 1243, the reset terminal of the second trigger 1244 is connected to the first trigger 1242, and the output terminal of the second trigger 1244 is connected to the reset terminal of the first trigger 1242.

[0068] The OR gate circuit 1245, the input end of the OR gate circuit 1245 is respectively connected to the output end of the first trigger 1242 and the output end of the second trigger 1244, and the OR gate circuit 1245 is used to output a valid trigger signal or a valid locking signal T2 to the first selection circuit 1233. If there is neither a valid trigger signal nor a valid locking signal, the first selection circuit 1233 outputs a fixed threshold voltage Vref2, and illustratively, the fixed threshold voltage Vref2 can represent 100% brightness of the lighting load 30.

[0069] It should be noted that the first trigger 1242 and the second trigger 1244 may also be other triggers derived from the RS trigger, and this application does not limit the type of trigger.

[0070] Furthermore, the dimming control circuit 12 further includes:

[0071] The second selection circuit 126, the two input ends of the second selection circuit 126 receive the impedance detection signal and the low-level signal respectively, the second selection circuit 126 and the first timing circuit 121 are connected to the logic circuit 125, so that the first timing circuit 121 can shield the impedance detection signal before obtaining the high-low impedance switching signal, to avoid starting the timer 1231 without the trigger signal T1 output by the first timing circuit 121 when the switch is never detected to be turned off.

[0072] Exemplarily, the second selection circuit 126 and the first timing circuit 121 are connected to two input terminals of the first AND gate circuit 1241. Before the first timing circuit 121 obtains the high-low impedance switching signal, the second selection circuit 126 can control one input terminal of the first AND gate circuit 1241 to be a low level, and the first AND gate circuit 1241 outputs a low level signal. At this time, the trigger signal T1 output by the first timing circuit 121 is invalid, and the timer 1231 cannot be started.

[0073] The third selection circuit 127, the two input ends of the third selection circuit 127 receive the impedance detection signal and the low-level signal respectively, the third selection circuit 127 and the second timing circuit 122 are connected to the logic circuit 125, so that the second timer 122 can shield the impedance detection signal in the non-dimming mode, and the second timing circuit 122 cannot output the locking signal.

[0074] Exemplarily, the third selection circuit 127 and the second timing circuit 122 are connected to two input terminals of the second AND gate circuit 1243. When the second timer 122 is in non-dimming mode, the second selection circuit 126 can control one input terminal of the second AND gate circuit 1243 to be low level, and the second AND gate circuit 1243 outputs a low level signal. At this time, the trigger signal T1 output by the second timing circuit 122 is invalid, and the timer 1231 cannot be stopped.

[0075] As an implementation, the power supply device 20 further includes a high-voltage isolation circuit 23, which is connected between the AC input terminal and the battery 22, and is used to isolate the AC input terminal and the battery 22 when an AC input voltage exists.

[0076] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the claims attached to this application.

Claims

1. An emergency lighting control circuit, wherein an AC input voltage supplies power to a lighting load through a power supply device, and the emergency lighting control circuit controls a battery to supply power to the lighting load, characterized in that: include: An impedance detection circuit, the impedance detection circuit is used to detect the impedance state between the high and low potential ends of the AC input to generate an impedance detection signal; A dimming control circuit, wherein the dimming control circuit is connected to the impedance detection circuit, when the impedance detection circuit outputs a first impedance detection signal representing a low impedance state, and the lighting load operates in a non-dimming mode, the current brightness of the lighting load is recorded as a first brightness, and if the dimming control circuit obtains N high-low impedance switching signals within a first preset time, the dimming control circuit controls the lighting load to operate in a dimming mode, and the brightness of the lighting load is reduced or increased by a set rate from the first brightness, wherein N is a positive integer, and the first preset time starts from when the impedance detection circuit outputs a second impedance detection signal representing a high impedance state.

2. The emergency lighting control circuit according to claim 1, characterized in that: After the lighting load enters the dimming mode, when the first brightness is reduced to the lowest brightness according to the set rate, the lowest brightness is recorded as the second brightness; Alternatively, when the first brightness is increased to a maximum brightness according to a set rate, the maximum brightness is recorded as the second brightness.

3. The emergency lighting control circuit according to claim 2, characterized in that: In the dimming mode, when the dimming control circuit obtains the high-low impedance switching signal N times within the second preset time, the dimming control circuit controls the lighting load to operate in the non-dimming mode, and the lighting load is maintained at a third brightness, which is any brightness in the process of decreasing or increasing from the first brightness to the second brightness at a set rate.

4. The emergency lighting control circuit according to claim 1, characterized in that: The impedance detection circuit obtains a voltage input signal and compares the voltage input signal with a reference threshold voltage to output the impedance detection signal. When the voltage input signal is greater than the reference threshold voltage, the first impedance detection signal is output; when the voltage input signal is less than or equal to the reference threshold voltage, the second impedance detection signal is output.

5. The emergency lighting control circuit according to claim 4, characterized in that: The dimming control circuit comprises: a first timing circuit connected to the output end of the impedance detection circuit, wherein in the non-dimming mode, the first timing circuit starts timing when receiving the second impedance detection signal, wherein the first timing circuit is configured to output a trigger signal within the first preset time; A second timing circuit is connected to the output end of the impedance detection circuit. In the dimming mode, the second timing circuit starts timing when receiving the second impedance detection signal, wherein the second timing circuit is configured to output a locking signal within the second preset time.

6. The emergency lighting control circuit according to claim 5, characterized in that: The dimming control circuit comprises: A reference voltage generating circuit, wherein the reference voltage generating circuit is respectively connected to the first timing circuit and the second timing circuit, wherein the reference voltage generating circuit outputs a variable reference threshold voltage when acquiring the trigger signal, and wherein the reference voltage generating circuit outputs a fixed reference threshold voltage when acquiring the locking signal. A current control circuit is connected to the output end of the reference voltage generating circuit and controls the current flowing through the lighting load according to the reference threshold voltage.

7. The emergency lighting control circuit according to claim 6, characterized in that: The dimming control circuit further includes a logic circuit, which receives the trigger signal and the lock signal to generate a control signal for controlling the reference voltage generating circuit.

8. The emergency lighting control circuit according to claim 6, characterized in that: The reference voltage generating circuit comprises: A counter, wherein the counter starts counting when receiving the trigger signal, generates a corresponding counting signal according to the number of bits of the counter, stops counting when receiving the locking signal, and outputs a fixed counting signal; A DAC module receives the counting signal and generates the corresponding reference threshold voltage according to the counting signal; A first selection circuit receives the control signal and outputs the reference threshold voltage to the current control circuit according to the control signal.

9. The emergency lighting control circuit according to claim 8, characterized in that: The dimming control circuit comprises: a second selection circuit, wherein two input ends of the second selection circuit receive the impedance detection signal and the low-level signal respectively, an output end of the second selection circuit and an output end of the first timing circuit are connected to the logic circuit, and the first timing circuit can shield the impedance detection signal before acquiring the high-low impedance switching signal, so that the counter cannot receive the trigger signal; A third selection circuit, wherein two input ends of the third selection circuit respectively receive the impedance detection signal and the low-level signal, the output end of the third selection circuit and the output end of the second timing circuit are connected to the logic circuit, and the second timer can shield the impedance detection signal in the non-dimming mode, so that the counter cannot receive the locking signal.

10. The emergency lighting control circuit according to claim 1, characterized in that: The power supply device also includes a high-voltage isolation circuit, which is connected between the AC input terminal and the battery and is used to isolate the AC input terminal and the battery when the AC input voltage exists.

11. An emergency lighting system, characterized in that: The method comprises the emergency lighting control circuit according to any one of claims 1 to 10.

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