LED lighting device and protection device thereof

Abstract

The utility model discloses an LED lighting device and a protection device thereof. The LED lighting device comprises a protection device, a driving unit and an LED light-emitting unit, the protection device is provided with an input end and an output end, the input end is electrically connected with an external signal source, the protection device comprises a heater and a fuse, the fuse is located at a position capable of receiving heat emitted by the heater, and the LED light-emitting unit is electrically connected with the heater. When an external signal provided by the external signal source reaches the protection standard of the protection device, the heater emits heat to assist the fuse in fusing. The output end of the protection device is coupled to the driving unit, and the driving unit is used for converting the external signal into a driving signal; and the LED light emitting unit is coupled to the driving unit, and the LED light emitting unit receives the driving signal output by the driving unit.

Description

Technical Field

[0001] This application relates to the field of lighting technology, and in particular to an LED lighting device and its protective device. Background Technology

[0002] With the development of LED technology, LED chips are widely used in high-power lighting devices to replace energy-intensive light sources such as HID lights. High-power LED lighting devices have high brightness and require high power, but they are incompatible with inductive ballasts. If a high-power LED lighting device is mistakenly connected to an inductive ballast, the light source's drive circuit may be damaged due to excessive current supplied by the inductive ballast, thus reducing its lifespan. Currently, most high-power LED lighting devices on the market do not have anti-misconnection circuits. Only a few devices use a small board to detect the connection and flash the LEDs to indicate a misconnection. However, this method is complex and costly, limiting its application. Summary of the Invention

[0003] To overcome the aforementioned deficiencies, this application proposes an LED lighting device and its protection device, which achieves the function of preventing misconnection at low cost, thereby solving the problems mentioned in the background art.

[0004] To achieve the above objectives, the embodiments of this application adopt the following technical solution: a detection device for an LED lighting device, wherein the LED lighting device includes an LED driver and an LED light-emitting unit, characterized in that the detection device includes: a circuit board having a first end, a second end, a third end, and a fourth end, wherein the third end and the fourth end are used to connect to a ballast or mains power; the first end and the second end are used to connect to the LED driver, the LED driver being electrically connected to the LED light-emitting unit; a detection unit disposed on the circuit board, wherein the detection unit includes a valve, one end of which is electrically connected to the first end; a heater, one end of which is electrically connected to the other end of the valve, and the other end of which is electrically connected to the second end; and a fuse electrically connected to the heater and one of the third end and the fourth end, the fuse being positioned to receive heat emitted by the heater.

[0005] Preferably, the valve is a discharge tube.

[0006] Preferably, the heating element is a cement resistor.

[0007] Preferably, the fuse is a thermal fuse.

[0008] Preferably, when the detection device is connected to the inductive ballast, the valve is short-circuited and the heater heats up for a preset time to blow the temperature fuse.

[0009] Preferably, the temperature fuse is configured as a surface mount type.

[0010] Preferably, the thermal fuse is tubular and is pluggably mounted on a base, which is mounted on the circuit board.

[0011] Preferably, the base has a first pin and a second pin, the first pin being electrically connected to the heater, and the second pin being electrically connected to the third or fourth terminal.

[0012] This application also proposes an LED lighting device, characterized in that it includes: a protection device having an input terminal and an output terminal, the input terminal being electrically connected to an external signal source, the protection device including a heater and a fuse, the fuse being located at a position where it can receive heat emitted by the heater, and the heater heating up to assist the fuse in blowing when the external signal provided by the external signal source reaches the protection standard of the protection device; a driving unit, the output terminal of the protection device being coupled to the driving unit, the driving unit being used to convert the external signal into a driving signal; and an LED light-emitting unit being coupled to the driving unit, the LED light-emitting unit receiving the driving signal output by the driving unit.

[0013] Preferably, one end of the fuse is coupled to the external signal source, and the other end is coupled to the drive unit.

[0014] Preferably, the protection device further includes: a valve, wherein the valve is connected in series with the heater and both ends are coupled to the external signal source and the drive unit;

[0015] Preferably, the valve is configured as a discharge tube.

[0016] Preferably, the heater is configured as a cement resistor.

[0017] Preferably, the fuse is configured as a thermal fuse.

[0018] Preferably, the direct supply means that the mains power is transmitted to the drive unit without any power conversion equipment.

[0019] Preferably, the protection criterion is that the external signal is provided via an inductive ballast.

[0020] Preferably, the discharge tube is disconnected, and the external signal enters the drive unit.

[0021] Preferably, the discharge tube is turned on / short-circuited, and the external signal does not enter the drive unit.

[0022] Based on the above, the apparatus provided in this application has the following advantages:

[0023] When an LED lighting device is mistakenly connected to an inductive ballast, the high voltage input causes the valve inside the protection device to open, increasing the power consumption and heat generation on the heater, which in turn causes the fuse near the heater to blow and open the circuit. The high voltage will not damage other components in the drive unit; after replacing the fuse, the drive unit will function normally. Attached Figure Description

[0024] The accompanying drawings are provided to illustrate the technical solutions of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the technical solutions of this disclosure and do not constitute a limitation on the technical solutions of this disclosure. The shapes and sizes of the components in the drawings do not reflect actual proportions and are only intended to illustrate the content of this application.

[0025] Figure 1 This is a circuit block diagram of an LED lighting device according to an embodiment of this application;

[0026] Figure 2 This is a functional topology diagram of an external signal source according to an embodiment of this application;

[0027] Figure 3 This is a circuit block diagram of a power drive circuit according to an embodiment of this application;

[0028] Figure 4 This is a functional topology diagram of a protection device according to an embodiment of this application;

[0029] Figure 5 This is a circuit block diagram of a power drive circuit according to an embodiment of this application; and

[0030] Figure 6 This is a functional topology diagram of an LED lighting device according to an embodiment of this application. Detailed Implementation

[0031] The above-described solution will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. The implementation conditions used in the embodiments may be further adjusted according to the conditions of specific manufacturers, and the implementation conditions not specified are generally those in routine experiments.

[0032] Unless otherwise defined, the technical or scientific terms used in the embodiments of this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. In this document, "electrical connection" includes the situation where constituent elements are connected together by an element having some electrical function. There is no particular limitation on the "electrically functioning element," as long as it enables the transmission and reception of electrical signals between the connected constituent elements. An "electrically functioning element" can be, for example, an electrode or wiring, a switching element such as a transistor, or other functional elements such as a resistor, inductor, or capacitor. "Up," "down," "left," and "right" are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0033] In this application, the terms "upper," "lower," "inner," "middle," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0034] This application provides an LED lighting device and its protection device. The LED lighting device is equipped with a power drive circuit and an LED light-emitting unit. The LED light-emitting unit is coupled to the power drive circuit to receive the drive signal output by the power drive circuit. The power drive circuit has a protection device, which is coupled to an external signal source and controls the conduction or interruption of the LED lighting device by judging the external signal provided by the external signal source. When the external signal comes directly from the mains power, that is, the mains power is transmitted to the power drive circuit without any power conversion equipment, the external signal (i.e., the input electrical signal) flows into the subsequent circuit (also called the drive unit). The drive unit converts the input electrical signal into the drive signal required by the LED light-emitting unit. When the external signal comes from an inductive ballast, that is, the mains power provides the input electrical signal through the inductive ballast, the fuse in the protection device blows, the input electrical signal cannot be transmitted to the subsequent circuit, that is, the drive unit fails and no longer works, thus preventing misconnection. The LED lighting device can be a HID lamp (HID-LED, High Intensity Discharge-LED), such as the LED lamp disclosed in the authorization announcement number CN 211010828 U, with a power between 150W and 300W and a luminous flux of about 20,000 to 45,000 lumens.

[0035] Please see Figure 1 The diagram shown is a circuit block diagram of an LED lighting device according to an embodiment of this application. Figure 1 As shown, an external signal source 10 is coupled to a power drive circuit 20 to provide an electrical signal Vin. The power drive circuit 20 has a first input terminal and a first output terminal, wherein the first input terminal is used to couple to the external signal source 10, and the first output terminal is coupled to the LED light-emitting unit 30. The power drive circuit 20 provides a drive signal Vo to the LED light-emitting unit 30 through the first output terminal. In some embodiments, the power drive circuit 20 and the LED light-emitting unit 30 can be connected by a wire.

[0036] External signal source 10 typically outputs electrical signal Vin in two ways. Method one involves directly supplying the signal Vin from the mains power supply, meaning the mains power is transmitted to the power drive circuit 20 without any power conversion equipment. Mains power usually refers to voltages within the range of 90V to 320V. For method two, please refer to [link to relevant documentation]. Figure 2 The external signal source 10 is shown to provide an electrical signal Vin after the mains power is adjusted by an inductive ballast. In some embodiments, the 120V mains power can output a voltage of 550V after passing through the inductive ballast.

[0037] Please see Figure 3 The diagram shown is a circuit block diagram of a power drive circuit according to an embodiment of this application. Figure 3As shown, the power drive circuit 20 includes a protection device 21 and a drive unit 22. The protection device 21 has an input terminal and an output terminal. Its input terminal is coupled to an external signal source 10 to receive the electrical signal Vin output by the external signal source 10. Its output terminal is coupled to the drive unit 22. When the external signal source 10 coupled to the input terminal of the protection device 21 is in mode one, the protection device 21 operates in a normal state, and its output terminal transmits an electrical signal to the drive unit 22, that is, the drive unit 22 operates, and the drive unit 22 outputs a drive signal Vo to the LED light-emitting unit 30. When the external signal source 10 coupled to the input terminal of the protection device 21 is in mode two, the protection device 21 operates in an abnormal state, and its output terminal does not transmit an electrical signal to the drive unit 22, that is, the drive unit 22 does not operate.

[0038] Further, please refer to Figure 4 The diagram shows a functional topology of a protection device according to an embodiment of this application. Figure 4 As shown, the protection device 21 includes a valve G, a heater R, and a fuse F. The valve G and the heater R are electrically connected in series, and both ends are coupled to an external signal source 10 and a drive unit 22. One end of the fuse F is electrically connected to the external signal source 10, and the other end is coupled to one end of the series connection between the valve G and the heater R. In other words, this end is electrically connected to the drive unit 22.

[0039] The valve has two modes: on and off, and a threshold value exists. When the external signal source coupled to the input of the protection device is in mode one, the external signal provided by the external signal source cannot reach the valve threshold. At this time, the valve is in the off mode, and almost no current flows through the valve, meaning the protection device is in normal condition. When the external signal source coupled to the input of the protection device is in mode two, the external signal provided by the external signal source can reach the valve threshold at least at one moment, causing the valve to switch to the on mode. At this time, a large current flows through the valve, meaning the protection device is in abnormal condition, and almost no current flows to the drive unit.

[0040] Heating units typically have characteristics such as large size, moisture resistance, heat resistance, vibration resistance, and fast heat dissipation, and can be used in applications with high current. In this embodiment, due to its large resistance and good heat dissipation performance, the heating unit can quickly respond to the large current flowing through it and dissipate heat when the valve enters the conducting state.

[0041] In this embodiment, the fuse is a pair of temperature-sensitive devices. It responds to the heat it generates and the heat received from the outside. When the total heat reaches a specified value, the fuse element melts, thus breaking the circuit. In other words, when the valve is in the conducting state, a large current flows through the heater and the fuse. The fuse, responding to the heat it generates and the heat received from the heater, disconnects, thus protecting the circuit.

[0042] In this embodiment, valve G can be a discharge tube G, and heater R can be a cement resistor R. The discharge tube G is connected in series with one end of the cement resistor R. One end of fuse F is electrically connected to the other end of cement resistor R (i.e., the end not connected to discharge tube G), and the other end of fuse F is coupled to external signal source 10. The protection device 21 is used to cut off the signal transmission between external signal source 10 and drive unit 22 when the external signal source 10 coupled to the first input terminal of power drive circuit 20 is in mode two (i.e., power drive circuit 20 is mistakenly connected to inductive ballast).

[0043] In one embodiment, the protection device 21 disconnects the electrical connection between the drive unit 22 and the external signal source 10 by blowing the fuse F. In this embodiment, the fuse F is a thermal fuse located at a position that can receive the heat generated by the cement resistor R, so as to fully receive the heat generated by the cement resistor R.

[0044] From another perspective, the protection device can also be a detection device, which includes: a circuit board, which is a hardware structure with a first terminal, a second terminal, a third terminal, and a fourth terminal. The third and fourth terminals are used to connect to a ballast or mains power; the first and second terminals are used to connect to an LED driver (e.g., connected to the LED driver via wires), and the LED driver is electrically connected to an LED light-emitting unit. The first and second terminals are the output terminals of the protection device 21, and the third and fourth terminals are the input terminals of the protection device 21. The LED driver is the driving unit 22.

[0045] The circuit board includes a detection unit comprising a discharge tube G, a cement resistor R, and a fuse F. The discharge tube G is electrically connected in series with the cement resistor R, and its two ends are electrically connected to a first terminal and a second terminal, respectively. The fuse F is electrically connected to the cement resistor R and a third or fourth terminal, and is used to melt and disconnect the electrical connection with the inductive ballast in case of misconnection. In this embodiment, the fuse F is a thermal fuse, located close to the cement resistor R to fully absorb the heat from the cement resistor R. Preferably, the thermal fuse is a surface mount type. In one embodiment, the thermal fuse is configured to be pluggable and mounted on the circuit board. The detection device also includes a base mounted on the circuit board. The base has a first pin electrically connected to the cement resistor R, a second pin electrically connected to the third or fourth terminal, and the thermal fuse is pluggable and mounted on the base, close to the cement resistor R.

[0046] The mechanism of this embodiment is as follows: If the external signal coupled to the input terminal of the protection device is in mode two, that is, if the input terminal of the protection device is mistakenly connected to the inductive ballast, the electrical signal Vin output by the inductive ballast to the protection device is higher than the threshold of the valve in the protection device. At this time, the valve is short-circuited / conducted, which increases the power consumption of the heater connected in series with it and releases heat. The fuse is located in a position that can receive the heat emitted by the heater. The heater can assist the fuse to blow through the heat emitted, which can more quickly prevent the electrical signal Vin from flowing to the drive unit and play the role of protecting the circuit.

[0047] In the above embodiments, the discharge tube is a high-voltage protection element. If the voltage across its terminals exceeds its protection specification value, a short circuit will occur internally, absorbing the input overvoltage. Alternatively, the discharge tube can be described as an overvoltage protection device, made using the thyristor principle, relying on the breakdown principle of the PN junction to conduct and discharge, allowing large surge currents or pulse currents to flow. The discharge tube has an off-state voltage (i.e., a threshold voltage). In this embodiment, the off-state voltage is 400V. When the applied voltage is lower than the off-state voltage of the discharge tube, the device is in an off-state state, i.e., when the external signal source 10 coupled to the input terminal of the protection device is in mode one, the protection device is in a normal state. When the applied voltage exceeds its off-state voltage (or the applied voltage continues to increase), i.e., when the external signal source 10 coupled to the input terminal of the protection device is in mode two, the protection device is in an abnormal state, and the discharge tube enters a conducting state due to the load effect, at which point it is almost short-circuited. When the applied voltage returns to normal, i.e., returns to the power supply mode of mode one, the discharge tube automatically resets and returns to a high-impedance state. In some embodiments, the 120V mains power can output a voltage of 550V after passing through the inductive ballast. This voltage is sent as an electrical signal Vin to the protection device 21. At this time, the electrical signal Vin is higher than the off-state voltage of the discharge tube, and the discharge tube enters a short-circuit / conduction state. A large current flows through the cement resistor connected in series with the discharge tube. The cement resistor releases heat, and the temperature-sensitive fuse receives a certain amount of heat dissipated by the cement resistor and then disconnects. The fuse can be a thermal fuse.

[0048] Alternatively, if mistakenly connected to an inductive ballast, the 120VAC input voltage of the inductive ballast will be pulled up to 550V. At this time, the discharge tube will short-circuit / conduct. The thermal fuse can be melted by setting the cement resistor value P = U² / R, allowing the cement resistor to dissipate heat. In some embodiments, the melting time of the thermal fuse can be controlled by matching the cement resistor value to achieve the required protection time, such as 1s, 3s, or 5s. This protection time is the time it takes for the thermal fuse to melt after 1s, 3s, or 5s, after tolerating the heat dissipated by the cement resistor and the heat it generates itself. For example, if the components surrounding the cement resistor are not sensitive to temperature or have little effect on them, the protection time can be controlled to 5s; if the surrounding components are important components such as the system's main control chip (IC) and are significantly affected by temperature, the protection time should be controlled to 1s, i.e., quickly cutting off the connection between the detection device and external signals. Furthermore, with a fixed cement resistor value, the melting time of the thermal fuse can be controlled by adjusting the distance between the cement resistor and the thermal fuse to achieve the required protection time.

[0049] In a preferred embodiment, the detection device is integrated into the LED driver, and the thermal fuse is installed on the LED driver in a pluggable manner. In this case, the cement resistor is located away from the LED driver's IC, capacitors, and other temperature-sensitive components. The LED driver's mainboard can be configured with two conductive layers: one for the LED driver's component layout and the other for the detection device's component layout (these can be configured on opposite sides to reduce the impact of temperature-sensitive components like the cement resistor). This achieves a low-cost anti-misconnection function.

[0050] Reference Figure 5 The diagram shows a schematic block representation of the driving unit circuit of an LED lighting device according to an embodiment. Figure 5 As shown, when the external signal source 10 coupled to the first input terminal of the power drive device is in mode one, the drive unit 22 converts the electrical signal Vin input from the external signal source 10 into the drive signal Vo required by the LED light-emitting unit 30. The drive unit 22 includes a rectifier module 221, a filter module 222, and a conversion module 223. The rectifier module 221 has an input terminal and an output terminal. The rectifier module 221 can be a half-wave rectifier, a full-wave rectifier, a full-wave bridge rectifier, or a voltage doubler rectifier; no limitation is made in this application. The electrical signal Vin output from the external signal source 10 is rectified by the rectifier module 221 to generate a DC signal. The input terminal of the rectifier module 221 is electrically connected to the external signal source 10. In this embodiment, the external signal source 10 is typically a mains voltage, i.e., an AC signal of 90V-320V, 50 / 60Hz, which can include every integer value point within the voltage range, such as 90V, 91V, 92V, etc.

[0051] The filter module 222 is used to filter the electrical signal output from the rectifier module 221, eliminating the AC component before supplying it to the subsequent circuitry. The filter module 222 typically utilizes devices with specific impedance characteristics to AC power to construct the filter circuit, such as capacitor filters, π-type RC filters (also known as π-type resistor-capacitor filters), π-type LC filters (also known as π-type inductor-capacitor filters), and electronic filters. This embodiment may use one of the above-mentioned filter circuits to construct the filter module 222. The filter circuit 222 has an input terminal and an output terminal, with its input terminal electrically connected to the output terminal of the rectifier module 221.

[0052] The conversion module 223 controls the drive signal Vo in the control circuit. For example, if the conversion module 223 is configured with a boost topology, the output voltage (drive signal Vo) of the power drive circuit 20 of the LED lighting device is greater than the input voltage (electrical signal Vin); if the conversion module 223 is configured with a buck topology, the output voltage (drive signal Vo) of the power drive circuit 20 of the LED lighting device is less than the input voltage (electrical signal Vin). The conversion module 223 has an input terminal and an output terminal. Its input terminal is electrically connected to the output terminal of the filter module 222, and its output terminal is electrically connected to the LED light-emitting unit 30.

[0053] Please see Figure 6 The diagram shows a functional topology of an LED lighting device according to one embodiment. Figure 6 As shown, when the external signal source 10 coupled to the first input terminal of the power drive device 20 is in mode two, the electrical signal Vin is provided by the inductor ballast. The electrical signal Vin is higher than the off-state voltage of the discharge tube G in the protection device 21. At this time, the discharge tube 21 is in the on / short circuit state, and the cement resistor R heats up and blows the fuse F, that is, no electrical signal enters the LED driver.

[0054] In summary, this application proposes an LED lighting device and its protection device. When the protection device receives an external signal lower than its own off-state voltage, the driving unit converts the external signal into a driving signal required by the LED light-emitting unit. If the detection device receives an external signal higher than its own off-state voltage, it blows the internal fuse to prevent the external signal from entering the driving unit, thus protecting the circuit.

[0055] The above embodiments are only for illustrating the technical concept and features of this application, and are intended to enable those skilled in the art to understand the content of this application and implement it accordingly. They should not be used to limit the scope of protection of this application. All equivalent changes or modifications made in accordance with the spirit and essence of this application should be included within the scope of protection of this application.

Claims

1. A protection device applied to an LED lighting device, wherein the LED lighting device comprises an LED driver and an LED light emitting unit, characterized in that, The detection device comprises: a circuit board having a first end, a second end, a third end and a fourth end, wherein the third end and the fourth end are used to connect to a ballast or a mains power supply; the first end and the second end are used to connect to the LED driver, and the LED driver is electrically connected to the LED light unit; a detection unit arranged on the circuit board, wherein the detection unit comprises: a valve having one end electrically connected to the first end; a heat generator having one end electrically connected to the other end of the valve and the other end electrically connected to the second end, the heat generator having a high-heat-dissipation resistor to quickly respond to a large current flowing through itself and dissipate heat; and a fuse electrically connected to the heat generator and one of the third end and the fourth end, the fuse being located at a position where it can receive heat emitted by the heat generator.

2. The protection device for LED lighting device according to claim 1, wherein The valve is a discharge tube.

3. The protection device for LED lighting device according to claim 1, wherein The heat generator is a cement resistor.

4. The protection device for LED lighting apparatus according to claim 1, wherein The fuse is a temperature fuse.

5. The protection device for an LED lighting device according to claim 4, wherein: when the detection device is connected to an inductive ballast, the valve is short-circuited, the heat generator generates heat for a preset time to melt the temperature fuse.

6. The protection device for an LED lighting device according to claim 4, wherein: the temperature fuse is configured as a patch type.

7. The protection device for an LED lighting device according to claim 4, wherein: the temperature fuse is a tube type and is pluggable on a base, and the base is arranged on the circuit board.

8. The protection device for an LED lighting device according to claim 7, wherein: the base has a first pin and a second pin, the first pin is electrically connected to the heat generator, and the second pin is electrically connected to the third end or the fourth end.

9. An LED lighting device, characterized by comprises: a protection device having an input end and an output end, the input end being electrically connected to an external signal source, the protection device comprising a heat generator and a fuse, the fuse being located at a position where it can receive heat emitted by the heat generator, when the external signal provided by the external signal source reaches the protection standard of the protection device, the heat generator generates heat to assist the fuse to melt; a driving unit, the output end of the protection device being coupled to the driving unit, the driving unit being used to convert the external signal into a driving signal; and an LED light unit coupled to the driving unit, the LED light unit receiving the driving signal output by the driving unit.

10. The LED lighting device of claim 9, wherein, One end of the fuse is coupled to the external signal source, and the other end is coupled to the driving unit.

11. The LED lighting apparatus of claim 10, wherein, The protection device further comprises: a valve, both ends of the valve being coupled to the external signal source and the driving unit after being connected in series with the heat generator.

12. The LED lighting apparatus of claim 11, wherein, The valve is configured as a discharge tube.

13. The LED lighting apparatus of claim 11, wherein, The heat generator is configured as a cement resistor.

14. The LED lighting apparatus of claim 10, wherein, The fuse is configured as a temperature fuse.

15. The LED lighting apparatus of claim 9, wherein, The external signal is directly provided by a mains power supply, and the direct provision means that the mains power supply is transmitted to the driving unit without being adjusted by any power conversion device.

16. The LED lighting apparatus of claim 9, wherein, The protection standard is provided by an inductive ballast.

17. The LED lighting apparatus of claim 15, wherein, The discharge tube is open, and the external signal enters the drive unit.

18. The LED lighting apparatus of claim 16, wherein, The discharge tube is on / short-circuited, and the external signal does not enter the drive unit.

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