Protection circuit for determining line status before powering security CCTV cameras

Abstract

The present invention relates to a protection circuit for determining the line status prior to power application for a security CCTV camera. In a security CCTV camera powered via PoE, the invention provides a protection circuit for a PoE-based CCTV camera that can prevent damage, malfunction, or repeated restarts of the CCTV camera in advance by circuitously determining the electrical status of the communication line before the PoE power is actually applied, and blocking the PoE power application itself if the communication line is in an abnormal state as a result of the determination. To this end, the present invention relates to a PoE switch hub (120) that supplies power to a security CCTV camera (130) via Power over Ethernet (PoE), comprising: a PoE power input unit (122) that receives PoE power input from an external power source; a line inspection circuit (123) configured to apply a line inspection voltage to inspect the line condition prior to power application to a communication line before the PoE power is applied to the CCTV camera; a resistance voltage divider circuit (1233) that converts an electrical signal corresponding to a leakage current detected from the communication line by the line inspection circuit prior to power application into a voltage divider; an analog comparator circuit (124) configured to compare the voltage divider voltage output from the resistance voltage divider circuit with an internal reference voltage; a power cutoff driving circuit (125) configured to drive a PoE power serial cutoff MOSFET connected in series on the power path to which the PoE power is applied to the CCTV camera according to the output of the analog comparator circuit to allow or cut off the application of the PoE power; and the power cutoff A protection circuit for determining the line status prior to power application of a security CCTV camera is provided, comprising a PoE power switching unit (126) configured to be controlled by a driving circuit so that the PoE power is selectively applied to the CCTV camera.

Description

Technology Field

[0001] The present invention relates to the field of in-house communication facilities, and more specifically, to a power protection circuit applied to a security CCTV camera that is powered via Power over Ethernet (PoE). In particular, the present invention relates to a protection circuit for a PoE-based CCTV camera configured to circuitly determine the electrical state of a communication line before PoE power is actually applied to the CCTV camera, and to block the power application itself if an abnormal state is detected. Background Technology

[0002] Recently, security CCTV cameras installed inside or outside buildings commonly utilize the Power over Ethernet (PoE) method, which supplies both data signals and power simultaneously through an Ethernet cable.

[0003] While such PoE-based CCTV systems offer the advantages of simplified wiring and reduced installation costs, problems may arise where the CCTV camera is damaged or malfunctions during the power supply process due to leakage in the communication line, poor grounding, moisture ingress, or cable damage.

[0004] In conventional technology, a technique has been proposed to recover from a problem by monitoring the operating status of a CCTV camera and then disconnecting and re-applying PoE power when an abnormality is detected.

[0005] However, these conventional technologies focus on post-recovery after power has already been applied, so they have limitations in fundamentally preventing circuit damage or repetitive malfunctions that may occur at the moment of power application. In other words, there is still a need for circuit technology that determines the status of the communication line and controls the power application itself at a stage prior to PoE power application.

[0006] The information described above disclosed in the background technology of this invention is intended only to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art. Prior art literature

[0007] Registered Patent Publication No. 10-2654359 (Publication Date: April 4, 2024) Registered Patent Publication No. 10-2782746 (Publication Date: March 18, 2025) The problem to be solved

[0008] The objective of the present invention is to solve the problems of the prior art as described above, and to provide a protection circuit for a PoE-based CCTV camera that can prevent damage, malfunction, or repeated restart of the CCTV camera in advance by circuitously determining the electrical state of a communication line before the PoE power is actually applied, and blocking the application of PoE power itself if the communication line is in an abnormal state as a result of the determination. means of solving the problem

[0009] A protection circuit for determining the line status prior to power application of a security CCTV camera according to the present invention comprises: a PoE switch hub that supplies power to a security CCTV camera via PoE (Power over Ethernet), a PoE power input unit that receives PoE power input from an external power source; a line inspection circuit prior to power application configured to apply a line inspection voltage to inspect the line status prior to power application to a communication line before the PoE power is applied to the CCTV camera; a resistance voltage divider circuit that converts an electrical signal corresponding to a leakage current detected from the communication line by the line inspection circuit prior to power application into a voltage divider; an analog comparator circuit configured to compare the voltage divider voltage output from the resistance voltage divider circuit with an internal reference voltage; and a power cutoff driving circuit configured to drive a PoE power serial cutoff MOSFET connected in series on the power path where the PoE power is applied to the CCTV camera according to the output of the analog comparator circuit, thereby allowing or blocking the application of the PoE power. and includes a PoE power switching unit configured to be controlled by the power cutoff driving circuit above so that the PoE power is selectively applied to the CCTV camera.

[0010] In one or more embodiments, the line inspection circuit prior to power application comprises: a line inspection voltage generating circuit configured to apply the line inspection voltage to the communication line; a leakage current detection unit configured to detect a leakage current generated in the communication line by the line inspection voltage; and a resistor voltage divider circuit that converts the output signal of the leakage current detection unit into a voltage divider voltage for providing to the analog comparator circuit. Effects of the invention

[0011] According to the present invention, by determining leakage current or electrical abnormalities in the communication line before PoE power is applied, damage to the CCTV camera that may occur during the power application process can be effectively prevented. Furthermore, unlike conventional technology, the reliability of the CCTV system can be improved as it does not rely on restarting or software recovery after power application. Additionally, by adopting an analog circuit-based protection structure including a comparator, a resistor voltage divider circuit, and a switching element, the present invention can operate stably without separate control software or a network control device. Moreover, the present invention can be directly applied to in-house communication facilities such as security CCTV cameras and can be applied to existing PoE-based systems without significant structural changes. Brief explanation of the drawing

[0012] Figure 1 is an overall configuration diagram of a security CCTV camera system according to the present invention. Figure 2 is an overall circuit block diagram of a PoE switch hub in a security CCTV camera system according to the present invention. FIG. 3 is a detailed block diagram of a line pre-inspection circuit of a PoE switch hub in a security CCTV camera system according to the present invention. FIG. 4 is a detailed block diagram of the power cutoff driving circuit of the PoE switch hub in the security CCTV camera system according to the present invention. Figure 5 is an operation sequence diagram of a PoE switch hub in a security CCTV camera system according to the present invention. Specific details for implementing the invention

[0013] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0014] The present inventions are provided to more fully explain the invention to those skilled in the art, and the following examples may be modified in various different forms, and the scope of the invention is not limited to the following examples. Rather, these examples are provided to make the disclosure more faithful and complete and to fully convey the spirit of the invention to those skilled in the art.

[0015] Additionally, in the drawings below, the thickness or size of each layer is exaggerated for convenience and clarity of explanation, and like reference numerals in the drawings refer to like elements. As used herein, the term "and / or" includes any one of the listed items and all combinations of one or more thereof. Furthermore, in this specification, the meaning of "connected" refers not only to cases where Member A and Member B are directly connected, but also to cases where Member C is interposed between Member A and Member B so that Member A and Member B are indirectly connected.

[0016] The terms used herein are for describing specific embodiments and are not intended to limit the invention. As used herein, the singular form may include the plural form unless the context clearly indicates otherwise. Additionally, as used herein, "comprise, include" and / or "comprising, including" specify the presence of the mentioned features, numbers, steps, actions, parts, elements, and / or groups thereof, and do not exclude the presence or addition of one or more other features, numbers, actions, parts, elements, and / or groups.

[0017] FIG. 1 illustrates the overall configuration of a security CCTV camera system (100) according to one embodiment of the present invention.

[0018] Referring to FIG. 1, a security CCTV camera system (100) according to the present invention may include a CCTV camera management server (110), a PoE switch hub (120), and a plurality of CCTV cameras (130).

[0019] The CCTV camera management server (110) is configured to receive video data transmitted from the plurality of CCTV cameras (130) via a network and can perform functions such as storing, displaying, searching, or analyzing the received video data. In one embodiment, the CCTV camera management server (110) may be a general server device including a video storage device, a display device, and a network interface, and may further include video analysis software, an anomaly detection algorithm, or a user interface as needed.

[0020] The above PoE switch hub (120) is equipped with a plurality of Ethernet ports and can be wired to each of the plurality of CCTV cameras (130) through the plurality of Ethernet ports. The above PoE switch hub (120) is configured to simultaneously provide power in the PoE (Power over Ethernet) method along with data signals through an Ethernet cable. That is, the above PoE switch hub (120) can supply operating power to the CCTV cameras (130) using a pair of signal lines or power lines of an Ethernet cable according to a PoE standard such as IEEE 802.3af, 802.3at, or 802.3bt.

[0021] In particular, the PoE switch hub (120) according to the present invention may include a protection circuit configured to inspect the condition of the Ethernet cable and communication line before the PoE power is applied to the CCTV camera (130), as described below. The protection circuit may be configured to detect, for example, a short circuit, open circuit, abnormal resistance, leakage current, or abnormal load condition of the communication line, and may selectively control whether to apply the PoE power based on the inspection results. Accordingly, the PoE switch hub (120) can prevent damage to the CCTV camera (130) or the connected network device by preventing the application of PoE power in an abnormal line condition.

[0022] The above CCTV camera (130) may be an IP camera that transmits video data through a wired network and may be configured to operate without a separate external power source by using PoE power supplied from the above PoE switch hub (120). In one embodiment, the above CCTV camera (130) may include an image sensor for capturing video, a video processing unit, and a network communication unit, and may transmit captured video data to the above CCTV camera management server (110) in real-time or in a storage manner.

[0023] In some examples, the CCTV camera management server (110) is not limited to a dedicated security system server but can be extended to a general management server linked with a building management system, an access control system, or other security systems. Additionally, a wireless AP, VoIP telephone, intercom device, various sensors, IoT lighting device, automatic door control device, small computing device, or other network device utilizing PoE power may be connected to the PoE switch hub (120) instead of or together with the CCTV camera (130).

[0024] However, the connection of these various devices is merely an example to explain the applicable scope of the present invention, and the technical concept of the present invention is not limited to a specific device configuration. The core technical feature of the present invention is to improve the stability and reliability of the system by preemptively checking the condition of the communication line before PoE power is applied through a protection circuit provided in the PoE switch hub (120), and controlling the power application according to the result.

[0025] In the following, in order to more clearly explain the technical features of the present invention, the present invention will be described in detail, focusing particularly on the structure and operation of the PoE switch hub (120) among the above-mentioned security CCTV camera system (100).

[0026] FIG. 2 illustrates the overall circuit block configuration of a PoE switch hub (120) in a security CCTV camera system (100) according to one embodiment of the present invention.

[0027] Referring to FIG. 2, the PoE switch hub (120) according to the present invention may include an Ethernet (Ethernet PHY) (121), a PoE power input unit (122), a line inspection circuit prior to power application (123), an analog comparator circuit (124), a power cutoff driving circuit (125), and a PoE power switching unit (126).

[0028] The above PoE switch hub (120) may include an uplink port connected to an upper network and one or more PoE port interfaces connected to a lower network device, such as a CCTV camera (130), and each PoE port interface may be configured to include a data path for data transmission and a power path for power supply, respectively.

[0029] The Ethernet (Ethernet PHY) (121) is a physical layer circuit for wired communication between a PoE switch hub (120) and a CCTV camera (130), and is configured to process data signals transmitted and received through an Ethernet cable.

[0030] Specifically, the Ethernet (Ethernet PHY) (121) may be configured to receive differential data signals input through an Ethernet cable and convert them into digital data, or to convert internally generated digital data into an Ethernet signal format and transmit it.

[0031] In the present invention, the Ethernet (Ethernet PHY) (121) provides a data path for transmitting and receiving image data, control data, or status information, and is configured to operate independently of whether PoE power is applied. That is, the Ethernet (Ethernet PHY) (121) is arranged circuitously separated from the line inspection circuit (123), analog comparator circuit (124), and power cutoff driving circuit (125) prior to PoE power application, thereby forming a structure in which data transmission functions and power control functions can be performed without mutual interference.

[0032] Accordingly, even when the PoE power is cut off, it may be possible to transmit and receive data signals or detect the link status through Ethernet (Ethernet PHY) (121).

[0033] The above PoE power input unit (122) is configured to receive PoE power supplied from an external power source or an upper network device and to transmit it to the internal power path of the PoE switch hub (120).

[0034] In one embodiment, the PoE power input unit (122) may include an input terminal, a protection element, and a filter circuit for receiving a PoE voltage applied through an Ethernet cable.

[0035] The PoE power received through the above PoE power input unit (122) can be applied to the CCTV camera (130) through the PoE power switching unit (126) after passing through the power application pre-line inspection circuit (123), analog comparator circuit (124), and power cut-off driving circuit (125) described later.

[0036] The above power supply pre-line inspection circuit (123) is a circuit configured to inspect the electrical condition of the Ethernet cable and communication line before PoE power is supplied to the CCTV camera (130).

[0037] Specifically, the line inspection circuit (123) prior to power application may be configured to apply a voltage for line inspection purposes to the communication line, and the inspection voltage applied at this time may be a minute voltage significantly lower than the actual PoE voltage. A leakage current or line response signal generated by the application of the inspection voltage is detected, and through this, it is possible to determine whether there is a short circuit, leakage, abnormal resistance state, or connection error in the communication line.

[0038] Accordingly, the line inspection circuit (123) prior to power application can detect abnormal conditions of the communication line in advance at a stage before the PoE power is actually applied, and the inspection result is transmitted to the analog comparator circuit (124) described later. The specific configuration and operating principle of the line inspection circuit (123) prior to power application will be explained in more detail with reference to FIG. 3.

[0039] The analog comparator circuit (124) is configured to compare the electrical signal output from the line inspection circuit (123) prior to power application with an internal reference voltage.

[0040] In one embodiment, the analog comparator circuit (124) may be implemented as an analog circuit including an operational amplifier (op amp), a reference voltage generation circuit, and an output buffer.

[0041] The analog comparator circuit (124) above may be configured to generate different output signals depending on whether the voltage or current signal corresponding to the line inspection result is greater than or less than a reference value. In the present invention, the comparison result is used as a control signal to directly control the power cutoff driving circuit (125) without going through a microcontroller or software judgment step.

[0042] Accordingly, power application judgment can be made in real time at the analog circuit level, and the risk of control delay or software malfunction can be minimized.

[0043] The above power cutoff driving circuit (125) is a circuit configured to allow or block the application of PoE power according to the output of the above analog comparator circuit (124).

[0044] In one embodiment, the power cutoff driving circuit (125) may be configured to drive a switching element connected in series to a PoE power path, and may be implemented, for example, by controlling the gate voltage of a PoE power series cutoff MOSFET (1253).

[0045] When an output signal indicating a normal state is applied from the analog comparator circuit (124), the power cutoff driving circuit (125) controls the PoE power serial cutoff MOSFET (1253) to a conducting state to allow the application of PoE power. On the other hand, when the communication line is determined to be in an abnormal state, the application of PoE power is blocked by controlling the PoE power serial cutoff MOSFET (1253) to a cutoff state.

[0046] A specific circuit configuration and operation example of the above power cutoff driving circuit (125) is explained with reference to FIG. 4.

[0047] The above PoE power switching unit (126) is controlled by the power cutoff driving circuit (125) and configured to selectively apply PoE power to the CCTV camera (130).

[0048] In one embodiment, the PoE power switching unit (126) may include a PoE power serial cutoff MOSFET (1253), and the MOSFET (1253) is arranged in series on the PoE power path to physically perform the application or cutoff of power.

[0049] Accordingly, the PoE switch hub (120) according to the present invention can effectively prevent overcurrent, heat generation, or device damage that may occur in a line abnormal condition by applying PoE power to the CCTV camera (130) only when the state of the communication line is determined to be normal.

[0050] FIG. 3 is a detailed block diagram of a line inspection circuit (123) prior to power application provided in a PoE switch hub (120) in a security CCTV camera system (100) according to one embodiment of the present invention.

[0051] Referring to FIG. 3, the line inspection circuit (123) prior to power application may include a line inspection voltage generating circuit (1231), a leakage current detection unit (1232), and a resistance voltage divider circuit (1233).

[0052] The above-mentioned pre-power application line inspection circuit (123) is a circuit for inspecting the electrical condition of the Ethernet cable and communication line in advance at a stage before the PoE power is actually applied to the CCTV camera (130), and is configured to preemptively determine whether there is an abnormality in the communication line before the final decision is made on whether to apply the PoE power. Accordingly, the above-mentioned pre-power application line inspection circuit (123) can detect abnormal conditions such as short circuits, leakage, abnormal impedance, or insulation failures in the communication line before the PoE power is applied.

[0053] The above line inspection voltage generating circuit (1231) is configured to generate a line inspection voltage for inspecting the electrical condition of a communication line and to apply it to the communication line.

[0054] The above line inspection voltage is a voltage distinct from the actual PoE power, and can be controlled to be output to the communication line only at the stage prior to the application of PoE power.

[0055] In one embodiment, the line test voltage may be set to a voltage level significantly lower than the PoE voltage, and may be selected to a level that can determine the electrical condition of the line without causing damage to the device or cable connected to the communication line. Accordingly, the line test voltage generating circuit (1231) provides a test voltage to check for abnormalities in the line at a stage prior to the actual application of PoE power to the communication line, and this is functionally clearly distinguished from a voltage intended for the supply of PoE power itself.

[0056] The above leakage current detection unit (1232) is configured to detect leakage current or corresponding electrical characteristic changes occurring in the communication line in response to the line inspection voltage applied to the communication line by the line inspection voltage generation circuit (1231).

[0057] Specifically, when the communication line is in a normal state and when it is in an abnormal state, the current response to the line inspection voltage, the impedance value, or the voltage change characteristics may appear differently. The leakage current detection unit (1232) detects the magnitude of the leakage current or changes in electrical characteristics according to the load state, insulation state, or abnormal state connected to the communication line by electrically detecting these differences.

[0058] Accordingly, the leakage current detection unit (1232) generates a basic signal to determine whether the communication line is in a normal state or an abnormal state, and this signal is transmitted to the resistance voltage divider circuit (1233) described later.

[0059] Meanwhile, this line condition detection is performed independently of the PD (Powered Device) detection procedure or power negotiation (handshaking) process defined in the PoE standard. That is, the line inspection circuit (123) prior to power application of the present invention operates independently of the power application procedure according to the PoE standard, purely for the purpose of determining in advance the safety and abnormality of the communication line.

[0060] The above resistance voltage divider circuit (1233) is configured to convert the electrical signal output from the leakage current detection unit (1232) into a voltage divider form so that it can be compared in the analog comparator circuit (124) described later.

[0061] In one embodiment, the resistor voltage divider circuit (1233) includes a plurality of resistor elements and can convert a signal corresponding to the voltage or current output from the leakage current detection unit (1232) into a voltage divider voltage within a preset voltage range. Accordingly, the voltage divider voltage is generated as an analog voltage signal that reflects the state (normal or abnormal) of the communication line.

[0062] The voltage divided by the above resistance voltage divider circuit (1233) is transmitted to the analog comparator circuit (124) described in FIGS. 2 and 4, and is used to determine whether the communication line is normal by comparing it with an internal reference voltage.

[0063] FIG. 4 is a detailed block diagram of a power cutoff driving circuit (125) provided in a PoE switch hub (120) in a security CCTV camera system (100) according to one embodiment of the present invention.

[0064] Referring to FIG. 4, the power cutoff driving circuit (125) may include a comparator (OP AMP) (1251), a gate driving circuit (1252), and a PoE power serial cutoff MOSFET (1253).

[0065] The power cutoff driving circuit (125) is configured to circuitously perform the operation of allowing or blocking the application of PoE power based on the voltage divider output from the line inspection circuit (123) prior to power application in FIG. 3. That is, the power cutoff driving circuit (125) performs the role of directly controlling the PoE power path according to an analog signal reflecting the state of the communication line.

[0066] The above comparator (OP AMP) (1251) is configured to compare the voltage divided by the output from the resistor voltage divider circuit (1233) described in FIG. 3 with an internal reference voltage.

[0067] The above reference voltage can be set as a threshold to distinguish between cases where the communication line is in a normal state and an abnormal state.

[0068] In one embodiment, the comparator (1251) may be implemented as an analog comparison circuit using an operational amplifier (op amp) and configured to generate different output voltage levels depending on whether the voltage divider is greater than or less than the reference voltage. For example, it may be configured to output a first output level when the voltage divider is greater than or greater than the reference voltage, and a second output level when it is less than the reference voltage.

[0069] In the present invention, the output of the comparator (OP AMP) (1251) is used as an analog control signal to control the gate driving circuit (1252) directly without going through microcontroller, firmware, or software processing. Accordingly, the determination of whether power is applied can be made in real time without digital computation delay, and rapid and stable cutoff operation is possible in the stage prior to power application.

[0070] The gate driving circuit (1252) is configured to drive the gate of a PoE power serial blocking MOSFET (1253) placed on the PoE power path according to the output of the comparator (OP AMP) (1251).

[0071] In one embodiment, the gate driving circuit (1252) may include a circuit that converts or amplifies the output voltage of the comparator (1251) to a voltage level suitable for applying to the gate of the PoE power serial cutoff MOSFET (1253). Accordingly, the output signal of the comparator (1251) can reliably control the turn-on or turn-off of the PoE power serial cutoff MOSFET (1253).

[0072] The gate driving circuit (1252) is configured to selectively switch the PoE power serial cutoff MOSFET (1253) to a conducting state or a cutoff state according to the output voltage level of the comparator (1251), thereby circuitously determining whether the PoE power is applied or cut off.

[0073] The above PoE power serial blocking MOSFET (1253) is connected in series on the PoE power path that is transmitted from the PoE power input section (122) to the CCTV camera (130).

[0074] That is, the above PoE power serial cutoff MOSFET (1253) functions as a switching element that physically controls whether PoE power is actually applied to the CCTV camera (130).

[0075] The above PoE power serial cutoff MOSFET (1253) switches between a conducting state and a cutoff state according to the control of the gate driving circuit (1252). When the communication line is determined to be in a normal state, the gate of the PoE power serial cutoff MOSFET (1253) is driven by the output of the comparator (1251) to switch to a conducting state, and accordingly, PoE power is supplied to the CCTV camera (130). On the other hand, when the communication line is determined to be in an abnormal state, the PoE power serial cutoff MOSFET (1253) remains in a cutoff state, preventing the supply of PoE power.

[0076] Accordingly, the power cutoff driving circuit (125) according to the present invention can effectively prevent problems such as overcurrent, heat generation, or damage to the connection device by fundamentally blocking the application of PoE power in an abnormal state of the communication line.

[0077] FIG. 5 illustrates the operation sequence diagram of a PoE switch hub (120) in a security CCTV camera system (100) according to one embodiment of the present invention.

[0078] The operation sequence illustrated in FIG. 5 represents the overall flow of line inspection and power control operations performed in the stage prior to the PoE power being applied to the CCTV camera (130).

[0079] Hereinafter, the operation of the PoE switch hub (120) according to the present invention will be described step by step with reference to FIG. 5. However, each step described below does not refer to a procedure executed sequentially by a microcontroller, firmware, or software control logic, but rather to an operation sequence that proceeds automatically according to the process of generating, transmitting, comparing, and driving electrical signals by the circuit configuration described in FIG. 2 to FIG. 4.

[0080] S1: Line inspection step prior to power application

[0081] In step S1, before PoE power is applied to the CCTV camera (130), the electrical state of the communication line is checked by the power application pre-line inspection circuit (123) described in FIG. 3.

[0082] Specifically, the line inspection voltage generation circuit (1231) applies a line inspection voltage to the communication line. The line inspection voltage applied at this time is a test voltage distinct from the actual PoE power, and is configured to be output only at the stage before the PoE power is applied. Accordingly, the basic electrical state of the line can be checked without overvoltage or overcurrent being applied to the communication line.

[0083] S2: Leakage current detection step

[0084] In step S2, a leakage current or a corresponding change in electrical characteristics occurring in the communication line in response to the line inspection voltage is detected by the leakage current detection unit (1232).

[0085] Since the current response to the line inspection voltage or impedance characteristics differ depending on whether the communication line is in a normal state or an abnormal state, the leakage current detection unit (1232) detects this difference in the form of an electrical signal. The signal generated at this stage functions as a basic judgment signal that reflects the normal or abnormal state of the communication line.

[0086] S3: Comparator output verification and determination step

[0087] In step S3, the electrical signal generated in the leakage current detection step is converted into a voltage divider by a resistor voltage divider circuit (1233) and then compared with an internal reference voltage by a comparator (OP AMP) (1251) described in FIG. 4.

[0088] The above comparator (1251) generates different output levels depending on whether the divided voltage is above or below the reference voltage. This output level is used as an analog control signal that directly indicates whether the communication line is in a normal state or an abnormal state.

[0089] In the present invention, this comparison result is not converted into a digital signal or interpreted by software, but is directly transmitted to the next stage power control circuit.

[0090] S4: Power Allow / Deactivate Control Step

[0091] In step S4, the gate driving circuit (1252) operates according to the output of the comparator (OP AMP) (1251) to control the conduction or cutoff state of the PoE power serial cutoff MOSFET (1253) connected in series on the PoE power path.

[0092] That is, when the output of the comparator (1251) indicates a normal state of the communication line, the gate driving circuit (1252) drives the gate of the MOSFET (1253) to switch to a conducting state. Conversely, when the output of the comparator (1251) indicates an abnormal state of the communication line, the PoE power serial cutoff MOSFET (1253) is controlled to remain in a cutoff state.

[0093] Accordingly, whether power is allowed or cut off is automatically determined based on the flow of electrical signals.

[0094] S5: (If allowed) PoE Power application stage

[0095] In step S5, PoE power is supplied to the CCTV camera (130) through the PoE power switching unit (126) only when the supply of PoE power is permitted in the power allow / cut off control step.

[0096] On the other hand, if the communication line is determined to be in an abnormal state and the application of PoE power is not permitted, the PoE power serial cutoff MOSFET (1253) remains in a cutoff state, and the state in which PoE power is not applied continues.

[0097] Accordingly, according to the present invention, a PoE switch hub is provided that includes a power supply pre-line inspection circuit configured to inspect the condition of a communication line before PoE power is supplied to a security CCTV camera (130), and a power cutoff driving circuit configured to allow or cut off the supply of PoE power according to the inspection result.

[0098] In addition, the present invention is configured to automatically perform the steps of checking the state of a communication line and controlling the application of PoE power by a circuit configuration including an analog comparator and a switching element for power cutoff, thereby enabling stable power control without separate software control, server intervention, or user operation.

[0099] In addition, by physically controlling whether PoE power is applied through a switching element for power cutoff arranged in series in the PoE power path, damage, malfunction, or system instability of the security CCTV camera that may occur due to abnormal conditions in the communication line can be effectively prevented.

[0100] Meanwhile, the present invention may further be spherical in various embodiments as follows.

[0101] In one embodiment, the PoE switch hub (120) according to the present invention may further include a configuration that allows the user to recognize a state in which PoE power is not applied due to an abnormality in the communication line.

[0102] Specifically, the output of the comparator (OP AMP) (1251) described in FIG. 4 can be used as an electrical status signal indicating whether the communication line is normal, and the status signal can be used as status information indicating that the PoE power is cut off due to a communication line abnormality while simultaneously performing power cut-off control.

[0103] In one embodiment, the status signal may be transmitted to a CCTV camera management server (110) through an internal interface of a PoE switch hub (120). For example, the status signal may be transmitted via a network message, a status packet, or a management protocol, and the CCTV camera management server (110) may receive it and provide it to a user through a display unit.

[0104] Accordingly, when PoE power is not applied to a specific CCTV camera (130), the user can clearly recognize that the PoE power has been cut off due to leakage current in the communication line or an electrical abnormality, rather than simply being in a non-operational state of the device.

[0105] In another embodiment, the PoE switch hub (120) according to the present invention may further include a display unit that indicates the operating status corresponding to each PoE port.

[0106] In one embodiment, the display unit may include a visual display element such as an LED, and the display element may display different display states depending on the output of the comparator (OP AMP) (1251) or the operating state of the power cutoff driving circuit (125). For example, a first display state may be displayed when the communication line is determined to be in a normal state and PoE power is applied, and a second display state may be displayed when the communication line is determined to be in an abnormal state and PoE power is cut off.

[0107] Accordingly, even without accessing the management server, maintenance personnel can intuitively check the PoE power cutoff status due to a communication line abnormality through the appearance of the PoE switch hub (120).

[0108] In another embodiment, the PoE switch hub (120) or CCTV camera management server (110) according to the present invention may be configured to store a history of PoE power being cut off due to an abnormality in the communication line.

[0109] In one embodiment, the history information may include the port where the PoE power was cut off, the time at which the cut-off occurred, and the cause of the cut-off, and the cause of the cut-off may correspond to a leakage current or abnormal impedance condition detected in the line inspection step prior to power application.

[0110] Accordingly, users can analyze recurring line abnormalities or perform maintenance measures such as cable replacement and connector inspection more efficiently.

[0111] In another embodiment, the line inspection and power cutoff control operations prior to power application according to the present invention may be performed independently of the Powered Device (PD) detection or power negotiation procedures defined in PoE standards.

[0112] In other words, if the PoE power is cut off due to a malfunction in the communication line, the power negotiation step according to the PoE standard can be controlled so that it is not performed, and conversely, the PoE standard procedure can be initiated only when the communication line is determined to be in a normal state.

[0113] Accordingly, the safety of the communication line can be ensured in the stage prior to performing the PoE standard procedure, and unnecessary retries, malfunctions, or device damage that may occur during the PoE power application process can be effectively prevented.

[0114] According to the additional embodiments described above, the present invention can significantly improve the reliability of system operation and maintenance efficiency by not only detecting abnormalities in communication lines in advance and cutting off PoE power, but also clearly communicating the cut-off status to the user.

[0115] In particular, as the user clearly recognizes the PoE power cutoff status caused by communication line abnormalities, it is possible to prevent the problem of mistaking CCTV camera malfunctions for device failures and to reduce the time required for fault cause analysis and on-site response.

[0116] The above description is merely one embodiment for implementing a protection circuit for determining the line status prior to power application of a security CCTV camera according to the present invention, and the present invention is not limited to the above-described embodiment. The technical spirit of the present invention extends to the scope in which various modifications can be made by anyone with ordinary knowledge in the field to which the invention belongs, without departing from the gist of the invention as claimed in the following patent claims. Explanation of the symbols

[0117] 100; Security CCTV camera system 110; CCTV Camera Management Server 120; PoE switch hub 121; Ethernet PHY 122; PoE power input 123; Line inspection circuit prior to power application 1231; Line inspection voltage generation circuit 1232; Leakage current detection unit 1233; Resistor voltage divider circuit 124; Analog comparator circuit 125; Power cutoff driving circuit 1251; Comparator 1252; Gate driving circuit 1253; PoE power series cutoff MOSFET 126; PoE power switching unit 130; CCTV camera

Claims

Claim 1 A PoE switch hub that supplies power to a security CCTV camera via PoE (Power over Ethernet) comprises: a PoE power input unit that receives PoE power input from an external power source; a pre-power application line inspection circuit configured to apply a line inspection voltage to inspect the line condition prior to power application to a communication line before the PoE power is applied to the CCTV camera; a resistive voltage divider circuit that converts an electrical signal corresponding to a leakage current detected from the communication line by the pre-power application line inspection circuit into a voltage divider; an analog comparator circuit configured to compare the voltage divider output from the resistive voltage divider circuit with an internal reference voltage; a power cutoff driving circuit configured to drive a PoE power serial cutoff MOSFET connected in series on the power path to which the PoE power is applied to the CCTV camera according to the output of the analog comparator circuit to allow or cut off the application of the PoE power; and a PoE power switching unit configured to be controlled by the power cutoff driving circuit so that the PoE power is selectively applied to the CCTV camera.The power-previous line inspection circuit is configured to apply a line inspection voltage lower than the actual PoE voltage to the communication line at a stage prior to the PoE power being applied to the CCTV camera, and is configured to detect whether there is a short, open, abnormal resistance state, leakage current, or connection error in the communication line based on the line inspection voltage, and the output of the analog comparator circuit is provided directly to the power cut-off driving circuit without passing through a microcontroller or software judgment stage to control the PoE power serial cut-off MOSFET, and the PoE switch hub further includes an Ethernet PHY that processes data signals, and the Ethernet PHY is a protection circuit for determining the line status prior to power application of a security CCTV camera that is circuitically separated from the power-previous line inspection circuit, the analog comparator circuit, and the power cut-off driving circuit. Claim 2 delete

Images