CN106303342B - Power supply circuit based on coaxial power supply technology - Google Patents
Power supply circuit based on coaxial power supply technology Download PDFInfo
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- CN106303342B CN106303342B CN201510248753.9A CN201510248753A CN106303342B CN 106303342 B CN106303342 B CN 106303342B CN 201510248753 A CN201510248753 A CN 201510248753A CN 106303342 B CN106303342 B CN 106303342B
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Abstract
A power supply circuit based on a coaxial power supply technology comprises a processing circuit of a video processing end, wherein the processing circuit comprises a detection circuit and a control circuit; the detection circuit is used for detecting the electric parameter of the access port of the video processing end; and the control circuit is used for controlling the on-off of the power supply output of the image acquisition terminal by the access port according to the electric parameter. The electric parameter is a voltage value and/or a current value, and the access port is a port accessed to the image acquisition terminal. Therefore, the power supply circuit based on the coaxial power supply technology can identify whether the image acquisition terminal externally connected with the video processing end supports the coaxial power supply or not by detecting and analyzing the electric parameters of the access port of the video processing end, and further judge whether the image acquisition terminal needs to be powered or not according to the analysis result, so that the safety is high.
Description
Technical Field
The invention relates to the technical field of security image acquisition, in particular to a power supply circuit based on a coaxial power supply technology.
Background
The Power Over Coax (POC) is a transmission technology for video, coaxial control, and Power overlay based on a coaxial cable. In the transmission process of the coaxial cable, the analog video signal, the coaxial signal and the power supply are transmitted, namely, the analog video signal, the coaxial signal and the like are combined with the power supply and transmitted on a coaxial line. By applying the POC technology to project wiring, considerable cost can be saved, construction time can be shortened, and the POC technology is widely applied at present. For a device supporting POC power supply, such as a POC camera (analog camera supporting coaxial power supply), after being connected to a coaxial power supply circuit through a coaxial line, a dc power supply is superimposed on the coaxial line, and the voltage ratio of the dc power supply is high, and generally can reach 10V or more. This voltage connection to POC cameras is satisfactory for power supply, but if a customer mistakenly connects a normal analog camera (not supporting POC) to this voltage, a problem arises that the normal camera is burned out.
Disclosure of Invention
The invention aims to provide a power supply circuit based on a coaxial power supply technology, which can distinguish whether an image acquisition terminal externally connected with a video processing end supports coaxial power supply or not by detecting an electric parameter of an access port of the video processing end, and further judge whether the image acquisition terminal needs to be powered or not, so that the safety is high.
According to the invention, the power supply circuit based on the coaxial power supply technology comprises a processing circuit of a video processing end, wherein the processing circuit comprises a detection circuit and a control circuit, and the detection circuit is electrically connected with the control circuit;
the detection circuit is used for detecting an electric parameter of an access port of the video processing end, wherein the electric parameter is a voltage value and/or a current value, and the access port is a port accessed to an image acquisition terminal;
and the control circuit is used for controlling the on-off of the power supply output of the image acquisition terminal by the access port according to the electric parameter.
Wherein the control circuit comprises a conduction unit and a cut-off unit;
the conduction unit is used for conducting the access port to output power to the image acquisition terminal if the electric parameter belongs to a preset first electric parameter range;
and the cutting-off unit is used for cutting off the power supply output of the access port to the image acquisition terminal if the electric parameter belongs to a preset second electric parameter range.
Wherein the control circuit comprises a conduction unit and a cut-off unit;
the conduction unit is used for conducting the power supply output of the image acquisition terminal from the access port when the power supply output of the image acquisition terminal from the access port is cut off and the variation value of the electric parameter exceeds the range of a preset stable electric parameter;
and the cutting-off unit is used for cutting off the power supply output of the access port to the image acquisition terminal when the power supply output of the access port to the image acquisition terminal is conducted and the variation value of the electric parameter exceeds the range of a preset stable electric parameter.
The processing circuit further comprises a power circuit, a video processing circuit, a first isolation unit, a superposition circuit, a switch and a voltage division unit.
The video processing circuit comprises a detection circuit, a voltage division unit, a control circuit, a switch, a power supply circuit, a power supply end and a video processing circuit, wherein the signal input end of the detection circuit is respectively connected with one end of the voltage division unit, a first access port of an external coaxial cable, a first immovable end of the switch and one end of a first isolation unit, the signal output end of the detection circuit is connected with the signal input end of the control circuit, the signal output end of the control circuit is connected with the movable end of the switch, a second immovable end of the switch is connected with one end of the superposition circuit, the other end of the superposition circuit is connected with the power supply circuit, the other end of the voltage division unit is connected with the input power end for detection, and the other end of the first isolation unit is connected with the video processing circuit.
The first isolation unit is a capacitor C1.
Wherein, the voltage division unit is a resistor R1.
And a second access port of the external coaxial cable is connected with the image acquisition terminal circuit.
The image acquisition terminal circuit comprises a coaxial power supply circuit, a video signal processing circuit, a power receiving circuit, a matching unit and a second isolation unit.
The video signal processing circuit comprises a power receiving circuit, a coaxial power supply circuit and a matching unit, wherein one end of the coaxial power supply circuit is connected with a second access port of an external coaxial cable and one end of the matching unit respectively, the other end of the matching unit is connected with one end of a second isolation unit, the other end of the second isolation unit is connected with the video signal processing circuit, and the other end of the coaxial power supply circuit is connected with the power receiving circuit.
Wherein the matching unit is a resistor R2.
Wherein, the resistance value of the resistor R2 is 75 ohms.
Wherein the second isolation unit is a capacitor C2.
The image acquisition terminal circuit comprises a matching unit and a video signal processing circuit.
One end of the matching unit is connected with the second access port of the external coaxial cable, and the other end of the matching unit is connected with the video signal processing circuit.
The processing circuit further comprises a plugging detection circuit, a signal input end of the plugging detection circuit is connected with the other end of the first isolation unit, and a signal output end of the plugging detection circuit is connected with the control circuit;
the plug-pull detection circuit is used for detecting a level signal of an access port of the video processing end; and when the level signal is switched from the alternating current level signal to the direct current level signal or from the direct current level signal to the alternating current level signal, cutting off the power supply output of the access port to the image acquisition terminal.
The invention provides a power supply circuit based on a coaxial power supply technology, which comprises a processing circuit of a video processing end, wherein the processing circuit comprises a detection circuit and a control circuit; the detection circuit is used for detecting the electric parameter of the access port of the video processing end; and the control circuit is used for controlling the on-off of the power supply output of the image acquisition terminal by the access port according to the electric parameter. The electric parameter is a voltage value and/or a current value, and the access port is a port accessed to the image acquisition terminal. Therefore, the power supply circuit based on the coaxial power supply technology can identify whether the image acquisition terminal externally connected with the video processing end supports the coaxial power supply or not by detecting and analyzing the electric parameters of the access port of the video processing end, and further judge whether the image acquisition terminal needs to be powered or not according to the analysis result, so that the safety is high.
Drawings
Fig. 1 is a block diagram showing a configuration of a power supply circuit based on a coaxial power supply technique according to a first embodiment of the present invention;
fig. 2 is a block diagram showing a configuration of a power supply circuit based on a coaxial power supply technique according to a second embodiment of the present invention;
fig. 3 is a block diagram showing a configuration of a power supply circuit based on a coaxial power supply technique according to a third embodiment of the present invention;
fig. 4 is a block diagram showing a configuration of a power supply circuit based on a coaxial power supply technique according to a fourth embodiment of the present invention;
fig. 5 is a block diagram showing a configuration of a power supply circuit based on a coaxial power supply technique according to a fifth embodiment of the present invention;
fig. 6 is a block diagram showing a configuration of a power supply circuit based on a coaxial power supply technique according to a sixth embodiment of the present invention;
fig. 7 is a block diagram showing a configuration of a power supply circuit based on a coaxial power supply technique according to a seventh embodiment of the present invention;
fig. 8 is a block diagram illustrating a power supply circuit based on a coaxial power supply technology according to an eighth embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the accompanying drawings in combination with the embodiments. It is to be understood that these descriptions are only illustrative and are not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
It should be noted that: hereinafter, the coaxial Power supply (POC, power Over coax) is a technology of video, coaxial control, and Power superposition based on the coaxial line. An Analog camera (Analog camera) is a camera that outputs an Analog signal as an output signal. An ADC (Analog-to-Digital converter) is an Analog-to-Digital converter or an Analog-to-Digital converter. POC cameras are analog cameras that support coaxial power. non-POC cameras are common analog cameras that do not support coaxial power. Impedance (Impedance) is an electrical Impedance, which is a complex number in ohms with a resistance value as a real part and a reactance value as an imaginary part.
Fig. 1 is a block diagram showing a configuration of a power supply circuit based on a coaxial power supply technology according to a first embodiment of the present invention.
The power supply circuit based on the coaxial power supply technology comprises a processing circuit of a video processing end, wherein the processing circuit comprises a detection circuit and a control circuit, and the detection circuit is electrically connected with the control circuit;
the detection circuit is used for detecting an electric parameter of an access port of the video processing end, wherein the electric parameter is a voltage value and/or a current value, and the access port is a port accessed to an image acquisition terminal;
and the control circuit is used for controlling the on-off of the power supply output of the image acquisition terminal by the access port according to the electric parameter.
The electric parameter refers to electric parameter data of the electric equipment. When detecting the voltage value, can select for use voltage sensor, when detecting the current value, can select for use current sensor, or directly select for use voltage current sensor, both can detect the current value and also can detect the voltage value.
The current sensor is a detection device which can sense the information of the current to be detected and convert the sensed information into an electric signal meeting certain standards or other information in required forms according to a certain rule for output so as to meet the requirements of information transmission, processing, storage, display, record, control and the like. The current sensors are mainly classified into a shunt, an electromagnetic current transformer and an electronic current transformer according to different measurement principles.
The voltage sensor is a detection device which can sense the information of the detected voltage and convert the sensed information into an electric signal meeting certain standards or other required information output according to a certain rule so as to meet the requirements of information transmission, processing, storage, display, recording, control and the like. The voltage sensor is mainly divided into a direct current voltage sensor and an alternating current voltage sensor, and the alternating current voltage sensor is an instrument capable of converting a measured alternating current (alternating current voltage) into a direct current voltage or a direct current according to a linear proportion and outputting the direct current voltage or the direct current. A dc voltage sensor is an instrument that can convert a measured dc voltage into a linear proportional output dc voltage or dc current.
The access port is an interface for accessing a coaxial line. The coaxial line is used for connecting the video processing end and the image acquisition terminal which are coaxially powered, and the interface of the coaxial line is preferably a BNC interface.
According to the power supply circuit based on the coaxial power supply technology, whether the image acquisition terminal externally connected with the video processing end supports coaxial power supply can be identified by detecting and analyzing the electric parameters of the access port of the video processing end, whether the image acquisition terminal needs to be powered is further judged according to the analysis result, and the safety is high.
Fig. 2 is a block diagram showing a configuration of a power supply circuit based on a coaxial power supply technique according to a second embodiment of the present invention. In the power supply circuit based on the coaxial power supply technology according to the second embodiment of the present invention, a conducting unit for conducting the power supply output from the access port to the image capturing terminal and a cutting unit for cutting off the power supply output from the access port to the image capturing terminal are added.
Preferably, the second embodiment of the present invention is based on the first embodiment of the present invention, wherein the control circuit comprises a conducting unit and a cutting unit;
the conduction unit is used for conducting the access port to output power to the image acquisition terminal if the electric parameter belongs to a preset first electric parameter range;
and the cutting-off unit is used for cutting off the power supply output of the access port to the image acquisition terminal if the electric parameter belongs to a preset second electric parameter range.
Preferably, the external image acquisition terminal is an analog camera, and the analog camera can be classified into a POC camera and a non-POC camera according to whether the analog camera can support POC power supply. The preset first electrical parameter range corresponds to a preset electrical parameter range of the POC camera, and the preset second electrical parameter range corresponds to a preset electrical parameter range of a non-POC camera.
The above mode is to analyze the absolute value of the electrical parameter, and by analyzing the absolute value of the electrical parameter, the external image acquisition terminal can be helped to identify whether the image acquisition terminal supports POC power supply. After the electric parameters are detected, the access port can finish the identification of an external image acquisition terminal and determine whether external power supply is needed or not through analysis.
Preferably, the second embodiment of the present invention is based on the first embodiment of the present invention, wherein the control circuit comprises a conducting unit and a cutting unit;
the conduction unit is used for conducting the power supply output of the image acquisition terminal from the access port when the power supply output of the image acquisition terminal from the access port is cut off and the variation value of the electric parameter exceeds the range of a preset stable electric parameter;
and the cutting-off unit is used for cutting off the power supply output of the image acquisition terminal by the access port when the power supply output of the image acquisition terminal by the access port is conducted and the variation value of the electric parameter exceeds the preset stable electric parameter range.
The above manner is to analyze the relative difference value of the electrical parameter, and by analyzing the relative difference value of the electrical parameter, it can help to identify whether the external image acquisition terminal supports the POC power supply. The preset stable electric parameter range can be set according to actually measured data, and the actually measured data can be different according to different models of external image acquisition terminals.
The power supply circuit based on the coaxial power supply technology according to the second embodiment of the present invention can complete the discrimination of the analog camera types by detecting the difference between the corresponding electrical parameters of the POC camera and the non-POC camera, and further automatically determine whether external power supply is required.
Fig. 3 is a block diagram illustrating a power supply circuit based on a coaxial power supply technology according to a third embodiment of the present invention. A power supply circuit according to a third embodiment of the present invention based on the coaxial power supply technology has explained a specific circuit configuration of the processing circuit.
Third embodiment of the present invention, on the basis of the first embodiment of the present invention, the processing circuit further includes a power circuit, a video processing circuit, a first isolation unit, a superimposing circuit, a switch, and a voltage dividing unit.
The detection circuit comprises a detection circuit and a video processing circuit, wherein the signal input end of the detection circuit is respectively connected with one end of a voltage division unit, a first access port of an external coaxial cable, a first motionless end of a switch and one end of a first isolation unit, the signal output end of the detection circuit is connected with the signal input end of a control circuit, the signal output end of the control circuit is connected with the motionless end of the switch, the second motionless end of the switch is connected with one end of a superposition circuit, the other end of the superposition circuit is connected with a power circuit, the other end of the voltage division unit is connected with an input power end for detection, and the other end of the first isolation unit is connected with the video processing circuit.
The power supply circuit based on the coaxial power supply technology according to the third embodiment of the present invention is an automatic detection circuit, and can automatically identify an external analog camera and determine whether the external analog camera can be supplied with power.
Fig. 4 is a block diagram illustrating a power supply circuit based on a coaxial power supply technology according to a fourth embodiment of the present invention. In the feeding circuit based on the coaxial feeding technology according to the fourth embodiment of the present invention, a specific circuit configuration of the processing circuit is described.
In a fourth embodiment of the present invention, in addition to the third embodiment, the first isolation unit is a capacitor C1, and the voltage dividing unit is a resistor R1.
Preferably, the signal input end of the detection circuit is respectively connected to one end of a resistor R1, a first access port of an external coaxial cable, a first stationary end of a switch, and one end of a capacitor C1, the signal output end of the detection circuit is connected to the signal input end of the control circuit, the signal output end of the control circuit is connected to the stationary end of the switch, the second stationary end of the switch is connected to one end of a superposition circuit, the other end of the superposition circuit is connected to a power circuit, the other end of the resistor R1 is connected to an input power end for detection, and the other end of the capacitor C1 is connected to the video processing circuit.
The processing circuit can realize power supply and video processing, and the subdivision of the processing circuit according to functional modules can be as follows: the power supply circuit is used for supplying power to the POC; a superimposing circuit for separating the power supply from the video signal; the switch is used for realizing whether external power supply is needed or not judged by the control circuit; and the detection circuit is used for detecting the electric parameter of the access port and determining whether the external analog camera supports POC power supply or not through the size of the electric parameter. VCC, i.e., a detection input voltage value (corresponding to a detection input power terminal), which is used to detect whether or not POC-capable power supplies are supported, and is generally a low voltage; r1, a voltage dividing resistor for detection, for detecting the voltage dividing resistor used; and C1, isolating the direct current power supply and inputting the video signal to the video processing circuit.
Preferably, the voltage value = detection input voltage value ×/[ equivalent resistance value/(the equivalent resistance value + the detection voltage-dividing resistance value) of the video signal processing circuit of the image capturing terminal externally connected thereto.
The power supply circuit based on the coaxial power supply technology according to the fourth embodiment of the present invention is an automatic detection circuit, and can automatically identify an external analog camera and determine whether the external analog camera can be supplied with power. And the selected electronic components are simple, the compactness of the whole power supply circuit is improved, and the cost of the power supply circuit is reduced.
Fig. 5 is a block diagram showing a configuration of a power supply circuit based on a coaxial power supply technology according to a fifth embodiment of the present invention. A power supply circuit based on the coaxial power supply technology according to a fifth embodiment of the present invention has been described with respect to a specific circuit configuration of an external image capturing terminal circuit.
In a fifth embodiment of the present invention, in addition to the fourth embodiment of the present invention, the second inlet of the external coaxial cable is connected to an image capturing terminal circuit.
The external image acquisition terminal is the analog camera, distinguishes according to whether can support the POC power supply, and the analog camera can be divided into two kinds of POC camera and non-POC camera. The following is a specific structure of the image capturing terminal circuit corresponding to the POC camera.
The image acquisition terminal circuit comprises a coaxial power supply circuit, a video signal processing circuit, a power receiving circuit, a matching unit and a second isolation unit.
Preferably, one end of the coaxial power supply circuit is connected to the second access port of the external coaxial cable and one end of the matching unit respectively, the other end of the matching unit is connected to one end of the second isolation unit, the other end of the second isolation unit is connected to the video signal processing circuit, and the other end of the coaxial power supply circuit is connected to the power receiving circuit.
The power supply circuit based on the coaxial power supply technology according to the fifth embodiment of the present invention is an intelligent circuit that automatically detects and supplies power, and can automatically recognize an analog camera and determine whether power can be supplied to the analog camera, and turn on or off the power supply according to the determination result.
Fig. 6 is a block diagram illustrating a power supply circuit based on a coaxial power supply technology according to a sixth embodiment of the present invention. The power supply circuit based on the coaxial power supply technology according to the sixth embodiment of the present invention describes a specific circuit configuration of an external image capturing terminal circuit.
Sixth embodiment of the present invention, in the fifth embodiment of the present invention, the matching means is a resistor R2. The resistance value of the resistor R2 is 75 ohms. The second isolation unit is a capacitor C2.
Wherein, coaxial supply circuit's one end is connected respectively external coaxial cable's second is inserted mouthful and resistance R2's one end, electric capacity C2's one end is connected to resistance R2's the other end, electric capacity C2's the other end is connected video signal processing circuit, coaxial supply circuit's the other end is connected the circuit that receives electricity.
The POC camera can support an analog camera with coaxial power supply, and can be subdivided into: the power receiving circuit is used for obtaining current from the coaxial power supply circuit and supplying power to the POC camera; the coaxial power supply circuit is used for transmitting a power supply to the power receiving circuit and keeping high resistance on video signals, and the coaxial power supply circuit can be equivalent to a resistor (larger resistance) before power supply; r2 and C2 are matching resistance and blocking capacitance. R3 is the equivalent resistance of the video signal processing circuit, and is generally small.
When the coaxial power supply video processing circuit is powered on, the control circuit turns on the switch, the coaxial power supply video processing circuit does not supply power to the outside temporarily, and the capacitors C1 and C2 present high impedance to direct current level. Because the resistance on the coaxial line is small and is in an ohm level, the resistance can be ignored. Therefore, the voltage V1 input by the detection circuit is: v1= VCCxR 4/(R4 + R1).
The power supply circuit based on the coaxial power supply technology according to the sixth embodiment of the present invention is an intelligent circuit that automatically detects and supplies power, and can automatically recognize an analog camera and determine whether power can be supplied to the analog camera, and turn on or off the power supply according to the determination result. And the selected electronic components are simple, the compactness of the whole power supply circuit is improved, and the cost of the power supply circuit is reduced.
Fig. 7 is a block diagram illustrating a power supply circuit based on a coaxial power supply technology according to a seventh embodiment of the present invention. The power supply circuit based on the coaxial power supply technology according to the seventh embodiment of the present invention has been described with respect to a specific circuit configuration of an external image capturing terminal circuit.
In a seventh aspect of the present invention, in addition to the fourth aspect of the present invention, the second inlet of the external coaxial cable is connected to an image capturing terminal circuit.
The external image acquisition terminal is the analog camera, distinguishes according to whether can support the POC power supply, and the analog camera can be divided into two kinds of POC camera and non-POC camera. The following is a specific structure of the image capture terminal circuit corresponding to a non-POC camera.
The image acquisition terminal circuit comprises a matching unit and a video signal processing circuit.
One end of the matching unit is connected with the second access port of the external coaxial cable, and the other end of the matching unit is connected with the video signal processing circuit.
Preferably, the matching unit is a resistor R2.
The image acquisition terminal circuit comprises a resistor R2 and a video signal processing circuit, one end of the resistor R2 is connected to the second access port of the external coaxial cable, and the other end of the resistor R2 is connected to the video signal processing circuit.
The non-POC camera differs from the POC camera in the coaxial power supply circuit and the second isolation capacitor.
When the processing circuit is powered on, the control circuit opens the switch, the processing circuit temporarily does not supply power to the outside, and the capacitor C1 presents high impedance to the direct current level. Since the resistance on the coaxial line (matching 75 ohms) is small, in ohms, negligible. Therefore, the voltage V2 input by the detection circuit is: v2= VCCxR 3/(R3 + R1).
Comparing the sixth embodiment of the present invention with the seventh embodiment of the present invention, the difference between the resistance values of R3 and R4 is large, so the voltage values of V1 and V2 are also large.
According to the power supply circuit based on the coaxial power supply technology, the detection circuit in the power supply circuit can use an ADC (analog to digital converter) conversion circuit or directly use a voltage comparator, a current comparator and other schemes according to the larger voltage difference to distinguish the POC camera from the non-POC camera, and output the result to the control circuit, and the control circuit determines whether the switch needs to be opened or not to supply power to the outside after receiving the signal.
Fig. 8 is a block diagram illustrating a power supply circuit based on a coaxial power supply technology according to an eighth embodiment of the present invention. The power supply circuit based on the coaxial power supply technology according to the eighth embodiment of the present invention is additionally provided with a plug detection circuit for detecting a level signal during hot plug.
Hot-plugging (Hot-plugging, hot Swap), which is Hot plugging, is supported by a Hot-plugging function to allow a user to take out and replace electronic components without shutting down the system or cutting off the power supply, thereby improving the timely recovery capability, expansibility and flexibility of the system to disasters.
Preferably, in an eighth embodiment of the present invention, on the basis of the first embodiment of the present invention, the processing circuit further includes a plugging detection circuit, a signal input end of the plugging detection circuit is connected to the other end of the first isolation unit, and a signal output end of the plugging detection circuit is connected to the control circuit;
the plug-pull detection circuit is used for detecting a level signal of an access port of the video processing end; and when the level signal is switched from the alternating current level signal to the direct current level signal or from the direct current level signal to the alternating current level signal, cutting off the power supply output of the access port to the image acquisition terminal.
The level signal is a voltage range that specifies an output high level >2.4V and an output low level <0.4V. At room temperature, the output high level is typically 3.5V and the output low level is 0.2V. Digital circuits typically have only a high level and a low level. The single chip microcomputer can directly detect level signals.
Sometimes, the user may replace the analog camera externally connected to the coaxial power supply video processing end without power failure, that is, perform hot plug of the analog camera. Under the condition that the power supply output of the externally-connected analog camera is conducted by the access port, if the POC camera is replaced by a non-POC camera, the non-POC camera is burnt; under the condition that the power supply output of the externally-connected analog camera is cut off by the access port, if a non-POC camera is replaced by a POC camera, the POC camera does not supply power and has no video images. Therefore, when the external analog camera is replaced under the condition of no power failure, the analog camera needs to be identified again so as to judge whether the power output of the external analog camera from the access port can be conducted or not. In order to realize this function, it is necessary to monitor a level signal change generated when the analog camera performs a hot-plug operation. The identification function of the analog camera under the condition of hot plugging can be realized by detecting the level signal of the access port of the coaxial power supply video processing end.
For dc levels, C1 is a high impedance, but for ac video signals, C1 is a low impedance. The voltage V3 signal is input into the plugging detection circuit, so that the damage of a superposed higher-voltage direct-current power supply to the plugging detection circuit can be avoided. When the hot plug is not performed at the access port, such as the BNC port, the plug detection circuit can detect a stable video signal, i.e., an ac signal. When hot plug takes place at BNC interface, in this period of time of pulling out analog camera, the outside does not have analog camera to connect, and plug detection circuitry's input is a direct current level signal, just can discern the external analog camera of coaxial power supply video processing circuit through this difference and carry out the level signal that the hot plug produced, and then accomplish the hot plug and detect. When the control circuit detects that hot plug occurs, the power output of the access port to the external analog camera is cut off, power supply is stopped, the detection circuit starts to work, and the type of the analog camera is detected again.
The power supply circuit based on the coaxial power supply technology according to the eighth embodiment of the present invention can automatically recognize an external analog camera and determine whether the external analog camera can be supplied with power. When the analog camera is hot-plugged, the power supply scheme can be changed in real time, and the reliability and stability of the whole power supply circuit are improved on the premise of ensuring the access of the analog camera.
In the above circuits, according to common general knowledge, in the technical background of the present technical solution, a person skilled in the art may select different circuit connection modes and components with different parameters to implement the corresponding functions of each circuit, which is not described herein again by way of example.
The invention aims to protect a power supply circuit based on a coaxial power supply technology, which can distinguish whether an image acquisition terminal externally connected with a video processing end supports coaxial power supply or not by detecting the electric parameter of an access port of the video processing end, and further judge whether the image acquisition terminal needs to be powered or not, so that the safety is high.
It should be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modifications, equivalents, improvements and the like which are made without departing from the spirit and scope of the present invention shall be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundary of the appended claims, or the equivalents of such scope and boundary.
Claims (16)
1. A power supply circuit based on a coaxial power supply technology comprises a processing circuit of a video processing end, and is characterized in that the processing circuit comprises a detection circuit and a control circuit, and the detection circuit is electrically connected with the control circuit;
the detection circuit is used for detecting an electric parameter of an access port of the video processing end, wherein the electric parameter is a voltage value and/or a current value, and the access port is a port accessed to the image acquisition terminal;
and the control circuit is used for distinguishing whether an image acquisition terminal externally connected with the video processing end supports coaxial power supply according to the electric parameters and controlling the on-off of the power supply output of the image acquisition terminal by the access port.
2. The power supply circuit based on the coaxial power supply technology according to claim 1, wherein the control circuit includes a turn-on unit and a turn-off unit;
the conduction unit is used for conducting the access port to output power to the image acquisition terminal if the electric parameter belongs to a preset first electric parameter range;
and the cutting-off unit is used for cutting off the power supply output of the access port to the image acquisition terminal if the electric parameter belongs to a preset second electric parameter range.
3. The power supply circuit based on the coaxial power supply technology according to claim 1, wherein the control circuit includes a turn-on unit and a turn-off unit;
the conduction unit is used for conducting the power supply output of the image acquisition terminal from the access port when the power supply output of the image acquisition terminal from the access port is cut off and the variation value of the electric parameter exceeds the range of a preset stable electric parameter;
and the cutting-off unit is used for cutting off the power supply output of the image acquisition terminal by the access port when the power supply output of the image acquisition terminal by the access port is conducted and the variation value of the electric parameter exceeds the preset stable electric parameter range.
4. The power supply circuit based on the coaxial power supply technology as claimed in claim 1, wherein the processing circuit further comprises a power supply circuit, a video processing circuit, a first isolation unit, a superposition circuit, a switch and a voltage division unit.
5. The power supply circuit based on the coaxial power supply technology according to claim 4, wherein a signal input end of the detection circuit is connected to one end of a voltage division unit, a first access port of an external coaxial cable, a first stationary end of a switch, and one end of a first isolation unit, respectively, a signal output end of the detection circuit is connected to a signal input end of the control circuit, a signal output end of the control circuit is connected to a moving end of the switch, a second stationary end of the switch is connected to one end of a superposition circuit, the other end of the superposition circuit is connected to a power supply circuit, the other end of the voltage division unit is connected to an input power end for detection, and the other end of the first isolation unit is connected to the video processing circuit.
6. The power supply circuit based on the coaxial power supply technology as claimed in claim 4 or 5, wherein the first isolation unit is a capacitor C1.
7. The power supply circuit based on the coaxial power supply technology according to claim 4 or 5, wherein the voltage dividing unit is a resistor R1.
8. The power supply circuit based on the coaxial power supply technology as claimed in claim 5, wherein the second access port of the external coaxial cable is connected to the image acquisition terminal circuit.
9. The power supply circuit based on the coaxial power supply technology of claim 8, wherein the image capturing terminal circuit comprises a coaxial power supply circuit, a video signal processing circuit, a power receiving circuit, a matching unit and a second isolation unit.
10. The power supply circuit based on the coaxial power supply technology according to claim 9, wherein one end of the coaxial power supply circuit is connected to a second inlet of the external coaxial cable and one end of a matching unit, respectively, the other end of the matching unit is connected to one end of a second isolation unit, the other end of the second isolation unit is connected to the video signal processing circuit, and the other end of the coaxial power supply circuit is connected to the power receiving circuit.
11. The power supply circuit based on the coaxial power supply technology as claimed in claim 9 or 10, wherein the matching unit is a resistor R2.
12. The power supply circuit based on coaxial power supply technology of claim 11, wherein the resistance value of the resistor R2 is 75 ohms.
13. The power supply circuit based on the coaxial power supply technology as claimed in claim 9 or 10, wherein the second isolation unit is a capacitor C2.
14. The power supply circuit based on the coaxial power supply technology as claimed in claim 8, wherein the image capturing terminal circuit comprises a matching unit and a video signal processing circuit.
15. The power supply circuit based on coaxial power supply technology of claim 14, wherein one end of the matching unit is connected to the second access port of the external coaxial cable, and the other end of the matching unit is connected to the video signal processing circuit.
16. The power supply circuit based on the coaxial power supply technology according to claim 4 or 5, wherein the processing circuit further comprises a plugging detection circuit, a signal input end of the plugging detection circuit is connected to the other end of the first isolation unit, and a signal output end of the plugging detection circuit is connected to the control circuit;
the plug-pull detection circuit is used for detecting a level signal of an access port of the video processing end; and when the level signal is switched from the alternating current level signal to the direct current level signal or from the direct current level signal to the alternating current level signal, cutting off the power supply output of the access port to the image acquisition terminal.
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| CN201510248753.9A CN106303342B (en) | 2015-05-14 | 2015-05-14 | Power supply circuit based on coaxial power supply technology |
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| CN201510248753.9A CN106303342B (en) | 2015-05-14 | 2015-05-14 | Power supply circuit based on coaxial power supply technology |
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| CN106303342B true CN106303342B (en) | 2022-11-22 |
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