Equipment control device, communication system, and equipment control method

Abstract

The present invention provides an equipment control device capable of properly protecting a system that controls equipment via a coaxial cable. [Solution] The device control device 100 comprises a power supply circuit, a communication circuit, a filter, a high-side switch, and a control unit 110. The control unit 110 includes a power supply voltage detection unit 111 that detects the power supply voltage supplied from the power supply circuit, and a current data acquisition unit 112 that acquires current data of communication signals transmitted and received from the communication circuit. The control unit 110 also includes a duty cycle acquisition unit 113 that acquires the duty cycle of the current data, and a current value determination unit 114 that determines whether the current value of the current data is equal to or greater than a predetermined current threshold. Furthermore, the control unit 110 includes a duty cycle adjustment unit 115 that reduces the ON ratio of the duty cycle when it is determined that the current value is equal to or greater than the current threshold.

Description

Technical Field

[0001] The present invention relates to an equipment control device, a communication system, and an equipment control method.

Background Art

[0002] Conventionally, when the current or temperature flowing through a semiconductor switch element that controls the on / off of the power supply of equipment (load) exceeds the upper limit value, a technique has been proposed to protect the equipment and electric wires by turning off the semiconductor switch. Patent Document 1 discloses a load control device that suppresses abnormal heat generation and degradation of resistance. When an abnormality is detected by any one of a plurality of parallel switches in the load control device disclosed in Patent Document 1, the power supply to all loads is turned off.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a system that supplies power to a sensing device such as a camera mounted on a vehicle, a method is used in which power and communication are superimposed on a coaxial cable to simplify the wiring. For example, when a coaxial cable is applied to the load control device disclosed in Patent Document 1, if the impedance of the coaxial cable is not appropriate, signal reflection and attenuation may occur, and an overcurrent such as an overshoot may occur.

[0005] The present invention has been made in view of such problems of the prior art. An object of the present invention is to provide an equipment control device capable of appropriately protecting a system that controls equipment via a coaxial cable.

Means for Solving the Problems

[0006] An embodiment of the present invention is an equipment control device that controls external equipment via a coaxial cable, comprising: a power supply circuit that supplies a power supply voltage; a communication circuit that transmits and receives communication signals; a filter that superimposes the power supply voltage and the communication signal onto the coaxial cable; a high-side switch that controls the on / off state of the power supply voltage supplied to the filter; and a control unit that controls the high-side switch, wherein the control unit includes: a power supply voltage detection unit that detects the power supply voltage supplied from the power supply circuit; a current data acquisition unit that acquires current data of the communication signal transmitted and received from the communication circuit; a duty cycle acquisition unit that acquires the duty cycle of the current data; a current value determination unit that determines whether the current value of the current data is equal to or greater than a predetermined current threshold; and a duty cycle adjustment unit that reduces the on ratio of the duty cycle when it is determined that the current value is equal to or greater than the current threshold.

[0007] A communication system according to an aspect of the present invention comprises the above-mentioned equipment control device, a coaxial cable connected to the equipment control device, and equipment connected to the coaxial cable.

[0008] An embodiment of the present invention is a device control method performed by a computer for controlling external equipment via a coaxial cable on which a power supply voltage and a communication signal are superimposed, the method includes detecting the power supply voltage supplied from a power supply circuit, acquiring current data of a communication signal transmitted and received from a communication circuit, acquiring the duty cycle of the current data, determining whether the current value of the current data is equal to or greater than a predetermined current threshold, and if it is determined that the current value is equal to or greater than the current threshold, reducing the ON ratio of the duty cycle. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an equipment control device that can properly protect a system that controls equipment via a coaxial cable. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows the configuration of the communication system according to this embodiment. [Figure 2A] This diagram illustrates the propagation of signals in the communication system according to this embodiment. [Figure 2B] This diagram illustrates the propagation of signals in the communication system according to this embodiment. [Figure 3] This diagram shows the configuration of the device control unit according to this embodiment. [Figure 4] This is a block diagram showing the configuration of the equipment applied to the communication system according to this embodiment. [Figure 5] This diagram illustrates the relationship between the high-side switch and current data in the communication system according to this embodiment. [Figure 6A] This diagram illustrates the high-side switch of the communication system according to this embodiment. [Figure 6B] This diagram illustrates the high-side switch of the communication system according to this embodiment. [Figure 7] This is a block diagram showing the functional configuration of the device control system according to this embodiment. [Figure 8A] This figure illustrates the relationship between the output waveform and duty cycle of the communication system according to this embodiment. [Figure 8B] This figure illustrates the relationship between the output waveform and duty cycle of the communication system according to this embodiment. [Figure 9] This figure illustrates the relationship between the energizing time and output power in the communication system according to this embodiment. [Figure 10] This flowchart shows an example of processing by the device control unit according to this embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, the communication system 10 and the device control device 100 according to this embodiment will be described in detail with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for convenience of explanation and may be different from the actual ratios. Also, in the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0012] (Configuration of Communication System 10) FIG. 1 is a diagram showing the configuration of a communication system 10 according to this embodiment. The communication system 10 includes a device control device 100, a plurality of devices 200, and a plurality of coaxial cables 300 that connect the device control device 100 and the plurality of devices 200.

[0013] The communication system 10 according to this embodiment is a system that supplies power to a sensing device (device) such as a camera mounted on a vehicle, for example. In order to simplify the wiring, the communication system 10 connects the device control device 100 and each device 200 via a coaxial cable 300 that superimposes power and a signal. In the example shown in FIG. 1, the device control device 100 can drive a large number of devices 200 with a small number of components by connecting a plurality of external devices 200 in parallel via the coaxial cable 300.

[0014] Further, the communication system 10 detects an abnormality in the power data required by each device 200 connected in parallel, and when an abnormality occurs, cuts off all outputs from the device control device 100 to prevent a failure of the device 200 such as a camera. Also, when an abnormality occurs, the communication system 10 can prevent an overload due to power redistribution to the plurality of coaxial cables 300 by cutting off all the coaxial cables 300. On the other hand, when using a coaxial cable 300, if the impedance setting is not appropriate, signal reflection and attenuation occur, making it difficult to manage the VSWR (Voltage Standing Wave Ratio) of the coaxial cable.

[0015] ​FIG. 2A is a diagram for explaining signal propagation in the communication system 10 according to the present embodiment. Further, FIG. 2B is a diagram for explaining signal propagation (standing wave) in the communication system 10 according to the present embodiment.

[0016] As shown in FIGS. 2A and 2B, when there is a mismatch in impedance matching between connected devices, a standing wave is generated by the incident wave and the reflected wave in the coaxial cable 300, which has an adverse effect on the system. The communication system 10 according to the present embodiment can calculate power data based on the power supply voltage and the detected current, and stabilize the output voltage according to the characteristics of the coaxial cable 300 by performing PWM control according to the power data. Further, the communication system 10 can reduce reflection in the transmission line by performing PWM control, enabling appropriate impedance matching. That is, the communication system 10 can improve the stability of the entire system in the simultaneous driving of the devices 200 connected in parallel by reducing the VSWR.

[0017] (Configuration of the device control device 100) FIG. 3 is a block diagram showing the configuration of the device control device 100 according to the present embodiment. The device control device 100 includes a control unit 110, a storage unit 120, a plurality of filters 130, a power supply circuit 140, a communication circuit 150, and a high-side switch 160. Details of the control unit 110 and the storage unit 120 will be described later.

[0018] The filter 130 has a function of preventing the high-frequency signal transmitted with power superimposed on the coaxial cable 300 from leaking out to the power line. Further, the filter 130 superimposes the power supply voltage supplied from the power supply circuit 140 on the coaxial cable 300 and the communication signal transmitted and received from the communication circuit 150. That is, the filter 130 appropriately superimposes or separates the signal and the DC power supply to maintain the signal quality. In the example shown in FIG. 3, a configuration including a plurality of filters 130a, 130b, and 130c corresponding to the plurality of coaxial cables 300 is shown. Hereinafter, when it is not necessary to distinguish and explain the filters 130a, 130b, and 130c, they will be simply referred to as "filter 130".

[0019] The power supply circuit 140, which supplies the power supply voltage, supplies the power supply voltage to the control unit 110 and the high-side switch 160. The communication circuit 150 sends and receives communication signals to and from the filter 130.

[0020] The high-side switch 160 controls the on / off state of the power supply voltage supplied to the filter 130. In the example shown in Figure 3, a configuration is shown that includes multiple channels of high-side switches 160a and high-side switch 160b. High-side switch 160a controls filters 130a and 130b. High-side switch 160b controls filters 130b and 130c.

[0021] In the example shown in Figure 3, the equipment 200 to which filters 130a and 130c are connected via coaxial cable 300 is a 2-megapixel camera, and the equipment 200 to which filter 130b is connected via coaxial cable 300 may be an 8-megapixel camera. That is, filter 130b may combine the power supplied from high-side switches 160a and 160b to drive a high-resolution camera. When it is not necessary to distinguish between high-side switches 160a and 160b, they should simply be referred to as "high-side switch 160".

[0022] (Configuration of equipment 200) Figure 4 is a block diagram showing the configuration of the device 200 applied to the communication system 10 according to this embodiment. The device 200 includes a filter 230, a power supply circuit 240, and a communication circuit 250.

[0023] Filter 230, like filter 130 of the equipment control device 100, has the function of preventing high-frequency signals transmitted with power superimposed on the coaxial cable 300 from leaking into the power line. Filter 230 also superimposes the power voltage supplied from the power circuit 240 onto the coaxial cable 300 and the communication signals transmitted and received from the communication circuit 250. In other words, filter 230 maintains signal quality by appropriately superimposing or separating the signal and the DC power supply. However, because the impedance characteristics required by the equipment control device 100 and the equipment 200 differ, the inductors used in the filters 130 and 230 are different. Furthermore, while filter 130 has a filter configuration that focuses on power supply and protection functions, filter 230 has a filter configuration that focuses on ensuring the quality of the received signal.

[0024] The power supply circuit 240, which supplies the power supply voltage, supplies the power supply voltage to the filter 230 and the communication circuit 250. The communication circuit 250 sends and receives communication signals to and from the filter 230.

[0025] (PWM control in high-side switch 160) Next, PWM control in the high-side switch 160 will be described. Figure 5 is a diagram illustrating the relationship between the high-side switch 160 and current data in the communication system 10 according to this embodiment. When the high-side switch 160 is turned on, a communication signal is transmitted at a predetermined PWM period.

[0026] Figures 6A and 6B illustrate the high-side switch 160 of the communication system 10 according to this embodiment. For example, as shown in Figure 6A, when an optimal duty cycle is achieved by PWM control, the output power is stabilized, improving the output waveform quality, which reduces reflections in the transmission line and provides the effect of impedance matching. On the other hand, as shown in Figure 6B, if the duty cycle is misaligned, an overshoot occurs where current is concentrated in one output channel (for example, high-side switch (1) ch1 in Figure 6B). This overshoot can cause overcurrent, overheating, noise, and / or reflections. The equipment control device 100 according to this embodiment appropriately performs PWM control to suppress the occurrence of overshoot.

[0027] (Functional configuration of the equipment control device 100) Next, the details of the control unit 110 and the storage unit 120 will be described. The control unit 110 is composed of, for example, a general-purpose microcomputer. In this case, the microcomputer may have a computer program installed that allows it to function as the device control unit 100. By executing the computer program, the microcomputer functions as one of the multiple information processing circuits provided by the device control unit 100.

[0028] In this embodiment, an example is shown in which multiple information processing circuits of the device control unit 100 are realized by software. However, it is also possible to configure the information processing circuits by preparing dedicated hardware to perform each of the information processing operations described below. Alternatively, multiple information processing circuits may be configured using separate hardware. Specifically, some or all of the information processing functions may be implemented using ASICs (Application Specific Integrated Circuits) or FPGAs (Field Programmable Graph Protocols). This can be executed using hardware such as an e Array.

[0029] Figure 7 is a block diagram showing the functional configuration of the device control device 100 according to this embodiment. As shown in Figure 7, the control unit 110 includes a power supply voltage detection unit 111, a current data acquisition unit 112, a duty cycle acquisition unit 113, a current value determination unit 114, and a duty cycle adjustment unit 115 as its functions. The control unit 110 also includes a power data calculation unit 116, a power data determination unit 117, and a switch control unit 118 as its functions.

[0030] Furthermore, the control unit 110 controls the entire device control device 100, for example, by running an operating system. In addition, the control unit 110 operates based on a program stored in the storage unit 120 and executes the functions described above. Note that the program is not limited to being stored in the storage unit 120, but may also be stored in a ROM (Read Only Memory) or the like (not shown) within the device control device 100.

[0031] The storage unit 120 stores the information contained in the current threshold information DB121 (DB: Database) and the cutoff threshold information DB122 as data. Note that there may be one or more storage units 120 that store this data. For example, a single storage unit 120 may be configured to store data in separate areas. Alternatively, the data may be distributed and stored in multiple storage devices located in physically separate locations.

[0032] The power supply voltage detection unit 111 detects the power supply voltage supplied from the power supply circuit 140. The current data acquisition unit 112 acquires current data of communication signals transmitted and received from the communication circuit 150. The current data acquisition unit 112 may also be configured to acquire data via the IS terminal (current detection terminal) of the high-side switch 160. The duty cycle acquisition unit 113 acquires the duty cycle of the current data.

[0033] The current value determination unit 114 determines whether the current value of the current data is equal to or greater than a predetermined current threshold. The current threshold is stored in the current threshold information DB 121 of the storage unit 120 in advance by the user. If the duty cycle adjustment unit 115 determines that the current value is equal to or greater than the current threshold, it reduces the ON ratio of the duty cycle.

[0034] Figure 8A is a diagram illustrating the relationship between the output waveform and duty cycle of the communication system 10 according to this embodiment under normal conditions. Figure 8B is a diagram illustrating the relationship between the output waveform and duty cycle of the communication system 10 according to this embodiment when an abnormality occurs. As shown in Figure 8A, under normal conditions, the ON ratio in the duty cycle of the output waveform is 50% to 80%.

[0035] On the other hand, as shown in Figure 8B, the duty cycle adjustment unit 115 reduces the ON ratio of the duty cycle when the output waveform exceeds the current threshold. Specifically, as shown in the adjusted Duty in Figure 8B, for example, the duty cycle adjustment unit 115 reduces the ON ratio to about 10% to 30%. It is preferable that the ON ratio of the duty cycle in the communication system 10 be 5% or more. This makes it possible for the equipment control device 100 to suppress overshoot in the coaxial cable 300 that superimposes the power supply voltage and the communication signal.

[0036] The power data calculation unit 116 calculates multiple output powers for multiple coaxial cables 300 based on the power supply voltage and current value. The output power is calculated by multiplying the power supply voltage by the current value.

[0037] The power data determination unit 117 determines if multiple output powers are above a predetermined cutoff threshold. It determines whether or not to proceed. The tripping threshold is stored in the tripping threshold information DB122 of the storage unit 120 in advance by the user. The tripping threshold is determined considering factors such as power during normal operation, voltage drop in the coaxial cable 300, transient current increase, and a 20% safety margin for the product.

[0038] For example, if device 200 is a 2M pixel camera, the power consumption during normal operation is P=V×I=12V×0.4A=4.8W. The assumed voltage drop across coaxial cable 300 is calculated as follows: with a resistance of 0.0338Ω / m×15m=0.507Ω, the voltage drop is 0.507Ω×0.4A=0.2028V, and the effective voltage is 12V-0.2V=11.8V. The effective power is 11.8V×0.4A=4.72W. As a result, the cutoff threshold is 4.72W×1.2=5.66W.

[0039] Furthermore, if device 200 is an 8M pixel camera, the power consumption during normal operation is P=V×I=12V×0.8A=9.6W. Also, the assumed voltage drop across coaxial cable 300 is calculated as follows, assuming a resistance of 0.0338Ω / m×15m=0.507Ω: the voltage drop is 0.507Ω×0.8A=0.4056V, and the effective voltage is 12V-0.4V=11.6V. The effective power is 11.8V×0.8A=9.27W. As a result, the cutoff threshold is 9.27W×1.2=11.12W.

[0040] Figure 9 is a diagram illustrating the relationship between energization time and output power in the communication system 10 according to this embodiment. The power data determination unit 117 determines that the output power of multiple coaxial cables 300 is above a predetermined cutoff threshold when the output power of multiple coaxial cables 300 exceeds a predetermined cutoff threshold.

[0041] The switch control unit 118 shuts off all power supply voltage outputs from the high-side switch 160 to the filter 130 if it determines that any one of the multiple output powers exceeds a shut-off threshold. This allows the communication system 10 to detect abnormalities in the power data required by each of the parallel-connected devices 200, shut off all outputs from the device control device 100, and prevent failure of devices 200 such as cameras. In addition, the communication system 10 can prevent overload caused by power redistribution to multiple coaxial cables 300 by shutting off all coaxial cables 300 when an abnormality occurs.

[0042] (Outline of the processing flow of the device control unit 100) Next, the flowchart shown in Figure 10 illustrates the processing flow in the device control unit 100. The series of operations of the device control unit 100 shown in the flowchart of Figure 10 begin when the device control unit 100 is powered on and end when the task is completed. Furthermore, the flowchart in Figure 10 also ends when the power is turned off or when an interrupt occurs indicating the end of processing. In addition, in the following explanation of the flowchart, the same content as described in the above-mentioned explanation of the communication system 10 and the device control unit 100 will be omitted or simplified.

[0043] In step S1001, the control unit 110 determines whether or not the power supply voltage supplied from the power supply circuit 140 has been detected by the power supply voltage detection unit 111. If the control unit 110 determines in step S1001 that the power supply voltage has been detected (step S1001: YES), the process proceeds to step S1002. On the other hand, if the control unit 110 determines in step S1001 that the power supply voltage has not been detected (step S1001: NO), the process proceeds to step S1009.

[0044] In step S1002, the control unit 110 determines whether or not an external input signal is ON. The external input signal is, for example, a signal to start control of the device 200. In step S1002, the control unit 110 determines whether or not an external input signal is ON. If a determination is made (step S1002: YES), the process proceeds to step S1003. On the other hand, if the control unit 110 determines in step S1002 that the external input signal is not ON (step S1002: NO), the process proceeds to step S1009.

[0045] In step S1003, the current data acquisition unit 112 acquires current data of the communication signal transmitted and received from the communication circuit 150. The current data acquisition unit 112 may also acquire the data via the IS terminal (current detection terminal) of the high-side switch 160. The duty cycle acquisition unit 113 acquires the duty cycle of the current data. After that, the process proceeds to step S1004.

[0046] In step S1004, the current value determination unit 114 determines whether the current value of the current data is equal to or greater than a predetermined current threshold. The current threshold is stored in the current threshold information DB 121 of the storage unit 120 in advance by the user. In step S1004, if the current value determination unit 114 determines that the current value of the current data is equal to or greater than a predetermined current threshold (step S1004: YES), the process proceeds to step S1005. On the other hand, in step S1004, if the current value determination unit 114 determines that the current value of the current data is not equal to or greater than a predetermined current threshold (step S1004: NO), the process proceeds to step S1006.

[0047] In step S1005, if the duty cycle adjustment unit 115 determines that the current value is greater than or equal to the current threshold, it reduces the ON ratio of the duty cycle by PWM control. Specifically, as shown in the adjusted Duty in Figure 8B, for example, the duty cycle adjustment unit 115 reduces the ON ratio to about 10% to 30%. After that, the process proceeds to step S1006.

[0048] In step S1006, the power data calculation unit 116 calculates multiple output powers for multiple coaxial cables 300 based on the power supply voltage and current value. The output power is calculated by multiplying the power supply voltage by the current value. The process then proceeds to step S1007.

[0049] In step S1007, the power data determination unit 117 determines whether the multiple output powers are above a predetermined cutoff threshold. The cutoff threshold is stored in the cutoff threshold information DB 122 of the storage unit 120 in advance by the user. In step S1007, if the power data determination unit 117 determines that the calculated power data, which is the output power, is above the cutoff threshold (step S1007: YES), the process proceeds to step S1008. On the other hand, in step S1007, if the power data determination unit 117 determines that the output power is not above the cutoff threshold (step S1007: NO), the process returns to step S1001, and the process from step S1001 is repeated.

[0050] In step S1008, the switch control unit 118 shuts off all power supply voltage outputs from the high-side switch 160 to the filter 130. Specifically, the switch control unit 118 operates the high-side switch 160 with a fast response speed (μs to ms) to protect the circuit from overcurrent when an abnormality is detected. After a certain period of time, the switch control unit 118 restores the output from the high-side switch 160 when the wire temperature returns to the normal range. In other words, during the output shutoff process of the high-side switch 160 in step S1008, the internal protection circuit of the high-side switch 160 activates to protect the components. After that, the process ends.

[0051] In step S1009, the switch control unit 118 turns off the output of the high-side switch 160. This process of turning off the output of the high-side switch 160 is performed from an external source. The switch will not recover until the input signal is turned on. Also, the process of turning off the output of the high-side switch 160 in step S1009 prevents the internal protection circuit of the high-side switch 160 from activating. In other words, after completion, the power supply voltage is detected and the input signal turns ON (steps S1001 and S1002: YES), causing the output of the high-side switch 160 to recover. The process then ends.

[0052] As described above, the device control device 100 is a device control device 100 that controls external devices 200 via a coaxial cable 300. The device control device 100 includes a power supply circuit 140 that supplies a power supply voltage, a communication circuit 150 that transmits and receives communication signals, and a filter 130 that superimposes the power supply voltage and communication signals onto the coaxial cable 300. The device control device 100 also includes a high-side switch 160 that controls the on / off state of the power supply voltage supplied to the filter 130, and a control unit 110 that controls the high-side switch 160. The control unit 110 includes a power supply voltage detection unit 111 that detects the power supply voltage supplied from the power supply circuit 140, and a current data acquisition unit 112 that acquires current data of communication signals transmitted and received from the communication circuit 150. The control unit 110 also includes a duty cycle acquisition unit 113 that acquires the duty cycle of the current data, and a current value determination unit 114 that determines whether the current value of the current data is equal to or greater than a predetermined current threshold. Furthermore, the control unit 110 includes a duty cycle adjustment unit 115 that reduces the ON ratio of the duty cycle when it is determined that the current value is equal to or greater than a current threshold.

[0053] As a result, the device control unit 100 calculates power data based on the power supply voltage and detected current, and stabilizes the output voltage according to the characteristics of the coaxial cable 300 by performing PWM control according to the power data. In addition, by performing PWM control, the device control unit 100 reduces reflections in the transmission line and enables appropriate impedance matching. In other words, by reducing the VSWR, the device control unit 100 improves the overall system stability when simultaneously driving the parallel-connected devices 200, and suppresses overshoot in the coaxial cable 300 where the power supply voltage and communication signal are superimposed.

[0054] Furthermore, the duty cycle adjustment unit 115 may adjust the duty cycle so that the ratio of the duty cycle being ON is between 10% and 30% when it is determined that the current value is equal to or greater than the current threshold. This enables the equipment control device 100 to perform more accurate PWM control on the data transmitted and received through the coaxial cable 300, thereby improving the overall system stability through appropriate impedance matching.

[0055] Furthermore, the control unit 110 of the equipment control device 100 includes a power data calculation unit 116 that calculates multiple output powers for multiple coaxial cables 300 based on the power supply voltage and current value. The control unit 110 also includes a power data determination unit 117 that determines whether the multiple output powers are above a predetermined cutoff threshold. In addition, the control unit 110 includes a switch control unit 118 that cuts off all power supply voltage outputs from the high-side switch 160 to the filter 130 if it is determined that any one of the multiple output powers is above the cutoff threshold.

[0056] As a result, the equipment control device 100 detects abnormalities in the power data required by each piece of equipment 200 connected in parallel, shuts off all output from the equipment control device 100, and prevents failure of equipment 200 such as cameras. In addition, the equipment control device 100 can prevent overload caused by power redistribution to multiple coaxial cables 300 by shutting off all coaxial cables 300 when an abnormality occurs.

[0057] (Other embodiments) The embodiments have been described in detail with reference to the drawings, but the contents of the embodiments described above are This embodiment is not limited thereto. Furthermore, the components described above include those easily conceivable by those skilled in the art, and those that are substantially identical. Moreover, the configurations described above can be combined as appropriate. In addition, various omissions, substitutions, or modifications of the configurations can be made without departing from the spirit of the embodiment.

[0058] Furthermore, a computer program (device control program) that causes a computer to execute the processing (device control method) in the device control device 100 described above, and a computer-readable recording medium on which the program is stored, are included within the scope of this embodiment. Here, the type of computer-readable recording medium is arbitrary. Moreover, the computer program is not limited to one stored on the recording medium described above, but may also be transmitted via telecommunication lines, wireless or wired communication lines, networks such as the Internet, etc.

[0059] The features of the equipment control device 100 are described below.

[0060] The first embodiment of the device control device 100 is a device control device 100 that controls external equipment 200 via a coaxial cable 300. The device control device 100 includes a power supply circuit 140 that supplies a power supply voltage, a communication circuit 150 that transmits and receives communication signals, and a filter 130 that superimposes the power supply voltage and communication signals onto the coaxial cable 300. The device control device 100 also includes a high-side switch 160 that controls the on / off state of the power supply voltage supplied to the filter 130, and a control unit 110 that controls the high-side switch 160. The control unit 110 includes a power supply voltage detection unit 111 that detects the power supply voltage supplied from the power supply circuit 140, and a current data acquisition unit 112 that acquires current data of communication signals transmitted and received from the communication circuit 150. The control unit 110 also includes a duty cycle acquisition unit 113 that acquires the duty cycle of the current data, and a current value determination unit 114 that determines whether the current value of the current data is equal to or greater than a predetermined current threshold. Furthermore, the control unit 110 includes a duty cycle adjustment unit 115 that reduces the ON ratio of the duty cycle when it is determined that the current value is equal to or greater than a current threshold.

[0061] According to the above configuration, power data is calculated based on the power supply voltage and detected current, and by performing PWM control according to the power data, it becomes possible to stabilize the output voltage according to the characteristics of the coaxial cable 300. In addition, by performing PWM control, the equipment control device 100 reduces reflections in the transmission line and enables appropriate impedance matching. In other words, by reducing the VSWR, the equipment control device 100 improves the overall system stability when simultaneously driving the parallel-connected equipment 200, and suppresses overshoot in the coaxial cable 300 where the power supply voltage and communication signal are superimposed.

[0062] In the second embodiment, the duty cycle adjustment unit 115 of the equipment control device 100 may adjust the duty cycle so that the ratio of ON duty cycles is 10% to 30% when it is determined that the current value is equal to or greater than the current threshold.

[0063] With the above configuration, the device control unit 100 can perform more accurate PWM control on the data transmitted and received through the coaxial cable 300, thereby improving the overall stability of the system through appropriate impedance matching.

[0064] The control unit 110 of the equipment control device 100 according to the third embodiment includes a power data calculation unit 116 that calculates multiple output powers for multiple coaxial cables 300 based on the power supply voltage and current value. The control unit 110 also includes a power data determination unit 117 that determines whether the multiple output powers are above a predetermined cutoff threshold. Furthermore, if the control unit 110 determines that any one of the multiple output powers is above the cutoff threshold, The system includes a switch control unit 118 that completely shuts off the output of the power supply voltage from the high-side switch 160 to the filter 130.

[0065] According to the above configuration, the equipment control device 100 detects abnormalities in the power data required by each piece of equipment 200 connected in parallel, shuts off all output from the equipment control device 100, and prevents failure of equipment 200 such as cameras. In addition, the equipment control device 100 can prevent overload caused by power redistribution to multiple coaxial cables 300 by shutting off all coaxial cables 300 when an abnormality occurs.

[0066] The communication system 10 according to the fourth embodiment comprises an equipment control device 100, a coaxial cable 300 connected to the equipment control device 100, and equipment 200 connected to the coaxial cable 300.

[0067] With the above configuration, the communication system 10 calculates power data based on the power supply voltage and detected current, and stabilizes the output voltage according to the characteristics of the coaxial cable 300 by performing PWM control according to the power data. In addition, by performing PWM control, the communication system 10 reduces reflections in the transmission path and enables appropriate impedance matching. In other words, by reducing the VSWR, the communication system 10 improves the overall system stability when simultaneously driving the parallel-connected equipment 200, and suppresses overshoot in the coaxial cable 300 where the power supply voltage and communication signal are superimposed.

[0068] The fifth embodiment of the device control method is a device control method executed by a computer that controls an external device 200 via a coaxial cable 300 on which a power supply voltage and a communication signal are superimposed. The device control method detects the power supply voltage supplied from the power supply circuit 140. The device control method also acquires current data of the communication signal transmitted and received from the communication circuit 150. The device control method also acquires the duty cycle of the current data. The device control method also determines whether the current value of the current data is equal to or greater than a predetermined current threshold. Furthermore, if the device control method determines that the current value is equal to or greater than the current threshold, it reduces the ON ratio of the duty cycle.

[0069] According to the above configuration, the equipment control method calculates power data based on the power supply voltage and detected current, and stabilizes the output voltage according to the characteristics of the coaxial cable 300 by performing PWM control according to the power data. Furthermore, by performing PWM control, the equipment control method reduces reflections within the transmission line and enables appropriate impedance matching. In other words, by reducing the VSWR, the equipment control method improves the overall system stability when simultaneously driving the parallel-connected equipment 200, and suppresses overshoot in the coaxial cable 300 where the power supply voltage and communication signal are superimposed. [Explanation of symbols]

[0070] 10 Communication Systems 100 Equipment control devices 110 Control Unit 111 Power supply voltage detection unit 112 Current data acquisition unit 113 Duty Cycle Acquisition Unit 114 Current Value Determination Unit 115 Duty Cycle Adjustment Section 116 Power Data Calculation Unit 117 Power Data Determination Unit 118 Switch Control Unit 120 Storage section 121 Current Threshold Information Database 122 Blocking Threshold Information Database 130, 130a, 130b, 130c, 230 filters 140, 240 power supply circuit 150, 250 communication circuits 160, 160a, 160b High-side switches 200 equipment 300 coaxial cable

Claims

1. A device control device that controls external equipment via a coaxial cable, A power supply circuit that supplies power voltage, A communication circuit that transmits and receives communication signals, A filter that superimposes the power supply voltage and the communication signal onto the coaxial cable, A high-side switch controls the on / off switching of the power supply voltage supplied to the filter, The system comprises a control unit for controlling the high-side switch, The control unit, A power supply voltage detection unit for detecting the power supply voltage supplied from the power supply circuit, A current data acquisition unit that acquires current data of the communication signal transmitted and received from the communication circuit, A duty cycle acquisition unit that acquires the duty cycle of the current data, A current value determination unit that determines whether the current value of the current data is equal to or greater than a predetermined current threshold, A device control device having a duty cycle adjustment unit that reduces the ON ratio of the duty cycle when it is determined that the current value is equal to or greater than the current threshold.

2. The device control device according to claim 1, wherein the duty cycle adjustment unit adjusts the duty cycle so that the ON ratio of the duty cycle is 10% to 30% when it is determined that the current value is equal to or greater than the current threshold.

3. The control unit, A power data calculation unit calculates multiple output powers for multiple coaxial cables based on the power supply voltage and the current value, A power data determination unit that determines whether the multiple output powers are above a predetermined cutoff threshold, The device control device according to claim 1, further comprising a switch control unit that, when it is determined that any one of the multiple output powers is equal to or greater than the cutoff threshold, cuts off all outputs of the power supply voltage output from the high-side switch to the filter.

4. A device control device according to any one of claims 1 to 3, A coaxial cable connected to the aforementioned equipment control device, A communication system comprising equipment connected to the aforementioned coaxial cable.

5. A device control method, executed by a computer, that controls external equipment via a coaxial cable with superimposed power supply voltage and communication signals, The power supply voltage supplied from the power supply circuit is detected, The current data of the communication signal transmitted and received from the communication circuit is acquired. The duty cycle of the current data is obtained, Determine whether the current value of the current data is equal to or greater than a predetermined current threshold. A device control method that reduces the ON ratio of the duty cycle when it is determined that the current value is equal to or greater than the current threshold.

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