JP2023181856A - Communication device and control method thereof - Google Patents

Abstract

To reduce communication errors due to load fluctuations.SOLUTION: A communication device includes communication means for communicating with an external device via a coaxial cable, power feeding means for superimposing a power supply on the coaxial cable to supply power to the external device, detection means for detecting execution of drive control using the power supply in the external device, and changing means for changing a communication frequency in the communication means in response to detection of the drive control by the detection means.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique for reducing errors in data communication.

Surveillance cameras for monitoring purposes such as crime prevention and recording are installed and operated in various environments. In addition, while there are cases in which a surveillance camera is installed in a position where it can be seen by the target to be monitored, there are also cases in which a surveillance camera is installed in a position that is difficult to see. For example, surveillance cameras may be hidden and installed inconspicuously within walls. It is desired that such a surveillance camera be small in size, and for example, a module type surveillance camera that is divided into a sensor unit (lens, sensor section) and a main unit has been realized.

A module type surveillance camera has a configuration in which a sensor unit and a main unit are connected via, for example, a coaxial cable. Patent Document 1 discloses a configuration in which power is superimposed on uplink/downlink signals in a coaxial cable that connects a head and a controller.

Japanese Patent Application Publication No. 2015-198303

However, in the technique disclosed in Patent Document 1, when load fluctuation occurs on the head (sensor unit) side, noise due to the load fluctuation is generated, and the noise may be superimposed on the coaxial cable. As a result, data communication between the sensor unit and the main unit may not be able to be performed correctly.

The present invention has been made in view of such problems, and an object of the present invention is to provide a technology that can reduce communication errors due to load fluctuations.

In order to solve the above problems, a communication device according to the present invention has the following configuration. That is, the communication device is
a communication means for communicating with an external device via a coaxial cable;
a power supply means for supplying power to the external device by superimposing a power supply on the coaxial cable;
detection means for detecting execution of drive control using the power source in the external device;
Changing means for changing the communication frequency in the communication means in response to the detection of the drive control by the detection means;
Equipped with

Or, the communication device is
a communication means for communicating with an external device via a coaxial cable;
a power supply means for supplying power to the external device by superimposing a power supply on the coaxial cable;
acquisition means for acquiring noise information regarding noise on a power line in the external device;
Changing means for changing the communication frequency in the communication means according to the noise information acquired by the acquisition means;
Equipped with

According to the present invention, it is possible to provide a technique for reducing communication errors due to load fluctuations.

FIG. 1 is a diagram illustrating a system configuration in a first embodiment. It is a figure explaining drive noise and frequency change. FIG. 3 is a diagram showing an example of a changed frequency list. FIG. 3 is a diagram illustrating a system configuration in Modification 1. FIG.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the claimed invention. Although a plurality of features are described in the embodiments, not all of these features are essential to the invention, and the plurality of features may be arbitrarily combined. Furthermore, in the accompanying drawings, the same or similar components are designated by the same reference numerals, and redundant description will be omitted.

(First embodiment)
As a first embodiment of a communication device according to the present invention, an imaging system having a sensor unit and a main unit connected via a coaxial cable will be described below as an example.

<Schematic configuration of imaging system>
FIG. 1 is a diagram illustrating the system configuration in the first embodiment. The imaging system includes a sensor unit 100, a coaxial cable 110, and a main unit 120. Although details will be described later, the sensor unit 100 is a device that captures images and transmits the captured data to the main unit 120 via the coaxial cable 110. The main unit 120 is a device that performs various image processing on the imaging data received from the sensor unit 100 and distributes the image (video) via the Internet Protocol (IP) network 130.

Further, the main unit 120 is connected to a client terminal device 140 via an IP network 130 so as to be able to communicate with each other. Main unit 120 controls the operations of main unit 120 and sensor unit 100 based on various control commands received from client terminal device 140 . The control commands include settings for imaging parameters, commands to start/stop imaging streaming, and the like. The client terminal device 140 is assumed to be an information processing terminal such as a personal computer, a server, or a mobile terminal, but is not limited thereto. The client terminal device 140 may perform various controls on the imaging system, as well as display and record video signals captured by the imaging system.

Coaxial cable 110 is a single-core coaxial cable, and is composed of an inner conductor and an outer conductor. The inner conductor is a single conducting wire, and the outer conductor is a shielded wire arranged in a cylindrical shape around the inner conductor. Although details will be described later, the coaxial cable 110 includes a bidirectional data signal and a power source superimposed thereon. The data signals include, for example, an image signal transmitted from the sensor unit 100 to the main unit 120, and various control signals (such as filter insertion/removal control to be described later) transmitted from the main unit 120 to the sensor unit 100.

The IP network 130 is composed of a plurality of routers, switches, cables, etc. that satisfy communication standards such as, for example, Ethernet (registered trademark). However, as long as the communication network is capable of communicating between the main unit 120 and the client terminal device 140, its communication standard, scale, and configuration are not critical. For example, the IP network 130 may be configured by a wired LAN (Local Area Network), a wireless LAN, a WAN (Wide Area Network), or the like.

The commercial power supply device 150 is a device that supplies commercial power to the main unit 120. Generally, the commercial power supply provides 100 V of alternating current (AC) to the main unit 120, and the necessary direct current (DC) power is generated via an AC-DC converter (not shown) in the power supply circuit 124 of the main unit 120. Ru. However, any configuration may be used as long as power is supplied to the main unit 120. For example, it may be possible to use PoE (Power over Ethernet), which supplies power through a wired LAN cable.

<Sensor unit configuration>
The sensor unit 100 includes a lens group 101 that is an optical system, an image sensor 102, an amplifier 103, and a serializer 104. Further, the sensor unit 100 is configured such that an infrared (IR) cut filter 107 can be inserted into and removed from the optical path between the lens group 101 and the image sensor 102. Furthermore, the sensor unit 100 includes a filter 105, a power supply circuit 106, a motor driver 109, and a motor 108.

The lens group 101 is composed of optical lenses for forming an optical image of a subject on the imaging surface of the image sensor 102. The image sensor 102 converts an optical image formed on an imaging surface via the lens group 101 into an electrical signal. The amplifier 103 amplifies the electrical signal output from the image sensor 102 to a predetermined level and outputs it as image data in a predetermined format. Imaging data is generally output as a signal such as MIPI (Mobile Industry Processor Interface) or LVDS (Low Voltage Differential Signaling).

The serializer 104 serializes the input imaging data. That is, the imaging data is input as a plurality of parallel signals such as a CLK signal and a DATA signal, but is converted into one serial signal by serially converting them. This serial signal is output via coaxial cable 110.

Filter 105 separates and extracts power (power supply voltage) from coaxial cable 110 . Although details will be described later, a power supply is superimposed on the coaxial cable 110 by the main unit 120. The power supply circuit 106 generates the power necessary for each part of the sensor unit 100. Although not shown, power is also supplied to the image sensor 102 and serializer 104.

The IR cut filter 107 is a filter inserted into the optical path depending on the shooting mode (day/night). Specifically, in the day mode, the IR cut filter is inserted into the optical path, and in the night mode, the IR cut filter is removed from the optical path. As a result, the image sensor 102 generates imaging data based only on light in the visible light range in the day mode, and generates imaging data based on light in the visible to infrared range in the night mode. As a result, in the night mode, it is possible to take pictures with high sensitivity in dark places such as at night. Note that in the night mode, IR illumination may be projected in the photographing direction. Note that control of insertion and removal of the IR cut filter 107 into the optical path is realized by driving the motor 108 via the motor driver 109.

<Main unit configuration>
Main unit 120 includes a deserializer 121, an image processing section 122, a communication control section 123, a power supply circuit 124, a filter 125, and an oscillator 126.

The deserializer 121 converts (restores) the serial signal (image signal) transmitted from the serializer 104 via the coaxial cable 110 into a plurality of parallel signals such as a CLK signal and a DATA signal, which are the original imaging data. The oscillator 126 generates a reference clock (CLK) used for serial communication between the serializer and the deserializer. For example, the deserializer 121 supplies a reference CLK to the serializer 104, and the serializer 104 generates a serial signal with a CLK that is a multiple of the reference CLK. Further, the deserializer 121 transmits various control signals (filter insertion/removal control, etc. to be described later) to the sensor unit 100.

The image processing unit 122 performs various image processing (such as development processing) on the imaged data restored by the deserializer 121 to generate predetermined imaged data.

The communication control unit 123 distributes the image data generated by the image processing unit 122 via the IP network 130. At this time, the communication control unit 123 may convert the imaging data into data compliant with a predetermined communication protocol and then distribute the data. Furthermore, the communication control unit 123 is configured to receive various control commands from the client terminal device 140 described above.

The power supply circuit 124 generates power necessary for each part of the main unit 120 and power supplied to the sensor unit 100 via the coaxial cable 110 from power supplied from an external commercial power supply 150. The filter 125 superimposes the power supply to the sensor unit 100 on the communication signal from the deserializer 121.

<System operation>
As described above, the imaging system includes the sensor unit 100 and the main unit 120, and the sensor unit 100 and the main unit 120 are connected via the coaxial cable 110. In the coaxial cable 110, not only video information but also power is superimposed.

By the way, when the motor 108 is driven to insert and remove the IR cut filter 107, drive noise 201 is generated. The drive noise 201 is generated due to load fluctuations occurring in the motor 108 due to high-speed switching control of the motor 108. This drive noise occurs not only in the motor control line (between the motor driver 109 and the motor 108) but also in the power supply line that supplies power. Since driving noise on the power supply line is also generated in the coaxial cable 110, it affects the video signal as noise.

FIG. 2 is a diagram illustrating driving noise 201 caused by load fluctuation and frequency change. Drive noise 201 (shown as an envelope) is composed of a peak frequency 202 that is the same as the drive switching frequency and a plurality of harmonic component noises 203. The plurality of harmonic component noises 203 are generated at frequency positions that are multiples of the peak frequency, and generally in a state where the level is lower than the peak.

When the communication frequency of the serializer in coaxial cable 110 is frequency 204, it matches the frequency of relatively high level harmonic component noise 203. In this case, the communication quality between the serializer and the deserializer will deteriorate due to the influence of the harmonic component noise 203. As a result, a communication error occurs, resulting in the occurrence of noise in the video, the occurrence of interruptions in the video, or the stoppage of the photographing operation.

Therefore, in the first embodiment, when the communication frequency of the serializer matches the frequency of harmonic component noise having a noise level equal to or higher than a predetermined level, the communication frequency of the serializer is changed. Here, the predetermined level means a noise level that affects communication between the serializer and the deserializer. In the example shown in FIG. 2, the communication frequency of the serializer is changed from frequency 204 to frequency 205. Although one of the harmonic component noises 203 also exists at the frequency 205, the noise level is lower than a predetermined level, so it does not affect the communication between the serializer and the deserializer. Of course, the frequency may be changed to a frequency that does not match any of the plurality of harmonic component noises 203. In the first embodiment, a list of frequencies to be changed is prepared in advance, and the frequency to be changed is determined by referring to the list.

FIG. 3 is a diagram showing an example of a changed frequency list. Here, it is stored and maintained as a list that defines communication frequencies corresponding to each combination in association with the combination of load fluctuation state and temperature. The state of load fluctuation may include the presence or absence of load fluctuation and the type of drive control that causes the load fluctuation. The temperature is, for example, the environmental temperature of the system (sensor unit, coaxial cable, main unit).

In a state where there is no load fluctuation (initial state), "1.0 GHz" is selected and used as the communication frequency between the serializer and deserializer. Thereafter, for example, when a control signal for performing "IR cut filter drive" is received from the client terminal device 140 in the "normal temperature" state, "1.4 GHz" is selected and changed as the communication frequency. After that, a control signal for "IR cut filter driving" is transmitted to the sensor unit 100. Thereby, even when "IR cut filter drive" is performed by the sensor unit 100, communication without communication errors is possible. Note that the reason why the frequency to be changed is changed depending on the temperature in the list of FIG. 3 is that the influence of harmonic component noise on communication depends on the temperature. Note that when the state returns to a state where there is no load fluctuation (for example, when "IR cut filter drive" is completed), the frequency may be returned to "1.0 GHz" before the change and communication may be continued.

As explained above, according to the first embodiment, the communication frequency between the sensor unit and the main unit is changed depending on the state of load fluctuation. This makes it possible to continue communication with reduced communication errors even when load fluctuations occur.

Note that in the above description, execution of "IR cut filter drive" was cited as the drive control that causes load fluctuations, but load fluctuations may be caused by other causes. For example, it may be a load change due to execution of control such as projection of IR illumination (lighting/dimming), driving of pan/tilt, driving of an optical system (focus/zoom), use of a heater, or the like. In addition, in the above explanation, the case where the sensor unit and the main unit are configured in a 1:1 ratio is explained, but it can also be applied to a case where the sensor unit and the main unit are configured in a 1:N ratio (N is an integer of 2 or more). be.

Furthermore, in the above description, it has been explained that a control signal for "driving an IR cut filter" is received from the client terminal device 140, but a mode in which a control signal for "driving an IR cut filter" is received from the sensor unit 100 is described. But that's fine.

(Modification 1)
As a first modification, a mode will be described in which power supply noise is measured in the sensor unit 100 and information regarding the power supply noise is provided to the main unit 120. Here, power supply noise means noise in the power supply line (which does not occur in a state where there is no load fluctuation), including drive noise in the first embodiment.

FIG. 4 is a diagram illustrating the system configuration in Modification 1. In contrast to the system configuration of the first embodiment (FIG. 1), a noise detection circuit 401 is further included in the sensor unit 100. Note that descriptions of the same components as in the first embodiment will be omitted.

Noise detection circuit 401 measures power supply noise (noise between power supply circuit 106 and motor driver 109) when driving IR cut filter 107. For example, voltage level and frequency are measured as information regarding power supply noise.

The serializer 104 provides the main unit 120 with noise information regarding power supply noise measured by the noise detection circuit 401. The main unit 120 determines a communication frequency that allows communication without communication errors (for example, excluding frequencies of noise whose voltage level is higher than a predetermined level among power supply noises) according to the acquired noise information (voltage level and frequency). frequency). For example, one is selected from a plurality of candidate frequencies prepared in advance. Then, the main unit 120 changes the frequency of the communication between the serializer and the deserializer to the selected frequency by changing the frequency of the oscillator 126. Note that if the noise information indicates that there is no noise in the power supply line, the frequency may be returned to "1.0 GHz" before the change and communication may be continued.

The above-described control makes it possible to adaptively determine a more appropriate changed frequency according to the characteristics (voltage level and frequency) of power supply noise generated due to load fluctuations of the sensor unit 100.

(Modification 2)
As a second modification, a mode in which a communication error is detected in the deserializer 121 will be described. Note that the system configuration is the same as the system configuration of the first embodiment (FIG. 1), so a description thereof will be omitted.

As described above, the deserializer 121 converts the serial signal transmitted from the serializer 104 via the coaxial cable 110 into a plurality of parallel signals such as CLK and DATA signals, which are the original imaging data. In addition to this conversion process, the deserializer 121 also monitors the communication status between the serializer and the deserializer. Specifically, it detects errors such as garbled or dropped bits in communication data. When the main unit 120 detects an error, it changes the oscillation frequency of the oscillator 126, changes the communication frequency between the serializer and the deserializer, and issues a retransmission request.

With the above-described control, even if a communication error occurs due to the influence of drive noise, by changing the communication frequency and performing retransmission, operation without a communication error is possible.

The disclosure of this specification includes the following communication device and control method.
(Item 1)
a communication means for communicating with an external device via a coaxial cable;
a power supply means for supplying power to the external device by superimposing a power supply on the coaxial cable;
detection means for detecting execution of drive control using the power source in the external device;
Changing means for changing the communication frequency in the communication means in response to the detection of the drive control by the detection means;
A communication device comprising:
(Item 2)
Further comprising storage means for storing a frequency list defining frequencies associated with the type of drive control,
The detection means detects the type of drive control,
An item characterized in that the changing means selects a frequency specified in the frequency list based on the type of drive control detected by the detecting means, and changes the communication frequency to the selected frequency. 1. The communication device according to 1.
(Item 3)
The frequency list defines a plurality of frequencies associated with a plurality of combinations of the drive control type and temperature,
The detection means further detects information on environmental temperature in the external device,
3. The communication device according to item 2, wherein the changing means selects the frequency specified in the frequency list based on a combination of the type of drive control detected by the detecting means and the environmental temperature.
(Item 4)
The communication device according to item 1, wherein the detection means detects execution of the drive control by detecting a communication error in the communication means.
(Item 5)
The communication means is characterized in that when a communication error is detected by the detection means, the change means changes the communication frequency, and then makes a retransmission request for the data in which the communication error has occurred. Communication device according to item 4.
(Item 6)
6. The communication device according to any one of items 1 to 5, wherein the changing means returns the frequency to the pre-change frequency after the execution of the drive control is completed.
(Item 7)
a communication means for communicating with an external device via a coaxial cable;
a power supply means for supplying power to the external device by superimposing a power supply on the coaxial cable;
acquisition means for acquiring noise information regarding noise on a power line in the external device;
Changing means for changing the communication frequency in the communication means according to the noise information acquired by the acquisition means;
A communication device comprising:
(Item 8)
The noise information includes the voltage level and frequency of the noise,
8. The communication device according to item 7, wherein the changing means changes the communication frequency to a frequency excluding the frequency of the noise whose voltage level is equal to or higher than a predetermined level.
(Item 9)
9. The communication device according to item 7 or 8, wherein the changing means returns the frequency to the frequency before the change when the noise information indicates that there is no noise in the power line.
(Item 10)
10. The communication device according to any one of items 1 to 9, wherein the changing means changes the communication frequency by controlling the frequency of an oscillator that generates a reference clock of the communication frequency.
(Item 11)
A method for controlling a communication device, the method comprising:
The communication device includes:
a communication means for communicating with an external device via a coaxial cable;
a power supply means for supplying power to the external device by superimposing a power supply on the coaxial cable;
Equipped with
The control method includes:
a detection step of detecting execution of drive control using the power source in the external device;
a changing step of changing the communication frequency in the communication means according to the detection of the drive control by the detecting step;
A control method characterized by comprising:
(Item 12)
A method for controlling a communication device, the method comprising:
The communication device includes:
a communication means for communicating with an external device via a coaxial cable;
a power supply means that superimposes a power supply on the coaxial cable to supply power to the external device;
Equipped with
The control method includes:
an acquisition step of acquiring noise information regarding power line noise in the external device;
a changing step of changing the communication frequency in the communication means according to the noise information acquired in the acquiring step;
A control method characterized by comprising:

(Other examples)
The present invention provides a system or device with a program that implements one or more of the functions of the embodiments described above via a network or a storage medium, and one or more processors in the computer of the system or device reads and executes the program. This can also be achieved by processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

The invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the following claims are hereby appended to disclose the scope of the invention.

100 sensor unit; 110 coaxial cable; 120 main unit; 104 serializer; 121 deserializer; 126 oscillator

Claims (12)

a communication means for communicating with an external device via a coaxial cable;
a power supply means for supplying power to the external device by superimposing a power supply on the coaxial cable;
detection means for detecting execution of drive control using the power source in the external device;
Changing means for changing the communication frequency in the communication means in response to the detection of the drive control by the detection means;
A communication device comprising: Further comprising storage means for storing a frequency list defining frequencies associated with the type of drive control,
The detection means detects the type of drive control,
The changing means selects a frequency defined in the frequency list based on the type of the drive control detected by the detecting means, and changes the communication frequency to the selected frequency. The communication device according to item 1. The frequency list defines a plurality of frequencies associated with a plurality of combinations of the drive control type and temperature,
The detection means further detects information about environmental temperature in the external device,
The communication device according to claim 2, wherein the changing means selects the frequency specified in the frequency list based on a combination of the type of drive control detected by the detecting means and an environmental temperature. . The communication device according to claim 1, wherein the detection means detects execution of the drive control by detecting a communication error in the communication means. The communication means is characterized in that when a communication error is detected by the detection means, the change means changes the communication frequency, and then makes a retransmission request for the data in which the communication error has occurred. The communication device according to claim 4. The communication device according to claim 1, wherein the changing unit returns the frequency to the pre-change frequency after the execution of the drive control is completed. a communication means for communicating with an external device via a coaxial cable;
a power supply means for supplying power to the external device by superimposing a power supply on the coaxial cable;
acquisition means for acquiring noise information regarding noise on a power line in the external device;
Changing means for changing the communication frequency in the communication means according to the noise information acquired by the acquisition means;
A communication device comprising: The noise information includes the voltage level and frequency of the noise,
8. The communication device according to claim 7, wherein the changing means changes the communication frequency to a frequency excluding a frequency of the noise whose voltage level is a predetermined level or higher. 8. The communication device according to claim 7, wherein the changing unit returns the frequency to the pre-change frequency when the noise information indicates that there is no noise in the power line. 10. The communication device according to claim 1, wherein the changing means changes the communication frequency by controlling the frequency of an oscillator that generates a reference clock of the communication frequency. A method for controlling a communication device, the method comprising:
The communication device includes:
a communication means for communicating with an external device via a coaxial cable;
a power supply means for supplying power to the external device by superimposing a power supply on the coaxial cable;
Equipped with
The control method includes:
a detection step of detecting execution of drive control using the power source in the external device;
a changing step of changing the communication frequency in the communication means according to the detection of the drive control by the detecting step;
A control method characterized by comprising: A method for controlling a communication device, the method comprising:
The communication device includes:
a communication means for communicating with an external device via a coaxial cable;
a power supply means for supplying power to the external device by superimposing a power supply on the coaxial cable;
Equipped with
The control method includes:
an acquisition step of acquiring noise information regarding power line noise in the external device;
a changing step of changing the communication frequency in the communication means according to the noise information acquired in the acquiring step;
A control method characterized by comprising:

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