JP2001007743A - Data communication system and terminal equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data communication system which can be easily and inexpensively installed with simple constitution for preventing deterioration of communication quality or the generation of radio failures due to generation of noises. SOLUTION: Plural terminal equipment 21-1 to 21-n connected via power source lines 100 and 101 with each other so that data signals can be transmitted via the power source lines 100 and 101 are connected via filter art 11 with a commercial power source 2. The filter part 11 allows the voltage of the commercial power source 2 to pass, and interrupts the data signal. In each terminal equipment 21-2 to 21-n, its own voltage monitoring part transmits a control signal for indicating whether or not the absolute value of a power supply voltage is less than a prescribed threshold to its own signal processing part, and its own signal processing part transmits and receives the data signal when the absolute value of the power supply voltage is less than the threshold, so that its own input and output part wound prevent power supply voltage from being erroneously impressed to its own signal processing part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a data communication system and a terminal device, and more particularly to a data communication system for performing data communication through a power line.

[0002]

2. Description of the Related Art Usually, when a network is constructed by connecting a plurality of terminal devices to each other by wire communication, a dedicated communication line for connecting the plurality of terminal devices has been laid. For this reason,
When constructing a network, a power supply line for driving a terminal device and a communication line have been separately laid.

[0003]

However, when the communication line and the power supply line are laid independently of each other, the hardware configuration for realizing the network has been complicated. In addition, installation work for realizing such a configuration is also complicated, which has been a factor that increases the cost of network construction.

On the other hand, in wired communication, data propagates over a communication line in the form of an electric signal. Therefore, if the power of the electric signal is large, noise is generated due to distortion of the electric signal. The noise may cause radio interference that affects the operation of the external device, and lowers the signal-to-noise ratio of the signal to be transmitted (that is, degrades the communication quality).

[0005] The present invention has been made in view of the above situation, and has as its object to provide a data communication system which can be installed easily and at low cost with a simple configuration. Also,
A second object of the present invention is to provide a data communication system in which deterioration of communication quality and occurrence of radio interference due to generation of noise are suppressed.

[0006]

In order to achieve the above object, a data communication system according to a first aspect of the present invention comprises a plurality of terminals including communication means for transmitting and / or receiving a data signal; It is connected to an external AC power supply that supplies AC power, is connected to each of the terminals via a power supply line, substantially prevents the data signal from propagating to the AC power supply, and reduces the AC power. Data signal removing means for supplying to each of the terminals, wherein each of the terminals is connected to the power supply line during a period in which a voltage supplied from the power supply via the power supply line satisfies a predetermined condition. At least one of transmission and reception of the data signal via the PC.

According to such a data communication system,
Since the power supply line serves as both the communication line and the power supply line, the hardware configuration is simplified, and the installation work is also simple and low cost. Further, if each terminal transmits and receives a data signal by selecting a timing at which the impedance of the AC power supply increases based on the value of the AC voltage generated by the AC power supply, the power of the data signal is reduced, Generation of noise is suppressed, and occurrence of radio interference and deterioration of communication quality are prevented.

Each of the terminals is provided with a determining means for determining whether or not the absolute value of the AC voltage generated by the AC power supply is smaller than a predetermined voltage threshold value. When it is determined that the voltage is smaller than the predetermined voltage threshold, at least one of data signal reception and transmission is performed via the power supply line, and when it is determined that the voltage is not smaller, reception or transmission of the data signal is stopped. Means may be provided. In this case, each terminal transmits and receives a data signal by selecting a timing at which the impedance of the AC power supply becomes high. Therefore, as a result of reducing the power of the data signal, generation of noise is suppressed, and occurrence of radio interference and deterioration of communication quality are prevented.

[0009] Each of the terminals is connected between the power supply line and the transmission / reception control means, and substantially shuts off supply of the AC voltage to the transmission / reception control means, and passes the data signal. The provision of the voltage removing means prevents a situation in which the voltage of the AC power supply is erroneously applied to each terminal and each terminal is destroyed.

The transmission / reception control means may include:
When the absolute value of the AC voltage is smaller than a predetermined voltage threshold and the AC voltage has a predetermined polarity, at least one of data signal reception and transmission is performed via the power supply line. It may be something. Thus, each terminal determines whether to transmit and receive a data signal according to the polarity of the voltage of the AC power supply. Therefore, if terminals that exchange data with each other perform transmission and reception of data signals at the same timing and perform the distribution of each terminal,
Data is exchanged smoothly and efficiently.

The terminal device according to a second aspect of the present invention is connected to an AC power supply via a power supply line, and is connected to the power supply line during a period in which an AC voltage supplied from the AC power supply satisfies a predetermined condition. A terminal device that performs at least one of reception and transmission of a data signal through, a determination unit that determines whether an absolute value of the AC voltage is smaller than a predetermined voltage threshold, and the determination unit includes: When it is determined that the absolute value of the AC voltage is smaller than a predetermined voltage threshold, at least one of reception and transmission of the data signal is performed through the power supply line. Or transmission / reception control means for stopping transmission.

Such a terminal device transmits and receives a data signal by selecting a timing at which the impedance of the AC power supply becomes high. Therefore, as a result of reducing the power of the data signal, generation of noise is suppressed, and occurrence of radio interference and deterioration of communication quality are prevented.

[0013] The terminal device is connected between the power supply line and the transmission / reception control means, and substantially cuts off supply of the AC voltage to the transmission / reception control means, and passes the data signal. The provision of the voltage removing means prevents a situation in which the terminal device is erroneously applied with the voltage of the AC power supply and the terminal device is destroyed.

[0014] The transmission / reception control means may include:
When the absolute value of the AC voltage is smaller than a predetermined voltage threshold and the AC voltage has a predetermined polarity, at least one of data signal reception and transmission is performed via the power supply line. It may be something. Thus, the terminal device determines whether to transmit and receive a data signal according to the polarity of the voltage of the AC power supply. Therefore,
If a plurality of terminal devices are distributed so that terminal devices that exchange data with each other transmit and receive data signals at the same timing, data exchange can be performed smoothly and efficiently.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A data communication system according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a configuration of a data communication system according to an embodiment of the present invention.

As shown in FIG. 1, the data communication system 1 includes a pair of power supply lines 100 and 101, a filter unit 11, and n (where n is a natural number of 2 or more) terminal devices 21-1 to 21-1. 21-n.

A pair of power supply lines 100 and 101 are connected to a pair of output terminals of the filter unit 11 described later and each terminal device 2.
Both ends of each of 1-1 to 21-n are connected one-to-one.
The filter unit 11 includes a pair of input terminals and a pair of output terminals. The input terminals are connected one-to-one to both poles of an external commercial power supply 2 that supplies single-phase AC power. Lines 100 and 101 are connected one-to-one.

The frequency of the single-phase AC voltage Vc generated by the commercial power supply 2 is, for example, 50 Hz or 60 Hz. The commercial power supply 2 includes a filter unit 11 and a power supply line 1
00 and 101, each terminal device 21-1 to 21-
n is supplied with single-phase AC power. In addition, each terminal device 21
-1 to 21-n are connected to the power supply line 100 as described later.
, And 101 to each other.

The filter section 11 allows a signal in the frequency band of the single-phase AC voltage Vc generated by the commercial power supply 2 to pass therethrough, and prevents a later-described data signal propagating on the pair of power supply lines 100 and 101 from passing therethrough. Performs the function of a low-pass filter. Specifically, the filter unit 11 includes, for example, a pair of inductors connected so as to connect each input terminal and each output terminal of the filter unit 11 on a one-to-one basis, and a capacitor connected between the input terminals. It is composed of

The terminal devices 21-1 to 21-n are connected to each other via power lines 100 and 101 to form a network. Then, the power supply lines 100 and 10
1 to mutually transmit data.

Each of the terminal devices 21-1 to 21-n is a rectifying load type device. That is, each of the terminal devices 21-1 to 21-21
-N rectifies the voltage Vc of the commercial power supply 2 from AC to DC, and drives each of them with the DC power obtained by the rectification.

The terminal devices 21-1 to 21-n have substantially the same configuration. The terminal device 21-1
As shown in FIG. 2, the CPU (Central Processing Uni
t) 40, a transmission / reception unit 41, an AC connector 42, and a power supply unit 43.

The CPU 40 exchanges data with another terminal device by controlling the transmission / reception unit 41.
The entire operation of the terminal device 21-1 is controlled.

The AC connector 42 connects the power supply lines 100 and 101 and both poles of the power supply unit 43 one to one.
The power supply lines 100 and 101 are connected to the transmission / reception unit 41.

The power supply unit 43 includes a bridge-type full-wave rectifier circuit composed of a diode, a smoothing capacitor, and the like, and rectifies the single-phase AC voltage Vc supplied from the commercial power supply 2 via the AC connector 42. The DC voltage is generated by smoothing, and the obtained DC voltage is supplied to each unit of the terminal device 21-1.

The transmission / reception unit 41 includes power supply lines 100 and 1
The terminal transmits and receives a data signal representing data to and from another terminal device via the terminal 01, and includes a voltage monitoring unit 53, a signal processing unit 54, and an input / output unit 52.

[0027] The voltage monitor 53 is provided with a voltage Vc of the commercial power supply 2.
Is smaller than a predetermined voltage threshold value + Vth (specifically, a predetermined value that is about one-half of the maximum value of the voltage Vc), and a control signal indicating the result of the determination is signaled. The information is transmitted to the processing unit 54.

The signal processing unit 54 controls transmission and reception of the data signal and processes the data signal. According to the control signal transmitted from the voltage monitoring unit 53, the signal processing unit 54 is in one of a communication enabled state and a communication stopped state. Take.

More specifically, when the control signal indicates that the absolute value of the voltage Vc of the commercial power supply 2 is smaller than the voltage threshold value + Vth, the signal processing unit enters a communicable state (ie, transmits a data signal). Or, a process of waiting for communication when there is no data to be received or transmitted is performed). On the other hand, in other cases, the signal processing unit 54 is in a communication stop state, interrupts the transmission of data that has already been performed, and does not start transmission of new data.

Further, the signal processing unit 54 converts a data signal to be transmitted from a digital format to an analog format, and converts the converted signal into the power supply lines 100 and 101 via the input / output unit 52 when the signal is communicable. Send to.

The signal processing unit 54 is connected to the power line 10
A data signal supplied from 0 and 101 via the input / output unit 52 is received, the data signal is analyzed, and it is determined whether or not the data signal is transmitted to itself. When it is determined that the data signal is transmitted to itself, the data signal is transferred to the CPU 40. When it is determined that the data signal is not transmitted to itself, it waits for the next data signal to be transmitted.

The input / output unit 52 is connected between the power supply lines 100 and 101 and the signal processing unit 54 via the AC connector 42, and a signal in the frequency band of the commercial power supply 2 is supplied to the signal processing unit 54. Is substantially prevented, and the signal processing unit 5
4 transmits and receives the data signal.

The input / output unit includes, for example, a high-pass filter including a first capacitor C81, a second capacitor C82, and an insulating transformer 80 as shown in FIG. The insulating transformer 80 includes a primary winding and a secondary winding,
One end of the primary winding is connected to the power supply line 100 via a capacitor C81, and the other end of the primary winding is connected to a capacitor C82.
, And both ends of the secondary winding are connected to the signal processing unit 54.

Next, the operation of the data communication system will be described. When the commercial power supply 2 generates the single-phase AC voltage Vc, the voltage Vc is applied between the power supply lines 100 and 101 via the filter unit 11. Power line 10
The voltage Vc applied between 0 and 101 is supplied to the power supply unit 43 of each of the terminal devices 21-1 to 21-n.

The voltage Vc of the commercial power supply 2 supplied to the power supply unit 43 is rectified, and the rectified voltage is smoothed by a smoothing capacitor and converted into a DC voltage Vd having a waveform shown in FIG. . This DC voltage Vd is
1 are supplied to each device.

More specifically, the terminal device 21-
1 to 21-n, when the absolute value of the instantaneous value of the voltage Vc supplied to its own power supply unit 43 is larger than the DC voltage Vd (sections A to B, C to C in FIG. 3A). D
At the timing shown as), electric power is supplied from the commercial power supply 2. On the other hand, the absolute value of the instantaneous value of
d (sections B to C, D in FIG.
(A to A), the power stored in the capacitors is supplied by discharging the smoothing capacitors included in the respective power supply units 43.

Therefore, the power supply line 100 is
And 101, the supply current Io supplied to the terminal devices 21-1 to 21-n has a pulse-like waveform as shown in FIG. That is, the absolute value of the current Io is substantially 0 during a period when the absolute value of the instantaneous value of the voltage Vc is smaller than the DC voltage Vd, and is equal to the difference between the absolute value of the instantaneous value of the voltage Vc and the voltage Vd during other periods. Substantially proportional.

In the section where the supply current Io flowing through the power supply lines 100 and 101 is substantially zero, the impedance of the commercial power supply 2 at the frequency of the voltage Vc increases compared to other sections, and therefore the power supply lines 100 and 101 The impedance between them also increases. For this reason, the terminal device 21-
Power supply lines 100 and 101 transmitted from 1 to 21-n
Is prevented from flowing to another external power supply line via the commercial power supply 2, and distortion of the voltage waveform of the data signal is suppressed. Further, data can be transmitted using a data signal having a small current value and a small voltage value.

On the other hand, the input / output unit 52 substantially prevents the voltage Vc of the commercial power supply 2 supplied to the transmission / reception unit 41 from being applied to the signal processing unit 54.

Next, the procedure of data transmission by each of the terminal devices 21-1 to 21-n will be described. In FIG. 2, an arbitrary terminal device as a transmission source (hereinafter, the transmission source is assumed to be a terminal device 21-1 for easy understanding)
It is assumed that a request to transfer data to an arbitrary terminal device (for example, the terminal device 21-n) as a transmission destination is given from outside.

At this time, the signal processing unit 54 of the terminal device 21-1 acquires a digital data signal representing data to be transferred from the CPU 40 of the terminal device 21-1.
The data signal is converted from a digital format to an analog format. The signal processing unit 54 is connected to the terminal device 2
When communication becomes possible in response to the control signal transmitted from the voltage monitoring unit 53 of 1-1, the analog data signal obtained by the conversion is sent to the input / output unit 52 of the terminal device 21-1. Supply.

Next, the operation of the voltage monitoring unit 53 of each of the terminal devices 21-1 to 21-n will be described. FIG. 4A shows a waveform of the absolute value of the voltage Vc of the commercial power supply 2, and FIG.
FIG. 7 is a schematic waveform diagram illustrating a waveform of a control signal generated by a voltage monitoring unit 53.

When the voltage monitoring unit 53 determines that the absolute value of the voltage Vc of the commercial power supply 2 is smaller than the voltage threshold + Vth in, for example, the sections B to C and the sections D to A, for example, TT
A high-level voltage in an L (Transistor-Transistor Logic) logic element is transmitted to the signal processing unit 54 as a control signal (communication period t1). In response to this control signal,
The signal processing unit 54 makes itself communicable.

On the other hand, for example, the voltage monitoring section 53
If it is determined that the absolute value of the voltage Vc is equal to or higher than the voltage threshold value + Vth in B or the sections C to D, for example, a low-level voltage in the TTL logic element is transmitted to the signal processing unit 54 as a control signal (communication stop). period). In response to this control signal, the signal processing unit 54 sets itself in a communication stopped state.

As described above, the voltage monitoring unit 53 transmits the control signal indicating the magnitude relationship between the absolute value of the voltage Vc of the commercial power supply 2 and the voltage threshold value + Vth to the signal processing unit 54. The signal processing unit 54 switches to one of the communication enabled state and the communication stopped state according to the control signal.

On the other hand, when the absolute value of the voltage Vc of the commercial power supply 2 is smaller than the voltage threshold value + Vth, that is, when the signal processing units 54 of the terminal devices 21-1 to 21-n are in a communicable state, Each signal processing unit 54 supplies the data signal converted into an analog format to the input / output unit 52 connected thereto.

The data signal supplied to the input / output unit 52 of each of the terminal devices 21-1 to 21-n is transmitted to the terminal device 21-1.
21-n to the power supply lines 100 and 101 via the input / output unit 52 and the AC connector 42. Input / output unit 52 and signal processing unit 54 of each terminal device 21-1 to 21-n
The impedance between the connection points is a value enough to pass a signal belonging to the frequency band of the data signal as viewed from the signal processing unit 54. For this reason, each of the terminal devices 21-1 to 21-2
The 1-n input / output unit 52 does not substantially prevent the passage of the data signal.

At the frequency of the data signal, the impedance at the connection point between the filter unit 11 and the power supply lines 100 and 101 is a sufficiently large value when viewed from the power supply lines 100 and 101. For this reason, the data signal propagating on the power supply lines 100 and 101 is substantially prevented from leaking to the commercial power supply by the filter unit 11. As a result, a situation where the data signal leaks to the commercial power supply 2 and further propagates to the external device connected to the commercial power supply 2 is prevented.

On the other hand, a data signal propagating on the power supply lines 100 and 101 is transmitted via the AC connector 42 and the input / output unit 52 of each of the terminal devices 21-1 to 21-n to each of the terminal devices 21-1 to 21-n. n signal processing units 54.
The signal processing unit 54 of each of the terminal devices 21-1 to 21-n obtains and analyzes the data signal supplied to each of the terminals 21-1 to 21-n in the communicable state, and determines whether each signal is a signal transmitted to itself. I do. When it is determined that the signal is transmitted to itself, the data signal is transferred to the CPU 40 connected thereto (that is, the data signal is received). When it is determined that the signal is not the signal addressed to itself, it waits for the next data signal to be supplied.

As described above, each terminal device 21-
Each of 1 to 21-n determines whether the signal received by itself is a signal transmitted to itself, and performs reception processing of the signal addressed to itself.

The commercial power source 2 and the signal processing unit 54
It is substantially insulated by the input / output unit 52. Therefore, when a DC overcurrent occurs in the power supply lines 100 and 101, each of the terminal devices 2
Leakage to the signal processing units 54 of 1-1 to 21-n is prevented, and the terminal devices 21-1 to 21-n are protected.

As described above, according to the data communication system of this embodiment, data can be transmitted through the power supply lines 100 and 101 without separately laying a communication line. Therefore, a low-cost data communication system with a simple configuration is constructed. In addition, since data communication can be performed using a signal with low power, a data communication system with little noise and little influence of noise on a signal is constructed even in high-speed communication with a baud rate of about several tens of kbps.

Incidentally, the data communication system of the present invention
The present invention is not limited to the above embodiment. For example, the number of terminal devices is arbitrary, and the format of the data signal created by the signal processing unit 54 is also arbitrary.

Further, among the terminal devices 21-1 to 21-n, those having different communication periods may be included. Therefore, as shown in FIG.
−A is the voltage V of the commercial power source 2 during the communication period t1.
When c has a positive polarity (communication period t2), communication becomes possible, and the terminal device 21-B sets the voltage Vc of the commercial power supply 2 during the communication period t1 to a negative polarity (communication period t3).
May be set to be in a communicable state. (However, the terminal devices 21-A and 21-B are the terminal devices 21-1 to 21-2.
1-n, two different terminal devices. )

According to this configuration, the plurality of terminal devices are sorted such that the terminal devices that exchange data with each other can communicate with each other at the same timing.
Data can be exchanged more smoothly and efficiently.

[0056]

As described above, according to the present invention, a data communication system which can be easily installed at a low cost with a simple configuration is realized. Further, according to the present invention, a data communication system in which deterioration of communication quality and occurrence of radio interference due to generation of noise are suppressed is realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a data communication system according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a configuration of a terminal device according to the embodiment of the present invention.

FIG. 3 is a graph showing waveforms of a DC voltage and a supply current supplied to a terminal device.

FIG. 4 is a graph showing a waveform of an absolute value of a voltage of a commercial power supply and a waveform of a control signal.

FIG. 5 is a graph showing communication periods of a plurality of terminal devices.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Data communication system 2 Commercial power supply 11 Filter part 21-1 to 21-n Terminal device 40 CPU 41 Transmission / reception part 42 AC connector 43 Power supply part 52 Input / output part 53 Voltage monitoring part 54 Signal processing part 80 Insulation transformer 100, 101 Power supply line C81, C82 Capacitor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shiro Fujiwara F-term (reference) 5K038 AA01 AA07 AA09 CC10 DD09 DD21 5K046 AA03 BA01 5-11-11 Higashi-Nippori, Arakawa-ku, Tokyo BB04 BB05 CC18 PP01 PS03 PS13 PS22 PS24 PS31 PS42 PS43 PS53 YY01

Claims (7)

[Claims] A plurality of terminals provided with communication means for transmitting and / or receiving data signals; and a plurality of terminals connected to an external AC power supply for supplying AC power, and connected to each of the terminals via a power supply line. Substantially preventing the data signal from propagating to the AC power source;
A data signal removing unit that supplies the AC power to each of the terminals, wherein each of the terminals performs a period in which a magnitude of a voltage supplied from the power supply via the power supply line satisfies a predetermined condition. Performing at least one of transmission and reception of the data signal via the power supply line. 2. The terminal according to claim 1, wherein said terminal determines whether an absolute value of an AC voltage generated by said AC power supply is smaller than a predetermined voltage threshold value, and said determining unit determines an absolute value of said AC voltage. When it is determined that the value is smaller than the predetermined voltage threshold, at least one of reception and transmission of the data signal is performed via the power supply line, and when it is determined that the value is not smaller, the reception or transmission of the data signal is stopped. The data communication system according to claim 1, further comprising: transmission / reception control means. 3. Each of the terminals is connected between the power supply line and the transmission / reception control means, substantially interrupts supply of the AC voltage to the transmission / reception control means, and passes the data signal. The data communication system according to claim 2, further comprising a power supply voltage removing unit that causes the power supply voltage to be removed. 4. The transmission / reception control means, wherein the determination means comprises:
When the absolute value of the AC voltage is smaller than a predetermined voltage threshold and the AC voltage has a predetermined polarity, at least one of data signal reception and transmission is performed via the power supply line. The data communication system according to claim 2 or 3, wherein: 5. A power supply line connected to an AC power supply,
A terminal device that performs at least one of reception and transmission of a data signal via the power supply line during a period in which an AC voltage supplied from the AC power supply satisfies a predetermined condition, wherein an absolute value of the AC voltage is a predetermined value. Determining means for determining whether or not the voltage is smaller than a voltage threshold; and when the determining means determines that the absolute value of the AC voltage is smaller than a predetermined voltage threshold, a data signal is transmitted via the power supply line. And a transmission / reception control means for stopping reception or transmission of a data signal when it is determined that the reception is not small. 6. A power supply voltage removing means which is connected between said power supply line and said transmission / reception control means, substantially cuts off supply of said AC voltage to said transmission / reception control means, and passes said data signal. The terminal device according to claim 5, comprising: 7. The transmission / reception control means, wherein the determination means comprises:
When the absolute value of the AC voltage is smaller than a predetermined voltage threshold and the AC voltage has a predetermined polarity, at least one of data signal reception and transmission is performed via the power supply line. The terminal device according to claim 5, wherein: