JPH0382098A - Prevention of noise from sometimes occurring in plural electronic devices mutually connected - Google Patents

Abstract

PURPOSE:To eliminate an malfunction, a runaway or an erroneous measurement, etc., generated in electronic circuits such as a controller, a robot, a measurement, etc., by connecting one end of a shield insulated from other in a connection cable to a base point 5 of a ground side in an electronic circuit of either one of a plurality of electronic devices by an electric conductor insulated from the other when the devices are connected to each other. CONSTITUTION:Both ends of a shield 8 in a connecting cable 7 for connecting a plurality of electronic devices 1 are cut at input/output plug sockets 6 to independently insulate base points 5 of electronic circuits 2 at the ground side in the devices 1, only either one of the shield 8 of the state insulated from the other is connected to the base point 5 of the circuit 2 at the ground side in the devices 1 of the same side by electric conductors 10 insulated from the other. The potential of the point 5 of the ground side in the circuit 2 and the potential of the shield 8 are set to the same value.

Description

[Detailed Description of the Invention] Each of the plurality of electronic devices individually generates noise.
Even if the equipment is small, when the guest outputs of a plurality of electronic equipment are connected and used, noise may be generated somewhere in the circuit of each electronic equipment even though the electronic equipment is not malfunctioning. The present invention aims to eliminate this "cause of noise generation" and prevent noise from occurring when a plurality of electronic devices are connected to each other. ``Methods for preventing the occurrence of noise that may occur.''

In conventional electronic equipment, the chassis surrounding the electronic circuit,
Each metal electrical conductor such as a shield, a metal main body case, etc. is connected to the ground side electrical conductor that becomes the ground side of this electronic circuit, and some of the ground sides of each component of the electronic circuit are connected to this metal electrical conductor. By connecting to any of the metal electrical conductors, you can indirectly connect to the ground side of this circuit, and by using the metal electrical conductor to which this part is connected itself as part of the ground side of this circuit, you can It forms the ground side. When connecting the inputs and outputs of multiple electronic devices with grounding circuits like this, connect both ends of the shield of the connecting cable between the devices to a metal piece such as the chassis of each electronic device. The input/output circuit of each electronic device is constructed by connecting the ground side of each circuit indirectly by connecting it to a manufactured electrical conductor.

When using multiple electronic devices like this connected to each other, if another object with a potential different from the potential that each device has with respect to the ground hits the metal electrical conductor of one of the devices. If you approach or touch electronic equipment, and the DC power source of electronic equipment is generated from AC, the potential that the AC side wiring in the V1 unit and the power transformer have with respect to the ground may share this AC power source. If the electrical potential of the ground itself fluctuates at the location where each electronic device is placed, these factors may cause the electrical potential of multiple electronic devices to change. The potential somewhere fluctuates. At this moment, the electrical conductor on the ground side of the electronic circuit in each device passes through the shield of each connection cable connecting multiple electronic devices and the metal electrical conductor of the chassis of each device. The potential also fluctuates in the same way, but during this fluctuation, the "capacitance" that each of the multiple electronic devices has and the "capacitance distributed between the components, wiring, etc. inside the device" etc. A transient current flowing through the capacitance flows within each electronic circuit.

In addition, if multiple electronic devices are grounded at two or more places or directly mounted on a common metal mount, etc., the earth or metal mount, etc. and the ``ground side of each electronic device circuit. ' electrical conductors' form a parallel circuit. When a forced current generated from another source flows into this "earth or metal frame," this forced current also flows in the electrical conductor on the ground side of each electronic circuit. Since the potential of the electrical conductor on the ground side also fluctuates, each component in the circuit,
A transient current that flows through the above-mentioned capacitance, etc. between the wirings, etc. flows in this electronic circuit.

While these currents flowing through each electronic circuit fluctuate, noise is generated somewhere within each electronic circuit.

When designing an electronic circuit, this is the connection point where the ground side of the DC power output is connected to the electrical conductor that becomes the ground side of the electronic circuit, and the ground side of each component, wiring, etc. in the circuit. The circuit is designed on the assumption that there is no potential difference between each connection point, but in the electronic circuit actually used, there is an element in which a relatively large current flows in the electrical conductor on the ground side. When this current flows, a voltage drop occurs in the electrical conductor on the ground side, causing a minute change in the potential at each connection point. In response to this change, the transient current of charging or discharging that flows through the above capacitance flows within this electronic circuit while fluctuating, so the characteristics of this electronic circuit differ from the circuit characteristics at the time of design, and the characteristics at the time of design The difference between the two is amplified within this circuit and appears as noise. Note that noise is generated while the potential of each connection point on the ground side fluctuates due to this fluctuating current, but when this fluctuating current changes to DC current, the potential of each connection point changes due to this minute voltage drop. Although it is stable at the value of , the level of the electronic circuit output changes because the characteristics of the electronic circuit change corresponding to the difference between the potential at each connection point and the potential at the time of design. If the polarity of the potential difference that occurs between the connection point where the ground side of the DC power supply output is connected on this ground side electrical conductor and each connection point where the ground side of other parts, wiring, etc. is connected is reversed. , (if the direction of the current flowing through the ground side is reversed), the direction in which this output level changes will also be reversed.

Therefore, in order to prevent potential differences from occurring at each connection point on the electrical conductor on the ground side of the electronic circuit, one point on the ground side of this DC power output is set as the base point, and each component, wiring, and metal electrical conductor in the electronic device , etc. are connected directly to this base point using an electrical conductor insulated from the others, so that there is no potential difference between each ground point, and each individual electronic device has no noise. Even if multiple electronic devices that no longer generate noise are connected to each other and are used, noise may still be generated. A method for preventing the occurrence of this noise will be described below.

Is there a strong υj current flowing from other sources into the ground or metal mounts surrounding multiple electronic devices that are connected to each other, or does the potential on the AC side of the rectifier circuit that creates the DC power source fluctuate? When the surrounding electric potential etc. fluctuate, noise may be generated somewhere in each circuit of multiple electronic devices due to these fluctuations. However, by simply changing the potential at the base point (5) on the ground side of this electronic circuit (2),
), this electronic circuit (2) can be
This is a method of preventing noise generated in the electronic circuit (2) without affecting the characteristics of the electronic circuit (2). This method will be explained using FIGS. 1, 2, and 3.

Shield (8) inside the connecting cable (7) in Figure 1
A method of bringing the base point (5) on the ground side to the same potential will be explained.

Multiple electronic devices (1) can be connected to each other by cutting both ends of the shield (8) in the connecting cable (7) at the input/output outlet (6). The base point of the ground side of each electronic circuit (2) in 1) (
5) are insulated from each other and made independent, and one end of the shield (8), which is insulated from the other, is connected to the ground in the circuit (2) - of the electronic device (1) on the same side. Connect to the base point (5) on the side with an electrical conductor (10) connected to the other ground. In this way, the potential of the base point (5) on the ground side in the electronic circuit (2) and the potential of the shield (8) become the same potential, and the potential of the shield (8) changes due to other reasons. However, at that moment, the potential at the base point (5) on the ground side changes in the same way, so the core wire (9) of the connection cable (7)
The potential between the shield (8) and the shield (8) remains stable without fluctuation.

In the capacitance distributed between the core wire (9) and the shield (8), only when the potential of the core wire (9) fluctuates, a transient current corresponding to this fluctuation flows through the core wire (9), but on the ground side Since the base point (5) and the shield (8) remain at the same potential, no noise is generated.

In the device (1) in Figure 2, where the DC N source (3) for the electronic circuit (2) in the electronic device (1) is generated from alternating current, this A transient charging or discharging current flows through the capacitance distributed between the alternating current side and each component, metal electrical conductor, etc. inside the device (1), but this article explains how to prevent this transient current from flowing. do.

A shield (13) is placed on the outside of the AC side wiring (12) inside the electronic device (1), and this shield (13) is
Insulate the outside of the Then, a certain negative point of this shield (13) and a base point (5) on the ground side are connected by an electrical conductor (16) insulated from others. Further, the iron core (14) of the power transformer on the AC side is installed insulated from other objects with an insulator (15). And this iron core (14) and the grounding side base point (5)
and are connected by an electrical conductor (16) insulated from the others. In this way, when the potential on the AC side fluctuates, there are This shielding (13) through distributed capacitance
The potential of the shield (13) and the iron core (10) fluctuate, but since the shield (13) and the iron core (14) are each directly connected to the base point (5) on the ground side, the potentials of these three points are the same, and All other objects connected to this base point (5) have the same potential on the ground side.

And, unlike in the past, the potential on the ground side of parts such as metal electrical conductors in electronic equipment (1) no longer varies directly through the capacitance distributed between this ground side and the AC side. Therefore, no potential difference occurs on the ground side of this electronic circuit, and no transient current flows, so no noise is generated.

In Figure 3, each electronic circuit (
The method of setting the base points (5) on the ground side in 2) to the same potential will be explained.

By attaching insulating legs (18) to the electronic device (1), the device (1) is insulated from the measuring table (19) and other objects around it. Then, attach a base terminal (17) insulated from other parts to an appropriate location on the electronic device (1), and connect this base terminal (17) and the ground side base point (5) inside the electronic device (1) to other parts. and an insulated electrical conductor (21). And multiple electronic devices made in this way (1
) to the base terminal (17) of any one of the electronic devices (1) of the base terminals (17) of (22) to connect each separately. Now multiple electronic devices (1)
In addition to making each base point (5) in each of them the same potential, conventionally the ground sides of the input/output circuits of multiple electronic devices (1) were connected with the shield (8) of the connecting cable (7). However, in the present invention, as a result, one end of this shield (8) is cut off, so by connecting these base point terminals (17) to each other, each base point (5) on each device (1) can be connected. This constitutes the ground side of each input/output circuit.

As mentioned above, each of the plurality of electronic devices (1) is insulated from the surroundings, and only one end of the shield (8) of each connection cable (7) is connected to the grounding point (5), so that forced current from others The current is no longer divided into each device (1).

And equipment (1) that generates DC power (3) from alternating current.
Now, by shielding (13) this AC side wiring (12) and connecting this shield (13) and the iron core (10) of the power transformer to the base point (5), this base point (5)
) and everything connected to it has the same potential as this shield (13) and iron core (14), so even if the potential on the AC side changes, only the potential at the base point (5) changes, and the electronic equipment The potential of each quantity in (1) is stable and does not fluctuate. In addition, each base point (5) on the ground side of multiple electronic devices (1)
) and each of the other base terminals (
17) are connected individually, even if the potential of the base point (5) in any electronic device (1) fluctuates due to other reasons, it will be connected through each base point terminal (17) at this moment. Since the base point (5) of each device (1) has the same potential, unlike the conventional case where the ground side of each electronic device (1) was connected with the shield (8) of the connection cable (7), the connection cable(
7), the potential applied to the capacitance distributed between the core wire (9) and the shield (8) no longer fluctuates. By doing these things, it becomes possible to prevent noise from occurring within the electronic circuit. Although it is impossible to eliminate distributed capacitance, if the potential applied to this distributed capacitance does not change, the transient current of charging or discharging will not flow, so it is the same as if this capacitance does not exist, which causes noise. This is because there will be no more. In conventional electronic equipment (1), a potential difference occurs between the output of the DC power supply (3) and the ground side of each connected load, which results in fluctuations in the voltage of this DC power supply (3) and generates noise. However, in the method of the present invention,
A point on the ground side of the output of the DC power supply (3) is used as a base point (5), and the ground side of each load and one point of each metal electrical conductor are connected to this base point (5), thereby generating a potential difference on this ground side. In addition to eliminating this, even if the potential anywhere on the ground side of this device (1) fluctuates due to other causes, each base point (5) will have this fluctuated potential, and the potential above the base point (5) will Since the voltage of the DC power supply (3) is applied independently to the voltage of the DC power supply (3), the voltage of the DC power supply (3) of this circuit (2) remains stable and does not fluctuate. Furthermore, since no transient current flows through the capacitors distributed within this device (1), no noise is generated. This is the biggest difference from conventional electronic devices, as well as its biggest feature.

If the method of the present invention is implemented when a plurality of electronic circuits are used in combination, it will be possible to improve control over equipment, robots, measurement,
The effects of this implementation are very large, since it is possible to eliminate extremely dangerous phenomena such as malfunctions of unknown causes and irreproducibility, runaways, and erroneous measurements that occur in electronic circuits.

[Brief explanation of drawings]

Figure 1 Connection diagram for making the shield and base point of the connection cable the same potential Figure 2 Connection diagram for bringing the AC side shield and core of the DC power supply and the base point to the same potential Figure 3 Various components in multiple electronic devices Connection diagram to make the potentials of the base points the same Electrical device Electronic circuit DC power supply Ground side of DC power output Base point on the ground side Outlet connection for input/output Cable shield connection of the connection cable Electrical conductor insulated from the core wire of the cable Power supply side AC Side wiring AC side wiring shield power transformer iron core Power transformer installation is for electrical conductor base terminal insulated with other insulators foot made of insulator Measuring stand Earth 1 electrical conductor insulated with others 2 electrical conductor insulated with others

Claims (3)

[Claims] (1) When connecting multiple electronic devices (1) to each other, connect one end of the insulated shield (8) in this connection cable (7) to the electronic device of either device (1). This shield (
8) and the base point (5) at the same potential. A method for preventing noise that may occur in a plurality of electronic devices connected to each other. (2) In electronic equipment (1) that creates a DC power supply (3) from AC, this AC side wiring shield (13)
and the iron core (14) of the power transformer are each connected to the base point (5) on the ground side in the electronic circuit (2) using an electrical conductor (16) insulated from the other, and this shield (1)
3) A method for preventing the occurrence of noise that may occur in a plurality of electronic devices connected to each other, characterized by making three points, the iron core (14) and the base point (5), at the same potential. (3) Each electronic circuit (2) in multiple electronic devices (1)
) to any one of the base terminals (17) connected to the base point (5) on the ground side of (2
A plurality of electronics connected to each other are characterized in that by connecting each one individually using 2), all of the base points (5) on the ground side in the plurality of devices (1) are made to have the same potential. A method to prevent noise that may occur within equipment.