JPH0620350B2 - Signal processor - Google Patents

Description

The present invention relates to a signal processing device such as a process input / output device and a telemeter device (remote measuring device), and more particularly to a lightning protection structure thereof.

(Prior Art) Conventionally, as a technology in such a field, there is one as shown in FIG. The configuration will be described below.

FIG. 2 is a schematic configuration diagram showing a configuration example of a telemeter device which is a conventional signal processing device.

This telemeter device is a device for indicating or recording an arbitrary amount of value at a remote point, and is equipped with a sensor 1 externally.
This sensor 1 is connected to the apparatus main body 3 by a pair of transmission lines 2. The device main body 3 includes a grounded housing 4, and a housing 4 in which a terminal block 5 having input terminals 5-0 and 5-1 and a signal processing circuit 6 are housed. The input terminals 5-0 and 5-1 are connected to the transmission line 2, and input an external signal transmitted from the sensor 1 through the transmission line 2 to give it to the signal processing circuit 6. The signal processing circuit 6 is a circuit that inputs an external signal and performs various electrical processes.

In this type of device, each input terminal 5-0,5-1
A lightning arrester 7-0, 7-1 such as a varistor is connected between the housing and the housing 4.

The arresters 7-0 and 7-1 have a characteristic that the resistance value suddenly decreases when a high voltage is applied. Therefore, if a high voltage is induced on the transmission line 2 by lightning, the dielectric current will
It flows out to the earth through 7-0,7-1. This eliminates the influence of lightning on the signal processing circuit 6 and protects the telemeter device from lightning.

(Problems to be Solved by the Invention) However, in the device having the above configuration, when the number of sensors 1 is increased and a large number of input terminals 5-0 and 5-1 are provided, the arrester 7-0 is provided for each input terminal. , 7-1, ... are connected to take measures against lightning,
The number of arresters 7-0,7-1, ... increases. Moreover, lightning arrester 7-0,7-
Since the lightning protection measures are implemented only by 1, there is a problem in that a large-capacity device capable of handling high-voltage dielectric lightning is required, which leads to an increase in the size and cost of the entire device.

The present invention provides a signal processing device which solves the problems that the above-mentioned conventional techniques have, that is, the size and cost of the entire device are increased by lightning protection.

(Means for Solving Problems) In order to solve the above problems, the present invention includes a plurality of input terminals connected to a plurality of transmission lines for transmitting an external signal, and a plurality of input terminals formed on a printed circuit board. , A wiring pattern whose one end is connected to the input terminal, and a plurality of external signals which are connected to the other end of the wiring pattern and which are input from the other end, select a specific signal as a control signal, and select the selection signal. A multiplexer circuit for outputting to a signal line; and a signal processing circuit connected to the signal line, for applying the control signal to the multiplexer circuit, and performing a predetermined signal processing on a selection signal sent from the signal line. In the provided signal processing device, the following means are provided. That is, in the present invention, a lightning arrester that is connected between the signal line and the ground and operates for a lightning potential equal to or lower than a certain potential, and a predetermined discharge gap is formed at one end of the wiring pattern. A ground pattern formed on the printed circuit board close to one end and performing aerial discharge with respect to a lightning potential exceeding the constant potential is provided.

(Operation) According to the present invention, since the signal processing device is configured as described above, the ground pattern on the printed circuit board performs aerial discharge between the ground pattern and one end of the wiring pattern against high-voltage inductive lightning,
It works so that the guided lightning flows to the ground. The multiplexer circuit connected to the other end of the wiring pattern, based on the control signal of the signal processing circuit, selects and outputs a specific signal from among the plurality of external signals input to the plurality of input terminals, It functions to reduce the number of lightning arresters connected to the signal line on the output side. Also, the lightning arrester works to discharge low-voltage induced lightning to the ground. This allows
The number of lightning arresters can be reduced and the capacity can be reduced. Therefore, the above problems can be eliminated.

(Embodiment) FIG. 1 is a schematic configuration diagram of a telemeter device which is one of signal processing devices according to an embodiment of the present invention.

This telemeter device has a plurality of external signal output sensors 11-0 to 11-3 on the outside, and each of the sensors 11-0 to 11-3 is connected to the device main body 13 by transmission lines 12-0 to 12-4. Connected with. Here, the transmission line 12-4 is commonly connected to each of the sensors 11-0 to 11-3 and functions as a common line.

The apparatus main body 13 includes a grounded metal housing 14 and the like, and a printed circuit board 15 for mounting a circuit is housed in the housing 14. A terminal block 16 is mounted on the printed board 15. The terminal block 16 has a plurality of input terminals 16-0 to 16-4, and the transmission lines 12-0 to 12-4 are connected to the respective input terminals 16-0 to 16-4.

In the vicinity of the terminal block installation location on the printed circuit board 15,
Conductive wiring patterns 17-0 to 17-4 connected to the input terminals 16-0 to 16-4 and conductive members close to the input terminals 16-0 to 16-4, such as the ground pattern 18, are provided. , Respectively. Each wiring pattern 17-0 to 17-4 is a multiplexer circuit
In addition to being connected to 19, the ground pattern 18 is connected to the housing 14 and grounded.

The multiplexer circuit 19 is a circuit that selects a specific signal from a plurality of external signals from the sensors 11-0 to 11-3 input via the wiring patterns 17-0 to 17-4. A signal processing circuit 21 is connected to the multiplexer circuit 19 via a plurality of signal lines 20-0 to 20-4. Signal processing circuit 21
Is based on the input signal D0 or D1 from the multiplexer circuit 19 input via the signal line 20-0 or 20-1, and performs various electrical processing of those input signals D0 and D1, and
It is a circuit which outputs control signals T0 and T1 and supplies them to the multiplexer circuit 19 via signal lines 20-2 and 20-3. In addition,
The signal line 20-4 functions as a common line.

Each signal line 20-0 to 20-3 has a resistor for suppressing overcurrent.
22-0 to 22-3 are connected in series and each resistor 22-0 to 22-3
Lightning arresters 23-0 to 23-4 such as varistors are connected to the signal processing circuit side and the signal line 20-4. Each arrester
23-0 to 23-4 are connected to the housing 14 and grounded.

FIG. 3 is a circuit diagram of an essential part showing a circuit configuration example of the multiplexer circuit 19 in FIG. This multiplexer circuit 19
Is composed of a diode matrix circuit, and a plurality of diodes 30-0 to 30-2 are connected between the signal lines 20-0 and 20-2 and the wiring pattern 17-0. 22-0,22-
3 and the wiring pattern 17-1, between the signal lines 20-1 and 20-2 and the wiring pattern 17-2, between the signal line 20-1 and 20-3 and the wiring pattern
A plurality of diodes are connected to 17-3, respectively. Signal line 20-4, which is a common line, and wiring pattern 17
-4 are connected to each other and grounded.

4 is a partially enlarged view of the wiring patterns 17-0 to 17-2 ... And the ground pattern 18 in FIG. Wiring pattern 17-0
~ 17-2 ... are formed on the printed circuit board 15 and have one end 17a-0 ~
17a-2 are connected to the input terminals 16-0 to 16-2 of the terminal block 16, and the other end is connected to the multiplexer circuit 19. Furthermore, the wiring patterns 17-0 to 17 on the printed circuit board 15
A ground pattern 18 is formed in the vicinity of one ends 17a-0 to 17a-2 of -2 with a gap (discharge gap) G.
Here, if the distance G is reduced, air discharge is likely to occur. For example, the discharge voltage is about 2.7 KV when the gap G is 0.5 mm. Also, when the discharge is started,
The resistance value at the distance G is significantly reduced.

Next, the operation of the signal processing device configured as above will be described.

(1) General Operation of Signal Processing Device In FIG. 1, the ON / OFF external signals of the sensors 11-0 to 11-3 pass through the transmission lines 12-0 to 12-4 and the input terminal 16 of the terminal block 16 is inputted. -0
When inputted to 16-4, the external signals are divided into groups by the multiplexer circuit 19 controlled by the signal processing circuit 21 and given to the signal processing circuit 21. This allows
The signal processing circuit 21 performs predetermined electrical processing on the input signal.

The operation of the multiplexer circuit 19 in FIG. 3 is as follows.

Of the control signals T0, T1 on the signal lines 20-2, 20-3 output from the signal processing circuit 21 to the multiplexer circuit 19, one control signal T0 is applied from the common signal line 20-4 potential (= 0V). When the other control signal T1 is set to the high level H level and the other control signal T1 is set to the same level L level as the signal line 20-4, the input on the signal line 20-0 output from the multiplexer circuit 19 to the signal processing circuit 21. The potential of the signal D0 is not affected by the ON / OFF of the sensors 11-1 to 11-3, but is affected only by the ON / OFF of the sensor 11-0.
That is, if sensor 11-0 is off, diodes 30-0,3
If the input signal D0 is at H level by 0-1 and the sensor 11-0 is on, the diode 30-0, 30-2 and the sensor 11-0 will be at L level between the diodes 30-0 and 30-1. Therefore, the input signal D0 becomes L level. The same applies to the input signal D1 on the signal line 20-1. When the sensor 11-2 is off, it is set to H level, and when it is on, it is set to L level.

Similarly, when one control signal T0 is set to the L level and the other control signal T1 is set to the H level, the input signal D0 turns on and off the sensor 11-1, and the input signal D1 turns the sensor 11-3. When the sensors 11-1 and 11-3 are turned off, the input signal D0 is set to the H level, and when the sensors 11-1 and 11-3 are turned on, the input signal D0 is set to the L level.

In this way, a plurality of external signals are sent to the multiplexer circuit 19
Since the lightning arresters 23-0 to 23-4 need to be provided only on the signal lines 20-0 to 20-4, the number of external signals is provided as in the conventional case. The number can be reduced compared to. For example, when the number of external signals is m × n, if the multiplexer circuit 19 is configured by m rows × n rows,
The number of lightning arresters is (m + n + 1), which enables lightning protection measures against m × n external signals.

(2) Lightning protection operation of the signal processing device In FIG. 3, when a lightning strike occurs on the transmission lines 12-0 to 12-4, the induced current due to the lightning is input to the input terminals 16-0 to 16-4 and the multiplexer circuit 19 Through the diodes 30-0 to 30-2, and the resistors 22-0 to 22-3, and to the lightning arresters 23-0 to 23-3. Therefore, the diodes 30-0 to 30-2 ... and the resistor 22-0
~ 22-3 is required to have performance suitable for the potential of lightning. Here, the resistors 22-0 to 22-3 suppress the current induced by lightning and act to limit the current flowing through the diodes 30-0 to 30-2. Further, the induced current may flow in the forward direction or the reverse direction with respect to the diodes 30-0 to 30-2 depending on the way of the lightning dielectric.

Therefore, the lightning arresters 23-0 to 23-3 perform lightning protection until a certain lightning potential, and the wiring patterns 17-0 to 17-4 and the ground pattern on the printed circuit board 15 are applied to the induced lightning having a higher potential. Lightning protection is performed by the air discharge between 18 and.
Hereinafter, these lightning protection processes will be described in detail with reference to FIGS. 4 to 6. Note that FIG. 5 is a characteristic diagram of the lightning potential VS, and FIG. 6 is a circuit diagram of essential parts for explaining the operation of FIG.

In Fig. 6, when a positive lightning potential VS is generated at the input terminal 16-0, the induced current is caused by the diodes 30-2, 30-1 →
It flows in the route of resistance 22-0 → lightning arrester 23-0 → ground.
In addition, when a negative lightning potential -VS is generated at the input terminal 16-0, the induced current changes from ground → lightning arrester 23-2 → resistor 22-2 → diode 30.
-0,30-2, flow.

Here, the lightning potential VS rises in the order of μsec as shown in FIG. In the case of a path, assuming that the passing voltage of the arrester 23-0 is V1, the forward potential of the diode 30-1 is V2, and the breakdown voltage of the diode 30-1 is V3, the resistance 22-0
The voltage applied to is VS-V1-V2-V3. An induced current flows in the direction of the path up to a certain voltage (approximately 2700V) of the lightning potential VS.

However, when the voltage exceeds 2700V, as shown in Fig. 4,
Air discharge occurs between the wiring pattern 17-0 to which the input terminal 16-0 is connected and the ground pattern 18, and both patterns 17-0 and 18
The resistance value in between decreases. Therefore, the induced current is
It flows between 17-0 and 18 and flows to the ground, so it stops flowing in the direction of the route. Thereby, the diodes 30-2, 30-1,
The resistor 22-0 and the arrester 23-0 are protected from lightning.

In this way, lightning arresters 23-0 to 23-4 are used for low lightning potential VS.
Due to the high lightning potential VS, the wiring pattern 17-0 to 17
Wiring pattern 17 by air discharge between -4 and ground pattern 18
-To protect the circuits after 0 to 17-4, connect the diodes 30-0 to 30-2 ... of the multiplexer circuit 19 and the resistors 22-0 to 22-3,
It should be considered so that it can withstand only a low lightning potential VS. Therefore, diodes 30-0 to 30-2 ... and resistor 22-0
The capacity of ~ 22-3 can be reduced, and the overall size and cost of the device can be reduced.

The present invention is not limited to the illustrated embodiment, and various modifications such as a circuit configuration other than that of the multiplexer circuit 19 are possible.

(Effects of the Invention) As described in detail above, according to the present invention, the number of external signals input is reduced by the multiplexer circuit, so the number of lightning arresters installed can be reduced. Moreover, since the ground pattern is arranged close to one end of the wiring pattern connected to the input terminal, the lightning arrester is used for a low lightning potential and the discharge between the wiring pattern and the ground pattern is performed for a high lightning potential. The lightning arresting operation is performed by each of the gaps. Therefore, it is possible to reduce the capacity of the constituent elements of the multiplexer circuit and the lightning arrester, and it can be expected that the overall size of the apparatus and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of a signal processing device showing an embodiment of the present invention,
FIG. 2 is a schematic configuration diagram of a conventional signal processing device, FIG. 3 is a circuit diagram of an essential part showing a configuration example of a multiplexer circuit in FIG. 1, and FIG. 4 is a wiring pattern and a ground pattern in FIG. Partially enlarged view, Fig. 5 is characteristic diagram of lightning potential, and Fig. 6 is third
It is a principal part circuit diagram for demonstrating operation | movement of a figure. 11-0 ~ 11-3 ... Sensor, 12-0 ~ 12-4 ... Transmission line, 16-0 ~
16-4 ... Input terminal, 17-0 to 17-4 ... Wiring pattern, 18 ...
… Grounding pattern (conductive member), 19 …… Multiplexer circuit, 21 …… Signal processing circuit, 23-0 to 23-4 …… Lightning arrester.

Claims (1)

[Claims] 1. A plurality of input terminals connected to a plurality of transmission lines for transmitting an external signal, a wiring pattern formed on a printed circuit board and having one end connected to the input terminal, and a wiring pattern of the wiring pattern. A multiplexer circuit connected to the other end and selecting a specific signal by a control signal from the plurality of external signals input from the other end and outputting the selected signal to a signal line; And a signal processing circuit which applies a signal to the multiplexer circuit and performs a predetermined signal processing on a selection signal sent from the signal line, wherein the signal processing device includes a signal processing circuit connected between the signal line and the ground. And a lightning arrester that operates with respect to a lightning potential equal to or lower than a certain potential, and on the printed circuit board close to one end of the wiring pattern so as to form a predetermined discharge gap with respect to the one end. Made is, the signal processing apparatus characterized by a ground pattern for performing atmospheric discharge against lightning position exceeding the predetermined potential provided.