JPS62250743A - Return signal generating circuit - Google Patents

Abstract

PURPOSE:To prevent the occurring of an unnecessary pulse with a long pulse width at the time of the initial time of communication by charging a smooth capacitor through the third resistance, applying the voltage through a diode to the connecting point of the first and second resitances through a diode and separating the smooth capacitor and an NPN transistor. CONSTITUTION: When the circuit is composed of the first NPN transistor TR4 to connect an emitter at the negative side of a diode bridge DB1, the third resistance R9 to connect it at the positive side, a smooth capacitor C1 to connect between other edge and the emitter of the TR4, a diode D4 to connect a cathode to the connecting point of the first and second resistances R7 and R8 and an anode to the connecting point of the R9 and the C1, a photocoupler PC2 to connect a photodiode D3 between the connecting point of the R7 and the R8 and the base of the TR4, and a switching element TR3 to connect directly with a light emitting diode D2 and turn on and off in accordance with the level of the return signal, the connecting points of the R7 and the R8 and the connecting points of the R9 and the C1 are separated by the D4 until the C1 is sufficiently charged, in the initial time of the communication with a master device, even when the voltage of the C1 is low, the base electrtic potential of an NPN transistor TR2 is not made lower by being influenced by this and the pulse width of an unnecessary pulse can be made narrower.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a remote control system that performs digital cyclic signal transmission between a parent device and a plurality of terminal devices using a moving electric path such as a trolley bus duct or a conductor such as a wiring duct. This invention relates to a return signal generation circuit installed in a terminal device of a multiplex transmission device.

[Background technology]

The transmission method in this remote multiplex transmission device is a cyclic time division method. This is a method in which a fixed address is given to each terminal device, and the parent device and each terminal device sequentially and cyclically transmit and receive pulse signals.

To explain with reference to FIG. 2, first, the master device P performs transmission and reception with the terminal device L, then transmits and receives with the terminal device 2, and then the terminal device 3.4°...・・・・・・、
Transmission and reception are performed sequentially between N-1 and N, and then terminal device 1
．． 2. . . . . , N will be cyclically and time-divisionally transmitted.

FIG. 3 shows a block diagram of the parent device P and the terminal device, for example 1. In this diagram, Pl is a multiplex transmission processing circuit, P2 is a multiplex transmission output circuit, P3 is a multiplex transmission input circuit, P4 is an abnormality detection circuit, IA is a multiplex transmission processing circuit, IB is a multiplex transmission detection circuit, IC is a reply signal generation circuit, ID is an on/off signal input circuit, IE is an on/off signal output circuit, and 1F is an abnormality detection circuit. LN is a signal line.

Below, based on this diagram, one terminal device 1 with a parent device P
I will explain the operation when sending and receiving data.

Multiplex transmission processing circuit (including microcomputer) Pl
The control signal (monitoring signal) to the terminal device 1 generated by
is converted into a pulse signal of a certain voltage by the multiplex transmission output circuit P2, and after being subjected to noise countermeasure processing (for example, giving a slope to the rise and fall of the pulse), it is output to the signal line LN. . This pulse signal is input to the multiplex transmission detection circuit IB of the terminal l, and after conversion, is input to the multiplex transmission processing circuit IA. The multiplex transmission processing circuit IA determines whether the signal is a signal addressed to the unique address of its own terminal device 1. If they match, and if they are control signals, the control contents are output to the on/off signal output circuit IE, and the on/off signal output circuit IIF drives relays, transistors, etc., and outputs them to the outside.

In the case of monitoring input, turn on/off information from the outside
The off signal input circuit 1D inputs the signal and outputs it to the multiplex transmission processing circuit IA. The multiplex transmission processing circuit IA transmits the control contents carried out by itself (the contents outputted to the on/off signal output circuit I) or the monitoring contents (the contents inputted from the on/off signal input circuit LD) to the reply signal generation circuit IC. It is sent back to the parent device P as a current pulse signal. The parent device P inputs the current pulse signal from the terminal device I through the multiplex transmission input circuit P3, converts it, and outputs it to the multiplex transmission processing circuit p. In addition,
During the response period, the parent device P connects a pair of signal lines 1. ,Il,,
A voltage is applied between them.

As described above, the parent device P performs transmission and reception with each of the terminal devices l to N.

Incidentally, the abnormality detection circuit P4 of the parent device P detects an abnormality (an overcurrent return, a signal line short circuit, etc.) from, for example, the terminal device 1 that is input to the multiplex transmission processing circuit P3.

Further, the abnormality detection circuit IF of the terminal device 1 detects a short circuit or an open circuit of the signal line LN. Further, the signal voltage sent through the signal line LN is about 60 to 200V.

As shown in FIG. 4, the reply signal generation circuit of the terminal device in the remote multiplex transmission device as described above has terminals s connected to the two signal lines 1, 12 constituting the signal line LN in FIG.
, , s2 are connected to a constant current switch circuit I, and
Constant current switch circuit depending on the level of reply signal RET■
It consists of a control circuit that turns on/off the

In the above reply signal generation circuit, the constant current switch circuit ■
An NPN transistor TR and a resistor R1 are connected in series to the DC end of the diode bridge DB, and a resistor R2 and a Zener diode ZD are connected to the DC end of the diode bridge DB.

A series circuit of the resistor R2 and the Zener diode ZD is connected to the base of the NPN transistor TR, and terminals s, s2 are provided at the AC end of the diode bridge DB.

The control circuit "is a resistor R3 and a phototransistor Q of a photocoupler PC1 at the DC end of the diode bridge DB.
1 series circuit is connected, and N is connected to the Zener diode ZD.
A PN transistor TR2 is connected in parallel with a resistor R3 and a phototransistor Q.

In addition to the circuit whose connection point is connected to the base of the NPN transistor TR2, a switch element T consisting of a resistor R4 connected to the terminal F to which the power supply voltage vE is applied, a light emitting diode D1 of the photocoupler PC1, and an NPN transistor.
R3 are connected in series, one end of a resistor R5 is connected to the input terminal of the reply signal RET, and the other end of the resistor R5 is connected to the base of the switch element TR3. In addition,
The emitter side of the switch element TR3 is grounded.

When the reply signal RET input from the input terminal E is at a high level, the switch element 1' R1 of the control circuit H is turned on, the light emitting diode D1 of the photocoupler PC is turned on, and the phototransistor Q1 is turned on, so that the NP
N transistor TR2 is turned off, NPN transistor TR becomes active, a constant current circuit is formed by NPN transistor TR, Zener diode ZD, and resistor R1, and the current flows through diode bridge DB in constant current switch circuit I. A reply signal current corresponding to the high level of the reply signal RET flows from the terminals s, , s2 to the parent device P through the signal lines tt, , i2.

Furthermore, when the above-mentioned reply signal RET is at a low level, NP
N transistor TR, is turned off, but NPN transistor TR2 of control circuit (■) is turned on, so resistor R2
Since current flows through the diode bridge DB in the constant current switch circuit I.

A pair of signal lines ll are connected from the terminals sl and s2 via the terminals sl and s2.

12, a low level return signal current flows to the parent device P. The reply signal 11 flowing when this reply signal RET is at a low level is connected to a resistor R2 and an NPN transistor TR.
The value is constrained by 2.

Such a conventional reply signal generation circuit includes a multiplex transmission processing circuit in a terminal device and a signal line 1. ．． A photocoupler PC is used to insulate the
Since the light receiving element of C1 was composed of a phototransistor Q, there was a problem that the response speed was slow.

In order to solve this problem, a reply signal generating circuit as shown in FIG. 5 has been proposed. As shown in FIG. 5, this reply signal generation circuit consists of a pair of signal lines 1. ．． 12
a series circuit of a diode bridge DB having a pair of alternating current ends connected to the diode bridge DB, first and second resistors R7 and Re having one end connected to the positive DC end of the diode bridge DB, and the first and second resistors R7 and Re; 2 resistance R? , Rg, the collector is connected to the other end of the series circuit, and the emitter is connected to the negative DC end of the diode bridge DB1.
transistor TR4 and the first and second resistors R
? , Re and the first NPN transistor T
A smoothing capacitor C, connected between the emitter of R,
and the first and second resistors R? , Re, and the base of the first NPN transistor TR, a photocoupler PC2 is connected with a photodiode D3, and the photocoupler PC2 is connected in series with the light emitting diode D2, and is turned on and off according to the level of the reply signal RET. a second NPN transistor TR2 whose base and emitter are respectively connected to the collector and emitter of the first NPN transistor TR4; and a base and emitter connected to the collector and emitter of the second NPN transistor TR2. a third N whose collector and emitter are respectively connected to the positive DC end and the negative DC end of the diode bridge DB;
PN transistor TR.

The difference between this fabrication example and the circuit shown in FIG. The photocoupler PC2 is used, and the resistor R7, REI and the smoothing capacitor C1 are provided to stably provide an appropriate bias voltage for properly operating the photodiode D3, which is the light receiving element of the photocoupler PO2, and the photodiode D3. The other configuration is the same as that in FIG. 4 except that an NPN transistor TRt which is turned on and off in response to the current is provided and a resistor R6 is inserted on the collector side of the NPN transistor TR+.

In this circuit, when the reply signal RET is at a high level, the switch element TR3 is turned on and the photocoupler PC
The second light emitting diode D2 lights up, so the photodiode D3 becomes conductive, the NPN transistor TR, turns on, and the NPN transistor TR2 turns off. On the other hand, the reply signal R[! When T is at a low level, the switch element TR is off, the light-emitting diode D2 is turned off, the photodiode D3 is therefore cut off, the NPN transistor TR is off, and the NPN transistor TR2 is on. Other operations are the same as in FIG. 4.

In this way, when the photocoupler PC2 having the photodiode D3 as the light receiving element is used, the photocoupler PC2 having the phototransistor Q1 as the light receiving element as in the conventional example is used.
, the response speed can be increased compared to using .

In addition, a resistor R is connected to the photodiode D3 of the photocoupler PC2.
? Since the voltage divided by R8 and smoothed by the smoothing capacitor C1 is applied as the bias voltage, the bias voltage can be set to an appropriate value and is stable, making it possible to stabilize the operating point of the photocoupler PC2, resulting in a good result. Switching characteristics can be provided to the NPN transistor TR.

However, in the reply signal generation circuit shown in FIG. 5, at the beginning of communication with the parent image, the base potential of the NPN transistor TR2 is not normally supplied until the smoothing capacitor C1 is charged. T.R.
, performs constant current operation and generates unnecessary pulses with wide pulse widths.

[Purpose of the invention]

An object of the present invention is to provide a reply signal generation circuit that can prevent the generation of unnecessary pulses with long pulse widths at the beginning of communication.

[Disclosure of the invention]

The reply signal generation circuit of the present invention connects a parent picture and a plurality of terminal devices, each having a different unique address, through a pair of signal lines, and transmits a transmission signal including an address signal from the parent picture as a voltage signal to the pair of terminals. At the same time, the terminal device receives the transmitted signal, and in response to a match between the address signal in the transmitted signal and its own unique address, transmits a reply signal as a current signal to the pair of signal lines. In the configured remote multimeter transmission device, a return signal generation circuit installed in the terminal device includes a diode bridge having a pair of AC ends connected to the pair of signal lines, and a positive DC side of the diode bridge. A series circuit of first and second resistors with one end connected to the other end, a collector connected to the other end of the series circuit of the first and second resistors, and an emitter connected to the negative DC end of the diode pre- and diode. a third resistor having one end connected to the positive DC end of the diode bridge; and a smoothing capacitor connected between the other end of the third resistor and the emitter of the first NPN transistor. and,
a diode having a cathode connected to a connection point between the first and second resistors and an anode connected to a connection point between the third voltage dividing resistor and the smoothing capacitor; a photocoupler having a photodiode connected to the base of the first NPN transistor; a switching element connected in series with the light emitting diode of the photocoupler to turn on and off according to the level of a reply signal; and a collector and emitter of the first ONPN transistor. a second NPN with its base and emitter connected respectively;
a third NPN transistor whose base and emitter are connected to the collector and emitter of the second NPN transistor, respectively, and whose collector and emitter are connected to the positive DC end and the negative DC end of the diode bridge, respectively. According to the configuration of the present invention, in order to charge the smoothing capacitor through the third resistor and apply the voltage of this smoothing capacitor to the connection point of the first and second resistors through the diode,
During the period when the smoothing capacitor is not charged at the beginning of communication with the parent device, the smoothing capacitor and the second NPN transistor are separated by the diode.
It is possible to prevent the generation of unnecessary pulses with long pulse widths at the beginning of communication.

Embodiment An embodiment of the present invention will be explained based on FIG. As shown in FIG. 1, this reply signal generation circuit consists of a pair of signal lines 1. , a diode bridge DB with a pair of AC ends connected to j2, and this diode bridge DB,
first and second resistors R, one end of which is connected to the positive DC end of
? , R, and the first and second resistors R?
A first NPN transistor TR4 has a collector connected to the other end of the series circuit of R8 and an emitter connected to the negative DC end of the diode bridge DB, and one end is connected to the positive DC end of the diode bridge DB. a third resistor R9, and the other end of the third resistor R and the first NPN
A smoothing capacitor C1 connected between the emitter of the transistor TR4 and the first and second resistors R1 and R
a diode D4 whose cathode is connected to the connection point of the third resistor R9 and the smoothing capacitor C, and whose anode is connected to the connection point of the third resistor R9 and the smoothing capacitor C, and the first and second resistors R? .

A photocoupler PC2 having a photodiode D3 connected between the connection point of R8 and the base of the first NPN transistor TR, and a light emitting diode D of this photocoupler PC2.
2 and a second NPN transistor T whose base and emitter are respectively connected to the collector and emitter of the first NPN transistor TR4.
R2, and a third NPN transistor whose base and emitter are respectively connected to the collector and emitter of the second NPN transistor TR2, and whose collector and emitter are respectively connected to the positive DC end and the negative DC end of the diode bridge DB. It is equipped with TR.

The difference between this embodiment and the circuit shown in FIG. 5 is that a control circuit ■'' is used instead of the control circuit ■'. Specifically, the smoothing capacitor C1 is charged through the voltage dividing resistor R9, and the smoothing capacitor The point is that the voltage of C, is applied to the connection point of the voltage dividing resistors R? and Re via the diode D4,
Others are the same as those in FIG.

With this configuration, until the smoothing capacitor C1 is sufficiently charged, the resistance R? , R, and the connection point of resistor R9 and smoothing capacitor C1 are separated by diode D4, so that even if the voltage of smoothing capacitor CI is low at the beginning of communication with the parent device, the base potential of NPN transistor TR2 remains the same. is not affected by this, and the generation of unnecessary pulses with long pulse widths at the beginning of communication as in the proposed example can be prevented, and the pulse width of unnecessary pulses at the beginning of communication can be narrowed.

In addition, a pair of signal lines 1. , B to send a reply signal RE.
The NPN transistor TR switches between a constant current operating state and an off state depending on the level of T.

Since the resistor R6 was inserted in series on the collector side of the NPN
When the transistor TR is in a constant current operation state, the power loss is shared between the NPN transistor TR and the resistor R6, and the heat generation of the NPN transistor TR can be suppressed, and the heat generation of the resistor R6 is also small, improving reliability. can be increased. Also, the heating point is an NPN transistor TR.

and resistor R6, the amount of heat generated by each of them is reduced, and heat dissipation measures can be easily taken.

As a result, it is possible to downsize the heat dissipation fins and the like, and it is also possible to intentionally adjust the temperature distribution within the housing housing the reply signal generation circuit.

Here, the point that the heat generation of the NPN transistor TR is reduced compared to the circuit shown in FIG. 4 will be explained. Now, constant current switch circuit! , 1", the voltage at the DC end of the diode bridge DB, is E (V), and assuming constant current operation, the power consumption of each transistor TR, in the case of Fig. 4, is p, = EX Is -Is 2XR.

In the case of Fig. 1, P2 =Ex 1s-Is ”XRI Is 2
XR6, and if the resistance values of the resistors R1 in both circuits are the same, then the NPN transistor TR in FIG.

The power consumption P2 of the NPN transistor TR in FIG. 4 is smaller by s2×R6 than the power consumption P1 of the NPN transistor TR in FIG.

heat generation can be reduced. Note that the reduction in power consumption in the NPN transistor TR is shared by the resistor R6.

In FIG. 1, the resistor R6 is shown as m-, but it may be a composite circuit of multiple resistors in series or parallel. In this case, the number of resistors increases, so The locations of heat generation can be further dispersed, allowing flexible circuit design in terms of heat dissipation.

Note that the other operations are the same as those already explained with reference to FIGS. 4 and 5, so the explanation will be omitted.

〔Effect of the invention〕

According to the configuration of the present invention, the smoothing capacitor is charged through the third resistor and the voltage of this smoothing capacitor is applied to the connection point of the first and second resistors through the diode, so that the initial communication with the parent device is performed. During the period when the smoothing capacitor is not being charged, the smoothing capacitor and the second NPN transistor are separated by the diode, thereby preventing the generation of unnecessary pulses with long pulse widths at the beginning of communication.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a remote multiplex transmission device, and FIG. 3 is a concrete block diagram of a parent device and a terminal device of the remote multiplex transmission device. FIG. 4 is a circuit diagram of a conventional reply signal generation circuit, and FIG. 5 is a circuit diagram of a proposed example. P... Parent device, l~N... Terminal device, LN, 1. ．． 12
...Signal line, 'l' R4, T R2, T R1...
・NPN transistor, TR controller...switch element,
PC2...Photocoupler, D2...Light emitting diode, D3...Photodiode, D4...Diode, R7-R9...Resistor, C1...Smoothing capacitor Patent applicant Shirimome Matsushita Electric Works Co., Ltd.

Claims (1)

[Scope of Claims] A parent device and a plurality of terminal devices each having a different unique address are connected by a pair of signal lines, and a transmission signal including an address signal from the parent device is used as a voltage signal to be connected to the pair of signal lines. at the same time, the terminal device receives the transmitted signal, and in response to a match between the address signal in the transmitted signal and its own unique address, transmits a reply signal as a current signal to the pair of signal lines. In the multiplex transmission device, a return signal generation circuit installed in the terminal device includes a diode bridge having a pair of AC ends connected to the pair of signal lines, and one end connected to the positive DC end of the diode bridge. a first NPN having a collector connected to the other end of the series circuit of the first and second resistors connected to each other and an emitter connected to the negative DC end of the diode bridge; a third resistor having one end connected to the positive DC end of the diode bridge; a smoothing capacitor connected between the other end of the third resistor and the emitter of the first NPN transistor; a diode having a cathode connected to the connection point of the first and second resistors and an anode connected to the connection point of the third resistor and the smoothing capacitor; a photocoupler having a photodiode connected between it and the base of the NPN transistor; a first switching element connected in series with the light emitting diode of the photocoupler and turned on and off according to the level of a reply signal; a collector of the first NPN transistor; A second NPN with the base and emitter connected to the emitter, respectively.
a third NPN transistor whose base and emitter are connected to the collector and emitter of the second NPN transistor, respectively, and whose collector and emitter are connected to the positive DC end and the negative DC end of the diode bridge, respectively. reply signal generation circuit.