JPS58207755A - Detecting circuit of polarity inversion - Google Patents

Abstract

PURPOSE:To detect accurately the polarity inversion only, by providing an FF storing the polarity of a communication line so as to prevent malfunction due to the transmission of a dial pulse intermitting a DC loop or hit of DC supply on the way of exchange. CONSTITUTION:A hook switch 2 is connected to a connecting terminal L1 of a telephone set, a series circuit comprising a telephone set circuit 1 and a power supply circuit 7 is connected between the other connecting terminal L2 and the switch 2 via a diode bridge DB for polarity coincidence, and a power supply tV is applied to each section from the circuit 7 in closing the switch 2. FF1, FF2 as bistable circuits are connected to the output side of the bridge DB respectively via diodes D1, D2 and transistors TRQ11, Q12 respectively. The FF1, FF2 are reset after the supply of a power supply +B with an output of a power- on reset circuit 6. When a pair of terminals L1, L2 has a prescribed polarity, the FF1 or FF2 is set, the outputs of the FF1, FF2 are ANDed at an AND circuit AND, allowing to detect accurately the polarity inversion.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit for detecting polarity reversal of a communication line.

When a call is made from a telephone connected to a telephone line and the called party answers, the polarity of the line is reversed by the action of the exchange. This reversed state continues during the call, and when the line is restored to end the call, the polarity is reversed again.

Figure 1 shows an example of a conventional circuit for detecting such polarity reversal, in which Ll and L2 are connection terminals between the telephone and the line, 1 is the telephone circuit, 2 is a hook switch, 3 is a diode bridge, 4 is a diode, 5 is a relay, and 6 is a capacitor. In the circuit shown in Fig. 1, when voltage is applied when the polarity of Ll is positive and the polarity of Ll is negative, diode 4 becomes forward direction, and relay 5
Relay 5 will not work unless short-circuited, but Ll + t
, 2 is reversed from the above state, the relay 5 is activated and the reversal of polarity can be detected by the contacts (not shown) of the relay 5.

However, the first drawback of this method is that because the LIIL2 4-wire characteristic is specified, it is necessary to check the polarity of the line when installing the telephone, making the installation work cumbersome.

Regarding the second drawback, if you send out a dial impulse signal that intermittents the 11 flow loop while the relay is operating, the relay 5 will repeatedly turn off and on at the same time as the dial impulse. A special circuit is required to prevent D-turn and surface signals from being treated as signals, and the circuit configuration becomes complicated for practical use.The third drawback is that the direct current of the telephone only exceeds the winding resistance of the relay 5. The resistance increases, the DC supply current to the telephone decreases, and the call performance deteriorates by 1 degree.

The fourth drawback is that in order to suppress the increase in alternating current (+1) loss caused by the insertion of the relay 5, a 1-unit AC/DC 6 is required in parallel with the relay 5, making it difficult to downsize the device.

The present invention eliminates these drawbacks and provides a polarity reversal detection circuit that can provide a stable polarity reversal detection output without specifying the polarity of the line at the time of installation.

The present invention will be explained in detail below.

FIG. 2 shows an embodiment of the present invention, in which IJI + Ll
is the telephone connection terminal, DB is the polarity-potable diode bridge, l is the telephone circuit, 7 is the power supply circuit, 6 is the power-on reset circuit, AND is the AND circuit, FF, FF2
is a 7-lip-flop as a bistable circuit, Qlt +
Q12 is a transistor, R1+ R2+ R3+ R
4 is a resistor, DI + D2 is a diode, self is a capacitor, and OUT is a polarity reversal detection output terminal.

In this embodiment, when the hook switch 2 is closed, L
A DC loop from Ll or Ll to Ll or Ll is closed through the path [diode bridge DB→telephone circuit 1→power supply circuit 7], and the power supply circuit 7 supplies V+' power to each part. The power-on reset circuit 6 is a circuit that generates an output for a certain period of time when power is supplied, and the flip-flops FF and FF2 are reset by the reset output.

The base of transistor Qll is connected to diode DI and resistor R.
8, connected to the terminal side, and transistor Q1□
The base of is connected to L2 terminal r through diode D2 + resistor R2.
・Connected to the side.

Therefore, if the polarity of the telephone terminal Ll e Ll is positive on the Ll side and negative on the L2 side, the transistor Qn is on and the flip-flop FF is not set.
The transistor Q12 is off, the set input terminal S2 of the clip-flop FF2 becomes high level, the clip-flop FF2 is set, and the output Q2 becomes low level.

Next, when the polarity of the line is reversed and becomes negative on the Ll side and positive on the L2 side, the transistor Qo turns off, contrary to the above state, flip-flop FF1 is hit, and the Q
The output of H becomes /.level. By reversing the polarity, each output Q+ of the flip-flops FF, , FF2,
Q2 are both at the 7-level level, and a leakage detection output can be obtained through the AND circuit.

The capacitor is a capacitor that prevents the V+ power supply from dropping below a certain value when the polarity is reversed when replacing +1 fill or when there is a momentary interruption of DC current that occurs when switching trunk connections.

FIG. 3 shows another embodiment of the present invention, in which MM is a monomultivibrator and OR is an OR circuit. In Figure 3, a mono multivibrator MM is connected to the circuit configuration shown in Figure 2, which generates an output at E level for a certain period of time when the output of the AND circuit becomes E level, and its output is used as a polarity reversal detection output pulse. At the same time, the flip-flop τff knob FFl l FF2 is reset through an OR circuit.

Therefore, even if there is a second or subsequent polarity reversal, a polarity reversal detection output pulse can be obtained by the same operation as described above.

h”r Figure 4 shows another embodiment of the present invention, where E is Mi:
Stem, pct, PO2 is photocoupler R5 is a resistor. Figure 2.

While the embodiment shown in Fig. 3 is a station power operated type in which a power supply circuit is installed in the telephone's DC loop to operate the circuit, the embodiment shown in Fig. 4 uses an external power supply, and the power supply circuit is operated on the telephone side. Photocoupler for separation from the power supply l)C.

It is configured to be carried out by PO2.

Figure 5 shows still another embodiment of the present invention, in which a thyristor is heavily used in a bistable circuit. In Figure 5, SCR, 5CR2 are thyristors, QIIIQ12 is a transistor, R11 + R12 * RI3 + RI
4 is a resistor, INV is an inverter, and other symbols are the same as those in the embodiments shown in FIGS. 1 to 4. In this example, a thyristor SC is used as a bistable circuit.
Since R,,5CIt2 is used, the transistor Q11 is used as a means to turn off the thyristor.
1QI2 is connected in parallel with thyristors 5CR4 and 5CR2.

As explained in detail above, the present invention has a configuration having a flip-flop that marks the polarity of the line without increasing the DC resistance of the telephone. Even if you send
Alternatively, even if there is a momentary interruption of the DC supply during the exchange connection, there will be no malfunction, and an accurate polarity reversal detection output can be made only when there is a polarity reversal. It has 11 applications in a wide range of fields such as automatic message sending devices.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram including blocks showing an example of the circuit configuration of a conventional polarity reversal detection circuit, and FIGS. 2, 3, 4, and 5 are circuit diagrams including blocks showing an embodiment of the present invention. It is a diagram. Patent Applicant: Iwasaki Tsushinki Co., Ltd., Agent: Nippon Telegraph and Telephone Public Corporation, Manabu Otsuka, Tsuneo Masamizu'f73, Phantom No. 4, Draft Procedure Amendment (Method), July 7, 1980, Commissioner of the Patent Office, Kazuo Wakasugi, Mr. 1 Indication of the case Japanese Patent Application No. 18165/1986 2 Name of the invention Polarity reversal detection circuit 3 Person making the amendment Relationship to the case Applicant (01B) Iwasaki Tsushinki Co., Ltd. 1=23-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo "Invention The description in the column "Detailed explanation of" has been amended as follows. (1. Correct the name of the invention to "Polarity Reversal Detection Circuit." 0. (2. Correct the scope of claims as shown in the attached sheet.) (3) Modify "Detection" in line 8 of page 2. Corrected to "detection." Claims (1) A first bistable circuit that is set when the polarity of one line of the pair of lines is a predetermined positive or negative polarity (V); The second line is sent when the polarity of one line of the other line is a predetermined positive or negative polarity.
a bistable circuit, and an AND circuit that takes the AND of the outputs of the first bistable circuit and the second bistable circuit to provide a detection output of polarity reversal of the pair of lines. Reversal detection circuit. (2) A first bistable circuit (other than C11 and the pair of lines) that is set when the polarity of one line of the pair of lines is a predetermined plus or minus polarity. A second bistable circuit that is set when the polarity of one line is a predetermined plus or minus polarity [[logical product of the 11 path and the outputs of the first bistable circuit and the second bistable circuit] an AND circuit that outputs the detection output of pole f1 inversion of the pair of lines;
A polarity inversion St<+ circuit comprising a reset means for resetting the first bistable circuit and the second bistable circuit according to the detection output.

Claims (2)

[Claims] (1) A first bistable circuit that is set when the polarity of one line of the pair of lines is a predetermined positive or negative polarity, and a first bistable circuit that is set when the polarity of one line of the pair of lines is a predetermined polarity. A second bistable circuit that is set when the polarity is positive or negative, and the outputs of the first bistable circuit and the second bistable circuit are logically ANDed to detect polarity reversal of the pair of lines. A polarity reversal detection circuit equipped with an AND circuit as an output. (2) A first bistable circuit that is set when the polarity of one line of the pair of lines is a predetermined positive or negative polarity, and a first bistable circuit that is set when the polarity of one line of the pair of lines is a predetermined polarity. A second bistable circuit that is set when the polarity is positive or negative, and the outputs of the first bistable circuit and the second bistable circuit are ANDed to perform quaternary inversion of the pair of lines. A polarity reversal detection circuit comprising: an AND circuit that outputs a detection output; and a gate means for resetting the first bistable circuit and the second bistable circuit using the detection output.