JPS6317389B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention provides a method for automatically reading meters for water, gas, electricity, etc. from a remote location using a telephone line during idle hours when telephone subscribers are not making calls.・Relates to a subscriber line voltage polarity reversal method for sending a signal to reverse the voltage polarity of the telephone line without ringing the telephone bell when activating a remote meter reading device (hereinafter referred to as a telemeter) that performs measurement. .

Background of the Technology When the voltage polarity of a subscriber line to which a telephone is connected is reversed, the bell within the telephone rings due to the charging and discharging current to the capacitor within the telephone.
Therefore, special measures are required to send out the voltage polarity inversion signal that activates the telemeter.

FIG. 1 shows an example of a circuit for realizing this type of conventional method. In FIG. 1, 10 is an integrating circuit;
1 is a zero voltage detection circuit, 12 is a control circuit, 13 is a power supply coil, 14 is a polarization switch, 15 is a battery,
16 is a ground, 101 is a transfer switch switched by relay 100, 111 and 112 are transfer switches switched by relay 110, 20 is a subscriber line, 30 is a telephone, and 31 is a telemeter.

The operation of the circuit shown in FIG. 1 will be explained using the time chart shown in FIG.

First, the control signal E becomes "High" (hereinafter referred to as "H") by the control circuit 12, and the relay 10
When 0 is excited, the switch 101 is switched to the ground 16 side. As a result, the input voltage of the integrating circuit 10 changes, the output voltage slowly changes toward zero as shown by C, and the voltage V _AB between terminals A and B also slowly changes toward zero. When the output voltage C reaches zero, the output F of the zero voltage detection circuit 11 becomes "H", and the control signal E output from the control circuit 12 becomes "Low".
(hereinafter referred to as “L”) Output control signal G is “H”
shall be. At this time, the relay 110 is excited by the output G, and the switch 111 is switched to the _J2 side.
2 switches to the K ₂ side. On the other hand, the relay 100 is demagnetized by the output E, the switch 101 is switched to the battery 15 side again, and the output voltage C of the integrating circuit 10 slowly changes toward -V ₀ . Here, switches 111 and 112 are H and H, respectively.
Since J ₂ , I and K ₂ are connected, the voltage V _AB changes slowly from zero towards -V ₀ . By the above circuit operation, the voltage polarity is slowly reversed, and the charging/discharging current of the capacitor in the telephone can be suppressed to a small level, so that ringing of the bell in the telephone can be prevented.

Further, voltage polarity reversal in the opposite direction is similarly slowly performed.

Prior Art and Problems Conventional devices of this type have been put to practical use in analog exchanges, and are installed at the back end of a network and used in common for a plurality of subscriber lines. Therefore, there is no strong demand for miniaturization and economicalization of the device, and electromagnetic components such as relays and coils, large-capacity capacitors, and the like are used as component parts.

However, in digital exchanges developed to construct economical telephone networks and expand services, since the network only passes digital signals, this type of equipment is placed in front of the network and connected to each subscriber's line. Each must be used separately. Therefore, it is extremely important to make this type of device more compact and economical. To achieve this, it is necessary to configure the device entirely with electronic components, without using electromagnetic components or large-capacity capacitors.

Purpose and Structure of the Invention The first invention of the present application transmits a subscriber line voltage polarity inversion signal that prevents the telephone from ringing by smoothly changing the voltage using an integrating circuit as in the conventional method. Instead, a series circuit consisting of a line-to-line switch and a resistor connected between subscriber lines is used to shunt part of the current flowing to the telephone, and at the same time, the voltage is changed step by step in steps with small voltage changes. It is characterized by being performed by going.

In the second invention of the present application, the voltage is changed little by little in steps with small voltage changes from an initial voltage state to a zero voltage state, and from the zero voltage state to an inverted voltage state whose polarity is different from the initial voltage state. It is characterized in that it is performed by forming a high resistance loop.

A common object of the first and second inventions of the present application is to provide a subscriber line voltage polarity reversal system that achieves miniaturization and economicalization of a device constituted by an electronic circuit that does not use a large-capacity capacitor. Furthermore, it is to be realized by a circuit configuration integrated with an electronic subscriber circuit having functions such as supplying call current to the telephone terminal, transmitting and receiving voice signals, and transmitting normal polarity reversal signals.

Embodiment of the Invention FIG. 3 shows an embodiment of a circuit configuration for realizing the present invention, and the same reference numerals as in FIG. 1 indicate the same parts. 41
and 42 are electronic power supply circuits (hereinafter referred to as power supply circuits), 43 to 48 are electronic switch elements (hereinafter referred to as switches), and 49 and 50 are resistance elements (hereinafter referred to as resistances). 14' is switch 43-4
6, 13' is a power supply circuit 41,
42, and 15' is a line voltage level setting section for the subscriber line supplied from the power feeding section 13', which consists of resistors 49 and 50 and switches 47 and 48 connected in series to the resistors 49 and 50, respectively. .

FIG. 4 shows a first example of a control sequence for sending out a voltage polarity inversion signal using the circuit configuration shown in FIG. 3, and the circuit operation shown in FIG. 3 will be explained using the control sequence shown in FIG. do. In the following description, the circuit closed and open states of the power supply circuits 41 and 42 and the switches 43 to 48 are referred to as on and off, respectively.

Note that the power supply circuits 41 and 42 in the present invention are constant resistance circuits used in ordinary electronic subscriber circuits (for example, IEICE: IEICE Technical Report SE80-39).
“A Study of IC Subscriber Circuits” Hamasato et al., May 1980
(published on the 23rd), we used a circuit that added a transistor for control signal input. FIG. 5 shows the power supply circuits 41 and 4.
An example of No. 2 is shown below. 500 is a constant resistance circuit of the electronic subscriber circuit; 501 is a control signal input transistor; the emitter and collector terminals are connected in parallel with the resistor R1; the base-emitter voltage of the transistor 501 is controlled; By turning on and off, the internal resistance value (impedance Ze) of the power supply circuits 41 and 42 is switched.
That is, by setting R1, R2>>RE, when the transistor 501 is on, it is ZeR2, and when it is off, it is ZeR1+R2/R1·RE. (Note that Ze=1/ _K1 ·RE/α, _K1 =R1/R1+R2.) I is a control signal input terminal, and O is an output terminal.

Initially, control signals L, M, and N from a control circuit (of an exchange not shown) are set to "H", control signals O and P are set to "L", power supply circuits 41 and 42 are turned on, switches 43 and 46 are turned on, switch 44,4
5, 47, and 48 are turned off, a negative potential -V ₀ is generated at terminal A along the path of battery 15 - power supply circuit 41 - switch 43 - terminal A, and ground 16 - power supply circuit 4
2-switch 46-terminal B path is in a state where zero potential is generated at terminal B, and the potential V _AB between terminals A and B is +V ₀ . At this time, the telephone 30
It is assumed that the DC loop of the telemeter 31 is in an open state and no DC current flows, and that the DC loop is also in an open state during the following circuit operation.

Further, the control signal P is set to "H", and the switch 47
and turn on 48. This allows grounding 16-
Power supply circuit 42 - switch 46 - resistor 50 - switch 48 - switch 43 - power supply circuit 41 - battery 15
Direct current flows through the path, and the voltage between terminals A and B
V _AB becomes the sum of the terminal voltage of the resistor 50 and the on-voltage of the switch 48 +V ₁ . Here, it is assumed that the on-resistances of the feeder circuits 41 and 42 are equal, and if the resistor 50 is set to n ₁ times the on-resistance of the feeder circuits 41 and 42, then the following equation is obtained by setting the on-resistance of the feeder circuits 41 and 42 to 1, respectively. To establish. However, the on-voltage of the switch is omitted. The same applies below.

V ₁ =n ₁ /n ₁ +2V ₀ (1) Next, the control signal M is set to “L”, and the power supply circuit 42
Turn off. At this time, the power supply circuit 42 is not completely open and has a high resistance. Power supply circuit 4
When the off-resistance of 2 is set to n ₂ times the on-resistance, the voltage V _AB between terminals A and B is given by V ₂ shown in the following equation.

V ₂ =n ₁ /n ₁ +n ₂ +1V ₀ (2) Next, control signals L and N are set to "L" to turn off power supply circuit 41 and switches 43 and 46. As a result, the DC current becomes zero and the voltage V _AB between terminals A and B becomes zero.

Next, control signals L and O are set to "H", power supply circuit 41 is turned on, and switches 44 and 45 are turned on. As a result, the ground 16-power supply circuit 42-
Direct current flows again through the path of switch 45 - switch 47 - resistor 49 - switch 44 - power supply circuit 41 - battery 15, but at this time the potentials of terminals A and B are reversed. If the resistor 49 is set to n ₃ times the on-resistance of the power supply circuit 41, the voltage V _AB between terminals A and B becomes -V ₃ as shown in the following equation.

−V ₃ =−n ₃ /n ₂ +n ₃ +1V ₀ (3) Next, the control signal M is set to “H” and the power supply circuit 42
Turn on. At this time, the voltage between terminals A and B is V _AB
becomes −V ₄ as shown in the following equation.

−V ₄ =−n ₃ /n ₃ +2V ₀ (4) Next, the control signal P is set to “L” and the switch 47
and 48 off. As a result, the DC current becomes zero, and in the path of battery 15, power supply circuit 41, switch 44, and terminal B, terminal B becomes _V0 , which is a negative potential.
Ground 16 - Power supply circuit 42 - Switch 45 - Terminal A
Since terminal A becomes zero potential in the path, terminals A and B
The voltage between V _AB becomes −V ₀ .

In the manner described above, the voltage polarity can be reversed step by step. The polarity reversal in the opposite direction is the same, so the explanation will be omitted. In order to prevent the telephone from ringing, it is necessary to suppress voltage changes as small as possible in order to suppress the charging and discharging current of the capacitor within the telephone. For example, the fourth
In order to make the voltage changes of the voltage V _AB shown in the figure equal intervals, n ₁ = n ₃ = 4, n ₂ = 7 (5) may be set in equations (1) to (4).

FIG. 6 shows an example of the experimental results of the first embodiment.
The power supply circuits 41 and 42 and switches 43 to 48 shown in FIG. 3 are all constructed of electronic components. Fourth
The difference from the control sequence in the figure is that the switch 43
~48 when power supply circuits 41 and 42 are turned off.
This is also turned off. This is because the switches 43 to 48 have weak current cutting ability.
From FIG. 6, it can be seen that the required step-like voltage waveform is obtained, and the charging/discharging current I _A flowing through the capacitor of the telephone when the voltage changes is also suppressed to 2.5 mA or less. At this time, it was confirmed that it was possible to prevent the telephone from ringing.

FIG. 7 shows a second embodiment of a control sequence for transmitting a subscriber line voltage polarity inversion signal using the circuit configuration shown in FIG. 3. The circuit operation will be explained.

The portion where the voltage V _AB between terminals A and B changes from +V ₀ to +V ₂ is the same as that in FIG. 4, so the explanation will be omitted. The change from +V ₂ to -V ₀ is performed as follows.

When the voltage V _AB between terminals A and B is +V ₂ , the circuit state is that the control signals L, N, P are "H", and the control signals M,
O is "L", power supply circuit 41 is on, power supply circuit 41 is off, switches 43, 46, 47, 48
is on, and switches 44 and 45 are off. At this time, the power supply circuit 42 is not in an open state but has a high resistance, so the ground 16 - the power supply circuit 42 - the switch 46 - the resistor 50 - the switch 48 -
A direct current is flowing through the switch 43 - power supply circuit 41 - battery 15 path.

Next, the control signals L, N, P are set to "L", the power supply circuit 41 is turned off, and the switches 43, 46, 47, 4 are turned off.
Turn off 8. As a result, the DC current becomes zero, and the voltage V _AB between terminals A and B becomes zero.

Next, control signals L and O are set to "H", power supply circuit 41 is turned on, and switches 44 and 45 are turned on.
As a result, zero potential is applied to the terminal A in the path of ground 16 - power supply circuit 42 - switch 45 - terminal A, and the battery 15
A negative potential is applied to terminal B through the path of - power supply circuit 41 - switch 44 - terminal B, and the voltage V _AB between terminals A and B changes to -V ₀ . When this voltage changes, a charging current flows to the capacitor of the phone, but the power supply circuit 4
2 is in a high resistance state, so the charging current can be kept small.

The same applies to voltage polarity reversal in the opposite direction, so a description thereof will be omitted.

FIG. 8 shows an example of experimental results according to the second embodiment. The on-resistance of the power supply circuits 41 and 42 is 220Ω,
This is when the off-resistance is 40KΩ. 8th
From the figure, it can be seen that the required voltage waveform V _AB is obtained, and the charging/discharging current I _A to the capacitor inside the phone is also suppressed to 2.5 mA or less. At this time, it was confirmed that it was possible to prevent the telephone from ringing.

Effects of the Invention As explained above, according to the present invention, it is possible to send out a voltage polarity inversion signal without ringing the bell of a telephone as in the conventional case. By adding a series circuit between a line switch and a resistor between subscriber lines, it is possible to shunt a portion of the current flowing through the telephone bell circuit and increase the number of voltage change steps. , because the current flowing through the bell circuit can be kept small. According to the present invention, the circuit can be constructed entirely from electronic components without using conventional integrating circuits that require large-capacity capacitors, and electromagnetic components such as relays and coils. Significant downsizing and economy can be achieved. Furthermore, the present invention can be realized by simply adding a series circuit of a switch and a resistor between subscriber lines, without changing the basic components such as the power supply circuit to a normal electronic subscriber circuit. Therefore, by keeping the switch in the OFF state except during a silent call, there is no effect on the normal operation and characteristics of the subscriber circuit (in particular, call current supply characteristics, ground unbalance characteristics, etc.). . Therefore, the subscriber voltage polarity inverting circuit according to the present invention can be integrated with a normal electronic subscriber circuit, allowing common use of the device and making the entire system more compact and economical. Therefore, this method is effective as a system for transmitting a subscriber line voltage polarity inversion signal that does not cause the telephone bell to ring in a digital exchange, where miniaturization and economicalization of the device are extremely important. Further, even if the present invention is applied to an analog exchange, the device can be made smaller and more economical, which is highly effective.

[Brief explanation of the drawing]

FIG. 1 shows a conventional subscriber line voltage polarity inversion signal sending circuit, FIG. 2 shows a time chart explaining the circuit operation of FIG. 1, FIG. 3 shows an example of a circuit configuration for realizing the present invention, and FIG. A first embodiment of a control sequence for sending a subscriber line voltage polarity inversion signal using the circuit configuration shown in FIG. 3, FIG. 5 shows an example of an electronic power supply circuit, and FIG. 6 shows the first embodiment. Examples of experimental results by
FIG. 7 shows a second embodiment of a control sequence for sending out a polarity inversion signal using the circuit configuration of FIG. 3, and FIG. 8 shows an example of experimental results based on the second embodiment. 10...Integrator circuit, 11...Zero voltage detection circuit,
12... Control circuit, 13... Power feeding coil, 1
3'...Power supply section, 14,14'...Polarization switch,
15...Battery, 15'...Subscriber line voltage level setting section, 16...Grounding, 100 and 110...
...Relays, 101, 111 and 112...Transfer switch, 20...Subscriber line, 30...
...Telephone, 31...Telemeter, 41 and 42
...Power supply circuit, 43-48 ...Electronic switch, 4
9 and 50...resistor, 500...constant resistance circuit of electronic subscriber circuit, 501...transistor.

Claims (1)

[Scope of Claims] 1. In a silent ringing signal sending system that inverts the polarity of a DC voltage without ringing the bell of a telephone and activates a terminal device connected in parallel with the telephone, two internal resistors are activated by a control signal. a power supply unit consisting of a pair of power supply circuits in which one of the states is selected; and a power supply unit connected between the power supply unit and the subscriber line, and configured to apply a positive polarity voltage, its inverted polarity voltage, or A subscriber line voltage level setting consisting of a series circuit of a reversing switch to which either zero voltage is applied, a line switch connected between the subscriber lines and turned on and off by a control signal, and a resistor. While reversing subscriber line voltage polarity, the interline switch is kept in the on state to shunt a part of the current flowing through the telephone set, and to control the voltage change.
A subscriber line voltage polarity reversal method characterized in that the polarity reversal is performed stepwise from an initial voltage state to an inverted voltage state having a polarity different from the initial voltage state. 2. In a silent ringing signal transmission method that reverses the polarity of the DC voltage without ringing the telephone bell and activates a terminal device connected in parallel with the telephone, one of two internal resistance states is selected by a control signal. a power supply unit consisting of a pair of power supply circuits; and a power supply unit connected between the power supply unit and the subscriber line, and configured to apply either a positive polarity voltage, its inverted polarity voltage, or zero voltage to the subscriber line according to a control signal. and a subscriber line line voltage level setting unit that is connected between the subscriber lines and is made up of a series circuit of a line switch and a resistor that is turned on and off by a control signal. From the initial voltage state to the zero voltage state, the line switch is kept in the on state to shunt a part of the current flowing through the telephone, and the voltage is changed in a stepwise manner, from the zero voltage state to the initial voltage state. is a subscriber line voltage polarity reversal method characterized by a high resistance loop until the reverse voltage state of different polarity is reached.