JPH0329240B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a power failure incoming circuit in a key telephone device.

In recent years, the number of so-called electronic key telephone devices that are configured to connect a plurality of key telephones and a plurality of office lines via a call switch network of electronic contacts has been increasing. This is due to its convenient and rich functionality.

Generally, the main device including the call switch network and control circuit and each button telephone are connected by a total of two pairs of cables, one pair of telephone lines and one pair of control data lines.

Here, control power (DC) for each button telephone is superimposed and sent from the device to the pair of wires for control data.
It is common knowledge that efforts are being made to reduce the number of core wires in cables.

However, the biggest disadvantage of electronic key telephone devices is that in the event of a power outage to the commercial AC power supply, most of the control circuits in the main device, the call switch network, and the control circuits in each key telephone device will not be able to perform their functions. , the entire system of button telephone devices becomes as good as a failure.

To remedy this situation, it is necessary to configure the system so that in the event of a power outage, at least the same number of button telephones as the number of central office lines can receive calls from and make outgoing calls to the central office line. be.

As mentioned above, the electronic button telephone device has one pair of control data lines in addition to one pair of communication lines between the main device and each button telephone, so if you switch and use this control data line, you can install new cable wiring. This means that there is no need to apply it.

FIG. 1 is a diagram showing an example of a conventional power failure receiving circuit that satisfies the above-mentioned conditions.

In the figure, ME is the main device, PF-KT is a key telephone that can be used during power outages, Lt is a central office line, Ls is a telephone line, and Lc
represents a control data line.

A telephone in an electronic button telephone device (hereinafter usually abbreviated as KT) generally consists of a talking circuit NW, a switch contact set HS, a telephone control circuit TC (including a DC receiving power supply circuit), and the like.

As shown in the diagram, the PF-KT button telephone for use during power outages has a ringer for use during power outages, compared to the KT for normal use.
In addition to RG, there is a switch K (not shown, its contact point K ⁰
and ^K1 only).

The main device ME consists of a telephone switch network SW, a central control circuit CC, an office line circuit COU (the number of COUs is equal to the number of office lines), etc. The illustrated COU mainly includes various circuits necessary for power outage countermeasures.

In the figure, PEC ₀ is a ringing signal (20Hz, several mA)
Diode bridge for calling signal rectification for full-wave rectification, G (the part surrounded by the dotted line) is the calling signal receiving circuit at the time of power outage, consisting of switching relay RB, diode _D3 , resistor _R3 , capacitor _C3 The full-wave rectified wave is smoothed to ensure reliable RB operation. In addition, REC ₁ is connected via the control data line during a power outage.
Supplied to PF-KT. This is a polarity rectifying diode bridge that keeps the local current (DC) at a constant polarity (this is a measure to prevent the polarity of the local current from reversing when the other subscriber responds in the case of an outgoing call).

The PS shown at the bottom of the ME is a power failure monitoring circuit.
The power failure monitoring relay PF, which is the main component, operates when the power switch is turned on, and is designed to be restored when the commercial AC power supply goes out.

Note that the PC is a photocoupler and is used to transmit the arrival of a calling signal to the CC during non-power outages, and is not involved during power outages.

The circuit configuration shown in FIG. 1 takes the following operational steps during a power outage. When the commercial AC power supply fails, the power failure monitoring relay PF is restored and its contacts Pf ⁰ , Pf ¹ , Pf ²
In each case, the state changes from a broken line state to a solid line state.

On the other hand, on the PF-KT side, the user notices the power outage and manually switches the switch K.

A central office line call is received in this state as follows. That is, the calling signal (20 Hz AC) arriving from the office line Lt passes through Co and REC ₀ .
The alternating current calling signal is full-wave rectified by REC ₀ and then applied to switching relay RB which has a smoothing circuit made up of D ₃ , C ₃ and R ₃ in parallel.

Since the calling signal arrives with a repeating cycle of 1 second continuous and 2 seconds off, relay RB also operates repeatedly with a 1 second operation and 2 second recovery cycle.

As a result, the make side contact of terminal b-C ₂ - ^{rb 0} - the upper line of Lc - Ca - RG - the lower line of Lc - rb ¹
A path from the make side contact to terminal a is formed, and the ringing signal from the office line is transmitted to the ringer RG, causing the ringer to ring. Note that C ₀ , C ₂ , and Ca are capacitors for blocking direct current.

When the user picks up the handset after hearing the ringer, the switch contact HS closes.

As mentioned above, the ringing signal repeats at a cycle of 1 second continuous and 2 second off, so during these 2 seconds, terminal b-
Diode 2 of REC ₁ - Solid line side of Pf ² - Solid line side of Rb ¹ - Lower line of Lc - k Solid line side of ¹ - HS - NW - k ⁰
The solid line side of - the upper line of Lc - the solid line side of rb ⁰ - the solid line side of pf ¹ - the diode 1 of REC ₁ - a direct current path passing through terminal a is created, and a ring trip relay (not shown) on the central exchange side is created. operates and stops sending out the ringing signal. As a result, the local current flows through the above-mentioned path, and the communication becomes possible.

Also, when making a call from a PF-KT, the route of the local current is the same as for the incoming call above, but when the called party answers, the polarity of the local current is reversed at the central office exchange, so the local current is Terminal a-REC ₁ diode 3-Pf ² solid line side-rb ¹ solid line side-Lc lower line-k ¹ solid line side-HS-NW-k ⁰ solid line side-Lc
Upper line - solid line side of rb ⁰ - solid line side of Pf ¹ - REC ₁
The signal flows through the diode 4-terminal b, and the communication becomes possible.

In addition, Da indicates that the station current flows to the telephone control circuit during a power outage.
This is to protect the data from flowing into the TC. In other words, during non-power outages, the control power (DC) supplied from the main device via the control data line is
and prevents local current from flowing into the TC during a power outage.

The conventional power outage receiving circuit in an electronic key telephone device has been described above, but according to this method, the calling signal receiving circuit G including the switching relay RB must be specifically provided only for power outage countermeasures, which is not economical. It is not a good idea from a practical point of view.

In addition, the switching relay RB continues the calling signal for 1 second.
Since the operation and recovery are repeated in synchronization with the 2-second interruption cycle, even if you pick up the handset to answer an incoming call on a power outage button telephone, _the local current (DC ), resulting in a disadvantage that the ring trip within the central office exchange is delayed.

The present invention aims to improve economy by eliminating the call signal receiving circuit during a power outage, and also to improve the above-mentioned drawbacks, and will be described below.

FIG. 2 is a diagram showing an example of an implementation configuration of a power failure receiving circuit according to the present invention.

As in Figure 1, ME is the main device, PF-KT is a key telephone that can be used during power outages, Lt is a central office line, Ls is a telephone line,
LC is the control data line, NW is the call circuit, TC is the telephone control circuit (including the DC receiving power supply circuit), RG is the ringer for power outages, SW is the call switch network, CC is the central control circuit, COU is the office line circuit, PC is a photocoupler, REC ₀ is a diode bridge for calling signal rectification,
REC ₁ is a polar rectifier diode bridge, and PF is a power failure monitoring relay.

Noteworthy points in the diagram are that there is no call signal receiving circuit and switching contact circuit in the event of a power outage;
A passive element circuit RN (the part surrounded by a dotted line in the figure) consisting of Ra and Rb is provided.

This passive element circuit RN is connected so as to be inserted in series between the station line Lt and PF-KT. Since it is a balanced type, the resistance value is Ra=Rb.

As will be described later, the RN is provided to form a path for transmitting a ringing signal (20 Hz AC) arriving from the office line during a power outage to the Ringer RG, which is a button telephone that can also be used during a power outage.

Below, referring to FIG. 2, the operation particularly at the time of power outage will be explained.

When a power outage occurs, the relay PF in the power outage monitoring circuit PS
is restored, and the contacts Pf ⁰ , Pf ¹ , and Pf ² move from the state shown by broken lines to the state shown by solid lines. In addition, in the PF-KT, the user manually switches K (not shown).
Press down to close its contacts k ⁰ and k ¹ .

In this state, when a calling signal (20Hz AC) arrives from the office line, the solid line side of terminal a- _C0 - ^Pf0-
Ra−Pf ¹ solid line side−Lc upper line−Ca−RG−Lc
A ringing signal flows through the path of the lower line - the solid line side of Pf ² - Rb - C ₂ - terminal b, and the ringer RG using the AC ringer for power outages rings. here
C ₀ , C ₂ , and Ca are capacitors for DC blocking. At this time, the ringing signal arriving from the station line Lt is routed from the station line Lt - local current polarity rectification diode bridge REC ₁ - DC blocking capacitor Ca - Ringer RG, which is different from the above route. (AC) is full-wave rectified by a diode bridge, and after rectification, a DC blocking capacitor is used.
It is blocked by Ca, and therefore Ringer RG becomes silent. When the user picks up the handset after hearing the ringer, the switch contact HS closes.

This causes diode 2- of terminal b-REC ₁ to
Solid line side of Pf ² - Lower line of Lc - Solid line side of k ¹ - HS
- Solid line side of NW-k ⁰ - Upper line of Lc - Solid line side of Pf ¹ - Diode 1 of REC ₁ - Local current (DC) flows through terminal a.

Since the conversation current in the voice frequency band flows superimposed on the above-mentioned station current, conversation can be carried out between the NW and the station line.

When transmitting from the PF-KT to the office line during a power outage, the office current flows along the same path as above, but when the called party answers, the polarity of the office current is reversed at the office exchange, and as a result, the office line circuit The route of the local current flowing through the inside changes slightly.

That is, the local current is terminal a - diode 3 of REC ₁ - solid line side of Pf ² - lower line of Lc - solid line side of k ¹ - HS - NW - solid line side of k ⁰ - upper line of Lc - Pf ¹ The solid line side of - the diode 4 of REC ₁ - flows through terminal b, and the voice conversation current also passes through this path.

However, the diode 3 of terminal a - REC _{1 -} resistor
A portion of the voice conversation current is shunted through the Rb-capacitor _C2 -terminal b path.

This will cause some call loss in the transmission between the office line and the NW, so the resistance value of Rb may be selected to be high to minimize the increase in call loss. On the other hand, (Ra+Rb) is the ringer
Since it will be inserted in series with the RG in terms of transmission, the resistance value should be as low as possible than the input impedance of the ringer.

As a practical matter, the input impedance of the communication circuit NW is several hundred Ω in the audio frequency band, so the input impedance of the ringer is several tens of Ω.
When using a resistance of Ω or more, if the resistance value of (Ra + Rb) is selected to be about several KΩ to 10 KΩ, the increase in call loss can be minimized to a negligible level, and it is also possible to make the ringer ring.

Passive element circuit in the power outage receiving circuit of the present invention
Two semiconductor varistors can also be used in RN instead of resistors Ra and Rb. Varistor is 10V
For large amplitude alternating current, the resistance value is several tens of ohms.
In addition, its resistance value is several kilohms or more for minute amplitude alternating current of 1V or less, so transmission loss due to series insertion is extremely small for calling signals, and for conversational currents it is several kilohms for NW. K
Since the parallel impedance is Ω or more, the effect on transmission loss is small.

Also, a blocking wire can be used instead of the resistors Ra and Rb. This is because the impedance of the obstructing coil is low for low-frequency alternating current such as a calling signal, and high impedance for conversational current in the voice frequency band.

Resistors, semiconductor varistors, flow coils, etc. are all passive elements, and are preferable circuit elements from the viewpoint of reliability.

Therefore, the power outage terminating circuit according to the present invention is superior in terms of economy and reliability than the conventional power outage terminating circuit, and provides a power outage terminating circuit which is extremely useful in electronic key telephone equipment.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a conventional power outage terminating circuit, and FIG. 2 is a diagram showing a power outage terminating circuit according to the present invention. PF-KT...Key telephone for use during power outages, NW...
...Call circuit, RG...Ringer for power outage, TC...
...Telephone control circuit, ME...Main device, SW...Telephone switch network, CC...Central control circuit, COU...
Station line circuit, REC ₀ ... Diode bridge for calling signal rectification, REC ₁ ... Diode bridge for local current polarity rectification, G... Calling signal receiving circuit for power outage,
RN...Passive element circuit, PC...Photocoupler, PS
...Power failure monitoring circuit, PF...Power failure monitoring relay, Lt
...Station line, Ls...Talking line, Lc...Control data line.

Claims (1)

[Claims] 1. In a button telephone device configured to connect a plurality of key telephones, including the same number of key telephones that can be used during power outages as the number of office lines, and a plurality of office lines via a call switch network, the button telephones that can be used during power outages are , a power outage ringer RG with a DC blocking capacitor Ca connected to the control data line Lc, and a communication circuit NW connected to the control data line from the communication line Ls during a power outage.
It is equipped with switches K ⁰ and K ¹ for switching to Lc, and the station line circuit COU includes a first DC blocking capacitor C ₀ , a second DC blocking capacitor C ₂ , and a diode bridge REC ₁ for local current polarity rectification. A passive element circuit RN and a power failure monitoring relay PF are provided.
The passive element circuit RN is configured to have an impedance value higher than the input impedance of the passage circuit of the button telephone that can also be used during power outages and lower than the input impedance of the ringer RG for power outages, and when energized, the control data line LC is connected to the power outage monitoring relay PF. It is connected to the central control circuit CC through the contacts of , and in the event of a power outage, the contacts of the power failure monitoring relay PF are switched, and the call signal is sent to the station line Lt, DC blocking capacitors C ₀ and C ₂ passive element circuit RN, and the power failure monitoring relay PF. Contacts (Pf ¹ , Pf ² ) flow through the path of the ringer RG during a power outage, the audio signal flows through the path of the ringer RG in the case of a power outage, the audio signal flows through the station line Lt, the diode bridge for local current polarity rectification REC ₁ , the contacts of the power outage monitoring relay PF (Pf ¹ , Pf ² ), changeover switch
A power outage call receiving circuit is characterized in that it flows through the paths of the ^K1 and ^K0 call circuits NW, and enables incoming calls and conversations to be made to a power outage button telephone during a power outage.