JPS5952594B2 - Local ring tone transmission method in button telephone equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a button telephone device, and more particularly to a button telephone device suitable for small businesses or residences.

Conventional key telephone devices of this type are configured to be wired using multi-core cables with approximately 20 core wires.
Wiring work is also not easy, and the arrangement of multi-core cables has the disadvantage of spoiling the aesthetics of the room and increasing construction costs.

In order to eliminate these drawbacks, there is a desire to reduce the number of core wires in distribution cables, but conventionally information between the main device and each slave device was transmitted in parallel within a multi-core cable. Therefore, when reducing the number of core wires, it is necessary to multiplex and transmit this parallel information. However, if all the information is multiplexed and transmitted over the information line, the configuration of the circuit used for information transmission becomes complicated and the cost increases. SUMMARY OF THE INVENTION An object of the present invention is to provide a system for transmitting a central office ring tone in a key telephone device, which is capable of reducing the number of core wires of a distribution cable with a relatively simple circuit configuration.

The present invention will be explained in detail below.

First, the principle of the entire system of the key telephone device according to the present invention will be explained.

In the present invention, information from the main device to the slave device and information from the slave device to the main device are divided into two clocks, and lamp and amplifier operation information from the main device to the slave device is multiplexed and sent to the information line. We decided to use the telephone line to send button selection, hold, and dial information from the handset to the main unit. The communication current of the telephone line is varied by a constant current circuit in the handset, and button selection, hold, and dial information are identified by a detection circuit in the main unit. Putting the above together, 2 central lines and 1 extension line
The table below shows the case of a button telephone device that accommodates lines and connects three handsets. Table 1 clarifies the information and transmission routes, and Table 2 shows an example of the relationship between the status of each handset and the communication current with respect to information sent over the communication line. The basic matters used in the present invention, including the type of transmission line, are listed below.

(1) The communication path is selected by switching one line at a cross point using SCR. (2) The selection of office line 1, office line 2, and extension line is made by identifying the difference in communication current.

(3) The determination of the communication current in order to accurately detect the difference in communication current as described in item (2) is performed by a constant current circuit using an operational amplifier in the handset.

(4) When using the cross-point switching method using SCR, transmission of dial pulses from slave units is an extremely difficult problem.

In the case of a normal telephone, when the communication current is cut off during dialing, the holding current of the SCR is cut off, and the formed cross point is canceled. In order to solve this problem, by controlling the constant current circuit on the handset side, even when the current is cut off by the dial, a talking current similar to the self-holding current of the SCR cross point will flow, and when the dial is connected, a predetermined talking current will flow. The difference is identified within the main device and the pulse is relayed to the line. (5
) When the hold button is pressed, the constant current circuit in the handset is controlled to increase the call current by about 20 mA compared to the normal call current, and this is detected.

(6) When there is a handset detection output on both the office line and the extension line and the trunk is empty, a trigger is input to the cross-point SCR to capture the line; otherwise, the line is not captured and the communication is confidential. (7) Individual extension calls and simultaneous calls to handsets are made by dialing a single digit.

(8) In the main device, voice calling of extension lines, transmission of incoming tone, etc., and selection of handset are performed by cross-point control.

(9) Information transmission via the information line is unidirectional from the main device to the slave device, and is performed by time division multiplexing.

Regarding the information content, 3 bits are used for the lamp information of the office line 1, office line 2, and extension line, and 1 bit is used for the amplifier operation information, so a total of 4 bits constitutes one frame. Based on the above principles, the transmission of information between the main device and each child device will be explained in more detail.

First, since a port-to-car battery system is used for transmission of dial pulses, it is necessary to relay the dial pulses sent from slave devices to the line within the main device.

In addition, since SCR crosspoint control is used to connect the handset and the central office line trunk, if the dial pulses caused by connecting and disconnecting the call current are sent directly from the handset to the main unit as in conventional telephones, the call current will be reduced. When the SCR is disconnected, the holding current of the SCR is lost, so the SCR is restored and the call loop is broken. In order to solve this problem, even when the call current is interrupted during dialing, a current of about 7 mA, which is higher than the holding current (5 mA) of the SCR, flows, and when the call current is connected, the call current (40 or 30 mA) is passed.
is streamed as is, the difference is detected and relayed to the line. 1st
The figure shows the change in communication current and the detection level of the office line detection circuit when dialing the office line 1 from the handset.

Regarding station line hold, the constant current circuit of the handset is controlled so that when the hold button of the handset is pressed, the call current increases by 20 mA from the normal call current, and this increase is detected within the main device.

On the information line, a total of 4-bit information, 3-bit lamp information and 1-bit amplifier operation information, sent from the main device to the slave device is time-division multiplexed and sent. Regarding the synchronization method, it is impossible to send the synchronization signal over a separate line, and since the start-stop synchronization method would complicate the circuitry of the handset, it is decided to send the information signal and the synchronization signal at the same time.

The synchronization signal is sent as a pulse with a level of about 10V, and the information signal is sent as a pulse with a level of about 24V superimposed on the synchronization signal, and the synchronization pulse and the information pulse are separated and used in the slave unit. Regarding the reset pulse, approximately 8 bits are used per frame for 4 bits of information on the information line, and 4 bits are used for each frame.
As for the bit, there is also no synchronization pulse, and when the synchronization pulse does not exist continuously, a reset pulse is generated within the slave unit. FIG. 2 shows an overview of the information content of the information line and the information processing within the handset.

In accordance with the above principle, the button telephone device according to the present invention can be constructed as shown in FIG.

The main device and each slave device #1, #2, #3 are connected by four wires. The four lines are a power (+) line P, a communication line T, an information line J, and a power (-) line G from the top of FIG.

Power is sent through a power (+) line P and a power (-) line G, and communication current is sent through a power (+) line P and a communication line T. Also, depending on the difference in the current flowing through the communication line T, information is sent from the slave device to the main device. Information sent from the main device to the slave device is sent as a 4-bit multiplexed signal through the information line. An incoming tone signal indicating an incoming call from the office line and a voice signal when an extension is called are sent through the communication line T and the power (-) line G, and are sent to the handset amplifier 24.
The signal is amplified and sent out from the speaker 25. The lamp status signal from the main device to the slave unit and the signal for operating the slave unit amplifier are as follows: [Slave unit lamp control circuit 9 → Incoming tone circuit 10 →
Parallel/serial conversion circuit 14→information line J→serial/parallel conversion circuit 23]
2, 33 and slave amplifier 24. The button selection information, central line capture and abandonment information, dial information, and hold information sent from the handset to the main device are controlled by the call current control circuit 21 in the handset and button or dial operations to control the call current to a set current value. Each slave device detection circuit 8-1, 82, 8-3 in the main device and the detection circuit 2-1 of the central office line 1
-2, Office line 2 detection circuit 2-2-2 and extension line detection circuit 3
-2 to identify and control the main device. Since the button selection information is information before the cross point is formed by the SCR, it is identified by the handset detection circuits 8-1, 8-2, and 8-3, and the SCR cross point is formed by the output thereof.
Office line 1, office line 2, and extension trunks 2-1, 2-2, and 3
are connected to each station line. When the Talos point is formed by SCR and the communication path is established, the handset detection circuit 8
-1, 82, 8-3 are separated from the communication path, and are replaced with each detection circuit 2-]-2, 2-2-2 for the central office line 1, central office line 2, and extension line.
, 3-2 becomes operational, dial information, hold information,
Identify and control the abandonment information of central office line extensions. FIG. 4 shows a specific example of the main device in the embodiment of FIG. 3, and FIG. 5 shows a specific example of the slave device.

Next, the operation of the basic functions will be explained.

(Operation of station line transmission) When the station line 1 button of handset #1 is pressed and the handset of the handset is up, the lift switch HS is activated, and the operational amplifier 0P is activated.
A communication current of 40 mA is determined by the resistor R2O3 of the constant current circuit constituted by the transistor Tr2Ol and the transistor Tr2Ol, and R2O4 selected by the button switch LKl, and this is determined by [telephone circuit network arrangement → switch LKl → foot switch HS → BS contact → from the telephone line T#1)] to the telephone line T.

In the main device, the output of IC4 is 10W, and since no current flows through the photocoupler PDl, the transistor Trl connected to it is 0FF, and the 0R circuit 1C2 and N
Through the OT circuit 1C3, the transistors Tr2 and Tr3
is in the 0N state. Here, when a communication current of 40 mA flows from the handset, the communication current flows to the resistor R3 through the transistor Tr3, and a voltage corresponding to 40 mA is generated across the resistor R3. The comparator COMP in the child device detection circuit 8-1 operates, and the output is input to the AND circuit 1C9. In addition, in the detection circuit 2-1-2 of the office line 1, the communication current flows through the transistor Tr3 and the resistor R3, and the transformer LTCO
Since no current flows through l and resistor R8, comparator CO
The mp4 is turned off and its output is 10W.
The output of the comparator COMP4 passes through a NOT circuit 1C54 and is applied to an AND circuit 1C9. In other words, when the trunk 2-1 of the central office line 1 is not in use, the handset detection circuit 8
-1 to capture the station line 1C0L1, A
The ND circuit IC9 is set to a high output and triggers the gate of the SI(7) SCR that connects the handset #1 and the office line 1 trunk 2-1. At the same time, the High output of the AND circuit 1C9 turns the transistors Tr2 and Tr3 0FF through the path of [0R circuit 1C4 → 0R circuit 1C2 → NOT circuit 1C3], and the communication current is changed to [resistance R4 → photocoupler PD
l → S1 SCR → Office line 1 transformer LTCOl → Resistor R
8]. When a communication current flows through the photocoupler PDl, the transistor Trl becomes 0N, and [NOT
The transistors Tr2 and Tr3 are maintained at 0FF through the path: circuit 1C1→OR circuit 1C2→NOT circuit, IC3]. When a communication current flows through the resistor R8, a voltage is generated across the resistor R8, the comparator COMP4 operates, and the high output causes the transistor Tr5 to turn ON, and the relay A1 operates. ．． The line of the office line 1C0L1 is closed by the contact a1-1, and the line of the office line 1C0L1 is connected to the office line 1 transformer LTCO.
Handset #1 completes acquisition of station line 1 through 1. Also,
When the A1 relay operates, the lamp signal of the station line 1 applied to the terminal 4 of the data selector IC67 by the contact a1-2 becomes H.
After parallel/serial conversion by the parallel/serial conversion circuit 14, the information line J(7)LDl information becomes High.
becomes. This signal is sent to the slave device through the information line J, separated into a synchronization pulse and an information pulse by the comparators COMP2Ol and COMP2O2, and serial-parallel converted by the serial-parallel conversion circuit 23, and the transistor Tr2O2
Set to 0N and turn on the lamp LDl. Here, when the handset #1 makes a dial call, the dial opens and closes the contact DPl, and when the contact DPl is open, the resistance R2 of the handset constant current circuit
O4 is separated by contact DPl, and the communication current is passed through resistor R.
It is determined by 2O3. It becomes 10mA.

Also, when the contact DPl is closed, the current is 40 mA, similar to when talking. Further, the contact DP2 short-circuits the telephone circuitry during dialing, which not only prevents noise from the receiver due to intermittent current, but also prevents disturbance of the waveform of the intermittent current caused by the telephone circuitry (7) L and C. The intermittent current generated by the dial is sent to the main device through the telephone line T, and this is the [dialing line T#1].
→ Resistor R4 → Photocoupler PDl → SCR of S1 → Office line transformer LTCOl → Resistor R8].
A voltage pulse is generated across resistor R8. This voltage pulse is detected by comparator COMP5, and the communication current is 1
When the current is 5 mA or less, the comparator COMP5 outputs a High output. The output of the comparator COMP5 turns the transistor Tr6 ON through the NOT circuit 1C12 and the AND circuit 1C13, and turns the D1 relay ON. D1
A dial pulse is sent to the line by the contact d1-1 of the relay. Since a minimum talking current of 7 mA is ensured even during dialing, the current flowing through the SCR of S1 becomes 5 mA or more, which is the minimum holding current of the SCR, and the SCR maintains the ON state. When dialing is complete, the call to the other party is trans-L.
This is done through TCOl. When handset #1 is talking through central line 1, handset #2 attempts to interrupt central line 1 by pressing the button on central line 1 and raising the handset. The communication line T#2) operates and transmits a predetermined communication current from the handset side.
to the main device. At this time, in the main device, since the transistors Tr9 and TrlO of the child device detection circuit 8-2 are in the ON state, the resistor Rl5 is passed through the transistor TrlO.
A communication current flows through the circuit, and a voltage is generated across the terminal, which causes the comparator COMP7 to operate, and the output of the comparator COMP7 is input to the AND circuit 1C10. However, at that time, the station 1 transformer LTCOl is
is in use, the communication current from handset #1 flows into the resistor R8 in the detection circuit 2-1-2 of the office line 1, and a voltage is generated across it. Therefore, the comparator COm
p4 operates, and its output is input to the AND circuit 1C10 through the NOT circuit 1C54. Since this input is at 10W level when the transformer LTCOl is in use, #
Even if there is an output from the handset detection circuit 8-2 of #2, the AND circuit 1C10 does not open, and the connection between handset #2 and the central line 1 transformer LTC
No trigger pulse is applied to the SCR of S2 that couples Ol, and slave unit #2 and station line 1 transformer LTCOl are not coupled. By the above-described operation, the confidentiality of the call on the central office line 1 of the handset #1 is protected. At this point, when handset #1 puts down the handset, the communication current disappears due to the switch HS (17) 0FF, and the holding current of the SCR of S1 that connects the station 1 trunk and handset #1 disappears, and S1 is restored. .

When S1 is restored, the voltage across resistor R8 disappears,
Comparator COMP4 becomes 0FF, and transistor Tr5 becomes 0FF. The relay A1 is restored by turning off the transistor Tr5, and its contact a1-1 is opened to open the line. When the relay A1 is restored, the station line 1 lamp information is set to 0FF by the contact a1-2, and this information is converted from parallel to serial by the parallel to serial conversion circuit 14, and then sent to each slave unit through the information line. The station line 1 lamp of each slave unit goes out. As described above, handset #1 acquires central line 1 from the state in which the handset is initially placed, but when using a key telephone, for example, immediately after the telephone call on central line 2 or an extension ends, When acquiring central office line 1, the acquired line may be changed by directly pressing the central office line 2 or extension button to the central office line 1 button without putting down the handset.

The operation of this device at this time is as follows. Assume that the button for the office line 2 is now switched to the button for the office line 1. While capturing office line 2,
→ Photocoupler PDl → SCR of S4 → Transformer LTCO2 of office line 2 → Resistor R2O → Earth] When the communication current flows through the path of → photocoupler PDl → SCR of S4 → office line 2 is captured by transformer LTCO2, switch LKl of the office line 1 button is activated. When set to 0N, it will be linked to the central office line 1 button and the BS in that call path will be activated for a moment.
The contact opens and the communication current is cut off. Therefore, the cross-point thyristor S4 is restored. Also, since the communication current is cut off, the photocoupler PDl becomes 0FF and the transistor Trl becomes 0FF. 0FF of transistor Trl
Accordingly, [NOT circuit 1C1 → 0R circuit 1C2 → NO
Transistor Tr2 becomes 0 through the path of T circuit 1C3]
The transistor Tr3 becomes 0N. Since the BS contact momentarily becomes 0FF and then immediately becomes 0N, the communication current determined by the contact LKl of the office line 1 button and the resistor R2O4 is as follows: [Power (+) line P → Constant current circuit → Telephone circuit arrangement → Switch LKl →Full switch HS →BS contact →Talking line T
#1)→transistor Tr3→resistance R3→earth], and thereafter operates in the same manner as the capturing operation of the station line 1 described above. (Operation of incoming call on central office line) When an incoming call is received on central office line 1 and a ringing signal is applied, relay R1 operates through capacitors Cl4 and Cl5, and its contacts r1-2 make the output of 0R circuit 1C66 High, and data selector IC67 The handset amplifier operation information applied to terminal 7 of is in the ON state.

This information is parallel-to-serial converted by a parallel-to-serial conversion circuit 14 and sent to each child unit through an information line J. On the handset side, the information is serial-parallel converted by the serial-parallel conversion circuit 23, and the transistor Tr2O5 is turned ON to operate the C relay. The amplifier circuit output is connected to the speaker 25 through the contact C, and the amplifier circuit becomes operational. Also, the incoming tone circuit 10 is operated by the r1-2 contact, and the tone ringer signal is amplified by the AMP circuit 11, and the tone ringer signal is amplified by the tone sending transformer T. It is input to T. One end of the secondary side of the transformer is given a potential of approximately 5 by a Zener diode ZD4, and the other terminals are connected to all slave units' communication lines T#1), T#2), T# through diodes D6, D7, and D8. 3) is connected.

Now, when handset #1 is not in use, [+5V→Transformer T. Current flows through the path T → diode D6 → communication line T#1) → hook switch HS → resistor R2O8],
The diode D6 becomes ON, and the tone ringer signal is superimposed on this path and transmitted to the handset #1, amplified by the handset amplifier 24, and the speaker 25 sounds. In addition, when handset #2 is talking on the central office line, the communication current flows through the path [communication path T#2 of handset #2 → photocoupler ZD2 → SCR of S5 → transformer LTCO2 of central line 2 → resistor R2O]. Therefore, the diode D7 is reverse biased and becomes 0FF, and no tone ringer signal is sent to the communication line T#2) of the handset #2. By the above operation, only the speaker 25 of the handset that is not in use is made to sound without affecting the call in use. Furthermore, for handsets that are preset to stop the station ringing signal, it is also possible to stop the station ringing tone by not installing the diodes D6, D7, or D8 that connect the communication line of the handset. When relay R1 operates, its contact r1-1 causes the oscillation circuit 0SC (2HZ) in the slave lamp control circuit 9 to oscillate a 2HZ square wave signal, and the A
The ND circuit 1C60 and the 0R circuit C64 add a 2Hz intermittent signal to the station line 1 lamp information. This is converted into parallel/serial, sent to each handset through the information image J, converted into serial/parallel, and the station line 1 lamp of all handsets flashes at 2Hz. Here, when handset #1 presses the office line 1 button and lifts the handset, it operates to make a call to the office line, and the output of the handset detection circuit 8-1 and the office line detection circuit 2-12 of office line 1 are activated. S1 that connects the station line 1 transformer LTCOl and slave unit #1 by status output
A trigger is applied to the gate of SCR to set S1 to ON.

The call current is [handset #1 → call line T#1] → resistor R4 → photocoupler PDl → SCR of S1 → transformer LTCOl →
The voltage generated across the resistor R8 operates the comparator COMP4, and its output turns the transistor Tr5 ON, thereby operating the relay A1. Rire A
1 is activated, the line of the central office line 1 is closed by its contact a1-1. When the central office line 1 is closed, the calling signal stops, so the relay R1 is restored, the tone ringer signal is stopped by the contact r1-2, and the amplifier 0N information to each slave/machine is added to the terminal 7 of the data selector IC 67. becomes 0FF, and the 2Hz intermittent signal of the station line 1 lamp becomes AN by contact RH.
Since it is blocked by the D circuit 1C60, it becomes a continuous signal, and the office line 1 lamp information becomes continuous lighting information through the 0R circuit 1C64. Operation OFF signal of slave unit amplifier and station line LA. The lamp lighting information is sent to the slave units through the information line J, and all the slave unit amplifiers are stopped, and the office line 1 lamp is turned on continuously.
The operation for terminating a call is the same as for calling a central office line. (
Station line holding and reacquisition operations). Next, an explanation will be given of the operation during holding and reacquisition after a call to the central office line.

Assume that the caller presses the hold button while handset #1 is talking on the local line using central line 1.

The structure is such that when the hold button is pressed, the station line 1 button is not restored, and when the hold 4 button is restored, the station line 1 button is restored at the same time. Therefore, when the hold button is pressed, a resistor R2O7 is added by the HK contact in addition to the current determining resistors R2O3 and R2O4 of the constant current circuit, so the current flowing through the resistor R2O7 is added to the normal call current. Resistor R2O7 so that this increase becomes about 20mA
Determine the value of Also, at this time, the HK contact short-circuits the telephone circuitry to prevent a voltage drop due to the telephone circuitry.

The increased talking current is sent to the main device through the talking line,
The voltage flows through the path of communication line T#1) → resistor R4 → photocoupler PDl → SCR of S1 → transformer LTCOl → resistor R8], and the voltage across resistor R8 increases. The comparator COMP6 detects this voltage increase, and its output turns the transistor Tr7 ON and operates the H1 relay. H
When the 1 relay operates, the line is closed by the contact h1-1 and the resistor R42 due to the operation of the contact h1-1. When the hold button is released at this point, the central line 1 button is restored together with the hold button, so that the communication current disappears, the SCR of S1 becomes 0FF, and the voltage across the resistor R8 disappears. When the voltage disappears, comparator COMP4, comparator C
Omp6 becomes 0FF. Comparator COMP
The A1 relay is restored by the output of 4, and its contact a1-1 is closed. Also, the transistor Tr7 becomes 0FF due to the output of the comparator COMP6, but the H1 relay is connected to the contact h1-2.
The control is held at the contact point a1-3, and the state is put on hold. Al
When the relay is restored and the H relay operates, contacts h1-3 and a
1-2, AND circuit IC62 and 0R circuit 1C64
By turning on, the station line 1 lamp information changes from continuous information to a 1/2Hz intermittent signal, which is sent to each slave unit through the information line J, and the station line 1 lamp of each slave unit changes from continuous lighting to 1/2Hz intermittent signal. /2Hz blinking. In this state, when handset #1 presses the office line 1 button again to raise the handset and go to reacquire it, the A1 relay operates in the same way as when making a call to the office line, and the line is disconnected from contact a1-1. transformer LTCO].

Also, the H1 relay is restored by the contact a1-3, and the AND circuit 1C62 and the 0R circuit 1C64 are activated by the contacts h1-3 and a1-2.
is turned off, the station line 1 lamp information changes from a 1/2 Hz intermittent signal to a continuous signal, and the station line 1 lamp of each slave unit changes from blinking to continuously lit. Termination of the call is the same as for the central office line originating operation. (Extension call and extension call) When the extension button of handset #1 is pressed and the handset is raised, switch LK3 operates a constant current circuit with resistors R2O3 and R2O6, and a call current of 20 mA flows. (+) line P → constant current circuit → telephone circuit arrangement → switch LK3 → switch LK2 → switch LKl → switch HS → BS contact → speech line T#1)].

In the main device, since the transistor Tr3 is set to 0N, the transistor Tr3 and the resistor R3 are connected to the communication line T#1).
, and a voltage is generated across the resistor R3. This voltage operates comparator COMP3, and AND circuit 1C
8 to the AND circuit 1C35. Also, when the extension transformer IT is not used, the extension detection circuit 3-
No current flows through the resistor R39 inside the comparator COMP.
Since l6 is not operating, NOT circuit IC4l and 0R
It is input to AND circuit 1C35 through circuit 1C38. Therefore, AND circuit 1C35 is opened and slave unit #1
A trigger is applied to the gate of the SCR of S7 for coupling with the extension transformer IT, and S7 is turned ON. AND circuit 1C3
The output of 5 is 0R circuit 1C4, 0R circuit 1C2 and N
It is connected to the transistor Tr2 through the OT circuit C3, and the transistor Tr2 is set to 0FF and the transistor Tr3 is also set to 0.
Become FF. The communication current flowing through the transistor Tr3 and the resistor R3 is switched to the SC of S7 when the transistor Tr3 is turned 0FF.
Since R is 0N, it flows through the path of [talk line T#]) → resistor R4 → photocoupler PDl → SCR of S7 → extension transformer IT-) and two resistors R39]. Since the communication current flows through the photocoupler PDl, the transistor Trl turns on,
[NOT circuit 1C1 → 0R circuit 1C2 → NOT circuit 1C
0F of transistors Tr2 and Tr3 through the path of
Maintain F. Call to resistor R39; current of 20 mA flows, so the voltage across it causes comparator COMP]6
works. The output of the comparator COMPl6 makes the extension lamp information 0N, and this information is converted into information by the parallel/serial conversion circuit 14 and sent to each child unit through the information line J. Comparator COMP2O in each slave unit
After it is separated into a synchronization pulse and an information pulse by COMP2O2, it is converted into parallel information by a serial/parallel conversion circuit 23, and the transistor Tr2O4 is set to ON through a resistor R2l2 and a Schmitt trigger IC2O7, and the extension lamp is turned on. Next, when handset #1 is dialed for individual calling or simultaneous calling, the following operations occur.

(1) In the case of individual calling, when the call current is cut off by dialing, the constant current circuit on the handset side is connected to the resistor R2 by contact DPL.
6 is disconnected, the communication current becomes 7 mA due to the resistor R2O3, and when the dial is connected, the resistance R2O6 is connected through the contact DPl, so that the same current as the communication current of 20 mA flows.

This intermittent current is sent to the main device through the communication line T#1), [Communication line T#1) → Resistor R4 → Photocoupler PD]
→ SCR of S7 → extension transformer IT → resistor R39], and the voltage across the resistor R39 changes.
Comparator COMP7 detects this and [NOT
Circuit 1C53 → AND circuit 1C50 → Counter IC49
] is input to the decoder IC 48 through the path. When the output corresponding to the dial is output to the decoder, the output is NO.
In the case of 2, [AND circuit 1C46 → 0R circuit 1C4
3 → Resistor R32 → Diode D4 → Extension transformer IT →
A calling current flows through the path of the resistor R39], and the diode D4 becomes ON. Due to the 0N of diode D4, the audio signal of handset #1 is transferred to [handset #1→talk line T#
1) → Capacitor C1 → SCR of S7 → Diode D4
→ Capacitor C9 → Capacitor C4 → Communication line T#2)
→ Hook switch HS → Capacitor C2O2 → AMP2
5→speaker 25], the speaker 25 transmits the calling voice of the slave unit #1. When the output is output from the decoder IC48, the decoder output is 0R circuit 1C52, IC
The amplifier operation information is set to ON through 66. This information is sent to the slave units through the information line J, and operates the C relay to put the amplifier 24 of each slave unit into an operating state. Also, during calling, from the output of decoder C48 [AND circuit 1C64 → 0R circuit 1C43 → 0R circuit I
C39→AND circuit 1C36], a high level is applied to the trigger gate input of the cross point SCR for the extension of the called slave unit.

When handset #2 responds to the call, the call current 2 is determined by resistors R2O3 and R2O6 in the constant current circuit.
0mA is [power (+) line P → constant current circuit → telephone circuit arrangement → switch LK3 → switch LK2 → switch LKl
→Hook switch HS→BS contact→Talking line T#2)]. Since the transistor TrlO is in the ON state, the communication current flows to the resistor Rl5 through the transistor Trl0, a voltage is generated across the resistor Rl5, and the comparator COMP9 operates. The output of comparator COMP9 is A through AND circuit 1C21.
It is input to the ND circuit 1C36. Now, AND circuit 1C3
Another one of 6. High is applied to the input from the output of decoder 1C48 through the path [AND circuit 1C46 → 0R circuit 1C43 → 0R circuit 1C39], so AND circuit 1C36 is opened and connects slave #2 and extension transformer IT. A trigger is applied to the SCR gate of S8 to turn S8 ON. The output of the AND circuit 1C36 passes through the path [0R circuit 1C] 7 → 0R circuit 1C15 → NOT circuit 1C16], and the transistor Tr9 is turned 0FF.
Therefore, the transistor TrlO also becomes 0FF. When the transistor TrlO becomes 0FF and the SCR of S8 becomes 0N, the communication current becomes [communication line T#2] → resistor Rl6 → phototransistor PD2 → SCR of S8 → extension transformer I
T→resistance R39]. When the voltage across resistor R39 increases, comparator COMPl82 operates, resets the output of counter IC49 through NOT circuit 1C51, and stops the output of decoder C48. Therefore, the calling diode D4 becomes 0FF, and the output of the 0R circuit 1C52 disappears, so the amplifier operation information becomes 20FF. Amplifier information is 0FF on the slave device
Therefore, the C relay is restored and the slave amplifier 24 is stopped.
Here, the SCR of S7 and S8 of handset #1 and handset #2 is 0.
Since it is N, it is connected by extension transformer IT,
A mutual conversation is established.

When the call ends and handset #1 and handset #2 both put down their handsets, the call current disappears and the SCRs of S7 and S8 are restored.

When the SCRs of S7 and S8 are restored, the voltage across resistor R39 disappears. Therefore, comparators COMPl6 and CO
mp]8 is turned OFF, the extension lamp information is turned OFF due to the OFF of the comparator COMPl6, and the extension lamp of each slave unit is turned off. (2) In the case of simultaneous calling, set the dial number for simultaneous calling to “O”, and use the decoder I
When the output of C48 is “0”, 0R circuit 1C42, IC
43, calling diode D3, D through IC44
4, D5 are all set to 0N, and the calling voice from handset #1 is sent to the communication lines of all handsets through diodes D3, D4, and D5, amplified by handset amplifier 24, and sent from speaker power 25. .

In addition, the output of the decoder IC 48 ゜“O゛” adds High to the gate IC (AND circuit) input for triggering each SCR, and no matter which handset captures the extension and responds, the communication path is connected to the extension transformer IT. Establish a communication path with handset #1.
When the communication path is formed, the output of the decoder IC 48 is stopped as in the case of an individual call, and the handsets other than those in the mutual communication state are disconnected from the extension transformer IT and placed in a confidential state. Termination of an extension call is the same as for an individual call.

Although the above example has been described in which two central office lines, one extension line, and three slave units are accommodated, the present invention is not limited to this example, and generally accommodates three or more central office lines and two extension lines. Of course, it can also be applied when accommodating more than 4 lines and 4 or more handsets, and depending on the number of lines and handsets required, the main device and the detection circuit and selection circuit in the telephone set may be required. This can be realized by making some changes.

As described above, according to the present invention, in the button telephone device in which the communication current system is DC-separated from the office line, each office line is provided with a ringing signal detection relay Rl, R2, and the contact of the ringing signal detection relay is provided. A local ringing tone generating circuit 10 for generating a local ringing tone that operates in response to the operations of r1-2 and r2-2.
and a transformer T. for transmitting the station ring tone. T, and a constant voltage power supply 7R connected to one end of the secondary winding of the transformer.
4O, ZD4, Cl2, and a plurality of diodes D each inserted into the communication path from the other end of the secondary winding and each handset.
6, D7, and D8, and the amplifier for amplifying the speaker input of the handset is enabled by the operation of the contacts of the calling signal detection relay, so that the station ringing tone is radiated from the speaker via the amplifier. It is possible to realize a central office ringing tone transmission system in a key telephone device equipped with amplifier operation signal sending means 1C66 and IC67 for sending out an amplifier operation signal. Here, the communication path of the handset includes constant voltage generating means ZDl, ZD2, ZD3, and during communication with the office line or extension line, the corresponding one of the plurality of diodes D6, D7, D8 is reverse biased to 0FF. In this state, the station ring tone can be configured to be prohibited from being sent to the corresponding handset.

As explained in detail above, the present invention can reduce the number of core wires in a distribution cable, and by using such a small number of core wires and a simple configuration, it is possible to transmit station ringtones from the main device to each slave device. This has the effect of being able to transmit and radiate station ringtones from the speaker of the handset.

[Brief explanation of the drawing]

FIG. 1 is a waveform diagram for explaining the transmission of dial pulses in the button telephone device according to the present invention, FIG. 2 is a waveform diagram for explaining the transmission of information in the button telephone device according to the present invention, and FIG. 4 and 5 are circuit diagrams of the main device and the telephone, respectively, showing detailed circuit configuration examples of the button telephone device according to the present invention. FIG. .

Claims (1)

[Claims] 1. In a button telephone device in which the communication current system for each handset is DC-separated from the central office line in the main unit, a relay for detecting a ringing signal is provided for each office line in the main unit, and the relay for detecting the ringing signal is provided in the main unit. a local ring tone generating circuit for generating a local ring tone that operates in response to the operation of the contact, a transformer for transmitting the local ring tone, and a constant connected to one end of the secondary winding of the transformer. The voltage power source, a plurality of diodes inserted into the communication path from the other end of the secondary winding to each of the slave units, and the contacts of the call signal detection relay are operated to detect the speaker input of each slave unit. and amplifier operation signal sending means for sending out an amplifier operation signal for enabling an amplifier that amplifies the local station tone so that the station ringing tone is radiated from the speaker via the amplifier; The communication path includes a constant voltage generating means, and during communication with a central office line or an extension line, a corresponding one of the plurality of diodes is reverse-biased by applying a voltage higher than the voltage of the constant voltage power supply.
A system for transmitting a central office ringing tone in a button telephone device, characterized in that the central office ringing tone is configured to be prohibited from being transmitted to a corresponding handset in an FF state.