JPS5950154B2 - Control method for 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 control system for a button telephone device that can reduce 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 blocks, 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, a talking current equivalent to the self-holding current of the SCR cross point will flow even when the current is interrupted by the dial, and a predetermined talking current will flow when the dial is connected. 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 the dial pulse transmission method is adopted, it is necessary to relay the dial pulses sent from the slave units to the line within the main unit.

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 bits of information, 3 bits of lamp information and 1 bit of amplifier operation information, sent from the main device to the slave device are 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 1CV, 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 per frame are used for the information amount of 4 bits on the information line, and 4 bits are used for each frame.
As for the bit, there is also no synchronization pulse, and a reset pulse is generated within the handset when synchronization pulses are not present continuously. 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. From the top of Figure 1, the four lines are the power (+) line P, the telephone line T, the information line J, and the power (-) line. It is G.

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. The incoming tone signal that notifies you of an incoming call from the central office line and the voice signal when an extension is called are transmitted through the telephone line.
It is sent through the talk line T and the power (-) line G, and is sent to the slave amplifier 2.
4 and sent out from the speaker 25. The lamp status signal from the main unit 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] through each lamp 31, 3 in each slave unit.
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. and transmits it to each slave device detection circuit 8-1, 8-2, 8-3 in the main device, and the detection circuit 2 of the central office line 1.
-1-2, is identified by the detection circuit 2-2-2 of the office line 2 and the extension detection circuit 3-2, and the main device is controlled. 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 output forms the SCR cross point. Office line 1, office line 2, and extension trunks 2-1, 2-
At points 2 and 3, it is connected to each station line. When a cross point is formed by SCR and a communication path is established, handset detection circuits 8-1, 8-2, and 8-3 are disconnected from the communication path, and instead detect each of central line 1, central line 2, and extension line. Circuit 2-1-2
, 2-2-2, and 3-2 are in operation to identify and control dial information, hold information, and abandonment information of central office line extensions. Fourth
The figure 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 R203 of the constant current circuit constituted by the transistor Tr201 and the transistor Tr201 and R204 selected by the button switch LK1, and this is determined by [telephone circuit network TEL → switch LK1 → switch HS-+BS contact → from the telephone line T#1)] to the telephone line T.

In the main device, the output of IC4 is low and no current flows through the photocoupler PD1, so the transistor Tr1 coupled to it is OFF, and the OR circuit 1C2 and N
Through the OT circuit 1C3, the transistors Tr2 and Tr3
is in the ON 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. Comparator Comp1 in slave device detection circuit 8-1 operates, and its output is input to AND circuit 1C9. In addition, in the detection circuit 2-1-2 of the central office line 1, the communication current flows through the transistor Tr3 and the resistor R3, and the transformer LTCO
1 and resistor R8, so the comparator Co
mp4 is turned off and its output is low.
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
When an output is added to capture the station line 1COL1 from -1, A
The ND circuit 1C9 is set to a high output and triggers the gate of the SCR of S1 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 is as follows: [0R circuit 1C4 → 0R circuit 1C2 → NOT circuit 1C
3] through the path, transistors Tr2 and Tr3 are turned off.
F, and the communication current is [Resistor R4 → Photocoupler PD1 →
S1 SCR → Office line 1 transformer LTCO1 → Resistor R8]
flows along the path of When a communication current flows through the photocoupler PD1, the transistor Tr1 is turned on, and the transistors Tr2 and Tr3 are kept off through the path [NOT circuit 1C1→OR circuit 1C2→NOT circuit IC3]. When the communication current flows through the resistor R8, a voltage is generated across the resistor R8, the comparator Comp4 operates, and the Hi
The transistor Tr5 is turned on by the gh output, and the relay A1 operates. The central line 1COL is connected by the contact a1-1.
The line No. 1 is closed, and the handset #1 completes acquisition of the office line 1 through the office line 1 transformer LTCO1. In addition, when the A1 relay operates, the data selector IC is
Since the lamp signal of the station line 1 applied to the terminal 4 of the terminal 67 becomes High, the information line J(7) LD1 information becomes High after parallel-to-serial conversion by the parallel-to-serial conversion circuit 14. This signal is sent to the handset through the information line J, separated into a synchronization pulse and an information pulse by comparators Comp201 and Comp202, and serial-parallel converted by the serial-parallel conversion circuit 23, turning on the transistor Tr202 and lighting the lamp LD1. When handset #1 makes a dial call, contact DP1 opens and closes due to the dial, and contact D
When P1 is open, the resistor R204 of the slave unit constant current circuit is connected to contact D.
It is separated by P1, and the communication current is 10 mA determined by resistor R203.

When the contact DP1 is closed, the current is 40 mA, similar to when talking. Also, contact DP2 connects telephone circuit T during dialing.
Short-circuiting EL not only prevents noise from the receiver due to intermittent current, but also prevents disturbance of the waveform of intermittent current caused by telephone circuit TEL(7)L,C. The intermittent current generated by the dial is sent to the main device through the communication line T, and this is transmitted to the SCR of [communication line T#1] → resistor R4 → photocoupler PD1 → S1.
→ station line transformer LTCO1 → resistor R8], and a voltage pulse is generated across the resistor R8. This voltage pulse is detected by comparator Comp5, and when the communication current is 15 mA or less, comparator Comp5 goes high.
Outputs ``high'' output. The output of comparator Comp5 is
The transistor Tr6 is turned ON through the NOT circuit 1C12 and the AND circuit 1C]3, and the D1 relay is turned ON. The contact d1-1 of the D1 relay sends out a dial pulse for rotation. Call current is at least 7mA even when dialing
is ensured, the current flowing through the SCR of S1 is S
The minimum holding current of the CR becomes 5 mA or more, and the SCR maintains an ON state. When the dialing is completed, the call to the other party is made through the transformer LTCO1. While handset #1 is talking on central line 1, handset #2 attempts to interrupt central line 1 by pressing the button on central line 1 and raising the handset. It operates and sends a predetermined communication current from the handset side to the main device through the communication line T#2).

At this time, in the main device, since the transistors Tr9 and Tr10 of the child unit detection circuit 8-2 are in the ON state, a communication current flows through the transistor Tr10 to the resistor R15, and a voltage is generated across the resistor R15, which causes the comparator C
omp7 operates, and the output of comparator Comp7 is A.
The signal is input to the ND circuit 1C10. However, at that time station 1
Transformer LTCO1 is in use by slave unit #1, so it is connected to station line 1.
The communication current from handset #1 flows into the resistor R8 in the detection circuit 2-1-2, and a voltage is generated across the resistor R8.
Therefore, the comparator Comp4 operates, and its output is input to the AND circuit 1C10 through the NOT circuit 1C54. Since this input is at a low level while transformer LTCO1 is in use, #2 slave device detection circuit 8-2
AND circuit 1C10 does not open even if there is an output from
No trigger pulse is applied to CR, and slave unit #2 and office line 1 transformer LTC01 are not coupled. By the above-described operation, the confidentiality of the telephone call on the central office line 1 of the handset #1 is protected. Here, slave #
When 1 puts down the handset, the hook switch HS (7) turns OFF.
Due to this, the communication current disappears, and the holding current of the SCR of S1 that connects the station 1 trunk and handset #1 disappears.
will be restored.

When S1 is restored, the voltage across resistor R8 disappears, comparator Comp4 turns OFF, and transistor T
r5 turns OFF. The relay A1 is restored by turning off the transistor Tr5, and its contact a1-1 is opened to open the line. When relay A1 is restored, the station line 1 lamp information is turned OFF by contact a1-2, and this information is transmitted in parallel and
After being parallel-to-serial converted by the serial conversion circuit 14, it is sent to each slave unit through the information line, and the office line 1 lamp of each slave unit is turned off. The operation of acquiring central line 1 from the state in which handset #] is initially placed on the handset is as described above, but when using a key telephone, for example, immediately after the telephone call on central line 2 or an extension ends, When acquiring station line 1, the acquisition time may be changed by pressing the station line 2 or extension button directly to the station 1 button without hanging up 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 station line 2, [power (+) line P → constant current times? -?
―Hatakeji =, Ni Engineering #1) → Resistor R4 → Photocoupler PD
1→S4 SCR→transformer LTCO2 of office line 2→resistance R20→earth], the telephone current flows through the path of transformer L.
When the station line 2 is captured by the TCO2, when the switch LK1 of the station line 1 button is turned on, the BS contact in that communication path opens momentarily in conjunction with the station line button, and the communication current is reduced. It will be terminated.

Therefore, the cross-point thyristor S4 is restored. Also, since the communication current was cut off, the photocoupler PD1 was turned off.
The FF retransistor Tr1 is turned off. By turning off the transistor Tr], [NOT circuit 1C1→
Through the path of OR circuit 1C2→NOT circuit 1C3, transistor Tr2 is turned on, and transistor Tr3 is turned on.
become. The BS contact turns OFF momentarily and then turns OFF immediately.
Contact point LK1 of station line 1 button and resistor R204 to become N
The communication current determined by [power supply (+) line P → constant current circuit → telephone circuit TEL → switch LK1 → hook switch HS->BS contact → communication line T#1) → transistor Tr
3→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 added, relay R1 operates through capacitors C14 and C15, and its contact r1-2 causes the output of OR circuit 1C66 to go 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 Tr205 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 5V by a Zener diode ZD4, and the other terminals are connected to the communication lines T#1), T#2), and T# of all slave units through diodes D6, D7, and D8. 3) is connected. Now, when handset #1 is not in use, [+5V
→Trans T. T→Diode D6→Talking line T#1)→
A current flows through the path from the switch HS to the resistor R208, turning the diode D6 ON, and the tone ringer signal is superimposed on this path and transmitted to the handset #1, where it is amplified by the handset amplifier 24 and the speaker 25 sounds. Child machine#
2 is in the middle of a telephone call on the central office line, the telephone current flows through the path [communication path T#2 of handset #2 → photocoupler ZD2 → SCR of S5 → transformer LTCO2 of central telephone line 2 → resistor R20]. Therefore, the diode D7 is reverse biased and turned off, 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 slave lamp control circuit 9 to oscillate a 2HZ square wave signal, and AND circuit 1C60 and OR circuit 1C64 generate station line 1 lamp information. A 2Hz intermittent signal is added to the signal. This is converted into parallel/serial and sent to each slave unit through the information line J.
Parallel conversion is performed and the station line 1 lamp of all slave units blinks at 2Hz. Here, when handset #1 presses the office line 1 button and lifts up the handset, it operates to make a call to the office line, and handset detection circuit 8-
1 and the status output of the station line detection circuit 2-1-2 of station line 1, a trigger is applied to the gate of SCR of S1 that connects station line 1 transformer LTCO1 and handset #1, and S1 is turned ON.
Let it be.

Telephone Dentsu is [handset #1 → telephone line T#1] → resistor R4 → photocoupler PD1 → SCR of S1 → transformer LTCO1 →
The voltage generated across the resistor R8 operates the comparator Comp4, and its output turns on the transistor Tr5, thereby operating the relay A1. When relay A1 operates, it closes the line of central office line 1 through its contact a1-1. When the office line 1 is closed 2, the calling signal is stopped, so the relay R1 is restored, the tone ringer signal is stopped by the contact r1-2, and the amplifier to each slave unit connected to the terminal 7 of the data selector IC 67 is turned on. The information is turned OFF, and the 2Hz intermittent signal of the office line 1 lamp is blocked by the AND circuits 1C and 60 by the contact r1-1, so it becomes a continuous signal, and the information about the office line 1 lamp becomes continuous lighting information through the OR circuit 1C64. The operation 0FF signal of the slave amplifier and the lighting information of the office line lamp are sent to the slave unit through the information line J, and all slave 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. (Operation of Holding and Reacquisition of Local Line) Next, the operation of holding and reacquiring after a call with the local line will be explained.

It is assumed that the caller presses the hold button while the handset #] is talking on the central line using central line 1.

When the hold button is pressed, the button for the central office line 1 is not restored, and when the hold button is restored, the central office line 1 button is also restored at the same time. So, if you press the hold button,
Since a resistor R207 is added by the HK contact in addition to the resistors R203 and R204 for determining the current of the constant current circuit, the current flowing through the resistor R207 is added to the normal communication current.
The value of resistor R207 is determined so that this increase will be approximately 20 mA. Further, at this time, the HK contact short-circuits the telephone circuit TEL to prevent a voltage drop due to the telephone circuit TEL. The increased communication current is sent to the main device through the communication line, [communication line T#1) → resistor R4 → photocoupler PD1.
→ SCR of S1 → transformer LTCO1 → resistor R8], and the voltage across resistor R8 increases. The comparator Comp6 detects this voltage increase, and its output turns on the transistor Tr7 to operate the H1 relay. When the H1 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 is turned off, and the voltage across the resistor R8 disappears. When the voltage disappears, the comparators Comp4 and Comp6 are turned off. The A1 relay is restored by the output of the comparator Comp4, and its contact a1
-1 is closed. Further, the transistor Tr7 is turned off by the output of the comparator Comp6, but the H1 relay is held at the contact point h1-2 and the contact point a1-3, and is in a suspended state. When the A1 relay is restored and the H relay operates, contact h1
-3 and a1-2, the AND circuit 1C62 and OR circuit 1C64 are turned on, and the station line 1 lamp information changes from continuous information to a 1/2Hz intermittent signal, and the information line J
The signal is sent to each slave unit through the cable, and the station line 1 lamp of each slave unit changes from continuously lit to blinking at 1/2 Hz. 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 its contact a1-1 disconnects the line. Trans LTCO
It is concluded by 1.

Also, the H1 relay is restored by the contact a1-3, and the AND circuit 1C62 and the OR 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, a constant current circuit is activated by resistors R203 and R206 by switch LK3, and a call current of 20 mA flows. (+) wire P → constant current circuit → telephone circuit TEL
→Switch LK3-Switch LK2→Switch LK1→
The signal is sent to the main device through the route of the switch HS → BS contact → communication line T#1).

In the main device, since the transistor Tr3 is ON, the communication line T#1) is connected to the transistor Tr3 and the resistor R3.
, 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 in the comparator Comp.
16 is not operating, the NOT circuit IC41 and OR
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 0R circuit 1C4, OR circuit 1C2 and N
It is added to the transistor Tr2 through the OT circuit 1C3,
Transistor Tr2 is OFF and transistor Tr3 is also OFF.
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 off.
Since R is 0N, [talk line T#1] → resistor R4 → photocoupler PD1 → SCR of S7 → extension transformer IT → resistor R
39]. Since the communication current flows through the photocoupler PD1, the transistor Tr1 turns on, and [N
OT circuit 1C1 → OR circuit 1C2 → NOT circuit 1C3]
The transistors Tr2 and Tr3 are kept OFF through the path. Since a communication current of 20 mA flows through the resistor R39, the voltage across the resistor R39 operates the comparator Comp16. The output of the comparator Comp16 turns on the extension lamp information, and this information is transferred to the parallel/serial conversion circuit 1.
4, the data is converted into information and sent to each slave unit via an information line J. In each slave unit, comparator Comp201, Co
After it is separated into a synchronization pulse and an information pulse by the mp202, it is converted into parallel information by the serial/parallel conversion circuit 23, and the transistor Tr204 is turned on through the resistor R212 and the Schmitt trigger IC207 to turn on the extension lamp. 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 R20 by contact DP1.
6 is disconnected and the talking current is 7 mA due to the resistor R203, and when the dial is connected, the resistor R206 is connected through the contact DP1, so the same current as the talking current of 20 mA flows.

This intermittent current is sent to the main device through the communication line T#1) → resistor R4 → photocoupler PD1 →
A current flows through the path from SCR of S7 to extension transformer IT to resistor R39, and the voltage across resistor R39 changes.

Comparator Comp17 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, if the output is black 2, [AND circuit 1C46 → OR 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 is turned on. By turning on the 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) → Foot switch HS → Capacitor C202 → AMP25 →
from speaker 25 to slave unit #1 via the route of speaker 25].
A ringing voice is sent out. When the output is output from the decoder IC48, the decoder output is OR circuit 1C52, IC66
Turn on the amplifier operation information through the 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, while calling, decoder I
From the output of C48 [AND circuit 1C64 → 0R which path 1C
43→OR circuit IC39→AND circuit 1C36] Cross point SC for the extension of the handset called through the route
Add High to the R trigger gate input.

When handset #2 responds to the call, the call current of 20 mA determined by resistors R203 and R206 in the constant current circuit is as follows: [Power (+) line P → Constant current circuit → Telephone circuit TEL → Switch LK3 → Switch LK2 → Switch LK1 → Switch HS->BS contact → Talk line T#
It flows to the main device through the route 2). Since the transistor Tr10 is in the ON state, the communication current flows through the transistor Tr1.
0 to the resistor R15, a voltage is generated across the resistor R15, and the comparator Comp9 operates. The output of comparator Comp9 is input to AND circuit 1C36 through AND circuit 1C21. Now, the other input of the AND circuit 1C36 is from the output of the decoder IC48 [AND circuit 1C46 → OR circuit 1C43 → OR
Since a high signal is applied through the path of the circuit 1C39], the AND circuit 1C36 opens and applies a trigger to the gate of the SCR of S8 that connects the handset #2 and the extension transformer IT, turning S8 ON. The output of the AND circuit 1C36 passes through the path of [OR circuit 1C17→OR circuit 1C15→NOT circuit 1C16], and transistor Tr9 is turned off.
The transistor Tr10 is also turned off. When the transistor Tr10 is turned off and the SCR of S8 is turned on, the communication current is [talk line T#2] → resistor R16 → phototransistor PD2 → SCR of S8 → extension transformer IT
→Resistance R39]. When the voltage across resistor R39 increases, comparator Co p18 operates,
The output of the counter IC49 is reset through the NOT circuit 1C51, and the output of the decoder IC48 is stopped. Therefore, the calling diode D4 is in the OFF state,
Also, since the output of the 0R circuit 1C52 is eliminated, the amplifier operation information becomes 0FF. Since the amplifier information has been turned off in the slave device, the C relay is restored and the slave amplifier 24 is stopped. Here, since the SCRs of S7 and S8 are ON, handset #1 and handset #2 are connected through the extension transformer IT, and are in a mutual communication state.

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, so comparators Comp16 and Com
p18 turns OFF, and comparator Comp16 turns OFF.
The extension lamp information is turned OFF by FF, and the extension lamps of each handset are turned off. (2) In the case of simultaneous calling, set the dial number for simultaneous calling to 6'', and use the decoder I
When the output of C48 is “0”, 0R circuit 1C42, IC
43, diode D3 for calling through IC44,
D4 and D5 are all turned on, 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 decoder IC 48's output 6 ``'' adds High to the trigger gate IC (AND circuit) input of each SCR, so that no matter which handset captures the extension and responds, the communication path is connected to the extension transformer IT. , and forms a communication path with handset #1.
When the communication path is formed, the output of the decoder IC 48 is stopped in the same way as in the case of individual calling, 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 in detail, according to the present invention, in a button telephone device in which the communication current system is separated from the office line in terms of direct current,
For each communication path connecting each slave device and the main device, the current value of the communication current is identified by comparing it with at least one predetermined reference value, and the current value is determined in a plurality of predetermined current ranges. handset detection means 8-1, 8-2, 8-3 that generates an output corresponding to which region it belongs to; and a telephone line for separating the handset detection means from the communication path when a communication current is present. Current monitoring means 2-1-2, 2-2-2, 3-2,
Thyristors 6-1, 6-2, and 7 for cross points are used to form a communication path between each office line or extension and each handset using the output of the handset detecting means, and communication is performed corresponding to each office line or extension. Office line or extension line detection means 2-1-2, 2- which detects changes in call current due to operations of handsets such as line acquisition, dialing, hold, abandonment, etc. after line formation and controls operation of the main unit 2-1-2, 2-
2-2 and 3-2 are provided, it is possible to realize a control method in a key telephone device characterized by providing the terminals 2-2 and 3-2.

According to the present invention, in addition to (1) being able to reduce the number of core wires in a distribution cable, and (2) ensuring the transmission and reception of information, and simplifying control, the detection circuit of the central office line Since it can be shared without providing it for each slave device, the effect of reducing the number of parts can be obtained.

[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. 1 is a block diagram showing the main configuration of the button telephone device according to the present invention, and FIGS. 4 and 5 are circuit diagrams of the main device and the telephone, showing detailed circuit configuration examples of the button telephone device according to the present invention.

Claims (1)

[Claims] 1. In a button telephone device in which the communication current system is DC-separated from the office line, at least one system with a predetermined current value of the communication current is used for each communication path connecting each handset and the main unit. A handset detection means that identifies the current value by comparison with a reference value and generates an output corresponding to which region of a plurality of predetermined current regions the current value belongs to; a communication current monitoring means for disconnecting from the communication path; a cross-point thyristor for forming a communication path between each office line or extension and each handset by the output of the handset detection means; Correspondingly, the present invention is characterized by the provision of a central office line or extension line detecting means for controlling the operation of the main device by detecting changes in call current caused by operations of the handset, such as line capture, dialing, holding, abandonment, etc. after a call path is formed. A control method for a button telephone device.