JPS5950153B2 - 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 will be complicated and the cost will be high. 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 shows the information and transmission routes, and Table 2 shows an example of the relationship between the status of each handset and the communication current for 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 slave units 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.

As for 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, making a total of 4 bits into 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. At the time of power outage, the time keeping 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 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 device. 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. The four lines are a power (+) line P, a communication line T, an information line J, and a power (1) line G from the top of FIG.

The power source is the power (+) line P and the power (-) line. The communication current is sent through the power (+) line P and the 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 central 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 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], each lamp 31 in each slave unit,
32, 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, detection circuit 2-1-2 of station line 1, detection circuit 2-2-2 of station line 2, and It is identified by 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 SCR, the slave device detection circuits 8-1, 8-2, 8-
3, and its output forms the SCR cross point, and each trunk 2-1, 2 of the office line 1, office line 2, and extension line
-2 and 3 are connected to the respective station lines. 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, and identify and control dial information, hold information, and 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 resistor R203 of a constant current circuit constituted by transistor Tr201 and transistor Tr201 and R204 selected by button switch LK1, and this is determined by [telephone circuit network TEL → switch LK1 → switch HS-+BS contact → communication line T#1)] and flows to communication line T.

In the main device, the output of IC4 is 10W, and since no current flows through the photocoupler PD1, the transistor Tr1 connected to it is OFF, and the 0R 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 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 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. That is, when the trunk 2-1 of the central office line 1 is not in use, the handset detection circuit 8-
When an output to capture station line 1COL1 is added from 1, AN
The D 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 AND circuit 1C9 is
[OR circuit 1C4 → 0R circuit 1C2 → NOT circuit 1C3
] Turn off transistors Tr2 and Tr3 through the path
, and the communication current is [Resistor R4 → Photocoupler PD1 → S
1 SCR → Office line 1 transformer LTCO 1 → Resistance ', =
゜:i′I. Na 2t Tomi ``^, Obishiri, [NOT circuit 1
C1→OR circuit 1C2→NOT circuit IC3], the transistors Tr2 and Tr3 are kept OFF.

When the communication current flows through the resistor R8, a voltage is generated across the resistor R8, the comparator Comp4 is activated, and the voltage becomes High.
The output turns on transistor Tr5, and relay A1
works. The line of the office line 1COL1 is closed by the contact a1-1, and the handset #1 completes the capture of the office line 1 through the office line 1 transformer LTC01. In addition, when the A1 relay operates, the data selector IC67 is activated by the contact a1-2.
Since the lamp signal of the office line 1 applied to the terminal 4 of the terminal 4 becomes High, the information line LD1 information of the information line J(7) becomes High after parallel-to-serial conversion by the parallel-to-serial conversion circuit 1-4. This signal is sent to the slave unit through the information line J, and is sent to the comparator C.
It is separated into a synchronization pulse and an information pulse by omp201 and Comp202, and converted into serial/parallel by a serial/parallel conversion circuit 23, turning on the transistor Tr202 and lighting the lamp LD1. Here, when handset #1 makes a dial call, contact DP1 opens and closes due to the dial, and contact DP
When 1 is open, the resistor R204 of the slave unit constant current circuit is the contact DP.
1, and the communication current is 10 mA determined by the 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 sent 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 bright output. The output of comparator Comp5 is
The transistor Tr6 is turned ON through the NOT circuit 1C12 and the AND circuit 1C13, and the D1 relay is turned ON. The contact d1-1 of the D1 relay sends a dial pulse to the line. 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 LTC01. 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. 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, transistors Tr9 and Tr10 of the slave device detection circuit 8-2 are turned off.
Since it is in the N state, a current flows through the resistor R15 through the transistor Tr10, and a voltage is generated across the transistor Tr10, 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, station 1 transformer LTC01 is being used by slave unit #1, so station line 1's detection circuit 2-1-2
The communication current from handset #1 flows into the resistor R8 inside.
A voltage is generated across it. Therefore, comparator Comp4 operates, and its output is output from NOT circuit 1C54.
It is input to the AND circuit 1C10 through. Since this input is at a low level while the transformer LTCO1 is in use, the AND circuit 1C10 will not open even if there is an output from the slave unit #2 and the office line 1 transformer LTCO1. No trigger pulse is applied to the SCR of S2 to be coupled, and slave unit #2 and station 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. At this point, when handset #1 lowers the handset,
When the switch HS (7) is turned OFF, the communication current disappears, and the holding current of the SCR of S1 that connects the trunk of station 1 and handset #1 disappears, and S1 is restored.

When S1 is restored, the voltage across the resistor R8 disappears, the comparator Comp4 is turned off, and the transistor I register Tr5 is turned off. Relay A1 is restored by turning off 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 turned OFF by the contact a1-1, and after this information is converted from parallel to serial by the parallel to serial conversion circuit 14,
The information is sent to each slave unit through the information line, and the station line 1 lamp of each slave unit turns off. The operation of acquiring office line 1 from the state in which handset #1 first places the handset is as described above, but when using a button telephone, for example, when using telephone number 5, office line 2 or an extension call When acquiring central office line 1 immediately after termination, the acquired line may be changed by pressing directly from 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 station line 2 or 5 is now switched to the station line 1 button. While acquiring office line 2, [power (+) line P → constant current circuit → telephone circuit TEL → switch LK2 → switch LK1 → switch HS + BS contact → talking line T#1
) → Resistor R4 → Photocoupler PD1 → SCR of S4 → Transformer LTCO2 of office line 2 → Resistor R20 → Earth], and the communication current flows through the path of
When the switch LK1 of the central office line 1 button is turned on when the central office line 1 button is captured, the BS contact in that communication path opens momentarily in conjunction with the central office line 1 button, 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 PD1 is turned off and the retransistor Tr1 is turned off. When the transistor Tr1 is turned off, the transistor Tr2 is turned on and the transistor Tr3 is turned on through a path of [NOT circuit 1C1→OR circuit 1C2→NOT circuit 1C3]. Since the BS contact momentarily turns OFF and then immediately turns ON, the communication current determined by contact LK1 of the office line 1 button and resistor R204 is as follows: [Power (+) line P → constant current circuit → telephone circuit TEL → switch LK1 →Full switch HS-
) BS contact→talk line T#1)→transistor Tr3→resistance R3→earth], and thereafter operates in the same way as the capture operation of the office 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.

: is parallel-to-serial converted by the parallel-to-serial conversion circuit 14, and sent to each child unit through the 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 output of the amplifier circuit is connected to the speaker 25 through the contact C, and the limit 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 about 5V by a Zener diode ZD4, and the other terminals are connected to the communication lines Tit1), T#2), T#3) of all slave units through diodes D6, D7, and D8. It is connected to. Now, when handset #1 is not in use, [+5V→
Trans T. Current flows through the path (T→Diode D6→Talking line T#1)→Hook switch HS→Resistor R208], diode D6 is turned on, and the tone ringer signal is superimposed on this path and transmitted to slave unit #1. The signal is amplified by the machine amplifier 24 and the speaker 25 sounds. Matata slave unit #2
is in the middle of a telephone call on the central office line, the telephone current is [communication path T#2 of handset #2] → photocoupler ZD2 → SCR of S5 → central office line 2
transformer LTCO2→resistance R20], the diode D7 is reverse biased and turned off, and the tone ringer signal is not 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 Rere R1 operates,
The contact r1-1 causes the oscillation circuit 0SC (2HZ) in the child unit lamp control circuit 9 to oscillate a 2HZ square wave signal,
By AND circuit 1C60 and OR circuit 1C64, office line 1
A 2Hz intermittent signal is added to the lamp information. This is parallel
It is serially converted and sent to each handset through the information line J, converted into serial/parallel, and the office line 1 lamp of all handsets flashes at 2Hz. Here, when handset #1 presses the office line 1 button and raises the handset, it operates to make a call to the office line, and handset detection circuit 8-1
A trigger is applied to the gate of the SCR of S1 that connects the station line 1 transformer LTCO1 and the handset #1 by the output of the station line 1 and the status output of the station line detection circuit 2-1-2 of the station line 1, thereby turning S1 ON.

The communication current is [handset #1 → communication line TI1] → 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. 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 is stopped, so the relay R1 is restored, the tone ringer signal is stopped by the contact r1-2, and the amplifier ON information to each slave unit is sent to the terminal 7 of the data selector IC 67. It becomes OFF,
The 2Hz intermittent signal of the station line 1 lamp is blocked by the AND circuit 1C60 by the contact r1-1, so it becomes a continuous signal.
The office line 1 lamp information becomes continuous lighting information through the R circuit 1C64. The operation 0FF signal of the slave amplifier and the lighting information of the office line lamp are transmitted through the information line J. The signal is sent to the slave units to stop all slave unit amplifiers and keep the station line 1 lamp on continuously. The operation for terminating a call is the same as for calling a central office line. (Holding and reacquisition of central office line) Next, the operation of holding and reacquisition after a call with the central office line. I will explain about the work.

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 button is restored, the station line 1 button is restored at the same time. Therefore, when the hold button is pressed, a resistor R207 is added by the HK contact in addition to the current determining resistors R203 and R204 of the constant current circuit, so the current flowing through the resistor R207 is added to the normal call current. Resistor R207 so that this increase becomes about 20mA
Determine the value of 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.
→ S1 bottom → transformer LTCO1 → resistor R8] flow! 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. If you release the hold button at this point, the station line 1 button will be restored along with the hold button, so the call current will disappear and the S1 S1 button will be restored.
CR is turned OFF and the voltage across resistor R8 disappears.
When the voltage disappears, the comparators Comp4 and Comp6 are turned off. Comparator C
A111re is restored by the output of omp4 and its contact a1
-1 is closed. Further, although the transistor Tr7 is turned off by the output of the comparator Comp6, the H1 relay is self-held by the contacts h1-2 and 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 office 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 lighting. 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 R203 and R206, and a call current of 20 mA flows. (+) wire P → constant current circuit → telephone circuit TEL →
The signal is sent to the main device through the following route: switch LK3 → switch LK2 → switch LK1 → switch HS → BS contact → communication line T#1).

In the main device, since the transistor Tr3 is ON, the communication line T#1) connects 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 that was flowing through transistor Tr3 and resistor R3 is now turned off when transistor Tr3 is turned off! :S7's S
Since CR is ON, the signal flows through the path of [talk line T#1] → resistor R4 → photocoupler PD1 → SCR of S7 → extension transformer IT → 5th resistor R39]. Since the communication current flows through the photocoupler PD1, the transistor Tr1 becomes 0N,
[NOT circuit 1C1 → 0R circuit 1C2 → N0T circuit 1C
3] of the transistors Tr2 and Tr3 through the path
Maintain F. 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 converted into information by the parallel/serial conversion circuit 14 and sent to each slave unit through the information line J. It will be done. Comparator Comp201 for each slave unit
, Comp 202, the pulse is separated into a synchronization pulse and an information pulse, and then converted into parallel information by a serial/parallel converter circuit 23. The transistor Tr204 is turned on through a resistor R212 and a Schmitt trigger IC 207, 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 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 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 diode D4, the audio signal of handset #1 is transferred from [handset #] → talk line T#]
) → Capacitor C1 → SCR of S7 → Diode D4 →
Capacitor C9 → Capacitor C4 → Communication line T#2) → Hook 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, during calling, from the output of decoder IC48 [AND circuit 1C64 → OR circuit 1
C43 → OR circuit IC39 → AND circuit 1C36] Cross point S for the extension of the handset called through the route
Add High to the CR trigger gate input. Here, when handset #2 responds to the call, the call current is 20 m determined by resistors R203 and R206 in the constant current circuit.
A is [power supply (+) line P → constant current circuit → telephone circuit TE
L → Switch LK3 → Switch LK2 → Switch LK1
→Full switch HS-+BS contact →Talking line T#2))
The signal flows to the main unit through the following route. Transistor Tr10 is ON
Therefore, the communication current flows through the transistor Tr10 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, AND circuit 1C
Since a high signal is applied to the other input of 36 from the output of decoder IC48 through the path [AND circuit 1C46 → OR circuit 1C43 → OR circuit 1C39], AND circuit 1C36 is opened and the connection between slave unit #2 and the extension transformer is applied. A trigger is applied to the SCR gate of S8 that connects IT, and S8 is turned ON. The output of AND circuit 1C36 is [
OR circuit 1C17 → OR circuit 1C15 → NOT circuit 1C
16], the transistor Tr9 is turned off, and 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 flows through the path of [communication line T#2] -> resistor R16 -> phototransistor PD2 -> SCR of S8 -> extension transformer IT -> resistor 1C, R39]. When the voltage across resistor R39 increases, comparator Comp18 operates,
The output of the counter 1C49 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 lost, the amplifier operation information is turned off. 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, SCR of S7 and S8 of handset #1 and handset #2 are ON.
Therefore, they are connected through the extension transformer IT, and a mutual communication state 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, 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 “0” and use the decoder I
When the output power of C48 is 0'', OR 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 out to the communication lines of all handsets through diodes D3, D4, and D5, amplified by handset amplifier 24, and sent out from speaker 25.

In addition, high is applied to the gate IC (AND circuit) input of the trigger of each SCR by the output ``0'' of the decoder IC48,
No matter which handset captures the extension and responds, the communication path is connected to the extension transformer IT to form a communication path with handset #1. Once the communication path is established, the decoder I
The output of C48 disappears, and the handsets other than those in the mutual communication state are disconnected from the extension transformer IT and become confidential. 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 in detail above, 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,
The main device includes a parallel-to-serial conversion means 14 for converting parallel information to serial information, and at least one device having a predetermined current value of communication current.
Identification means 2-1 for identifying by comparison with two reference values;
2-2 and 2-3 are provided, and the cordless handset includes a serial/parallel conversion means 23 for converting serial information into parallel information, and a plurality of predetermined setting values for determining the current value of the communication current by operating a telephone key. Call current control means 2 that controls to a value corresponding to the operating state.
1, and the slave unit control information to be transmitted from the main unit to the slave unit is transmitted to each slave unit through the control information line as a time division multiplexed signal by the parallel-to-serial conversion means 14, and each slave unit transmits the serial-parallel control information to the slave unit. The conversion means 23 extracts the control information from the time-division multiplexed signal to control the handset, and the handset transmission information transmitted from the handset to the main device is controlled by the call current control means. The main device is configured to control and transmit the communication current to the main device, and in the main device, the current value of the communication current is identified and detected by the identification means, and the main device is controlled. A control method for a button telephone device can be realized. According to the present invention, by separating information between the main device and the slave device and using a communication line to transmit information from the slave device to the main device, the number of cable cores is reduced, the circuit configuration is simplified, and costs are reduced. The effect that can be achieved 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 separated from the office line in terms of direct current, the main device includes parallel-to-serial conversion means for converting parallel information to serial information, and at least one standard for predetermining the current value of the communication current. The cordless handset includes a serial/parallel conversion means for converting serial information into parallel information, and a telephone key operation to select the current value of the communication current from among a plurality of predetermined setting values. A communication current control means is provided for controlling the communication current to a value corresponding to the operating state of the main device, and the slave device control information transmitted from the main device to the slave device is transmitted through the control information line as a time-division multiplexed signal by the parallel-to-serial converter. slave unit transmission information that is transmitted to a slave unit, in each slave unit extracts the control information from the time division multiplexed signal by the serial conversion means to control the slave unit; and transmits slave unit transmission information from the slave unit to the main device; The talking current is controlled by the talking current control means and transmitted to the main device, and in the main device, the current value of the talking current is detected by the identifying means to identify and detect the slave device sending information, and the main device is controlled by the talking current. A control method for a button telephone device, characterized in that it is configured to control.