KR840002134B1 - Telephonic communication systems - Google Patents

Abstract

An expandsion system for a telephone can connect five telephones to one main telephone line and allows one of them to be used as a doorphone as well. The five telephones can also be used as interphones respectively following the operation and transfer of the main call to one of the extension numbers by dialing the counterpart number.

Description

Automatic telephone extension device

1 is a block diagram illustrating the invention as a whole.

FIG. 2 is a detailed circuit diagram of the trunk line switching circuit during power failure shown in FIG.

3 is a detailed circuit diagram of a ring signal detection circuit and a dial circuit shown in FIG.

4 is a detailed circuit diagram of the audio signal relay circuit shown in FIG.

FIG. 5 is a detailed circuit diagram of the call connection switch shown in FIG.

6 is a detailed circuit diagram of the relay driving circuit shown in FIG.

7 is an external connection diagram of the central processing unit shown in FIG.

8 is a detailed circuit diagram of the ring signal and direct current supply circuit and direct current supply detection circuit shown in FIG.

9 is a detailed circuit diagram of the tone generating circuit shown in FIG.

FIG. 10 is a detailed circuit diagram of the ring signal generation circuit shown in FIG.

11 is a detailed circuit diagram of a door phone and a door phone connection device.

12 is a detailed circuit diagram of the power supply circuit of FIG.

* Explanation of symbols for main parts of the drawings

1: Trunk line switching circuit in case of power failure 2: Ring signal detection circuit

3: dial circuit 4: voice signal relay circuit

5: communication path connection switch 6: relay drive circuit

7: central processing unit 8: ring signal and DC current supply circuit

9: DC current supply detection circuit 10: tone generating circuit

11: ring signal generation circuit CO: trunk line

12: Door phone and its connecting device EX1-5: Extension phone 1-5

13: power supply circuit 1200A: door phone

1200B: Door phone connection device

The present invention relates to an automatic telephone extension device which enables the use of up to five general telephones on a trunk line, in particular, an automatic telephone extension device which allows one of the five extension telephones to be used as a door phone.

Conventional small telephone exchange devices such as key phones and manual telephone switchers were available, but key phones were not able to use ordinary telephones, and specially designed dedicated telephones and main devices were needed. There was a drawback of having to make a lot of phone calls and extension calls by holding a lot of buttons and manually operating a separate button.In the case of a manual telephone phone, only one or two of the changers can be expanded and the operation is manual, which is inconvenient to use. .

The object of the present invention is to enable up to five subscribers to one trunk line, unlike the above method, thereby maximizing the efficiency of the trunk line so that mutual calls can be made between not only the trunk line call but also five extension telephones. Five of them can be used as a door phone device to increase the use efficiency of the present invention.

The automatic telephone expansion apparatus according to the present invention complements the disadvantages of the conventional small simple exchange apparatus described above, and can be easily used as a door phone by using a general telephone having two connection lines than a key phone. It is designed to have a larger number of expansion units than a manual telephone changer and to automatically operate the device. The dial operation of the telephone connected to the present invention (for example, from the extension 1 telephone to the extension telephone 3 to call the CO line) In case of handing over the call, dial '3' to connect.) It is a device to make a call between CO line and extension.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention consists of blocks (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) as shown in FIG. First, the structure and operation of each block will be described.

end. Trunk Line Switching Circuit in Case of Power Failure (Block 1: 2nd Figure)

The circuit consists of four circuit switching contacts 10, 11, 10 'and 11' and a relay 13 for driving this contact.

This circuit connects the switching contacts 10, 11, 10 'and 11' as shown in the drawing when the power supply to the present invention is interrupted, and directly connects the expansion converter EX1 to the trunk line. In general, when power is supplied to the present invention, a voltage is applied to the relay 13 so that the switching contacts 10, 11, 10 ', and 11' are operated in reverse, thereby making the trunk line a into the call path b, The extension telephone call path (c) is directly connected to the call path (d).

In other words, the purpose of this circuit is to connect the trunk line with an extension phone immediately once the power supply to the device of the present invention is interrupted so that the call does not interfere.

I. Ring signal detection circuit and dial circuit (blocks 2, 3: FIG. 3)

This circuit is a switch that detects ring signals coming from trunk lines, connects trunk lines to voice signal transmission transformers, and switches for dial operation, and its configuration is a two-circuit switching contact 20a (20b) corresponding to a hook switch of a general telephone. ) And a relay 20 for driving this contact point, and contacts 30 ', 31' and relays 30 and 31 corresponding to the dial portion.

When the contacts 20a and 20b are connected as shown in FIG. 3, when the ring signal flows into the communication path b from the trunk line, the ring signal is transmitted to the bridge diode 25 through the capacitor 21 and the resistor 22. When the full-wave rectified signal is transmitted through the zener diode 26 to the diode 27 in the optical coupling element of the diode 27 and the transistor 28, the transistor 28 is turned on, and the t of FIG. ₆ ) a low signal is applied. Here, the capacitor 21 serves as a DC blocking function, and the zener diode 26 prevents malfunction due to noise. When the ring signal is detected by the low signal, the contacts 20a and 20b are connected in the opposite direction to the third degree by the operation of the IC ₄ of FIG. 7, the IC _{3 of} FIG. 6, and the relay 20 of the central processing unit. At this time, the trunk line loop is connected to the voice signal relay circuit (FIG. 4) through the communication path b, the contact point 30 ', and the communication path f.

When dialing is performed in an extension telephone for calling a trunk line, the contacts 30 'and 31' perform a dial operation of a general telephone to open and close the trunk line path b and send out a pulse.

For example, turning dial '5' detects a dial pulse from IC ₄ of FIG. 7, which is a central processing unit, and drives relays 30 and 31 through IC ₃ of FIG. The pulse relay is prevented from going out of the signal relay circuit, and the contact 30 'operates five `` on''and `` off''operations corresponding to the dial' 5 '. The capacitor 21 and the resistor 32 which are not described serve to prevent the spark of the contact point 30 '.

All. Voice signal relay circuit (Block 4: 4th)

This circuit is to make DC loop on trunk line and to transmit voice signal transmitted from trunk line to communication line connection switch (fifth degree).

This circuit is composed of a transformer 40, 41 for transmitting a voice signal, a capacitor 42 for blocking DC, and a varistor 43 for suppressing overvoltage. DC current of the trunk line is made of the communication path (f) from the communication path (f) through the transformer 40 again, the capacitor 42 blocks the direct current flowing through the transformer 41 and the winding and passes only the voice signal. The voice signal passes through the transformer 41 and the communication path g to the communication path connection switch of FIG.

la. Channel connection switch (Block 5: Fig. 5)

This circuit connects the call charge between each extension telephone or between trunk line and extension telephone, and it is a switch circuit for sending tone signal to each extension telephone.

The part shown in FIG. 5 represents the contacts of each relay operating by driving of the relays 560-575 connected to the relay driving circuit (FIG. 6) controlled by the central processing unit (FIG. 7).

The configuration of the communication line connection switch includes a relay line call call relay 560, a contact point 500, a line termination line resistor 50 at the time of a hold line hold, and a line line call line connection relay 561- (565). ) And its contacts 501, 502, 503, 504, 505, internal circuit connection relays 566-570 and their contacts 511, 512, 513 514) 515, relays 571-575 for transmitting various tones (dial tones, call tone tones, ring back tones, warning tones), and their contacts 521 (522), (( 523, 524, and 525, resistors 51-60 for adjusting the tone level sent to each extension telephone, and a transformer 550 for separating between the tone signal generating circuit and the communication line connection switch. . In the figure, reference numeral g denotes a trunk line call path, and (h)-(I) indicate a call path of each extension phone EX 1-EX 5.

Connection between CO line and extension phone is as follows. For example, in the case of the second extension telephone, the call path i is connected to the trunk line path g through the contact 500 through the connection of the relay contact 502. At this time, if the handset is lifted from the extension telephone called by dialing the number of the other extension telephone to another extension telephone, the relay 560 is operated so that its contact point 500 is connected to the termination line of the trunk line. Since the direct connection is made, the trunk line call is in the HOLD state.

In the extension call of the extension telephone period, for example, in the case of a call in the extension telephone number 3 and the extension telephone number 4, the call path j is connected to the relay contact point 513 and the contact point 514 to the call path k. Leads to.

In addition, the tone signal sent to each expansion telephone is connected to the relay contacts 521, 522, 523, 524, 525, and the tone signal supplied from the tone generating circuit (FIG. 9 u) is applied to the transformer 550. It passes through the relay contact and enters the channel (h)-(I).

hemp. Relay drive circuit (block 6: Fig. 6)

This circuit consists of an integrated circuit (IC ₁ ) (IC ₂ ) (IC ₃ ) and a resistor (64), a transistor (65), a diode (66), each integrated circuit comprising a central processing unit (IC _{4 in} FIG. 7). It stores 8 input data from and drives 8 relays connected to the integrated circuit by this data, and also turns on the transistor 65 by one data from the central processing unit through the output terminal (s). Drive the relay 1200 connected to. The operation of the integrated circuits IC _l (IC ₂ ) (IC ₃ ) uses 8-bit parallel data transmitted from the central processing unit, and the central processing unit has three control lines for controlling each integrated circuit. . .

It transfers the data to eight lines (p) from the central processing unit, and one of the control lines 61, 62, 63 of the integrated circuit is shortened to '1' and then to '0'. ' In this way, the data on line 1 is stored inside each integrated circuit, and relays 560-(575) and (20) (30) (31) (81) (82) (83) (84) 85 are driven. At this time, even if data for another integrated circuit appears on the line P, the internal data of each integrated circuit is not changed unless the control lines 61, 62, and 63 are driven.

bar. Central Processing Unit (Block 7: Fig. 7)

This circuit is a circuit for controlling all operations of the present invention, and its configuration is mainly composed of a single ship computer (IC ₄ ) having programmed a CPU and a semiconductor memory in accordance with the functions of the present invention. A reset capacitor 71, a clock frequency oscillation crystal 72, and a capacitor 7ε 74 are formed. In this circuit, the 8-bit input terminal (t) is connected to the DC current detection (loop detection) circuit of five extension telephones of Fig. 8 (t _l -t ₅ ) and the ring signal detection circuit of Fig. 3 (t ₆ ). So that their output state is always input to the single-chip computer IC ₄ of the central processing unit.

The input daida is processed internally and transferred to the relay driving circuit of FIG. 6 by the 8-bit output terminal (p), the 3-bit output terminal (g), and the output terminal (s) to operate the contacts connected to each relay. do.

four. Ring signal supply and DC current supply circuits and their detection circuits (Blocks 8, 9: Fig. 8)

These circuits supply 20Hz ring signal to each extension telephone, supply the DC current necessary for call and dialing, separate the voice signal transmitted from both ends of the line, and transmit it to the line connection switch 5 and at the same time It is a circuit for monitoring current.

As shown in FIG. 8, the ring signal supply and direct current supply circuit 8 includes capacitors 87, 91, resistors 88, 89, 90, 95, and relay contacts 801 and 802. ), Its relay 8l, induction coil 92, etc., and the DC current supply detection circuit 9 includes resistors 901, 902, 904, capacitors 903, 907, and diodes 905. ) And a transistor 906.

In the case of FIG. 8, it is illustrated to explain a path of calling the extension telephone EX 1 from the CO line or another extension telephone EX 2 -EX 5 of FIG. That is, when a signal for calling the extension telephone EX 1 from the CO line is applied to the central processing unit (FIG. 7) via the ring signal detection circuit and the dial circuit (see FIG. 3), the central processing unit is relayed. As the relay 81 corresponding to the extension telephone (EX 1) is operated through the driving circuit (FIG. 6), the ring signal is removed when the contacts 801 and 802 repeat the "on""off" operation. It is applied to the extension telephone (EX 1) from 10 degrees (V) to ring the Gringer. At this time, when the extension telephone (EX 1) user hears the handset and the relay contact 801 is stuck in the state shown in the drawing, the + 24V DC is the resistance 90 and the induction coil 92, the relay contact 801, and the expansion. It flows to the ground point through the telephone EX1, the induction coil 92, and the resistor 95. At this time, the voltage across the resistor 95 is also applied to the DC current supply detection circuit 9. At this time, the voltage across the resistor 95 is removed from the high-frequency components in the resistors 901 and 902 and the capacitor 903, attenuated by a certain number of groups in the resistor 904, and supplied to the base of the transistor 906. Accordingly, as the transistor 906 is energized and its collector potential is lowered, a collector current in a low state is applied to the central processing unit (FIG. 7) through the line t _l , which is processed by the central processing unit. By connecting the relay (561 of FIG. 6) and the contact points 501 (501) (see FIG. 5) associated with the extension telephone (EX 1), communication with the trunk line is enabled. The capacitor 907, which is not described in FIG. 8, is connected to the collector and base of the transistor 906 to prevent rapid switching of the transistor, and the diode 905 prevents breakage of the transistor 906 due to reverse bias, and the ring The capacitors 93 and 94 of the signal supply and direct current supply circuit 8 make it possible to pass only the audio signal and to block the direct current. The case of the extension telephone (EX 1) has been mentioned so far, and the same is true of the other extension telephones (EX 2-EX 5).

Ah. Tone Generation Circuit (Block 10: Fig. 9)

The circuit serves to amplify the tone signal generated in FIG. 7 so that it can be supplied to five expansion telephones, and protects the DC resistance capacitor 101 and the operational amplifier IC ₅ . ), High frequency oscillation prevention capacitor 104, resistor 103, power bypass capacitor 106, operational amplifier (IC ₅ ) internal regulator capacitor (107), operational amplifier (IC ₅ ), high frequency noise suppression A capacitor 108, an input coupling capacitor 109, and resistors 110, 111, 113, 114, 115, and capacitor 112.

The tone signal transmitted from FIG. 7 (t ₇ ) by the operation of the circuit is attenuated to the proper level by the resistors 114 and 115 to appropriately attenuate the high frequency components by the resistor 113 and the capacitor 112, and then the resistor 110. And attenuates to match the input of the operational amplifier (IC ₅ ). This supplied signal is amplified by the operational amplifier IC ₅ and supplied to the transformer of the connection switch in the call of FIG.

character. Ring Signal Generation Circuit (Block 11: Fig. 10)

This circuit converts the digital signal transmitted from the central processing unit into an analog signal, amplifies it with an operational amplifier so as to drive the ringer of the telephone, boosts the transformer, and supplies it to the ring signal supply circuit.

The circuit arrangement comprises resistors 116, 117, 118 and 119 as D / A converters and integrated circuits IC ₇ which store the digital signals transmitted from FIG. 9 around the operational amplifier IC ₆ . 120, 121, 122, 123, low pass resistors 124, 126, 128, 129, and capacitors 125, 127, and a capacitor 130 outside the operational amplifier (IC ₆ ). 131, 132, 133, 135, 138, resistors 134, and diodes 136, 137, and a boost transformer 140 is connected to an output side thereof.

The operation of the circuit is that data temporarily stored by the integrated circuit IC ₇ is converted into analog signals by the resistors 116-123. A signal similar to the 20 Hz sine wave delivered to the resistor 124 passes through the low pass filters 124, 125, 126, 127 to become a pure 20 Hz sine wave.

This signal is appropriately attenuated by resistors 128 and 129, passed to the input of operational amplifier IC ₆ , and then amplified and boosted to transformer 140 to a voltage necessary for driving the ringer of the telephone.

car. Door phone and door phone connection device (Block 12: Fig. 11)

11 illustrates in detail the door phone 1200A and the door phone connection device 1200B when the door phone is used instead of the 5th extension phone EX 5. When the automatic telephone extension apparatus of the present invention is installed in a house, the door phone pusher for the call of the visitor and the extension telephone period is a door phone button 1220 for call calling, a diode 1221 for configuring a call loop, and an amplifier 1222. , A speaker 1223 and a microphone 1224. Since the door phone is installed externally, there is no handset of the telephone, and the contacts 1201 and 1202 of the relay 1200 installed in the relay driving circuit 6 are connected to the hook switch of the general telephone. Connected to the terminal.

The door phone connection device 1200B uses the door phone 1200A, the above-mentioned ring signal supply and DC current supply circuit 8, and DC current when the door phone 1200A is used instead of the example 5 extension phone EX 5. Functions as an interface with the detection circuit 9, the contacts 1201, 1202, resistors 1203, 1204, 1206, 1208, 1209 of the relay 1200 installed in the relay driving circuit FIG. And a diode 1205, a chime bell 1212 driving relay 1213, and a transistor 1207 and 1210.

In FIG. 11, when the positions of the contacts 1201 and 1202 of the relay 1200 of the door phone connecting device 12000B are as shown in the drawing, a person presses the pushbutton 1220 of the door phone 1200A. When pressed, a + 24V power line, resistors 1206, 1204, relay contacts 1202, buttons 1220, relay contacts 1201, resistors 1203, and a current loop connected to the ground point are configured to flow the current. Since the base bias current of the transistor 1207 is kept low, the transistor 1207 is energized, and the collector current flows through the resistors 1208 and 1209 so that the voltage dropped across the resistor 1209 is decreased. Applied to the base of the transistor 1210. Accordingly, the transistor 1210 is energized and the relay 1213 is operated so that the relay contact 1211 is connected, so that the wearing bell 1212 rings to notify the call from the door phone 1200A. At this time, when the user who hears the chime sounds picks up the extension telephone and dials '5' to call the telephone number 5, the relay 1200 of the relay driving circuit 6 is operated to switch its contacts 1201 and 1202. Therefore, the door phone 1200A is connected to the line 1 instead of the 5 extension telephone (EX 5) through the line (m) and the contacts 1201 and 1202 of the relay 1200, and the 5 extension telephone (EX 5). As in the call of), the door phone 1200A can be used.

That is, the DC current is a + 24V power line and a resistor 90, an induction coil 92, a relay 1200, a contact 1201, a line m, a diode 1221 of the door phone 1200A, an amplifier 1222. And, through the line (m), relay (1200) contact (1202), induction coil (92), resistor (95) to ground point, bias current in door phone (1200A) is supplied. Thereafter, the processing of the voice signal through the microphone 1224 is the same as in the use of the extension telephone.

Ka. Power supply seam (Block 13: 12th)

This circuit is a power supply circuit for supplying stable DC 24V and DC 5V voltage at AC 110 / 220V and integrates power transformer 1301, bridge diode 1302, capacitor 1303 (1305) (1307), and 3-terminal integration. Circuit regulators 1304 and 1306.

The voltage charged in the capacitor 1303 is stabilized at 24 V DC in the regulator 1304 to be charged in the capacitor 1305, and the direct current 24 V voltage charged in the capacitor 1305 is stabilized at 5 V DC in the regulator 1306 to stabilize the capacitor. Charged at 1307, the voltage charged at capacitors 1305 and 1307 is supplied to each power supply terminal.

The overall operation of the present invention is as follows.

1. Incoming CO

When a 20 Hz ring signal flows from the trunk line, this signal passes through FIG. 2 (if power is supplied to the present invention, the same below) and enters the ring signal detection circuit of FIG.

The rectified signal turns on the transistor 28 in the optical coupling element and sends a low signal to t ₆ of the central processing unit FIG.

The central processing unit drives the relay 81 in the ring signal supply circuit of FIG. 8 via the relay drive circuit 6 to send the ring signal to the extension telephone 1 EX 1. When the relay 81 is driven, the contact 801 is connected and the 20 Hz ring signal generated by the ring signal generation circuit of FIG. 10 is transmitted to the first extension telephone EX 1 to operate the ringer in the telephone. Upon hearing the ringer sound, the subscriber of the first extension telephone (EX 1) picks up the handset and the DC current is supplied. Thus, the central processing unit (line 7) is connected through the line t _{l in} FIG. Since the low signal is applied to the central processing unit, the relay driving circuit operates the relay 561 in FIG. 6 to connect its contacts 501 and 501 in FIG. Therefore, the number 1 extension telephone (EX 1) is connected to the trunk line call (g) to make a trunk line call.

2. CO Line

When one subscriber out of five extension phones picks up the telephone handset and sends dial '9', the trunk line call is established, and the loop status is transmitted to the seventh degree by the loop monitoring circuit of FIG. The change is analyzed by the central processing point, and one of the trunk line call connection switches 501-505 of FIG. 5 is connected to the call paths g and f, and the relay contacts 20a and 20b of FIG. This operation forms a DC loop of the trunk line.

The operation of such a relay is performed by operating the relay driving circuit of FIG. 6 in the central processing unit. When the dial is connected to the CO line by turning the dial '9' from the extension phone, the CO line dial tone is transmitted to the receiver of the extension phone. When the user dials the counterpart number, the relay contact 30 'of the communication path f corresponding to the telephone number is 0N / OFF. In this operation, the central processing unit senses a dial pulse train to operate the relay driving circuit of FIG. 6 to drive the relays 30 and 31 of FIG. 3 to relay the bonen pulse train to the CO line in the extension telephone.

If the other party answers after dialing pulse, the call is made immediately. After the call, the user of the extension telephone puts down the telephone handset, and the state of the telephone is transmitted to Figure 7 through the loop monitoring circuit of Figure 8. The control operates the relay driving circuit of FIG. 6 to restore the relay contacts 20a and 20b of FIG.

3. Currency consultation

If the user dials one of the number (1)-(5) of the extension telephone to be called when the user needs to hand over the telephone to another extension telephone connected to the present invention during the call by the incoming / outgoing call, Is transmitted to the central processing unit via the loop monitoring circuit of FIG. 8, which operates the relay driving circuit of FIG. 6 to send a ring signal to the called telephone.

When the subscriber hears the signal, the subscriber will be connected to the local line at the same time so that the call can be negotiated between the extension telephones.

This operation is performed by driving one of the connection relays 561-565 over the trunk line call by detecting that the call loop of the telephone called from the central processing unit is continued. At this time, the DC signal output circuit 9 of the extension telephone with a handset is applied to the input terminal of the central processing unit. Therefore, the central processing unit detects that two low signals are simultaneously input to its input terminal. The relay drive circuit operates the relay 560 of FIG. 6, so that its contacts 500 and 500 of FIG. 5 are connected to a resistor 50 for termination of the trunk line to hold the trunk line call and to communicate during the extension telephone period. This prevents the contents from being output to the trunk line. When the subscriber who wants to hand over the telephone line to the telephone conference call drops the handset, a high signal is output from the DC current detection circuit 9 and applied to the central processing unit so that only one low signal is applied to the central processing unit. Accordingly, the central processing unit stops the operation of the relay 560 and restores the contacts 500 and 500 thereof. Therefore, the call path (h-1) of the extension telephone holding the handset after hearing the ring signal is converted to the trunk line call (g). It is connected to keep the trunk line call.

4. Extension call

When the subscriber of the 4th extension phone picks up the handset for the internal call, a DC current flows through the telephone line, and the DC current detection circuit operates by the flow of this current to inform the central processing unit that the subscriber has picked up the handset. The central processing unit immediately activates the relay 574 to send dial tone to the extension telephone 4 times and connects its contact point 524, and the subscriber who hears the dial tone number '1' and '2' of the extension telephone to be called. Dial one of '3' and '5'.

In order to call the extension telephone No. 1, when the dial '1' is turned, the relay driving circuit controlled by the central processing unit is operated via the DC current detection circuit 9 to operate the relay 81 of FIG. Since 802 is connected, the ring signal is transmitted to the first extension telephone. At the same time, the central processing unit operates the relay 569 of the relay driving circuit 6 to connect its contacts 514 and 514. At this time, when the subscriber listens to the ringer and the subscriber picks up the handset, a DC current flows in the communication path (d) of the first telephone. This current turns on the transistor 906 to send a low signal to the central processing unit. The processing apparatus operates the relay 566 of FIG. 6 to connect its contacts 511 and 511 of FIG. 5, so that the communication path k of the extension telephone EX 4 is relayed 569 and 566. Through the contacts 514, 514, 511 and 511 of the extension phone (EX 1) is connected to the call path (h) it is possible to make an extension call. At the same time, the central processing unit stops the operation of the relay 81 to restore the contacts 801 and 802 thereof. If the handset is dropped after such extension call is pulled out, the operation of the relay driving circuit restores the contact point of the relay connected to the call path of each extension telephone.

5. Door phone call

The door phone call is a unique function of the present invention, so that the call can be made during the extension phone and the door phone installed outside the present invention.

As shown in FIG. 11, when the door phone is used, the extension phone 5 cannot be used because the door phone uses the call path of the extension phone 5 (EX 5).

In FIG. 11, the DC current through the resistors 1206, 1204, the contacts 1202 of the relay 1200 and the connection terminal ⑤ at the terminal ① of the circuit is cut off by the diode 1221 inside the door phone ( Polarity is reversed). Therefore, no call can be made between the door phone and the present invention.

In this state, when the visitor presses the door phone button 1220, a DC loop is configured through this switch, and this current turns on the transistors 1207 and 1210 to operate the relay 1213 and thus is connected to its contact 1221. The chime 1212 will ring.

When one of the extension phones (EX 1-EX 4) hears this buzzer, listens to the handset of the phone and turns the dial '5' to make a call with the door phone.

When the dial '5' is turned, the central processing unit detects this signal through the DC current detection circuit 9 of the telephone and operates the relay 1200 of the relay driving circuit 6 so that its contacts 1201 and 1202 are called. The central processing unit is connected to the furnace (n) and connects the door phone communication path (m) to the communication path (n) connected to the communication path (1) of the 5th extension telephone (EX 5). One of the relays 566-569 is operated so that one of its contacts 511-514 connected to the extension telephone path of FIG. 5 is connected so that the door phone 1200A is connected to the extension telephone (EX 1). It can be connected to one of-(EX 4) subscribers.

In this case, since the contacts 1201 and l202 of the relay 1200 are connected, + 24V is supplied to the connection terminal ④ of the door phone through the resistor 90 and the induction coil 92 from the terminal ②, and the terminal ⑤ is connected to the terminal ③. And an induction coil 92 and a resistor 95 to the ground point. This causes the diode 1221 inside the door phone to be forward biased (polarity reverses the reverse direction of the initial state) so that current flows into the door phone internal circuit to form a call loop and operate the door phone device to operate the amplifier 1222, The speaker 1223 and the microphone 1224 operate to make a call. In addition, when the contacts 1201 and 1202 of the relay 1200 are connected to the communication path n, the transistors 1207 and 1210 are turned off, so the relay 1213 stops operating, and thus the contact point ( 1211 is opened to stop the operation of the chime 1212. If the handset of the extension telephone is dropped after the call with the door phone, the relay is restored by the extension of the telephone by the control of the central processing unit as in the case of an extension call, and the contacts 1201 and 1202 of the relay 1200 are also Restore to original position.

Claims (2)

In case of a power failure, the CO line is connected to the central processing unit 7 through the CO line switching circuit 1, the ring signal detection and the dial circuit 2 ', and through the audio signal relay circuit 4 to the communication line switch ( 5) and the extension telephone line (EX 1-EX 5) is connected to the communication line connection switch (5) through the ring signal, DC current supply circuit (8), DC current detection circuit (9), and The furnace connection switch 5 to the central processing unit 7 via the relay drive circuit 6 and at the same time through the tone generating circuit 10 and the ring signal generating circuit 11, respectively. ), The ring signal and the DC current supply circuit (8), and the door phone and the door phone connection device (12) to the DC current detection circuit (9) and at the same time the relay drive circuit (6) the dial circuit (3) and an automatic telephone extension device connected to the voice signal relay circuit (4), the door phone and the door phone connection device (12). The contact line of claim 1, wherein the + 24V power line is connected to the resistors 1206, 1204, and the relay 1200 of the relay drive circuit 6, the door phone button 1220, and the relay 1200. 1201, the resistor 1203 is connected to the point point, and the connection points of the resistors 1206 and 1204 are connected to the base of the transistor 1207 so that its emitter is connected to the + 24V power line and its collector is It is connected to the base of the transistor 1210 through the resistor 1208, and the collector of this transistor 1210 is connected to the relay 1213 connected to the + 24V power supply line to drive the driving circuit of the chime 1212 driving relay 1213. And a + 24V power supply line, and the upper coil of the resistor 90 and the induction coil 92, the contact 1201 of the relay 1200, the diode 1221, the amplifier 1222, and the contact of the relay 1200. 1202, the lower coil of the induction coil 92, the automatic telephone extension device, characterized in that to connect to the ground point through the resistance (95) to configure the call path of the door phone (1200A).

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