JPS6110352A - Subscriber line interface circuit - Google Patents

Abstract

PURPOSE:To miniaturize a call signal transmission circuit by using a switching regulator for a call signal transmission circuit to generate a low frequency call signal in 16Hz without using a low frequency transformer. CONSTITUTION:The call signal generator circuit CRG consists of a high frequency transformer HFT, a switching circuit SWC, a rectifier circuit REF and a counter CNT. A ring-on signal RG from a sub-controller and a switching regulator high frequency signal from the counter CNT are inputted to the switching circuit SWC. The switching circuit SWC ANDs the signals, drives a transistor (TR) and its output is fed to the primary winding of the high frequency transformer HFT. Thus, a signal boosted to 75V, 16Hz required for the ringing of a bell is obtained at the secondary winding of the transformer from a voltage 24V at the primary winding and the boosted signal is rectified by the rectifier circuit REF and a continuous ringer signal tone is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a subscriber line interface circuit in a switching system, and particularly includes a calling signal sending circuit which is miniaturized using a high frequency transformer for a switching regulator. The present invention relates to a subscriber line interface circuit for a two-wire telephone terminal that can be accommodated in combination with a four-wire telephone terminal.

Generally, in a two-wire subscriber telephone line, a low frequency ringing signal of 16 Hz is sent to the telephone line. In order to make the ringer ring, a low frequency signal with an effective value of 75V is required.

Calling of an extension telephone terminal connected to a private branch exchange is also carried out by sending a 16 Hz low frequency calling signal similar to the above to the telephone line. Therefore, it is necessary to provide a 16 Hz paging signal sending circuit within the exchange.

On the other hand, in a switching system that accommodates key telephones and 4-wire multi-function telephones that have many function (multi-function) buttons and enable various services other than telephone calls, each terminal is Since it has a built-in transmitter, there is no need to send out a 1682 call signal to the telephone line.

Such a switching system that accommodates a mixture of two-wire telephone terminals and four-wire multifunction telephones will be required for future communication forms, such as building-installed telephone systems. In this case, there is a demand for miniaturization of the calling signal sending circuit for calling the two-wire telephone terminal.

[Conventional technology]

A conventional 16 Hz calling signal sending circuit uses a 16 Hz oscillation circuit and a low frequency transformer for boosting 48 V to the required effective value of 75 V.

However, since the low frequency transformer is large in size, the mounting area of the paging signal sending circuit becomes large, and it cannot be housed in the same package as other circuits in the subscriber line interface circuit. In addition, since the low-frequency transformer is supplied with a busy calling signal, power is consumed even when it is not necessary to send out a calling signal, which is uneconomical.

Furthermore, conventionally, there has been no known switching system that accommodates both 2-wire telephone terminals and 4-wire telephone terminals, and the switching system that accommodates 4-wire telephone terminals is independent from that of 2-wire telephone terminals. It was set up.

FIG. 18 is a block diagram showing an example of a conventional switching system accommodating four-wire telephone terminals. In the same figure, 4
Call information from wire telephone terminal A (or B) is transmitted via two wires (
2H) and a subscriber control circuit (LN
G) directly to the switching switch (SW) 181 through the interface circuits 184 and 185, and then sent to telephone terminal B (or A) via the extension trunk (IO?') 187, or to the central office. line trunk (
BHT) 186 to a private branch exchange or other station to form a communication path as is well known in the art.

Control information such as call information and key information 2 from the 4-wire telephone terminal A or B is transmitted through a control line j! consisting of 2 wires (2W). 2
and the subscriber control circuit (LNG) 184°185 and the main control unit (MC) 18 directly via the bus line Bus.
Control information for controlling blinking of lamps, ringing of a ringer, etc. in 4-wire telephone terminal A or B is sent from main controller 182 to subscriber control circuit 184.
, 185 and the control line 12 to the four-wire telephone terminal A.
Or sent to B. In addition, such exchange control is performed by the main controller 1.
82 and the program, data, etc. stored in the storage device (MI!l'l) 183.

In addition, in order to mix 2-wire telephone terminals and 4-wire telephone terminals within the same facility, conventional
A switchboard (E) that accommodates only wireline telephone terminals (for example, A)
A system is constructed by connecting an exchanger (Ex2) 192 which accommodates general two-wire telephone terminals (for example, C) above it.

The 4-wire telephone terminal A has a subscriber circuit 19 as shown in FIG.
6 to the exchange switch 193, and
Control information is exchanged with the main control device 194 and the storage device 195 via the bus. On the other hand, the two-wire telephone terminal C is connected to the conversion switch 1 via the subscriber circuit (LC) 202.
98, main controller 199 and storage device 200
The exchange is controlled under the control of. Each exchange 191, 19
2 is a bidirectional trunk 197.2 with other exchanges. 201.
202. 203 (or outgoing trunk, incoming trunk, etc.). Therefore, as a switching system, switchboards 192 and 191 are connected to trunk 198 in the same premises, etc.
, 201, etc., to create a system that accommodates a mixture of 2-wire and 4-wire telephone terminals.

In this way, conventionally two-wire and four-wire systems were installed in the same facility.
There were problems in that different types of exchanges had to be installed separately, and the hardware was large and expensive.

In Figure 19, a 4-wire exchange (EXI) 19
Although it is possible to accommodate a two-wire telephone terminal in 1,
For this purpose, the main controller 194 in the exchange 191 has four
The terminal type must always be identified using information for identifying wire-line telephone terminals and two-wire telephone terminals, which poses a problem in that the load on the software of main controller 194 becomes extremely large and processing becomes complicated.

[Problem that the invention seeks to solve]

In view of the above-mentioned problems in the conventional calling signal sending circuit, an object of the present invention is to miniaturize the calling signal sending circuit by eliminating the need for a low frequency transformer, based on the concept of using a switching regulator for DC-DC conversion. This enables high-density packaging and the implementation of a ringing signal sending circuit in one package of the subscriber line interface circuit. The object is to be able to accommodate a 2iJI type telephone terminal simply by mounting an interface circuit.

[Means for solving problems]

In order to achieve the above object, the present invention provides a high-frequency transformer for direct current voltage conversion and a high-frequency transformer on the primary side of the high-frequency transformer in a circuit that sends a calling signal to a telephone line connected to a telephone terminal. It is equipped with a switching means for switching and controlling the supplied current, and a control device connected to an input of the switching means, and the control device is configured to control the telephone terminal, which also serves as a control signal, only when a ringing signal is to be sent to the telephone terminal. A low frequency signal for making the ringer ring is applied to the switching means, and the switching means constantly receives the high frequency signal for switching the current flowing through the high frequency transformer. A superimposed signal obtained by superimposing a frequency signal and a high-frequency signal is supplied to the primary side of the high-frequency transformer, thereby making it possible to obtain a predetermined calling signal on the secondary side of the high-frequency transformer. This is a subscriber line interface circuit.

[For production]

Since no low frequency transformer is used, the calling signal sending circuit can be miniaturized. Furthermore, since the power supply to the high frequency transformer can be controlled by turning on and off the control signal, power is not constantly consumed, and power consumption can be reduced.

As a result of the above, simply by mounting the subscriber line interface circuit according to the present invention in a switching system that accommodates four-wire telephone terminals, it becomes possible to accommodate two-wire telephone terminals.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit diagram of a calling signal (CI? superimposed signal generation circuit) according to an embodiment of the present invention. In the same figure, a detailed circuit diagram of CRG is shown. In FIG. 11, the CR signal generation circuit CRG is , a high frequency transformer HFT, a switching circuit SWC, a rectifier circuit REF, and a counter CNT.The switching circuit S-C includes an AND gate AG and a transistor TR whose base receives the output of the AND gate AG.The collector of the transistor TR is High frequency transformer IF
It is connected to the primary winding of ↑, and the emitter is grounded. The ring-on signal RG (also serving as a 16 tlz call signal) from the sub-controller SOB 1 and the 15 kHz high-frequency signal for the switching regulator from the power counter CNT are input to the input of the AND gate AG. The counter CNT is based on a signal of 2M)Iz, which is a clock signal used in, for example, a subcontroller 5IIBl (see FIG. 3 below), which corresponds to a subscriber circuit that interfaces between the main body of the exchange and the telephone terminal. The above 15kHz signal is always given to AND gate 8G.

A DC voltage of 24V is applied to the primary side of the high frequency transformer IIFT.

FIG. 2 is a diagram of voltage waveforms at various parts of the circuit of FIG. 1. In the same figure, as shown in (al and (bl),
+On signal RG (16Hz) is the subcontroller S
Under the control of the control section in OB1, the on and off operations are repeated at appropriate intervals necessary for ringing the transmitting/receiving bell. Since a 15kHz signal is always given to the AND gate by the counter CNT, its output is (1 shown in CI).
A signal in which 6Hz and 15kHz signals are superimposed is obtained,
This signal drives the transistor TR, and the superimposed signal is applied to the primary side of the high frequency transformer HFT. As a result, on the secondary side of the high frequency transformer HFT, a 16 Hz signal with a peak value is obtained by converting 24 V to, for example, 75 V, which is necessary for ringing a bell, by the action of the switching regulator (Fig. 2 (d)), and rectification. Depending on the circuit 16)1
The AC components of the two signals are rectified to provide a continuous ringer signal CR at the output. The continuous ringer signal CR is turned on or off by turning on or off the ringing-on signal RG from the sub-controller SUB1.

Since the CR signal generating circuit CRG shown in FIG. 1 uses a high frequency transformer, it has the advantage of being extremely compact compared to conventional CR signal generating circuits.

Conventionally, a 16Hz signal was directly converted into a 16Hz continuous ringer signal with an effective value of 75V using a low frequency transformer.
Since the low frequency transformer is large, the size of the CR signal generation circuit becomes large, making it impossible to accommodate it in each subscriber line interface circuit. Furthermore, in the past, a 16Hz, 75V signal was generated even when the continuous ringer signal CR was turned off between on and off, and this was switched using other switching means, which caused the problem of high power consumption. .

In contrast, the CR according to the embodiment of the present invention shown in FIG.
According to the signal generation circuit, it is possible to downsize the circuit as described above, and it becomes possible to house it in the same package as each subscriber line interface circuit.

Further, since the ringing on signal RG also serves as the power on/off switching, power consumption can be reduced.

Is Figure 3 the CI of Figure 1? FIG. 2 is a circuit configuration diagram of a two-wire subscriber line interface circuit including a signal generation circuit.

In Fig. 3, a two-wire subcontroller (SOB l
) 8 is a CR signal generation circuit CRG, a state detection circuit RT including a ring trip function, and a relay circuit R,
Equipped with R5 etc. A main control device (MC) 2 connects the telephone terminal (not shown) to another telephone terminal (not shown) on the extension or central office line to a telephone terminal placed on the floor.
When there is an incoming call on 1, the sub controller (SOB 1)
A calling signal sending command is issued to the control unit 44 in 8. The sub-controller (SUB l) 8 drives the relay circuit R corresponding to the position l, opens its contact T, and connects the communication line L.
j, L2 are connected to the C11 signal generation circuit CRG, and a ringing-on signal RG is given to the CR signal generation circuit CRG. The ring-on signal RG is output when at least one of the plurality of telephone terminals controlled by the control unit 44 is called. CR signal generation circuit CRG is a ringing on signal RG
When the receiver receives the call, the communication line L-1 is
A 16 Hz continuous ringer signal CR is sent to L2. The telephone FI station 1 receives this continuous ringer signal CR and generates a ringing ring tone. When the handset T1 is lifted, a loop is formed between the communication lines Ll and L2, and the current flowing through the communication line L2 is detected by the photocoupler PC in the state detection circuit RT, and a detection signal is given to the control section 44. The control unit 44 scans the loop state of the subscriber at 5 msec intervals, and determines that the handset T1 is off-hook when it detects through the above scanning that the photocoupler PC remains on for at least 80 msec or more.

In this way, off-hook of the telephone end floor stand 1 is detected by the state detection circuit RT, and the sub-controller SOB 1 receives the detection signal.

It should be noted that a plurality of relay circuits R are provided corresponding to a plurality of (for example, eight) telephone terminals, and therefore the output of the CR signal generation circuit CRG is connected to a plurality of pairs of relay contacts, and when called The ringer signal CR is sent only to the telephone terminal.

FIG. 4 is a timing waveform diagram showing the ring trip operation in the circuit of FIG. 3. In Figure 4, la)
is a waveform diagram of a signal in which 24 V DC is superimposed on the continuous ringer signal CR introduced onto the communication line Li in the transformer T (bl is the hook switch HS).

(C1 is the state detection circuit 1
? 3 is a waveform diagram of the output voltage of T. FIG. Hook switch H31
In the on-hook state where tel is open, no DC loop is formed in the communication lines Ll, I, and 2, so only the 16Hz continuous ringer signal CR is supplied to the communication line L2, and as shown in tel, when this signal is at a high level, the photo The coupler PC conducts and its output becomes Ov, and at low level, the photocoupler PC cuts off and its output becomes the power supply voltage 5■. The sub-controller SOB l has a photocoupler P inside it.
It has a counter that receives the output of the photocoupler PC, and this counter is used when the output of the photocoupler PC is, for example, 80 msec or more.
If v is continued, a carrier signal is output. Since one cycle of the continuous ringer signal CR is 50 msec, the counter does not output a carrier signal in the on-footer state.

When the hook switch H5 closes at time t and enters the off-hook state as shown in FIG. 4('b), the communication line CI,
A DC loop is formed in L2, the photocoupler PC is always in a conductive state, and its output is always Ov. When the counter in the sub-controller SOB l counts the output Ov of the photocoupler PC for 80 msec or more, it outputs a carrier signal, thereby detecting an off-hook state.

FIG. 5 is a block diagram schematically showing an exchange system to which the present invention is applied. . In the figure, 1 is outside the exchange switch, 2 is the main controller MC13 is a storage device (memory) ME
M, 4 is the subcontroller SUB for 2-wire system, 1.5 is the subcontroller SUB for 4-wire system, 2.6 is the trunk that interfaces with other exchanges (for example, bidirectional trunk), BWT, 7 is the interconnection within the own exchange. In the trunk IOT, 8 is a two-wire telephone terminal, 1 is a four-wire telephone terminal, and 2 is a four-wire telephone terminal.

Here, the 2-wire sub-controller 4 and 4-wire sub-controller 5 and the main controller 2 are connected to the same interface, and when looking at the telephone terminal side from the main controller 2, the terminal is 2-wire, 4-wire It is now possible to control without being aware of the distinction between wire types.

That is, in the present invention, attention is paid to the fact that the interface between the exchange switch S- and the telephone terminal is a sub-controller for two-wire systems and four-wire systems, instead of the conventional subscriber control circuit LNG.

FIG. 6 is a block diagram illustrating a two-wire subscriber line interface circuit according to one embodiment of the present invention.

In FIG. 6, the same reference numerals as in FIG. 5 indicate the same objects, and the parts related to the present invention are shown in detail. In general, the two-wire telephone terminal 8 is equipped with a handset/receiver (J+), a communication circuit (NW+) 81, a hook switch (H3), a ringer (TR), etc. . The two-wire number controller 4 connected to the two-wire telephone terminal 8 connects the communication lines (also called subscriber lines) Ll and L2 with a DC superimposition transformer (
T゛) 41 to the exchange switch l, while
A control unit (CONT 1) 44 that controls the reception of on-hook, off-hook information, selection signals, etc. of the 2-line second telephone terminal 8, and controls the transmission of a calling signal to the telephone terminal 8, etc., and controls the control information with the main controller 2. Buffer memory for sending and receiving (
B? lR, B? 1S) 42, 43, Calling signal generation circuit (CRG) 49 for sending a calling signal to the telephone terminal
, switching relay circuits R and R5 for sending out a calling signal, a state detection circuit RT for detecting the state of the telephone, and the like. The control unit 44 further includes an analysis unit (CA) 45 that receives a control signal (control command) from the main control device 2 and analyzes the command, and a ringer sending control that controls sending out a calling signal based on the control command, etc. Department (RTC) 46,
Status monitoring unit (LS) 48 that monitors and detects the status of the telephone
, a code converter (CV) 47 that encodes and sends necessary information to the main controller 2.

On the other hand, the memory area of the storage device 3 is provided with an area for storing control commands sent from the main controller 2 to the sub-controller 4, and an area for storing control codes sent from the sub-controller 4 to the first controller 2. It is being The contents written in the memory area t4hR are read out and written into the buffer memory 42 of the sub-controller 4, and the contents written in the buffer memory 43 of the sub-controller 4 are read out and written in the memory area t4hR. Written to MW.

Each memory area stores read control information (e.g., information from the telephone end floor O (path shown)) and write control information (e.g., information from the telephone end floor O (path shown)) consisting of, for example, 1 word and 4 bits. Store it in a predetermined memory area.

Further, as the buffer memories 42 and 43, for example, 3
RA with a capacity of 27 words? It is controlled by one sub-controller and has an appropriate capacity depending on the number of telephone terminals, number of buttons, etc.

FIG. 7 is a block circuit diagram illustrating a four-wire subscriber line interface circuit according to one embodiment of the present invention. In FIG. 7, 4-wire telephone terminal (position 2>9 is a handset T2, a telephone line (N button 2) 96, and a telephone circuit 96).
The tone ringer Tl+ is switched via the tone ringer Tl+, the hook switch input section 94 is linked to the hook switch H52 and the Funoku Isochi H32, and the key human power section (KEY).
92, a lamp control unit (LED) 93, a ringer sending unit 95 that provides a calling signal to the tone ringer TR,
Call circuit N-2, lamp control LED, tone ringer T
It is provided with a control section (CNT2) 91 and the like that controls R, etc. and generates a control code based on input information from a key input section 92 and a hook switch input section 94. Control unit 91
is a 4-wire sub-controller (SIJB 2)
The above control is performed based on signals from the KEY 5 and the KEY 92. For this purpose, the control section 91 is connected to the sub-controller 5 via control lines L3 and L4.

The sub-controller 5 has an interface between the four-wire telephone terminal 9 and the exchange side, and in addition to the communication line L2 interface, the control line L3 . Control unit (CONT 2) for receiving/transmitting input/output information from L4
54 and buffer memories (BMR, BMS) 52 , 53 for exchanging information with the main control device 2
It is equipped with The control unit 54 includes a command analysis unit (CA') 55 for analyzing control commands from the main controller 2 and sending control codes to the 4-wire telephone terminal 9; and receiving information from the 4-wire telephone terminal 9 ( A code converter (CV') 56 sends a control code from the main controller 2 (code) to the main controller 2; a transmitter (S) 59 and a receiver (R ) consists of 58 mag. In addition, the main controller 2
, the interaction with the storage device 8 is similar to that of the two-wire telephone terminal described above.

FIG. 8 is a flowchart showing the calling operation of the two-wire telephone terminal 1 in the circuit shown in FIG.

In the same figure, the telephone end is placed on the floor at 1.
1, the footer switch H51 closes and the communication line L
i, a loop is formed in L2. Sub controller (S
The loop state monitoring unit 48 in IIB1)4 scans the loop state of the subscriber at, for example, 5 msec intervals, and the loop state monitoring unit 48 in IIB1)4 scans the loop state of the subscriber at intervals of, for example, 5 msec. Detect L 1 off footer (
2). When the state monitoring unit 48 detects an off-footer, it writes the control code "off-hook" information into the area I of the writing side memory (MEM) 3 via the buffer memory 43 (3). Main controller (MC) 2
reads the "off-hook" information written in the memory (Ml!M) 3 (4) and performs the necessary switching connection processing corresponding to the off-hook (5), where it replaces the extension trunk (IOT) 7. By connecting via the switch S-, a dial tone DT is sent to the telephone terminal floor 1 (6).

The subscriber picks up the handset T1 and sends out a dial (
7). The status monitoring unit 48 in the sub-controller (SUBl) 4 detects "dial" information by loop scanning (8) and stores this in the memory (Mll!M) 3.
(9). The main controller 2 reads the "dial" information written in the memory (MEM) 3 and performs necessary exchange connection processing such as calling the other party corresponding to the "dial" information (11).

Then, the telephone number of the called party is called, and when there is a response from the called party, a telephone conversation is made (12).

Next, when the handset T1 is put down, the hook switch H32 is opened and the loop of the communication lines Li and L2 is opened (13).

The status monitoring unit 48 in the sub-controller (SOB 1) 4 detects the on-footer of the handset T1 by loop scanning (14) and stores this in the memory (MEM).
3 (15). The main controller (MC) 2 reads the "on-hook" information written in the memory (MEM) 3 (16) and performs the necessary exchange connection processing corresponding to the on-hook (17).The line is thus disconnected. .

FIG. 9 is a flowchart showing the incoming call operation of the two-wire telephone terminal 1 in the circuit shown in FIG.

In the figure, when a main controller (MC) 2 receives an incoming call to a telephone end floor mount 1, it sends out a ring tone to an area MR of a reading side memory (Ml!M) 3 in order to call the corresponding telephone end floor mount 1. Write the command (21).

(22). The command analysis unit CA in the sub-controller (SIJB 1 ) 4 receives the ring tone sending command from the memory (MEM) 3 via the buffer memory 42 ,
This is analyzed and a ringer sending command is given to the ringer sending control unit RTC (23). Ringer sending control unit 11TC
In response to this, a 16Hz ringing signal is sent to the telephone terminal equipment.
It is sent to the tone ringer TR in l (24).

As a result, the ringer of the telephone V&terminal device 1 rings.

Next, when you pick up the handset 'I'1 and answer the incoming call, the hook switch H5 closes and a loop is formed (25).
, Sub: 1 controller (SUB 1) 4 detects an off-hook state by scanning the line of 1 placed on the floor at the end of the telephone, stops the ringtone, and sends a message to the area stand of the writing side memory (MR gate) 3. Write "off-hook" information (26), (27). Main controller (-C
) 2 reads the area M- of the writing side memory (MR gate) 3 (28) and confirms the response of the telephone end 1, and then sends the command to stop the ring tone to the reading side memory (
MEM) Write 3's MR (29), (
30).

Sub controller (SUB 1) 4 is readout 1
11 Memory (MUM) 3 receives a "stop incoming call" command from MR (31), but since the ring tone has already been stopped, no special processing is performed (32). In this way, a telephone conversation is started (33).

Thereafter, the disconnection process is the same as that shown in FIG. 8, and by putting down the handset of the telephone (34), the sub controller (SOB l) 4 detects this on-off state using the state monitoring unit 48, Write to the area of the memory (liver M) 3 via the buffer memory 43 (35),
(36). The main control bag W (anus) 2 has a memory (MEM).
)3 area? Read the on-hook status of the telephone from I-37) and perform the communication path release process (37).
38).

On the other hand, flowcharts of the operation of calling and receiving calls by the 4-wire telephone terminal (position 2) 9 in the 4-wire subscriber line interface circuit shown in FIG. 7 are shown in FIGS. 10 and 11, respectively.

First, call control by a four-wire telephone terminal will be explained below with reference to FIG.

Telephone (position 2) Lift the handset at 9 (4)
1). At this time, the hook inch closes and a loop is formed via the lines , , , and 2 as in the case of the destination 2-line subscriber, but the off-hook information is transmitted to the hook switch input section 94 linked to the hook switch of the telephone. The control unit 91 detects off-hook and changes the control line L3. It is encoded and sent as off-hand information to the sub-controller (StlB 2 ) 5 via L, 4 (42). Sub controller 5
receives the code and converts the code as necessary to the converter 56.
The memory (ME) is reorganized via the buffer memory 53
M) Write to the predetermined area of 3 (43). Main controller (
MC) 2 was written in memory (MEM) 3.
By reading the "off-hook information" (44), necessary exchange connection processing corresponding to off-hook is performed (45).Then, in the same way as explained for the two-wire telephone (Fig. 8), the trunk (IOT) 7 and The connection causes the dial tone DT to be sent through the telephone line (46).

Next, all dial input from the terminal is done by the key human power department 9.
2 (47), and each time the destination information (dial information) is detected by the control unit 91, it is encoded and sent to the sub-controller (48). Sub controller (SL
In the IB2) 5, when code information from the terminal side is received via the control line L4, code conversion is performed as necessary, and the code information is stored in the memory (MEM) via the buffer memory 53.
) Write in area M- of 3 (49).

The main controller (MC) 2 reads out the 2-dial information written in the memory (anus) 3 (5o) and performs necessary exchange connection processing such as calling the other party corresponding to the dial information. (51).

When the other party responds, the call state is established (52
).

For disconnection, when the handset is put down (53), the control section 91 detects on-hook from the hook-up input section 94 and sends on-hook information to the sub-controller (SOB2) 5 (54). Sub controller (SII
B 2 > 5 is stored in the memory (MEM
) Write on-hook information to area MW of 3 (55)
, and the main controller (MC) 2 has a memory (MEM).
) Read the on-hook information from 3. 56) Perform release processing (57).

Next, the incoming call processing in the four-wire telephone terminal will be explained below with reference to FIG.

The main controller (MC) 2 arrives at the filling machine end device l (if there is an i, it writes a ring tone sending command to the area MR of the read side memory (MEM) 3 to call the corresponding telephone end device 1. (61), (62).

Sub-controller (StlB2) 5 is the memory
(Read out the ring tone sending command from the area MR of MB2 via the sofa memory 52 from the command analysis unit 55 -> 6
3) Analyze this command (64) and send it to the transmitter 5
A ring tone command is sent to the control section 91 of the telephone terminal (position 2) via the telephone terminal 7 (65). Telephone terminal (position 2)
Upon receiving the incoming command, the control section 91 of ) performs controls such as making the tone ringer 95 ring and lighting a predetermined lamp of the lamp section 93 (66).

On the other hand, when the handset of the telephone terminal goes off-hook (6
7) The control unit 91 transmits the off-hook information to the sub-controller (SOB 2 ) by detecting the off-footer.
5 (68). Sub controller (StlB
2) 5 Edit the command and memory (Ml!M
) Write the information to area MW of 3 in the same way as sending (6
9).

When the main controller (MC) 2 confirms the response from the memory (MEM) 3 (70), it sends the ringtone stop command to the subcontroller (S[IB 2) 5 to the memory (
MEM) Notify via 3 (71),
(72). The sub-controller reads the ring tone stop command from the memory (?IEM) 3 (73) and notifies the control unit 91 of the telephone terminal (position 2) (74).
, (75). The control unit 91 of the telephone terminal stops the ringtone (76). Then, it becomes a call state.

Disconnection is done by turning the handset on-hook (7g) in the same way as in Fig. 10, and then using the sub-controller (SOB 2'').
5 to receive on-hook and off-hook information79)
, on-hook information from the sub-controller (SOB 2) 5 is notified to the main controller (MC) 2 via the memory (MEM) 3 (110), (
81).

The main controller (MC) 2 receives the off-hook information and
Performs processing such as releasing the communication path.

As is clear from the above operation description, the sub-controllers (SOB 1, 5UB2) 4, 5 according to the present invention
The control exchange between the main control unit (MC) and the 2-wire system is exactly the same for the 2-wire and 4-wire systems, and the control at the sub-controller 4.5 may differ between the 2-wire system and the 4-wire system. Recognize.

Therefore, the present invention eliminates the need for the conventional method of identifying each terminal and changing control in the main controller when attempting to accommodate a mixture of 4-wire and 2-wire terminals on the exchange side. Not only can the control of the main controller be unified, but also the complexity of program control can be prevented.

FIG. 12 is a diagram showing an example of control information given to the main controller from the 2-wire and 4-wire sub controllers. As shown in the figure, the control information DATA is (al(bl
, (One word is made up of 8 pins from 0 to 7 of c+, and the state where the most significant bit "7" of 81 is θ" indicates an on-hook state. (bl indicates a code by function. and fcl indicates each individual information.

Therefore, off-hook is detected when the most significant bit "7" becomes 1. If the lower 6 to 0 bits are all "θ" in the off-hook state, it indicates that no button has been pressed and the terminal does not change. , when the 6th to 4th bits are OOl, it indicates the dial number O to 9.#7* according to the lower 3 to 0 bits, and when the 6th to 4th bits are 010, it indicates the dial number to hold, according to the lower 3 to 0 bits. It represents the functions such as group, station line transmission 1, etc., and when the 6-0 focus is 1010101, it represents the response to the test command.In addition, the shaded part in the 2-wire interface is the information from the 2-wire terminal. is not entered.

FIG. 13 is a chart showing an example of control information given from the main controller MC to the 2-wire type, 4-wire type sub, and controller. In the figure, when the most significant bit of fdl of the control information 11ATA is "0", it indicates a receivable state, and when it is "1", it indicates a receivable state. This information is used to notify the sub-controller of the processing status on the main controller side depending on the traffic volume, and if it is unreceivable "1"
In the case of , it indicates that one-way notification control is performed from the main controller. Control information DATA (e), (f
When bit 6 of l is "0", it indicates a visible display, and "1" indicates an audible display (functioning as a tone sound, etc.). The visual display function (i.e., indicating the lamp control function) is only possessed by the 4-wire telephone terminal 2, and the 2-wire telephone terminal 1
does not have. Bits 5 to 0 of the control information represent various functions such as hold, group, central line origination, extension ring tone, transfer call paging, central line ring tone 2, and so on.

When the control information is 11000000, tone off, 11
1111.01 indicates a reset, 11111110 indicates a test command, and all "1" indicates NOP.

As you can see in Figures 12 and 13, the main controller (?lC)
In each control, predetermined data is created and sent to the sub-controller, so if the sub-controller is a two-wire system and does not require control, it will be automatically dropped within the sub-controller.

Also, when sending the control code from the sub-controller to the main control device, in the case of a two-wire type, one without a control code is not automatically created, so there is no problem in terms of exchange control. .

FIG. 15 is a flowchart showing step S4 in FIG. 14 in more detail. In FIG. 15, in step 541, the state of hook switch H51 is detected as described with respect to FIG. If it is in the on-hook state, the hook information is stored in the memory HEH in step S42, and the process returns to the initial stage of the loop scan. If it is in the off-hook state, the hook information is stored in the memory M in step S43.
It is stored in EM, and it is determined in step S44 whether or not the ringer is ringing.

If the ringer is ringing, the relay circuit R (Fig. 3) of the corresponding line is restored in step S45, and the ringer on signal RG (Fig. 3) from the ringer sending control section 46 is turned off in step S46. The ringer signal is stopped, and then a dial pulse is detected in step S47. If the ringer is not ringing in step 344, the process immediately moves to step S47. When the dial information is detected in step S47, the detected dial information is stored in the memory MEM in step S48, and the process returns to the initial state of the loop scan. Even when no dial pulse is detected in step S47, the loop scan returns to the initial state again. I”
A loop scan is performed by repeating the operations - at 5 msec intervals.

FIG. 16 is a flowchart showing step S5 in FIG. 14 in more detail. In FIG. 16, the contents of the memory HEM are read out in step S51, and the contents of the memory HEM are read out in step S51.
In step 2, the read command is analyzed by the command analyzer CA (FIG. 6). If the read command is tone-off, the ringer-on signal RG is turned off in step S53 to stop the 16 Hz ringer signal, and the relay of the corresponding line is restored in step S54 to end the ringer control. If the read command is a command for an extension call or a central office line call, in step S55, the ringer-on signal RG is turned on to generate a 16Hz ringer signal, and the controller 2 knob S is turned on.
At step 56, the ringer is made to ring by operating the corresponding line L/- circuit, and the ringer control is completed.

Figure 17 is a memo for Figures 15 and 16! ? lE
12 is a flowchart showing operations of writing to and reading from memory. In Figure 17, memory E
Reading/writing to M is done by an external interrupt routine. That is, writing to the memory MEH is performed by writing to the memory MEMζ from the sofa memory BM (FIG. 6) in the external interrupt routine, and the memory ? Reading from the II conversion is done by writing from the memory back to the sofa memory in an external interrupt routine.

〔Effect of the invention〕

As explained above, according to the present invention, by using a switching regulator in the calling (d number sending circuit),
For example, since a 16 Hz low-frequency calling signal can be generated without using a low-frequency transformer, the calling signal sending circuit can be miniaturized and mounted with high density, making it possible to implement the calling signal sending circuit in a pan case. user interface circuit is obtained. In particular, the present invention facilitates the realization of a switching system that accommodates a mixture of two-wire telephone terminals and four-wire telephone terminals.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an output signal generation η-circuit according to an embodiment of the present invention, FIG. 2 is a voltage waveform diagram of each part of the circuit of FIG. 1, and FIG. 3 includes the circuit of FIG. 1. A circuit diagram showing a tone ringer in a two-wire subscriber line interface circuit, FIG. 4 is a voltage waveform diagram of each part of the circuit in FIG. 3, and FIG. 5 is a block diagram showing an outline of a switching system to which the present invention is applied. FIG. 6 is a block circuit diagram illustrating a two-wire subscriber line interface circuit according to an embodiment of the present invention, and FIG. 7 is a block circuit diagram illustrating a four-wire subscriber line interface circuit according to an embodiment of the present invention. 8 is a flowchart showing the calling operation of the two-wire telephone terminal in the circuit shown in FIG. 6, FIG. 9 is a flowchart showing the receiving operation of the two-wire telephone terminal in the circuit shown in FIG. 6, Figures 10 and 11 show 4 in the circuit shown in Figure 7.
A flowchart showing the operation of making and receiving calls by a wired telephone terminal, Fig. 12 is a diagram showing an example of control information given from the telephone terminal to the main control device, and Fig. 13 shows control given to the telephone terminal from the main control device. 14 is a flowchart showing the flow of the operation of the sub-controller in the circuit of FIG. 6; FIG. 15 is a flowchart showing step S4 in FIG. 14 in more detail; FIG. FIG. 17 is a flowchart showing the write and read operations for the memory in FIGS. 15 and 16; FIG. 18 is a conventional switching system accommodating a 4-wire telephone terminal; FIG. 19 is a block circuit diagram showing an example of a switching system accommodating a conventional two-wire telephone terminal and a four-wire telephone terminal. 8.9 (Location I, TBL21-telephone terminal, Ll,
L2--Talking line, 0FT--High frequency transformer, 5tnc--Switching circuit, 4, 5 (SIIB 1, SOB 2)-Sub controller, 1 (SW)--Replacement switch, 2 (MC ) -1.--main control device, 3 (M
[iM) - one memory.

Claims (1)

[Claims] 1. In a circuit that sends a calling signal to a telephone line connected to a telephone terminal, a high-frequency transformer for DC voltage conversion, and a switching device that controls switching of the current supplied to the primary side of the high-frequency transformer. means and a control device connected to an input of the switching means, the control device applying a low frequency signal to the switching means only when a ringing signal is to be sent to the telephone terminal; is characterized in that it constantly receives a high frequency signal for switching the current flowing through the high frequency transformer, and supplies a superimposed signal obtained by superimposing the low frequency signal and the high frequency signal to the primary side of the high frequency transformer. personal line interface circuit.