JPS6017265B2 - Digital telephone connection method - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in digital telephones.

In particular, the present invention relates to a digital telephone in which a plurality of digital telephones are branch-connected to one digital subscriber line to enable simultaneous calls. [Prior art] In recent years, with the aim of improving the quality of voice communication and the advanced integration of information communication and voice communication, all-digital technology has been developed to digitize not only exchanges and inter-office transmission lines, but also subscriber lines and telephones. A communication system is in place.

On the other hand, branch connections have traditionally been used to connect multiple telephones to a single subscriber line and allow calls to be made from any of the telephones. Even when applied to subscriber lines, simultaneous calls cannot be made from multiple telephones.
FIG. 4 is a block diagram of a conventional digital telephone. The output of the transmitter 1 is an analog signal, which is converted into a digital signal by an encoder 2 and sent to a multiplexer 5.
and is applied to the line interface 7 via the transmission buffer 6. Line interface 7 is connected to digital subscriber line 8 . Further, the output digital signal of the line interface 7 is converted into an analog signal by a decoder 14 via a reception buffer 11 and a demultiplexer 13, and is provided to a receiver 16. This line interface 7 is given an output control signal of a hook switch 9 of this telephone, and this hook switch 9
When the hook switch 9 is closed, the line interface 7 is enabled and the line interface 7 is arranged to be disconnected from the digital subscriber line 8 when the hook switch 9 is released.

FIG. 5 is an operation time chart of this device.
Figures a to e show signal waveforms a to e marked with x in Fig. 4.

That is, the output analog signal a of the transmitter 1 is converted by the encoder 2 into a digital signal b. This digital signal is transmitted from the line interface 7 to the digital subscriber line 8. As shown in FIG. 5c, a transmission signal and a reception signal are transmitted to the digital subscriber line 8 in a time-division manner, and the line interface 7 utilizes the transmission buffer 6 to transmit the signal of the section 21 to the section 21. At 24, the signals of section 22 are transmitted to section 26, respectively. On the other hand, section 23 and section 2
The signal 5 is a received signal, and is a signal at the line interface 7.
inputs this into a receiving buffer and distributes it as a digital signal d to sections 28 and 29, respectively. This digital signal d is converted into an analog signal shown in FIG. 5c by the decoder 14 and is applied to the receiver 16. [Problems to be Solved by the Invention] Even in the case of such digital telephones and digital subscriber lines, customers are required to make branch connections between multiple telephones and connect multiple telephones in the same way as with conventional analog telephones. There is a desire to make simultaneous calls from the telephone.

However, in the above-mentioned conventional digital telephone, if branch connections are made to multiple telephones using the digital subscriber line 8, and the line interface 7 of the hook switch is branch-connected to the subscriber line 8, one telephone This is fine when the hook switch 9 is activated (closed) and only one line interface 7 is enabled, but if the hook switch 9 is activated on multiple telephones at the same time, each line interface 7 becomes the digital subscriber line 8. The digital signals sent and received by the computer will be confused and make no sense.

Therefore, with such a conventional device, it is not possible to make a branch connection as is done with an analog telephone, and it is not possible to make a branch connection to the input terminal 4 of another digital device provided at the input of the multiplexer 5 in FIG. 4 or to the output of the demultiplexer 13. Connection was limited to using the provided output terminal 15.

In this connection, the multiplexer 5 or demultiplexer 13 only selectively combines one of its inputs or outputs, and does not simultaneously perform thin speech from a plurality of fin talkers. The present invention improves this and
In response to the above wishes of customer subscribers, an object of the present invention is to provide a connection system in which a plurality of digital telephones are branch-connected to one digital subscriber line, and calls can be made simultaneously from the plurality of digital telephones.

[Means for solving problems]

The present invention includes a hook switch, a transmitter, an encoding means for converting an analog signal from the transmitter into a digital signal, transmitting the digital signal to a digital subscriber line,
line interface means for receiving a received digital signal from the digital subscriber line and enabled by a control signal sent by the hook switch; decoding means for converting the received digital signal into an analog signal; In a digital telephone connection system in which a plurality of digital telephones are connected to one digital subscriber line, each of the plurality of telephones is connected to a control signal sent by the hook switch. A line control circuit is provided in the circuit provided to the line interface, and for the plurality of digital telephones, a transmitting parallel means connects the transmitters of each telephone in parallel, and a receiver parallel means connects the handsets of each telephone in parallel. and a means for interconnecting the line control circuits of the telephones, and the line control circuit is configured to connect the line control circuits of the plurality of telephones to one another even if the hook switches of the plurality of telephones operate. includes a logic circuit for transmitting the control signal, and the logic circuit is configured such that the logic circuit of the telephone that first activated the hook switch continues to transmit the control signal until the hook switches of all telephones are restored. It is characterized by

The line control circuit includes two input terminals and two output terminals, an AND gate circuit and an OR gate circuit in which the output of a hook switch is connected to one input of each, and the output of the AND gate circuit is connected to a set input. A flip-flop is provided in which the output of the OR gate circuit is connected to the reset input, and the output Q thereof serves as a control signal output, and the first input terminal of the one input terminal is connected to the inhibit input of the AND gate circuit. The second input terminal of the two input terminals is connected to the input of the OR gate circuit, the first output terminal of the two output terminals is connected to the output Q of the flip-flop, and the second input terminal of the two input terminals is connected to the input of the OR gate circuit. The second output terminal of the two output terminals is configured to be connected to the output of the hook switch, and the means for interconnecting the control circuits is configured to connect the first output terminal to the first output terminal for a plurality of telephones. Preferably, the second input terminal is connected to the second input terminal, and the second output terminal is connected to the first input terminal in sequence in a loop.

[Operation] In this connection method, for multiple branch-connected telephones, the transmitter and handset of each telephone are connected in parallel with analog signal lines, so the transmitter analog output of each telephone is connected to all telephones. The decoder analog output of each telephone is input to the handset of all telephones.

Therefore, each telephone's handset or handset signal can be transmitted and received via the encoder or decoder of any one telephone. Furthermore, the line control circuit controls the multiple telephones connected in this branch so that only the line interface of that one phone is enabled, so digital signals are not sent or received from a phone whose line interface is not enabled. , there is no digital signal disruption, and multiple telephone calls are sent and received from one telephone with line interface enabled to the digital subscriber line. In this manner, the system of the present invention allows calls to be made simultaneously from a plurality of telephones branch-connected via subscriber lines without signal confusion. In the method of the present invention, when the hook switches of a plurality of telephones operate, the line control circuit of the telephone whose hook switch operates first sends out a control signal.
Even if this telephone is the first to restore hook switch operation, the line control circuit of the telephone whose hook switch was first activated continues to send control signals until the hook switches of all telephones are restored.

〔Example〕

FIG. 1 is a block diagram of a digital telephone according to an embodiment of the present invention.

The output of the transmitter 1 is an analog signal, which is connected to the input of an encoder 2 which converts it into a digital signal. The output digital signal of the encoder 2 is connected to a line interface 7 via a multiplexer 5 and a transmission buffer 6. The line interface 7 is coupled to a digital subscriber line 8 and transmits the output digital signal of the transmit buffer 6 to this digital subscriber line 8. Further, a received signal arriving at this digital subscriber line is inputted to a receiving buffer 11 through a line interface 7, and its output is given via a demultiplexer 13 to a decoder 14 that converts the digital signal into an analog signal. The analog output of this decoder 14 is input to a receiver 16. The synchronization circuit 12 is for synchronizing the operation of the telephone with the signals on the digital subscriber line. The output of the dial 3 is connected to the input of the multiplexer 5, and the input terminal 4 and output terminal 15 for connecting other digital devices are connected to the multiplexer 5 and demultiplexer 1, respectively.
Connected to 3. Furthermore, the ringer 10 is a circuit that sends out a calling signal as an acoustic signal. The basic configuration and operation of these circuits are the same as those explained in the conventional example circuit above.

Here, the features of the present invention are that a terminal 30 is provided at the input of the encoder 2, a terminal 31 is provided at the output of the decoder 14, and a hook switch 9 is provided for enabling the line interface 7. Output control signal to line control circuit 3
It is configured to be given via 2. Line control circuit 32 has two input terminals 35 and 36 and two output terminals 37 and 38. Referring to FIG. 2, a connection circuit for branch connection of this telephone will be explained.

A and B shown in FIG. 2 are digital telephones having the configuration shown in FIG. 1, respectively. First, the digital subscriber lines 8 of these two telephones are commonly branch-connected. Further, the terminals 30 to which the output analog signals of the handset are connected are connected to each other, and the terminals 31 to which the input analog signals of the handset are connected are connected to each other. As a result, the transmitter outputs of telephones A and B are connected in parallel, and the receiving outputs of telephones A and B are connected in parallel. moreover,
Regarding the terminals 35 to 38 of the line control circuit, as shown in FIG. 2, the output terminal 37 of telephone A is connected to the input terminal 35 of telephone B, and the output terminal 38 of telephone A is connected to the input terminal 36 of telephone B. , the output terminal 37 of telephone B is connected to the input terminal 35 of telephone A, and the output terminal 38 of telephone B is connected to the input terminal 36 of telephone A.

As a result, the line control circuits 32 of the branch-connected telephones A and B are now connected to each other. Returning to FIG. 1, the line control circuit 32 will be further explained.

The input terminal 35 is connected to the inhibit input of the gate circuit 4. One end of the hook switch 9 is connected to the input of this gate circuit 41. The potential at one end of this hook switch 9 is also connected to the input of the gate circuit 42 . The other input of this gate circuit 42 includes input terminal 3.
6 is connected. These gate circuits 41 and 4
The outputs of flip-flop 2 are connected to the set and reset inputs of flip-flop 4, respectively. The output Q of the flip-flop 43 is connected to the input terminal 31 and branched off to the line interface 7. One end of the hook switch 9 is also connected to an output terminal 38. The operations of machine A and machine B connected in this way will be explained based on the operation time chart shown in FIG. 3.

t in FIG. 3 shows the passage of time. a to e in Figure 5
is the operating waveform at the point indicated by the cross in FIG. a is an operating waveform diagram of hook switch 9 of machine A, b is an operating waveform diagram of hook switch 9 of machine B, and c is a diagram of flip-flop 4 of machine A.
3 is an operating waveform diagram of the flip-flop 43 of the B machine, and e is a state diagram of the digital subscriber line 8 commonly connected to the A machine and the B machine. When the hook switch 9 of machine A is operated at the current time, the gate 41 performs an AND operation and sends out an output.

An output is also sent to gate 42, and flip-flop 43 is set. The output Q of the flip-flop 43 enables the line interface 7, and the digital subscriber line 8 is acquired by the A machine. At this time, outputs are provided to output terminals 37 and 38. Next, the hook switch 9 of Aircraft B is activated at the time. At this time, the output terminal 3 of the machine A is connected to the gate circuit 41 of the machine B.
The gate circuit 41 of machine B has no output because the output is inverted and inputted. Therefore, the flip-flop 43 of the B machine is not set, and the digital subscriber line 8 is not captured by the B machine. At this time, an output is provided to the output terminal 38 of the B machine. Next, in Time et al.
Restore (open) hook switch 9 of the machine.

As a result of this operation, an output is sent to the gate circuit 41 of machine A. However, since the signal is input from the output terminal 38 of the B machine to the gate circuit 42 of the A machine, the gate circuit 42
has no output. Therefore, flip-flop 4 of machine A
3 retains its output Q, its line interface 7 is enabled, and machine A continues to acquire the digital subscriber line 8. Next, at time L, the hook switch 9 of aircraft B is restored.

As a result of this operation, the output from the output terminal 38 of the B machine is cut off. Therefore, the input provided from the input terminal 36 of the machine A to the gate circuit 42 of the machine A is also cut off, and the output of the gate circuit 42 is sent out. The output of this gate circuit 42 resets the flip-flop 43 of machine A.
Digital subscriber line 8 is released. By configuring the line control circuit 32 in this way, the digital subscriber line 8 is captured only by the telephone that first activated the hook switch 9, and the digital subscriber line 8 is captured only by the telephone that activated the hook switch 9 later. Digital subscriber line 8 is not captured.

Therefore, since only one telephone is connected to the digital subscriber line 8 at the same time, the digital subscriber line 8
The transmitting digital signals are not mixed together as digital signals. The transmission signal is an analog signal output from the transmitter 1 of the machine A, and a transmission parallel connection terminal 30 of the machine B, which is connected to the parallel transmission connection terminal 30 of the machine A.
is mixed with the analog signal output from the transmitter 1 of the B machine.

The transmitted speech signal mixed as an analog signal is input to the encoder 2 of machine A. The received signal is converted into an analog signal by the decoder 14 of machine A. This analog signal is distributed to the receiver 16 of the A machine and the receiver 16 of the B machine via the receiver parallel connection terminal 31 of the B machine, which is connected to the receiver parallel connection terminal 31 of the A machine. In this way, it is possible to make simultaneous calls with machine A and machine B. Note that the above example describes the case of two telephones, but in the case of N branches (N is an integer of 3 or more), the gate circuits 41 and 42 can be replaced with gate circuits each having N input terminals. For example, it can be configured similarly. Furthermore, although not shown in the above example,
By disconnecting the transmitter 1 and the handset 16 using the information of the hook switch 9 as necessary, the hook switch 9 can be operated and the influence on other branch-connected telephones can be eliminated when the hook switch 9 is not present.

Note that the configuration of the logic circuit of the line control circuit 32 can be configured using other circuits having the same logic, and the present invention can be implemented in the same manner.

〔Effect of the invention〕

As explained above, according to the present invention, the digital subscriber line is captured only by the telephone whose hook switch is activated first, so that only one telephone is connected to the digital subscriber line at the same time. The digital signals for outgoing calls are not mixed together as digital signals.

Moreover, since the transmitted and received signals operate in parallel as analog signals, it is possible to obtain a connection system for a digital telephone that allows branch operation in the same way as a secondary analog type telephone. The present invention has an excellent effect of providing a digital telephone connection method suitable for an all-digital communication system.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2 is a diagram showing the connection between machine A and machine B in the above example, Fig. 3 is an operation time chart of the example shown in Fig. 1 above, and Fig. 4 is a diagram showing the connection between machine A and machine B in the above example. The figure is a conventional example configuration diagram, No. 5
The figure is an operation time chart of a subordinate example. 1... Transmitter, 2... Encoder, 3...
...Dial, 4...Input terminal, 5...
・Multiplexer, 6...Transmission buffer, 7.
...Line interface, 8...Digital subscriber line, 9...Hook switch, 10
...Ringer, 11...Reception buffer, 12...
・Synchronous circuit, 13...Demultiplexer, 14
...Decoder, 15...Output terminal, 16
...Handset, 30...Transmitter parallel connection terminal, 31...Handset parallel connection terminal, 32...
... Line control circuit, 35, 36 ... Input terminal, 37, 38 ... Output terminal, 41, 42 ...
...Gate circuit, 43...Flip-flop. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A switch, a transmitter, an encoding means for converting an analog signal from the transmitter into a digital signal, and transmitting the digital signal to a digital subscriber line and transmitting the digital signal to the digital subscriber line. Line interface means for receiving a received digital signal from the line and enabled by a control signal sent by the box switch; decoding means for converting the received digital signal into an analog signal; and a receiver for inputting the analog signal. In a digital telephone connection system in which a plurality of digital telephones are connected to one digital subscriber line, each of the plurality of telephones is provided with a control signal sent by the telephone switch to the line interface. A line control circuit is provided in the circuit, and for the plurality of digital telephones, a transmitting parallel means for connecting the transmitters of each telephone in parallel, a receiving parallel means for connecting the receivers of each telephone in parallel, means for interconnecting the line control circuits, the line control circuit is configured such that even if the switch of a plurality of the plurality of telephones is operated, only one of the plurality of telephones transmits the control signal. includes a logic circuit to
This logic circuit has a logical configuration in which the logic circuit of the telephone that first operates the switch will continue to send out the control signal until the switch of all the telephones is restored. 2 The line control circuit has two input terminals and two output terminals, an AND gate circuit and an OR gate circuit in which the output of the hook switch is connected to one input of each, and the output of the AND gate circuit is connected to the set input, and the above circuit is connected to the set input. The output of the OR gate circuit is connected to the reset input, and the flip-flop whose output Q is a control signal output, the first input terminal of the two input terminals is connected to the inhibit input of the AND gate circuit, The second input terminal of the two input terminals is connected to the input of the OR gate circuit, the first output terminal of the two output terminals is connected to the output Q of the flip-flop, and the two output terminals A second output terminal of the terminals is connected to the output of the switch, and the means for interconnecting the control circuits is configured such that the first output terminal is connected to the second input terminal of the plurality of telephones. The digital telephone connection system according to claim 1, wherein the second output terminal is connected to the first input terminal.