JPH027558B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a four-wire button telephone device.

Conventional devices of this type include those shown in FIGS. 1 and 2. In FIG. 1, A is the main device and B is a telephone. Reference numeral 51 is a speech current supply device, 52 is a tone back link, 53 to 55 are hybrid transformers, 56 is a handset, 57 is a microphone, and 58 is a speaker.

59 and 62 are data senders, 60 and 6, respectively.
1 is a data receiver, and 63 and 64 are power supplies.

In FIG. 2, C is the main device and D is a telephone. 71 is a tone back link, 72 to 74 are each a hybrid transformer, 75 and 76 are each a power supply, 77 and 80 are each a data sender, 78 and 79 are each a data receiver, and 81
82 is a microphone, and 83 is a speaker.

The device shown in FIG. 1 is configured so that the talking current of telephone B is sent from the main device A, and the device shown in FIG. A method is used to create a sound source, an ECM microphone is used as a handset, and a circuit system is used that does not allow direct current to flow through the communication path. However, in all of these systems, in order to perform the tone back function, signals from the microphones 57 and 82 and output signals to the speakers 58 and 83 require a separate hybrid circuit dedicated to talk back, in addition to the hybrid circuit of the telephone circuit. Therefore, the disadvantage is that the circuit inside the phone becomes complicated. Furthermore, the first
In the device shown in the figure, direct current is superimposed on the communication path, so a relay contact or the like is required for switching, which has disadvantages such as lack of economic efficiency.

The present invention focuses on these points and eliminates the conventional drawbacks by eliminating the dedicated hybrid circuit for talkback and using the hybrid circuit of the telephone circuit for both calls using the original handset and toneback. It is.

The present invention will be described below along with examples thereof. In FIG. 3, E is the main device, F is the line, and G is the telephone. 1 is a communication transformer connected to the telephone circuit on the main device E side, 2 is a data transmission transformer, 3 is a transformer transmission circuit, 4 is a data reception circuit, 5 is a power supply circuit, and 6 is a power supply to telephone G. 7 is a communication line between the main device E and the telephone G, and 8 is a data and power supply line between the main device E and the telephone G. Reference numeral 9 denotes a telephone hybrid circuit within the telephone G, which constitutes a bridge type hybrid circuit using two transformers 9a and 9b. 10 is a balanced network, selected so that the sidetone is optimal for the line impedance of the central office line. Reference numeral 11 denotes a handset, and in this embodiment, a carbon transmitter is used. 1
2 is a current supply circuit to the transmitter, and a transistor is provided for current cutting. 13, 14,
15 and 16 are analog switch circuits, 1
7 is a speaker amplifier, 18 is a speaker for ringing and receiving calls, 19 is a microphone for talkback, 20 is a microphone amplifier, 21 is an interrupt sound or warning sound for receiving a call when the phone is busy, etc. necessary inside the phone. 22 is a control section for controlling the inside of the telephone, 23 is a power supply circuit, 24 is a power supply circuit, 25 is a transformer for data transmission and reception, 26 is a data transmitter, and 27 is a data receiver.

Next, the operation of this embodiment will be explained. During normal office line and extension calls, the control unit 22 turns off all analog switches 14, 15, and 16 except for the analog switch 13.
Therefore, the received voice that has passed through the hybrid circuit 9 is not output to the speaker 18, but is output to the handset 11.
output only to the handset. Also microphone 1
The analog switch 16 receives the audio input from 9.
Since it is turned off, it is not output to the communication path, and only the output from the handset of the handset 11 is output to the communication path through the hybrid circuit. At this time, transistor 12 is turned on and supplies direct current to the carbon transmitter.

Next, during talkback, the analog switches 13 and 15 are turned OFF under the control of the control section 22.
14 and 16 turn on. Also, the transistor 12
The operation of the handset 11 is stopped because the direct current supply to the carbon handset 11 is cut off. Therefore, the output of the microphone 19 is outputted to the communication path through the hybrid circuit 9, and the received voice is further outputted to the speaker 18 through the analog switch circuit 14 and the speaker amplifier 17.

As described above, the hybrid circuit 9 can be used for both normal calls and talkback, but since the balance network 10 is originally matched to the impedance Z _o of the central office line as shown in FIG. For talkback, since the impedance of the communication path is different, mismatching occurs and good hybrid characteristics cannot be obtained.

Therefore, in this embodiment, an impedance circuit consisting of a resistor RE and a capacitor C having impedance characteristics equivalent to those of the central office line is inserted into the telephone line dedicated to extension lines as shown in FIG.
0 matches both the local office line and the extension line to provide good hybrid characteristics.

In the above explanation, an example of a circuit that supplies talking current inside the telephone has been described, but a circuit system that supplies current from the main device can also be implemented by switching the circuit configuration of transformer 9b in hybrid circuit 9 using a relay, etc. Needless to say, this can be easily achieved.

As is clear from the above embodiments, the present invention has the feature that a key telephone device can be realized with a simple configuration without requiring a hybrid circuit dedicated to talkback. In particular, according to the present invention, an impedance circuit consisting of a resistor and a capacitor having impedance characteristics equivalent to that of the central office line is inserted into the internal communication line in the main device, so that the balance network for hybrid circuits is , and extension lines, and has the advantage that good hybrid characteristics can be obtained.

[Brief explanation of drawings]

1 and 2 are block diagrams of a conventional button telephone device, FIG. 3 is a block diagram of a button telephone device according to an embodiment of the present invention, and FIGS. 4 and 5 are schematic diagrams of the same essential parts, respectively. It is a wiring diagram. 9... Hybrid circuit, 11... Handset, 13
~16...Analog switch, 18...Speaker, 1
9...Microphone, 22...Control unit.

Claims (1)

[Claims] 1 Consists of a main device and a plurality of key telephones connected to the main device via a telephone line, and a hybrid circuit connected to the telephone line within the key telephone;
A microphone and speaker for extension talkback connected to the above-mentioned telephone line via this hybrid circuit, a handset for normal telephone calls connected in parallel to the above-mentioned microphone and speaker, and the above-mentioned hybrid circuit and the above-mentioned microphone and speaker. a switch means provided between the hybrid circuit and the handset, and a controller for controlling the switch means to connect either the microphone and speaker or the handset to the hybrid circuit. A dedicated extension communication path is provided in the main device to form a communication path between each key telephone when making an extension call, and a resistor and a capacitor having impedance characteristics equivalent to those of the central office line are installed in this extension communication path. A key telephone device having an impedance circuit connected thereto, and a balance network matching both the central office line and the extension line connected to the hybrid circuit.