JPH03255800A - Key telephone system - Google Patents

Abstract

PURPOSE:To enable line wire transfer speech with volume not to be different from normal speech by inserting a ringer tone preventing means between amplifiers and sound exchange switches on a side to be transferred and on a transferring side at the time of line wire transfer. CONSTITUTION:A main unit 1 is equipped with hybrid circuits 61-6n connecting two-line side input and output to respective trunk lines 12, amplifiers 811-8n1 and 821-8n2 for compensating the line loss of the trunk line to be connected to the four-line side input and output of the hybrid circuits 6 on the side to be transferred and the transferring side at the time of line wire transfer, analog switches 913-9n3 and 915-9n5 and sound exchange switch 5 to transfer the sound. Especially, the ringer tone preventing means are inserted between the amplifiers 811-8n1 and 821-8n2 on the side to be transferred and the transferring side and the sound exchange switch 5 at the time of line wire transfer, to prevent the trespassing amounts of the hybrid circuits 61-6n on the side to be transferred and the transferring side and the ringer tone caused by the amplifiers 811-8n1 and 821-8n2 on the side to be transferred and the transferring side.

Description

[Detailed description of the invention] [Industrial application field] INDUSTRIAL APPLICATION This invention is utilized for the external line transfer circuit of a button telephone device.

〔overview〕

The present invention is a button telephone device that allows outside line transfer calls to be made at the same volume as a normal call by inserting a loss in the receiving side when sending a call and in the sending side when receiving a call to transfer the outside line. It is.

[Conventional technology]

FIG. 3 is a block diagram of a circuit for compensating for line loss when transferring an outside line in a conventional button telephone device. FIG. 4 is an explanatory diagram of outside line transfer of the key telephone device.

Conventionally, key telephone devices have been equipped with amplifiers that compensate for line losses in the forwarded and forwarded outside lines.

In FIG. 4, 1 is the main device of the button telephone device, 21-
23 is the local exchange, 41 is the caller, 4° is the responder, 11
1 to 114 are losses in the subscriber line, A1 to A are attenuation amounts, 121 is the central office line of the external line to be transferred, and 12□ is the central line of the external line to be transferred. When the caller 41 is transferred to an outside line to the responder 4□, the route shown by the solid line in FIG. 4 is used. That is, when the caller 41 calls the central office line 121 via the local exchange 22.21, the main device 1 of the key telephone device calls the central exchange 2.21. ．． The outside line transfer is performed by calling the responder 4□ via 23. Assuming that the amount of attenuation between the central exchanges is "0", the caller 4. A loss of the magnitude of attenuation A3 ・A1 ・A2 ・A4 is inserted into the conversation between the answerer 4 and the responder 4□.

Therefore, if the gains G11, G12, G21, and G22 of the amplifier 8.1.812.8□1.8□2 are made too large, the gain of the loop (a-b-c-d-e-f) becomes 1 or more. That is, G11・gl −G, 2・G2+・g2 ・G22>1
The circuit oscillates and makes a noise. In the conventional button telephone device, losses 11, . 11
When □ is large, the gains Gll, G12, G2+, G22
If the attenuation amounts A1 and A2 are made large enough to compensate for the noise, the gains G I I, G12, G2 □,
It was not possible to increase G2°, and the speech level was low.

Therefore, compared to the attenuation amounts A3 and A4 in a normal call route that is not an outside line transfer shown by the dotted line in FIG. 4, the attenuation amounts A and -A2 are extra inserted. As a result, the call level of an external line transfer call is lower than that of a normal call. In order to take this countermeasure, it is necessary to compensate for the gain of A1 and A2 by increasing the amount of attenuation inside the main unit 1 of the key telephone device.

Here, in FIG. 3, 6. ．． 62 is a /'% hybrid circuit, 811.812.8□1.822 is an amplifier that compensates for line loss during outside line transfer, G l l, G1□, G
21 and G22 are the gain thereof, and gl and g2 are the amount of input from the transmitter to the receiver in the hybrid circuit 60 and 62.

Hybrid circuit when transferring external lines 6. ．． Ideally, the signal should be transmitted in the direction of the solid arrow at 62, but due to changes in the termination conditions of the subscriber line, transmission occurs in the direction of the dotted arrow shown in FIG.

[Problem that the invention seeks to solve]

However, in such conventional key telephone devices, when the gain of the amplifier that compensates for the line loss of the transferred external line and the transferred external line is increased, the follow-up signal is transmitted from the transmitting to the receiving during 2-wire to 4-wire conversion to the line. Amplified by an amplifier that compensates for losses,
Because of the ringing, it is not possible to sufficiently compensate for the line loss between the transferred external line and the transferred external line, and the external line transferred call has the disadvantage that the call volume is lower than that of a normal phone call.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned drawbacks, and aims to provide a button telephone device that allows an outside line transfer call to be made at the same volume as a normal call.

[Means for solving problems]

The present invention includes a main device that connects a plurality of key telephones and a central office line corresponding to each of the key telephones, and the main device includes a hybrid circuit in which a two-line side input/output is connected to each central office line, and an outside line. An amplifier for compensating for office line line loss is connected to the 4-wire side input and output of the hybrid circuit on the transferred side and the transfer side during transfer, and an amplifier on the transferred side and an amplifier on the transfer side are connected during external line transfer. In a button telephone device including a voice exchange switch that transfers voice, when an external line is transferred, the circuit is inserted between the amplifiers on the transferred side and the transfer side and the voice exchange switch, and the circuit of the hybrid circuit on the transferred side and the transfer side is inserted. The present invention is characterized by comprising a noise prevention means for preventing noise caused by the input signal and the amplifiers on the transferred side and the transfer side.

Further, in the present invention, the above-mentioned ringing prevention means can be constituted by an audio switch circuit that inserts a loss into the receiving side when transmitting a call and into the transmitting side when receiving a call.

[Effect]

A noise prevention means inserted between the amplifiers on the transferred and forwarding sides and the voice exchange switch when transferring an external line, depending on the amount of circulation of the hybrid circuit on the transferred and forwarding sides and the amplifiers on the transferred and forwarding sides. Prevents noise from occurring.

Furthermore, the sound switch circuit can prevent the generation of noise.

With the above operations, you can transfer an outside call at the same volume as a normal call.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram of a button telephone device according to an embodiment of the present invention.

Multiple button telephone 3. ~3, and each button telephone 31~
3. The central office line corresponding to 12. ~12. ．． The main device 1 includes a hybrid circuit 6 , which has a two-line input/output connected to each station line 12 . ~6o, and amplifiers 8.1~8hl, 8□1~8n2 and Analog switches 913-9. ．． 3.9□5 to 9 ns, and a voice exchange switch 5 that connects the amplifier on the side to be transferred and the amplifier on the transfer side to transfer the voice at the time of external line transfer.

Here, the feature of the present invention is that when an external line is transferred, it is inserted between the amplifiers on the transferred side and the transferring side and the voice exchange switch 5, and and a noise prevention means for preventing noise from being generated by the amplifier on the transfer side.

Further, the ringing prevention means inserts a loss into the receiving side when transmitting a call and into the transmitting side when receiving a call. , consists of.

The operation of the button telephone device having such a configuration will be explained. FIG. 2 is a block diagram of a circuit for compensating line loss during outside line transfer according to the present invention.

In FIG. 2, the voice switch circuit 71 compares the receiving level from the local line 121 of the transferred external line and the local line 12° of the transferred external line, sets the gain of the attenuator with the larger level to "1", and attenuates the other. Reduce the gain of the device. Here, the attenuation amount all and the attenuation amount a12 of the attenuator do not become "1" at the same time, and the attenuation amount all·a12 can be made sufficiently small. Therefore, the loop (a-b-
In Fig. 2, the gain of c-d-e-f) is determined by the attenuation amount all・
By reducing a12, the gain G I can be adjusted to a value that sufficiently compensates for the attenuation amounts A1 and A2 in FIG.
Even when increasing l, CI2, G2+, and G22, Gllog1°G12°a12°G2I'g2°G22
°a<1, and no noise is generated.

FIG. 1 shows the circuit shown in FIG. 2 incorporated into a button telephone device. In FIG. 1, when making a call using the central office line 12I with the button telephone 3I, analog switches 911 to 9,5 and analog switch 9
Connect between 12 and 9.6 to form an audio switch circuit 7. And the operation is performed without going through the amplifier 811.8□2.

External line transfer to central line 12. and the central office line 122, all analog switches 911 to 9□6 are connected horizontally in FIG. and amplifier 8
．． Insert 1.812. In addition, the analog switch 92
1 to 923 and analog switches 922 to 924 are connected, analog switches 925 and 926 are connected in the horizontal direction of FIG. 1, and the audio switch circuit 7 is not inserted, but an amplifier 8°1.822 is inserted.

After that, the voice exchange switch 5 connects the central office line 121 and the central office line 12.
External line transfer is performed by connecting the communication path between 2 and 2.

〔Effect of the invention〕

As explained above, the present invention has the excellent effect of allowing an outside line transfer call to be made at the same volume as a normal call.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a button telephone device according to an embodiment of the present invention. FIG. 2 is a configuration diagram of a circuit for compensating for line loss during outside call transfer in the button telephone device of the present invention. FIG. 3 is a configuration diagram of a circuit for compensating for line loss during outside line transfer in a conventional button telephone device. FIG. 4 is an explanatory diagram of outside line transfer of the key telephone device. 1... Main device of button telephone device, 2□-23... Central office exchange, 31-3. ,...button telephone, 41...
- Caller, 42... Responder, 5... Voice exchange switch, 6, to 6o... Hybrid circuit, 71 to 71.
...Audio switch circuit, 8□1-8. ．． 1... Transmitting amplifier when transferring an external line, 8.2-8 n2... Receiving amplifier when transferring an external line, 9.1-9 h6... Analog switch, 10.1.11.2... Attenuator, 111-11
4...Loss of subscriber line, 12. ~12. ．． . . . Office line, A1-A4 . . . Loss of subscriber line 11. ~114
Attenuation amount, all, G12"' attenuator 1010.101
2 attenuation, Gll, G1□, G2+, G2゜... Gain of amplifier 8 II, 812.820.8□2, g+
, g2...No1 The amount of input from the transmission to the reception of the hybrid circuits 6□ and 62.

Claims (1)

[Claims] 1. A main device that connects a plurality of button telephones and a central office line corresponding to each button telephone, the main device being a hybrid system in which a two-line side input/output is connected to each central office line. circuit, an amplifier for central line line loss compensation connected to the 4-wire side input and output of the hybrid circuit on the transferred side and the transfer side during external line transfer, and an amplifier on the transferred side and an amplifier on the transfer side during external line transfer. In a button telephone device including a voice exchange switch that connects an external line and transfers voice, the voice exchange switch is inserted between the amplifiers of the transferred side and the transfer side and the voice exchange switch when transferring an outside line, and the voice exchange switch of the transferred side and the transfer side A button telephone device characterized by comprising a ringing prevention means for preventing ringing caused by the amount of rotation of the hybrid circuit and the amplifiers on the transferred side and the transfer side. 2. The button telephone device according to claim 1, wherein the ringing prevention means is constituted by a voice switch circuit which inserts a loss into the receiving side when transmitting a call and into the transmitting side when receiving a call.