JPS59208972A - 4-wire telephone set - Google Patents

Abstract

PURPOSE:To transmit information without deterioration even if a 4-wire telephone set is inserted to a line over multi-stages by providing the 1st switching circuit switching and outputting an input and an output of the 1st D/A and A/D converter mutually and the 2nd switching circuit switching and outputting an input and an output of the 2nd D/A and A/D converter mutually. CONSTITUTION:A contact is provided, which changes over an input signal and an output signal of an A/D converter 6 and is connected to an output terminal 2. In using only a switching circuit 4 to pass through a telephone signal in this 4-wire telephone set, an input signal itself is transmitted to the output terminal 2 by connecting the contact of the switching circuit 4 to the position (a). Then, in transmitting a signal from this 4-wire telephone set, the same circuit constitution as a conventional circuit is obtained by connecting the contact of the switching circuit 4 to the position (b), and a transmission signal is transmitted from the output terminal 2 to a 4-wire telephone set of the next stage via the contact (b) after passing through the A/D converter 6 from an internal circuit 3. That is, the output signal is switched to either the input signal or the signal passing through the circuit in the telephone set by means of the connecting method of the contacts of the switching circuit 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a four-wire telephone that uses digital signals as an interface.

Conventionally, this type of four-wire telephone has been constructed as shown in FIG. That is, the digital signal input to input terminal 1 is D
The signal is converted into an analog signal by the A/A converter 5, passes through the internal circuit 3, is converted back to a digital signal by the A/D converter 6, and is sent from the output terminal 2 to the next four-wire telephone.

As shown in FIG. 2, the above-mentioned four-wire telephones 10, 11 and 12 are usually connected in multiple stages. In a line like this,
Since the D/A converter and A/D converter of each 4-wire telephone are connected in multiple stages, the number of stages of the 4-wire telephone is limited in order to maintain line quality.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional drawbacks and to provide a four-wire telephone that can transmit information without deterioration even if four-wire telephones are inserted into a line in multiple stages.

The four-wire telephone of the present invention includes first and second I/A converters for converting manually input first and second digital signals into analog signals, respectively, and an internal circuit for inputting seven digital signals. a circuit, and first and second A/D converters that convert output sounds corresponding to the respective human power into digital signals, wherein the first D/A converter's human power and the A first switching circuit that switches the output of the first A/D converter and outputs the blade, and a second switching circuit that switches and outputs the manual power of the second D/A converter and the output of the second A/D converter. C having a switching circuit.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 3 is a circuit diagram showing an example of the present invention.

In this actual example, the signal to the blade terminal 2 has a contact point that can be switched to either a large power signal or an output signal of the A/I converter 6. When this 4-wire telephone is used only to pass telephone signals, by connecting the contact of the switching circuit 4 to the a side, a human input signal is sent to the 1 output terminal 2. Even in this case, the receiving circuit of this device is still operating, so it is possible to receive telephone signals as before.

Next, when sending a signal from this 4-wire telephone, by connecting the contact of the switching circuit 4 to the b side, the circuit configuration is the same as before, and the transmission signal is sent from the internal circuit 3 via the A/D converter 6. The signal is sent from the output terminal 2 to the next four-wire telephone via the rear contact point. That is, depending on the connection method of the contacts of the switching circuit 4, the output signal can be switched to either a human input signal or a signal via the circuit inside the telephone.

Figure 4 shows an example in which main line telephones are connected in multiple stages.1-8 In this figure, the 4-wire telephones 21 and 23 perform transmission and reception, and the 4-wire telephone 22 operates only when receiving data.
In this case, the switching circuit of each 4-wire telephone is operated so that the signal from the telephone 21 is passed through as is.

When the telephone 22 receives the signal, it can be transmitted and received in the same way as the telephones 21 and 23 by switching the connection of the Deba signal.

As is clear from the above explanation, if a 4-wire telephone having the Deba signal switching circuit of the present invention is used, there is no restriction on the number of stages caused by deterioration in the quality of telephone signals when 4-wire telephones are connected in multiple stages. becomes.

The present invention has the effect of completely eliminating the limit on the number of stages when connecting telephones in multiple stages, which is affected by the circuitry within the four-wire telephone in a digital line, and also eliminating signal deterioration due to the insertion of telephones.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional 4-way telephone; Fig. 2 is a connection diagram showing a multi-stage connection of the telephone shown in Fig. 1; Fig. 3 is a block diagram showing an example of the present invention; The figure is a connection diagram showing an example of a case where the four-wire telephone set of FIG. 3 is connected in multiple stages. 1...Manual terminal, 2...Group output terminal, 3...Internal circuit, 4...Switching circuit, 5...
・D/A converter, 6------A/D converter p
, 10, 11, 12°21, 22. 23...
・4R type telephone. ,′・,〜・8 Agent 9P Physician Uchihara Wave =””,,! '
, 'ni/

Claims (1)

[Claims] First and second D/A converters that convert input first and second digital signals into analog signals, internal circuits that manually generate the blades, and blades that correspond to the respective large forces. In a four-wire telephone having first and second A/D converters each converting into a digital signal, the output of the first D/A converter and the first A/I converter is switched. a first switching circuit that outputs, and the second D/
A four-wire telephone set, comprising: a second switching circuit that switches and outputs the input of the A converter and the output of the second A/D converter.