JPS6347185B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a calling circuit for a digital telephone that transmits and receives voice calls and control signals for making and receiving calls to and from an exchange in the form of digital signals.

With conventional analog telephones, when making a call,
A large-amplitude AC ringing signal sent from the exchange makes the bell or tone ringer of the telephone ring circuit ring, and when the handset is disconnected, a large-amplitude AC howler signal sent from the exchange causes the telephone receiver to ring directly. I'm letting you do it. For this reason, it was necessary to design the telephone circuit to have a high withstand voltage, which had the disadvantage that it was not suitable for making the telephone circuit into an LSI. Furthermore, the calling circuits of digital telephones that have been proposed so far have a configuration in which the digitized calling signal and howler signal sent from the exchange are converted into analog signals by a D/A converter, and then amplified to the required volume. This has the disadvantage that the circuit becomes complicated. Furthermore, when dialing,
It does not use a two-frequency audible sound signal like a conventional analog telephone (push phone) as a selection signal,
The dial character code corresponding to the push button is sent. For this reason, the selection signal cannot be used as a dial confirmation sound as in the past,
Another drawback was that it required a separate oscillator to generate the dial confirmation sound, making the circuit complex.

The present invention has been made in order to eliminate the drawbacks of the prior art as described above, and therefore, an object of the present invention is to provide a digital telephone that eliminates the need for a high-voltage design of the circuit and allows for the simplification of the circuit. The purpose is to provide a calling circuit.

The main point of the configuration of this invention is to provide a tone generator inside the telephone, decode the calling code and howler code sent from the exchange, and use the signal generated by this decoding as a trigger to generate the corresponding tone using the same tone generator. When dialing, a similar tone generator is used to generate a confirmation sound triggered by the press code generated when the push button is pressed, and the same sounding body is sounded. By doing so, it is possible to eliminate the need for high-voltage design of the telephone circuit and to simplify the circuit.

The figure is a block diagram showing one embodiment of the present invention, in which 1 and 2 are line terminals of a digital telephone, 3
is the digital telephone circuit excluding the calling circuit and the power supply circuit (hereinafter referred to as the digital telephone circuit), 4 is the power supply circuit, 5 is the signal decoder, and 6 is the oscillation frequency F ₁
7 is an oscillator with oscillation frequency F ₂ , 8 is two frequencies F ₁ and F ₂ generated by oscillators 6 and 7
These 6 to 8 oscillators are _collectively called a tone generator. 9 is an intermittent oscillator for making the ringer ring for 1 second and then pause for 2 seconds; 10 is a push button;
11 is a dial character generator; 12 is a logic circuit that uses the oscillators 6 to 9 to assemble a ringing sound, a howler sound, and a confirmation sound, and controls whether to ring the sounding body or the telephone; 13, an electronic switch; 14 is a receiver amplifier, 15 is a receiver, 16
is an amplifier, 17 is a sounding body, A is a ringing tone trigger signal path, B is a howler sound trigger signal path, and C is a confirmation sound trigger signal path, and the levels of A, B, and C are 1 at the same time.
It is never set to “HIGH”.

The operating principle of the embodiment shown in FIG. 1 will be explained below.
When making a call, when a call code is sent from the exchange, it is input to the signal decoder 5 via the circuit 3. In the signal decoder 5, when the calling code is input, the level of the ringing tone trigger signal path A is set to "HIGH". This “HIGH” signal causes the logic circuit 12 to
As a ring tone, the output F ₁ of the oscillator 6 and the output F ₂ of the oscillator 7 are alternated at the frequency F ₃ of the oscillator 8, and the oscillator 9 rings for 1 second and pauses for 2 seconds, and the electronic switch 13, which is closed when on-hook, is activated. Thereafter, the signal is amplified by the amplifier 16 and a ringing tone is generated from the sounding body 17. The ringing tone is stopped by opening the electronic switch 13 during off-hook.

When the telephone receiver is disconnected, when the howler code is sent from the exchange, it is input to the signal decoder 5 through the circuit 3, as in the case of a call. When the howler code is input, the signal decoder 5 sets the level of the howler sound trigger signal path B to "HIGH". With this "HIGH" signal, the logic circuit 12 outputs the output F ₁ of the oscillator 6 and the output F 2 of the oscillator ₇ as a howler sound.
A signal that is alternated at the frequency _F3 of the oscillator 8 is output continuously. At the same time, the level of the howler sound trigger signal path B set to "HIGH" closes the electronic switch 13 which is open due to the off-hook, and the howler sound is amplified by the amplifier 16 via the electronic switch 13 and generated from the sounding element 17. .

When dialing, when the push button 10 is pressed, the dial character generator 11 sends the corresponding dial character to the digital telephone circuit 3, and at the same time sets the level of the confirmation sound trigger signal path C to "HIGH". The dial character sent to circuit 3 is converted into a form suitable for line transmission and sent to the exchange, and at the same time a confirmation sound control signal C
Therefore, while the push button is pressed, the logic circuit 12 outputs only the output F ₁ of the oscillator 6 or the output F ₂ of the oscillator 7 to the receiver 1 as a dial confirmation tone.
Output to 5.

In this embodiment, as the ring tone and howler tone,
We have shown an example of alternating sounds at two frequencies using oscillators 6, 7, and 8, but depending on your preference, it is also possible to synthesize sound with more oscillators or generate sound with a single oscillator. It is.

As explained above, according to the present invention, as a calling circuit of a digital telephone, a digital code signal sent from an exchange to the telephone is decoded, and a trigger signal generated by this decoding is used to trigger one tone provided inside the telephone. Since the generator can also be used to generate the ringing tone, howler tone, and confirmation tone, there is no need to use large amplitude AC signals when making a call or disconnecting the handset, and the high voltage withstand design of the telephone is no longer required. It is advantageous for making the circuit into an LSI, and it also has the advantage of simplifying the circuit by using it as a tone generator as well.

[Brief explanation of drawings]

The figure is a block diagram showing one embodiment of the present invention. Explanation of symbols, 1, 2... Digital telephone line terminal, 3... Digital telephone circuit, 4... Power supply circuit, 5... Signal decoder, 6... Oscillation frequency F ₁
oscillator, 7... oscillator with oscillation frequency F ₂ , 8...
...oscillator with oscillation frequency _F3 , 9...intermittent oscillator,
DESCRIPTION OF SYMBOLS 10...Push button, 11...Dial character generator, 12...Logic circuit, 13...Electronic switch, 14...Telephone amplifier, 15...Telephone receiver, 16...Amplifier, 17...Sounding body, A... ...Ring tone trigger signal path, B...Howler sound trigger signal path, C...Confirmation tone trigger signal path.

Claims (1)

[Scope of Claims] 1. In a calling circuit of a digital telephone that sends and receives voice calls and control signals to and from an exchange in the form of digital signals, a signal decoder that decodes control signals from the exchange and a code signal corresponding to the operation of a push button are provided. A dial character generating section that generates a dial character, a tone generator, and an output signal from the signal decoder are used as a trigger to control the operation of the tone generator to control generation of a ringing tone or howler tone, 1. A calling circuit for a digital telephone, comprising: a logic circuit that controls the operation of the tone generator using a code signal from a tone generator as a trigger to control generation of a dial confirmation tone.