KR930010277B1 - Automatic pulse/tone shifting device - Google Patents

Abstract

The circuit comprises a band pass filter section (1) for passing only frequency band signal inputted from the exchange among output signals of speech network, an envelope detecting section (2) for detecting envelopes by inputting the output signal of band pass filter section (1), a comparing section (3) for outputting high or low signal by comparing the output signal of envelope selecting section (2) with reference signal, a pulse/tone mode signal generating section (4) for selecting and generating pulse/tone mode signal inputted in to dialer (9) of telephone according to the output signal of comparing section (3).

Description

Pulse / tone automatic switching circuit of telephone

1 is a conventional circuit diagram.

2 is a circuit diagram of the present invention.

3 is an output waveform diagram of each part of FIG. 2;

* Explanation of symbols for main parts of the drawings

1 band pass filter 2 envelope detection unit

3: comparison unit 4: pulse / tone mode signal generation unit

5: hook switch 6, 6a: bridge diode

7 ringer 8 dial pulse switching unit

9: buzzer 10: speech network

11: speaker 12: microphone

13: dialer 14: dialer keypad

15: Pulse / Tone Manual Switch OP ₁ -OP ₄ : Operational Amplifier

R ₁ -R9: resistor C ₁ -C ₄ : capacitor,

D ₁ -D ₂ : Diodes FF ₁ -FF ₂ : D Flip Flop

NA ₁ -NA ₂ : endgate.

The present invention relates to a circuit for automatically switching between a pulse method and a tone method of a telephone, and in particular, when receiving a service such as control of a home appliance or a balance check of a bank through a telephone line in a mechanical exchange subscription line. After dialing, it automatically connects to tone method and after call, it automatically switches to the original pulse method.

Conventionally, when a user wants to use a telephone by switching between a pulse method and a tone method, the user has to operate a manual switching switch each time.

This will be described with reference to the attached FIG. 1 as follows.

1 is a conventional circuit diagram of a telephone, a hook switch 5, a bridge diode 6, 6a, a ringer 7, and a dial for telephone on and off. Pulse switching unit 8, buzzer 9, speech network 10, speaker 11, microphone 12, dialer 13, dial key It consists of a pad (Dial Key Pad) 14 and a pulse / tone manual changeover switch 15.

When the user first picks up the handset, the hook switch 5 is positioned at the terminal b, and if the receiver is placed, the terminal is placed at the terminal a. The buzzer 9 will be raised.

If the telephone user of the mechanical exchange subscription line wants to receive the various services described above, the pulse / tone manual transfer switch 15 is first set to a mechanical pulse terminal DP, and then dialed. 15) is converted into an electronic tone-type terminal (DTMF) to receive various telephone services such as home appliance control or bank balance check.

After the telephone service is provided, the user manually switches the switch 15 to the original pulse type terminal DP and uses the telephone.

According to the conventional configuration of the telephone as described above has the following disadvantages.

First, there is inconvenience that must be operated manually.

Second, after switching to the tone method to receive the telephone service, even if the telephone service is finished, if it is not converted to the original pulse method, crosstalk occurs when using the telephone.

Third, if it is applied to FAX (Facimile), it becomes inconvenient because the manual switching operation is intervened when communicating by continuously transmitting a tone after automatic dialing.

An object of the present invention is to provide a telephone circuit which automatically switches to a pulse / tone method when receiving a telephone service from a mechanical switchboard.

In order to achieve the above object, the present invention provides a telephone having a manual switching switch for pulse / tone switching, which is connected to an output side of a speech network of the telephone and inputs a signal from a switch to receive a dial tone signal and a busy tone. And a band pass filter for passing only a predetermined frequency band signal to a ring back tone signal, an envelope detector for detecting an envelope by inputting an output signal of the band pass filter, and an output of the envelope detector. A comparator which compares the signal with a reference signal and outputs a high or low signal, and is connected between the comparator and the manual changeover switch and the dialer of the telephone and according to the output signal of the comparator And a pulse / tone mode signal generator that is generated by selecting a pulse / tone mode signal input to the dialer.

This will be described below with reference to FIGS. 2 to 3.

2 is a circuit diagram showing an embodiment of the present invention, in a conventional telephone used in a mechanical pressure exchanger having a manual switching switch for pulse / tone switching, an operational amplifier OP ₁ and a resistor R ₁ -R ₉ ), the bandpass filter unit 1 consisting of capacitors (C ₁ -C ₂ ), operational amplifiers (OP _2- OP ₉ ), capacitors (3), diodes (D _1- D ₂ ), and resistors (R _4). Envelope detection unit (2) consisting of the operational amplifier (OP ₄ ) and the comparison unit (3) consisting of resistors (R ₅ , R ₇ ), and the first and second D flip flop (FF ₁ ) (FF ₂ ) And a pulse / tone mode signal generator 4 including first and second end gates NA ₁ and NA ₂ .

First, when a user picks up the handset for receiving a service, a dial tone signal sounds from the telephone office switchboard and a dial key is input at this time, the dial signal is received at the switchboard and a ringback tone or busy tone signal is heard.

Therefore, when the user lifts the hook switch 5 by lifting the handset while the user selects the pulse method to receive the telephone service, the hook switch 5 is positioned at the terminal b and the operation starts as a result.

At this time, the hook switch waveform is shown in FIG. 3A.

Subsequently, at the time t + 1 of FIG. 3, a dial tone signal (typically 400 Hz ± 15%) as shown in FIG. 3b is transmitted from the telephone exchange, which is output through the speaker 11 and input to the bandpass filter unit 1 at the same time. The bandpass filter unit 1 outputs a signal as shown in FIG. 3E, and the signal is output to the comparator 3 after being output as a signal as shown in FIG. 3 through the envelope detector 2.

The comparator 3 outputs a high signal such as 3g when the signal of FIG. 3f is input, and accordingly, the first and second D flip flops FF ₁ (FF ₂ ) of the pulse / tone mode signal generator 4. Each output terminal (Q) (Q) of) will output a high signal such as 3h, i degrees.

So far, the operation has corresponded to the time point t _{1 of} FIG. 3 and when the user enters the time point t ₂ and the user starts to transmit the dial pulse as shown in FIG. The tone signal is lost.

At this time, the output signal of the comparator 3 goes low as shown in Fig. 3g, and after completion of the dial pulse transmission as in time t ₉ , the ringback tone signal (typically 400Hz ± 15%) ), The first D flip flop FF ₁ outputs a low signal through the output terminal Q as shown in 3h, and the output terminal Q of the _second D flip flop FF ₂ is in the previous state as shown in FIG. 3i. High signal is output.

Subsequently, when the next ringback tone signal, such as 3d, is input at the time t ₄ , the output terminal Q of the _first D flip-flop FF ₁ becomes high again as shown in FIG. 3h, and the 2D flip-flop FF ₂ Output terminal (Q) is in a low state and the pulse / tone mode signal generator (4) irrespective of the input signal of the second and gate (NA ₂ ) selected by the terminal position of the pulse / tone manual changeover switch (15). ) Makes the pulse / tone mode signal input to the dialer 13 low, thereby fixing the tone mode in the DTMF mode.

At this time, since the output terminal Q of the 2D flip flop FF ₂ goes low to block the input of the clock signal of the 1D flip flop FF ₁ , the tone type is independent of the input of another ring back tone signal. The fixation of the DTMF mode is maintained.

Then, when the user enters the time point t ₅ and releases the handset after receiving all the telephone service, the hook switch 5 is positioned at the terminal a to go low as shown in FIG. 3a, and the operation of the circuit is stopped.

Here, the present invention can be easily applied to a FAX in which a circuit for detecting dial tones, ring back tones and busy tones is incorporated.

As described above, according to the present invention, there is an effect that the tone signal can be automatically sent out after dialing without manually operating the manual changeover switch 15 when using the pulse type telephone.

Claims (2)

In a telephone equipped with a manual switch (15) and a dialer (13), a hook switch (5), a speech network (10), etc. for pulse / tone switching, speech is connected to the output of the speech network (10) of the telephone. A band pass filter unit 1 for passing only a frequency band signal input from the exchange among the network output signals, an envelope detector 2 for detecting an envelope by inputting an output signal of the band pass filter unit 1, and the envelope detector A comparator 3 for outputting a signal in a high or low state by comparing the output signal of (2) with a reference signal, and between the comparator 3 and the manual changeover switch 15 and the dialer 9 of the telephone. And a pulse / tone mode signal generator (4) which is connected and generated by selecting a pulse / tone mode signal input to the dialer (9) of the telephone according to the output signal of the comparison section (3). Pulse / tone of the telephone Type automatic switching circuit. The pulse and tone mode signal generator (4) according to claim 1, wherein the output signal of the comparator (3) is the first and gate (NA ₁ ). A first AND gate first 1D flip-flop (FF ₁₎ and the 1D of the output signal of the flip-flop (FF ₁₎ to the clock signal and the inverter output signal first to the output signal of the (NA ₁₎ to the clock signal The 2D flip flop FF ₂ , which is the type force signal of the AND gate NA ₁ , the inverter output signal of the 2D flip flop FF ₂ , and the output signal of the manual switch 15 for pulse / tone switching. A pulse / tone type automatic switching circuit of a telephone, characterized in that it comprises two input signals and a second and gate (NA ₂ ) outputting the output signal to the dialer (9) of the telephone as a pulse / tone mode signal.