KR950004456Y1 - Ringing signal detecting circuit - Google Patents

Abstract

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Description

Ring signal detection circuit of telephone

1 is a circuit diagram of a ring signal detection signal in the related art.

2 is a circuit diagram of a ring signal detection circuit according to the present invention.

* Explanation of symbols for main parts of the drawings

10: ringer generator 20: transformer

30: speaker 40: switching unit

50: smoothing circuit

The present invention relates to a telephone, and more particularly to a circuit for detecting a ring signal.

In general, a multifunctional telephone, a cordless telephone, etc. detects a ring signal input from a trunk line and notifies the control means of the telephone to perform a necessary service according to an incoming call.

As described above, a conventional ring signal detection circuit for detecting a ring signal includes a ringer integrated circuit (IC1), a capacitor (C1-C4), and a resistor (R1-R2) as shown in FIG. Ringer generation unit 10 for generating a ringer signal in response to the input of the ring signal from the trunk lines (T, R), and by driving the speaker 30 which is a voice conversion means by the ringer signal (bell) It is composed of a transformer 20 for generating sound, a photo coupler PC1, a resistor R3-R4, and a capacitor C5. The ringer IC (IC1) uses a general-purpose telephone tone ringer IC chip, and for example, a phone tone ringer IC chip of KA2418 of Samsung Semiconductor Korea or MC34012 series of Motorola of the United States of America may be used.

Referring to FIG. 1, a conventional ring signal detection operation is as follows. When the ring signal arrives from the trunk lines T and R and is applied to the input terminals AC1 and AC2 of the ringer IC IC1 through the capacitor C1 and the resistor R1, the ringer IC IC1 has a set frequency. The ringer signal is oscillated and output through the output terminal R0. Typically, the ring signal has a frequency of 60 Hz and the ringer signal has a frequency of several hundred Hz to several KHz. The ringer signal output from the ringer IC IC1 is applied to the speaker 30 through the capacitor C4 and the transformer 20 so that a ring tone sounds through the speaker 30. In addition, the output ringer signal of the ringer IC IC1 is applied to the photo coupler PC1 through the resistor R3 to switch the port coupler PC1. Accordingly, the photo coupler PC1 is " on " during the positive period of the ringer signal in synchronization with the period of the ringer signal and " off " during the negative period so that the power supply voltage Vcc and the ground level are alternated. Generates a square wave signal that is repeated repeatedly. The generated square wave signal is smoothed by a smoothing circuit composed of a resistor R4 and a capacitor C5 and then applied to a control means (not shown) of the telephone as a ring detection signal DET. At this time, the ring detection signal DET becomes logic "high" when no ring signal is input from the trunk lines T and R, and becomes logic "low" when the ring signal is input.

Therefore, the control means of the telephone detects the input of the ring signal by the ring detection signal DET generated as described above to perform the necessary service according to the incoming call.

In the conventional ring signal detection circuit as described above, it is difficult to design a circuit on a printed circuit board (PCB) by using a photo coupler for insulation between the ringer generating means and the control means of the telephone. there was.

Therefore, an object of the present invention is to provide a ring signal detection circuit that can facilitate the design of the circuit in the telephone and reduce the cost.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a circuit diagram of an embodiment of a ring detection circuit according to the present invention, in which the ringer generator 10, the transformer 20, and the speaker 30 are the same as in the above-mentioned conventional FIG. The same is true. Unlike the related art, the speaker 40 is switched by an output signal of the transformer 20 to generate a square wave signal synchronized with a cycle of a ringer signal, without using a photo coupler, at the output terminal of the transformer 20. A parallel circuit 50 is connected to the output terminal of the switching section 40, connected in parallel to the switching section 40, and the smoothing circuit 50 for smoothing the square wave signal of the switching section 40 and outputting it as a ring detection signal DET. The switching unit 40 is divided by two resistors R11-R12, which are divided means for dividing a constant output signal of the transformer 20, and the divided signal, and the square wave signal synchronized with the period of the ringer signal. Is composed of a transistor Q11 which is a switching element that generates. The smooth signal 50 includes a resistor R13 and a capacitor C11.

Hereinafter, a specific operation example in FIG. 2 according to the present invention will be described in detail.

First, when the ring signal arrives from the trunk lines T and R, the ringer signal is output from the ringer IC IC1 and applied to the speaker 30 through the capacitor C4 and the transformer 20, thereby ringing through the speaker 30. This ringing is the same as before.

At this time, the ringer signal output from the transformer 20 to drive the speaker 30 is also applied to the resistors R11 to R12 to be divided to operate the transistor Q11. As a result, the transistor Q11 is switched in synchronization with the period of the ringer signal to output a square wave signal. In other words, the transistor Q11 is " on " during the defining period of the ringer signal and " off " during the negative period, thereby generating a square wave signal in which the power supply voltage Vcc and the ground level are alternately repeated. The square wave signal output from the transistor Q11 is smoothed by charge / discharge according to the RC time constant of the resistor R13 and the capacitor C11 in the smoothing circuit 50, and then the control means of the telephone as the ring detection signal DET. (Not shown). Therefore, the ring detection signal DET becomes logic "high" when no ring signal is input from the trunk lines T and R, and becomes logic "low" when the ring signal is input. Here, the transformer 20 is insulated between the ringer IC IC1 and the control means of the telephone.

Therefore, the control means of the telephone detects the input of the ring signal by the ring detection signal DET generated as described above to perform the necessary service according to the incoming call.

On the other hand, while many details are described in detail in the above description, they should be interpreted as an example of a preferred embodiment rather than limiting the scope of the invention.

As described above, the present invention facilitates the design of the circuit and reduces the cost by detecting a ring signal without using a photo coupler.

Claims (1)

A ring signal detecting circuit of a telephone having ringer generating means for generating a ringer signal in response to an input of a ring signal from a trunk line, and a transformer for driving a voice converting means by the ringer signal, the ring signal detecting circuit of the telephone comprising: A voltage divider which is connected in parallel with the voice conversion means and divides the output signal of the transformer by a predetermined voltage, a transistor which is switched by the divided signal to generate a square wave signal synchronized with the period of the ringer signal, and is generated from the transistor. And a smoothing means for smoothing the square wave signal and outputting it as a ring detection signal.