JPS6178251A - Device for preventing resonance - Google Patents

Abstract

PURPOSE:To prevent malfunction of a ringing device of a telephone call tone transmission circuit by a dial pulse by turning on/off a switching circuit through the detection of the presence of an incoming signal. CONSTITUTION:When an incoming signal exists, a square wave is outputted from two terminals of a telephone tone transmission circuit 4, a voltage of a capacitor C2 is E1, a switching circuit 2 is set, the square wave is fed to a ring device 3 and a call tone is generated. When a dial pulse is inputted, a voltage across the capacitor C2 is E2, the switching circuit 2 is reset, and even if a square wave is outputted from the two terminals of the telephone tone transmission circuit 4, no square wave is fed to the ring device 2 and no telephone call tone is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a technology for a dial tone generation circuit connected to a telephone line.

[Background technology]

When connecting a telephone to a public telephone line, one phone per line,
A telephone ringing tone generating circuit is required that notifies the incoming call by generating a ringing tone. FIG. 1 shows a connection diagram of the telephone ringing tone generating circuit 3. W-phones are connected in parallel to the telephone line.

The telephone ringing tone generating circuit λ at this time is as shown in FIG. The LL and L proverbs in Figure 2 are connected to the telephone port IsK.
Ru. The waveforms of each part of the telephone tone sending circuit section d are shown in FIG. L
When there is a telephone incoming signal as shown in FIG. 4 (1) on L Lm, the DC component is cut by the capacitor of CI, and the signal A as shown in FIG. input to the terminal. This input voltage is rectified by the telephone tone sending circuit section d, and is charged in the capacitor C1 as a smoothed waveform B as shown in FIG. Then, when the voltage of CI becomes a certain constant voltage ■1 or more, the telephone tone ringing sending circuit lFi,
A ringing device 1c outputs a square wave Cf as shown in Figure 3 from the No. 2 terminal.
7Il, the ringing device e generates a telephone ring tone.

Also, when there is no incoming signal, capacitor C! Kage v1. At the beginning, if the voltage drops below a certain level, there will be no output from terminal 2. However, in the case of the configuration shown in FIG. 1, when making a call from the telephone, it is difficult to lift the handset and turn the dial.

So, the L+L 輯) waveform when the dial is turned all the way is the 4th waveform.
This is shown in Figure (2).

At this time, the waveform in Figure 4 (2) is input to the L+ Ia terminal in Figure 2, and is also input to the 1.8 terminal of the ILR speech output path section d, which is internally rectified and charges the C proverb. ,do. When the charged voltage reaches a certain voltage (1) or higher, a square wave C is output from the second terminal, and a sound is generated from the ringing device e.

Therefore, there is a problem in that even if there is no telephone ringing tone, a dial pulse telephone ringing tone is generated.

[Purpose of the invention]

This invention was made by paying attention to the above-mentioned circumstances, and its purpose is to
To provide a resonance prevention device which prevents a telephone ring tone generation circuit from generating a telephone ring tone.

[Disclosure of the invention]

The present invention will be described below based on FIGS. 5 to 6 (2) showing one embodiment. The entire circuit diagram of the present invention is shown in FIG. A voltage detection circuit 1 is provided on the Φ side of the smoothing capacitor,
The ringing device 8 is connected to the telephone tone sending circuit 4 by a switching circuit section 2 controlled by a detection circuit 1vC.

Next, the operation of this circuit will be explained.

L*[The voltage of Cm when there is an incoming signal is El.

If Em is the voltage of Ca when the telephone connected to L+Ia turns the dial, then El>El is always satisfied due to the difference in signals generated between L and L. Therefore, the voltage E1 at which the voltage detection circuit operates is set as El)Es)Et, and IE
The switching circuit 2 is turned on when the voltage is I, and is turned off when the voltage is El.

Here, when there is an incoming call signal and a square wave is output from the two terminals of the telephone sound output path 4, (the voltage of a is El and the switching circuit 2 is turned on 7, the square wave is output from the ringing device. 8 to generate a ring tone.Also, when the dial pulse inputs the voltage of C2, the voltage of C2 is EI, and the switching circuit g is OFF.
Since a square wave is output from the two terminals of the main phone, no square wave is applied to the ringing device 8, and no telephone ringing tone is generated. Therefore, malfunctions such as telephone ringing due to the dial palace do not occur.4 In Fig. 6 (1), a Zener diode is used for the voltage and voltage detection circuit 1, a switching circuit 2K) is used, and a transistor is used, and the ringing device F#s is an electromagnetic type. It uses speakers. Zener voltage E$ of Zener diode is El)
El) By setting Et, it is possible to prevent sound generation (resonance) caused by turning the dial /L/. Also, the 6th
In FIG. 2, a piezoelectric speaker whose capacitance is isometrically equal to that of the ringing device 8 is used, and the circuit is such that a diode DI is connected in parallel to a transistor TRI as shown in the figure. In the case of a piezoelectric speaker, when the square wave at terminal 2 of the telephone sound output path 4 becomes 4, voltage is applied to the piezoelectric speaker, but when it becomes 1, the polarity of the transistor is reversed, so the piezoelectric There is no loop through which the speaker charge is discharged. Therefore, the diodes DI are connected in parallel to form a discharge loop.

In addition to the voltage detection circuit using a single Zener diode, there are other methods such as resistance division, and it is also possible to use a thyristor or a relay in the switching circuit 2.

[Effects of the Invention] As explained above, in this invention, the presence or absence of an incoming @ signal is detected by the voltage detection circuit 1 and the switching circuit section 2f is turned on/off. The ringing device of the telephone ringing tone sending circuit 4 +i! A resonance prevention device is obtained which completely prevents the generation of telephone ringing tones in the non-arrival state when the /8 is projected.

[Brief explanation of drawings]

1 to 4 (2) show conventional example 4, and FIG.
1 is a circuit diagram, 3 is a waveform diagram, 1 is a waveform diagram, and 4 is a circuit diagram (1).
), FIG. 4(2) is a waveform diagram. FIG. 5 to FIG. 6 (2) show a first embodiment of this invention,
5, 6(1), and 6(2) each have one circuit. 1: Voltage detection circuit, 2 switching circuit, 8: Ringing device, 4: 1) Speech sound transmission circuit.

Claims (2)

[Claims] (1) Regarding the telephone ring generation circuit that is connected to a telephone line and sends out a telephone ring tone when an incoming telephone signal is input from the telephone line, when an incoming telephone signal is input from the telephone line, the circuit rectifies the above-mentioned telephone incoming signal. A telephone tone sending circuit unit is provided which outputs a square wave for smoothing the power supply with a capacitor and generating a telephone ring tone, and a voltage detection circuit for detecting the capacitor voltage is connected to the capacitor, and the voltage detection circuit is connected to the voltage detection circuit. A telephone ringing tone generating circuit comprising a controlled switching circuit section, and preventing application of a square wave output from the telephone tone sending circuit section for generating a telephone ringing tone to a ringing device by a switching operation of the switching circuit section. . (2) The resonance prevention device according to claim 1, wherein the voltage detection circuit is a Zener diode.