JP2001045110A - Bell signal detector for telephone set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate dispersion in a photocoupler, to enhance accuracy of receiving a BELL signal through detection of a frequency, to decrease the space and the cost. SOLUTION: A BELL signal detection circuit 7 consists of a loop circuit consisting of capacitors C2, C3 and resistors R2-R4 and a transistor(TR) 7a that is driven by a signal divided by an impedance depending on the capacitors and the resistors so as to eliminate dispersion in the sensitivity by a photocoupler. Since a signal is received at a high impedance, the time constant can be decreased to be negligibly small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a device for detecting a BELL signal for operating a ringer circuit in a telephone device connected to a telephone line.

[0002]

2. Description of the Related Art Generally, a telephone device is connected to a telephone line and has a circuit for detecting a BELL signal from the line.

Hereinafter, a conventional BELL signal detecting device of a telephone device will be described with reference to the drawings.

FIG. 2 shows BELL in a conventional telephone device.
FIG. 2 is a configuration diagram of a signal detection device. As shown, a BELL signal detection device includes a diode bridge 2 for rectifying the polarity of a telephone line 1 and a speech network circuit 3 for converting a signal from the telephone line 1 from two cores to four cores. A ringer circuit 4 for outputting a ring tone upon receiving a BELL signal, a control circuit 5 for outputting a signal to the ringer circuit 4, a capacitor C1 using a high withstand voltage film, a resistor R1, and a photocoupler 6a. B transmits the BELL signal received by the resistor R1 to the control circuit 5 via the photocoupler 6a.
An ELL signal detection circuit 6 is provided.

[0005] The operation of the conventional BELL signal detecting device in the telephone device configured as described above will be described below.

[0006] A telephone exchange 1 (not shown) connects B to telephone line 1.
When the ELL signal is input, an AC signal is generated at both ends of the telephone line 1. Thereby, the capacitor C1, the resistor R1, and the one of the photocoupler 6a in the BELL signal detection circuit 6 are connected.
An AC signal is similarly generated at both ends of the next series.
Then, the signal converted by the time constant by the capacitor C1 and the resistor R1 flows through the primary side of the photocoupler 6a, thereby turning on the transistor on the secondary side of the photocoupler 6a.
Let it. Then, the control circuit 5 detects that the BELL signal has entered by detecting the LOW signal, and outputs a control signal to the ringer circuit 4. The ringer circuit 4 receiving this signal emits a sound and notifies the outside that the BELL signal has arrived.

[0007]

However, in the above-described conventional BELL signal detecting device in a telephone device, the B
Since the time constant of CR in the ELL signal detection circuit 6 was large, the frequency of the BELL signal could not be detected. Also,
Since the photocoupler 6a is used, the variation in sensitivity is large, and it takes time to set. In order to further operate the photocoupler 6a, a capacitor C1, a resistor R1
Must be reduced, and a large-sized component must be used in order to obtain a withstand voltage.

For example, when the BELL signal is ON 0.4s,
Assuming that a signal of 20 Hz is input at a cycle of OFF 0.2 s, ON 0.4 s, and OFF 2.0 s, the conventional circuit cannot detect the frequency of 20 Hz, and the ON0.
The signal of 4 s could be detected as a signal only in one lump. For this reason, 10Hz or 100H outside the BELL signal frequency
Even if the signal of z arrives, it is detected as a BELL signal and malfunctions. In addition, ON and O
The circuit cannot detect a break between N and can detect only a continuous signal.

In the conventional BELL signal detecting device, a photocoupler is selected and used in order to reduce variation, an electrolytic capacitor is added to a signal line of a control circuit in order to prevent BELL resonance, , Hitting occurs due to the use of large capacity capacitors,
It has been a factor of cost increase such as defeating processing, bond lock, and retrofitting. In addition, the size of the high withstand voltage capacitor and the photocoupler has been a constraint on the mechanical design of a printed wiring board and a cabinet.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is intended to eliminate the variation of a photocoupler, to improve the accuracy of receiving a BELL signal by frequency detection, and to reduce the space and cost of a telephone device.
It is an object to provide an ELL signal detection device.

[0011]

In order to achieve this object, the present invention provides a BELL signal detection circuit comprising a loop circuit of a capacitor and a resistor, and a transistor driven by a signal whose impedance is divided by the capacitor and the resistor. This is a BELL signal detecting device of the telephone device.

According to the present invention, it is possible to eliminate the variation caused by the photocoupler as in the prior art, and to receive the signal at the HIGH impedance, so that the time constant can be reduced to a negligible level. As a result, the frequency can be seen. Further, the components can be made smaller, and as a result, a circuit with lower cost can be realized.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises a BELL signal detection circuit for operating a ringer circuit via a control circuit, wherein the BELL signal detection circuit is a loop circuit of a capacitor and a resistor. And a BELL signal detection device including a transistor driven by a signal whose impedance has been divided by the capacitor and the resistor, that is, a conventional photocoupler in the BELL signal detection circuit is changed to a transistor to output a signal with a high impedance. As a result, there is no variation, and the time constant can be reduced to a negligible level. As a result, the frequency can be seen and the components can be further reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a configuration diagram of a BELL signal detecting device in a telephone apparatus according to Embodiment 1 of the present invention. In FIG. 1, the same components as those in the conventional example are denoted by the same reference numerals as those in the conventional example.

As shown in FIG. 1, the BELL signal detecting device in the telephone device according to the first embodiment includes a diode bridge 2 for rectifying the polarity of the telephone line 1, and a signal from the telephone line 1 from two cores to four cores. Speech network circuit 3 for conversion, capacitors C2 and C3 and resistors R2, R3 and R
4 loop circuit, the capacitors C2 and C3 and the resistor R
2, a BELL signal detection circuit 7 including a transistor 7a driven by a signal whose impedance has been divided by R3, R4, a control circuit 5 for outputting a control signal based on a signal from the BELL signal detection circuit 7, It is provided with a ringer circuit 4 that emits a ring tone when a control signal of the circuit 5 is received.

The operation of the BELL signal detecting device in the telephone device according to the first embodiment configured as described above will be described below.

B from the telephone exchange (not shown) to the telephone line 1
When the ELL signal is input, an AC signal is generated at both ends of the telephone line 1. As a result, an AC signal is similarly generated in the loop circuit of the capacitors C2 and C3 and the resistors R2, R3 and R4 in the BELL signal detection circuit 7. Therefore, a signal whose impedance is divided by these capacitors and resistors drives the transistor 7a. Then, the control circuit 5 detects that the BELL signal has entered by detecting the LOW signal, and outputs a control signal to the ringer circuit 4. The ringer circuit 4 which receives the signal emits a ring tone and B
Inform the outside that the ELL signal has arrived.

The BELL signal detection device according to the first embodiment has a configuration in which the photocoupler in the conventional BELL detection circuit is changed to a transistor as described above to receive a signal with a HIGH impedance, and the variation in the case of the photocoupler is reduced. Since it can be eliminated and the signal is received at the HIGH impedance, the time constant can be reduced to a negligible level, and as a result, the frequency can be seen. Further, the size of the components can be reduced, and the circuit can be manufactured at low cost.

In the first embodiment, a telephone having a ringer circuit as a base unit has been described. However, a telephone having a cordless handset or a cordless telephone having a plurality of subunits, A signal obtained by converting an incoming signal into digital data, such as a modem, may be used. If the BELL signal is detected and the signal can be used, such as a modem incoming signal for personal computer communication, the same effect can be obtained.

[0021]

As is apparent from the above description, the BELL signal detecting device in the telephone device of the present invention is a BELL signal detecting device.
The time constant of CR can be made negligibly smaller than that of the conventional circuit by making the impedance of the capacitor and the resistor for receiving signals several hundred kilometers to several mega. Since the withstand voltage is increased, the capacitor and the resistor of the chip can be used. Therefore, the waveform of the BELL signal can be detected, the frequency of the signal can be detected, and the detection accuracy can be improved by several steps. Further, since the components of the chip can be used, it is possible to greatly reduce the space and cost.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a BELL signal detection device of a telephone device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional BELL signal detection device of a telephone device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Telephone line 2 Diode bridge 3 Speech network 4 Ringer circuit 5 Control circuit 7 BELL signal detection circuit 7a Transistor C1, C2, C3 Capacitor R1, R2, R3, R4 Resistance

Claims (1)

[Claims] 1. A BELL signal detecting circuit for operating a ringer circuit via a control circuit, wherein the BELL signal detecting circuit is a loop circuit of a capacitor and a resistor, and a signal having an impedance divided by the capacitor and the resistor. A BELL signal detecting device for a telephone device, comprising a driving transistor.