JPS63236455A - Device for preventing automatic ringing of telephone set - Google Patents

Abstract

PURPOSE:To prevent automatic ringing from being generated while sending a dial pulse with simple circuit constitution and with resulting low cost, by supplying a central office current to a light emitting diode intermittently via a signal line at the time of generating a dial pulse signal from a dial pulse sender. CONSTITUTION:When the dial pulse signal is impressed on the base of a transistor Tr141 in the dial pulse sender 14 at a state that a handset is set at an off-hook state (call state), the Tr141 is turned ON, and the dial pulses are generated on central office lines 1 and 2. At this time, the central office current flows on the light emitting diode 11A of a photocoupler 11 via a high resistor 15 when a central office signal line 9 is set at high impedance, then, the diode 11A emits light. Thereby, the light receiving diode 11B of the photocoupler 11 is turned ON at the time of the high impedance of the signal line 9, and a tone ringer circuit 12 is placed under an operation disabled state. In such a way, the circuit 12 is set at the operation disabled state even when the dial pulses generated on the central office lines 1 and 2 are inputted to the circuit 12 via a diode bridge 5, etc., thereby, the automatic ringing can be prevented from being generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a self-ringing prevention circuit for a tone ringer circuit during dialing in a dial pulse type telephone.

(Prior art) Conventionally, this type of device uses a mute signal in the dial to control the tone 1 non-caller circuit to prevent self-sounding.
Self-sounding prevention is being carried out. As a result, a power supply was required for the control circuit that controlled the tone ringer circuit, and when using a separate power supply such as an AC adapter or a station line power supply, a large capacity capacitor was required to smooth the power.

(Problems to be Solved by the Invention) Conventional devices require a separate power supply such as an AC adapter or a smoothing capacitor for the station line power supply to prevent self-ringing.
The disadvantage is that the cost of the equipment increases. SUMMARY OF THE INVENTION The present invention aims to eliminate the above-mentioned drawbacks, and aims to provide a telephone ringing prevention device that can prevent self-ringing during dial pulse transmission with a simple circuit configuration and at low cost.

[Configuration 1 of the Invention (Means for Solving the Problems) The present invention provides
! % In a telephone equipped with a tone ringer circuit that generates a tone and a dial pulse sender that generates a dial pulse on a central office line via a hook switch, an impedance adjustment element is provided between the hook switch and the dial pulse sender. a light-emitting element connected to the light-emitting element; and a light-receiving element that disables the tone ringer circuit only when receiving light from the light-emitting element; The impedance adjustment element has a configuration in which the value of the impedance adjustment element is adjusted so that a line current flows into the impedance adjustment element.

(Function) In the self-ringing prevention device for a telephone according to the present invention, when the dial pulse sender generates a dial pulse at high impedance, the station line current flows through the impedance adjustment element connected between the hook switch and the dial pulse sender. The light flows to the light emitting element and causes the light emitting element to emit light. The light receiving element that receives the light emitted from the light emitting element turns on, rendering the tone ringer circuit inoperable. Therefore, even if a signal for activating the tone ringer circuit is input to the tone ringer circuit during high impedance when the dial pulse is generated, the telephone does not ring. It should be noted that at the time of low impedance when the dial pulse is generated, the activation signal for making the tone ringer circuit ring is not inputted, so the tone ringer circuit does not ring even if it is in an operable state.

(Example) An example of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing an embodiment of the self-ringing prevention device for a telephone according to the present invention. 1.2 is the office line, 3 is the capacitor for dial pulse extraction, 4 is the resistor for dial pulse extraction, 5.8 is the diode bridge for signal rectification, 9 is the signal line, and 11 is the operation of the tone ringer circuit 12. 12 is a tone ringer circuit that generates a ringing sound in response to a calling signal; 13 is a hook switch; 14 is a dial pulse sender that generates a dial pulse; 15
1 is a resistor for adjusting impedance, and 17 is a communication circuit for transmitting and receiving calls to and from the other party via the office line 1.2.

Next, the operation of this embodiment will be explained. First, when an incoming signal arrives between the office lines 1 and 2 while the handset is in an on-footer state (not in a talking state), this incoming signal is input to the diode bridge 5 via the capacitor 3 and the resistor 4.

Here, the incoming signal becomes a signal with a constant polarity and is input to the tone ringer circuit 12, which causes the tone ringer circuit 12 to ring. At this time, since the hook switch 13 is open as described above, the light emitting diode 11A of the photocoupler 11 is not emitting light, and the light receiving diode 11B of the photocoupler H is in the off state. Therefore, the tone ringer circuit 1
2 is in an operational state.

On the other hand, when the handset is off-footed and the hook switch 13 is turned on, the dial pulse signal is transmitted to the transistor 14 of the dial pulse sender 14.
When applied to the base of 1, this transistor turns on,
off and generates a dial pulse on the central office line 1.2. At this time, a local current flows through the light emitting diode 11A of the photocoupler 11 through the high resistance 15 when the local signal line 9 is at high impedance, causing the light emitting diode 11A to emit light. Therefore, when the signal line 9 is at high impedance, the light receiving diode IIB of the photocoupler 11 is turned on, rendering the tone ringer circuit 12 inoperable.

Therefore, the dial pulse generated on the office line 1.2 is transmitted to the tone ringer circuit 12 via the diode bridge 5, etc.
Even if the signal is input to the tone ringer circuit 12, the tone ringer circuit 12 is in an inoperable state when the signal line 9, which causes the tone ringer circuit 12 to vibrate, is at high impedance.
No self-sounding will occur.

According to this embodiment, when a dial signal is generated from the dial pulse sender 14, the station line current is applied to the signal line 9 to the light emitting diode 11A of the photocoupler 11 that constitutes the self-ringing prevention circuit.
Since the tone ringer circuit 12 is prevented from ringing by itself by being intermittently supplied through the hook switch 13, a separate power supply or a capacitor to smooth the station line power supply is required to prevent the tone ringer circuit 12 from ringing by itself. The self-ringing prevention circuit can be constructed simply and at low cost.

FIG. 2 is a diagram showing another embodiment of the present invention.

In this example, the line switch and dial pulse sender 18
is provided, and the hook switch is electronically constructed by a transistor 142. That is, when transistor 142 is off (on hook), transistor 14
3 is also turned off, disabling the dial pulse generation by the transistor 141, and at the same time, no current is applied to the light emitting diode 11A of the photocoupler 11, and the tone ringer circuit 12 is in an operable state. Furthermore, when the transistor 142 is on (at the time of off-footer), the transistor 1
43 is in the on state, and when a dial pulse is applied to the base of this transistor 143, the transistor 141 is turned on and off in response to the on and off of this dial pulse, and the dial pulse is turned on and off between central lines 1 and 2. will be sent to. Further, at this time, when the signal line 9 is at high impedance, a local line current flows to the light emitting diode IIA via the high resistance 15. As a result, the light emitting diode 11A emits light and turns on the light receiving diode itB, thereby rendering the tone ringer circuit 12 inoperable and preventing self-ringing. This example also has the same effect as the previous example.

[Effects of the Invention] As described above, the telephone self-ringing prevention device of the present invention has the effect of being able to prevent self-ringing during dial pulse transmission at low cost with a simple circuit configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the telephone self-ringing prevention device of the present invention, and FIG. 2 is a diagram showing another embodiment of the telephone self-ringing prevention device of the present invention. 1.2... Office line 5.8... Diode bridge 11... Fu, Odocoupler 12... Tone ringer circuit 13... Hook switch 14... Dial pulse sender 17... Call circuit agent Patent Attorney Nori Chika Ken Shu Kanshu Sanno −

Claims (1)

[Claims] A self-ringing prevention device for a telephone comprising a tone ringer circuit that generates a ringing tone in response to a ringing signal input from a central office line, and a dial pulse center that generates a dial pulse on the central office line via a hook switch, wherein the hook switch and A light emitting element connected to the dial pulse center via an impedance adjustment element, and a light receiving element that disables the tone ringer circuit only when receiving light from the light emitting element, and at least from the dial pulse sender. A self-ringing prevention device for a telephone, characterized in that a value of the impedance adjustment element is selected such that a central line current flows into the light emitting element when the impedance is high when a dial pulse is generated.