JPS595766A - Bell circuit - Google Patents

Abstract

PURPOSE:To prevent resonance phenomenon by releasing an extended incoming bell circuit once the talking circuit of a telephone set is formed in terms of direct current. CONSTITUTION:When the handset of the telephone set 1 is lifted and a call dialing operation state is entered, the hook switch of the telephone set 1 is closed and a DC current flows through the telephone set 1. At this time, the voltage between terminals L1 and L2 drops because the loop resistance of the telephone set 1 and the resistance value of a coil 7 are small, but the coil 7 is energized to break a normally closed contact 6, holding the voltage between terminals A and B at a potential (high voltage of 48V) before the coil is conducted electrically. When dialing operation is performed at this time, the terminals A and C are connected and disconnected intermittently through a dial contact, but the dial contact and normally closed contact 6 are placed in the opposite operations, so the voltage between the terminals A and B of the extended incoming bell circuit is held nearly at the high voltage of 48V, preventing resonance phenomenon due to the dialing operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bell circuit in a telephone that is free from malfunctions such as resonance.

Generally, an incoming call bell (also called an additional bell) is connected in parallel with a telephone set to a telephone line of the negative set, and is designed to ring together with the bell of the telephone set in response to an incoming call signal. However, when the telephone dial is operated to make a call, the incoming call bell also rings in response to the dialing operation, causing a so-called resonance, which causes discomfort to the user.

Therefore, in order to prevent such resonance, for example, in the case of incoming call bells using magnetic bells, a mechanical structure was adopted in which a spring prevents the malfunction of a vibrating iron piece with a hammer part, but it is difficult to adjust. Moreover, it has the disadvantage that it is not possible to prevent malfunctions due to dial pulses containing crystal level components.

The present invention has been made in view of the above-mentioned problems, and its object is to provide a bell ring that solves the above-mentioned problems by opening the incoming call ring circuit when the telephone line is formed in a direct current manner. The purpose is to provide circuits.

Examples of the present invention will be described below. The figure is a circuit diagram showing one embodiment of the same, in which 1 is a telephone, 2 is an incoming bell,
3 is a capacitor, and this incoming bell 2 and capacitor 3
The incoming bell circuit is configured. Reference numeral 4 indicates a telephone line of telephone L, and reference numeral 5 indicates a relay, and the normally closed contact 6 of the relay 5 is connected in series between one terminal L2 of the telephone line terminals L1 and L2 at the entrance of the subscriber's home and the incoming call bell 2. The coil 7 of the relay 5 is connected in series between the telephone 1 and the terminal L2. A, B, and C are terminals.

In the above, when making a call from telephone 1, before lifting the receiver, the flap switch of telephone 1 is in an open state, and terminals A and C are opened in terms of direct current, so that coil 7 of relay 5 is not excited, and the sealed contact 6 is in a closed state. In addition, the voltage of the local power supply (high voltage 48V) is applied between the terminals Ll and L2, and the terminals A and
The voltage remains high for 8 hours.

Next, when the handset is lifted, the hook switch of telephone 1 is closed and direct current flows through telephone l. At this time, since the loop resistance of telephone L and the resistance of coil 7 are small, the voltage between terminals L+ and L2 decreases, but as coil 7 is energized and excited, normally closed contact 6 is opened, and terminal A .

The voltage between 8 and 8 is maintained at the voltage before energization (high voltage 48V).

Here, when dialing the telephone 1, the dial contact in the telephone 1 connects terminals A and C, but since the operations of the dial contact and the normally closed contact 6 are reversed, terminal A of the incoming bell circuit , B is almost maintained at a high voltage of 48V, and is not affected by the dialing operation of the telephone 1, thereby preventing resonance.

On the other hand, if an incoming signal arrives with the receiver of telephone 1 on the hook, the normally closed contact 6 of relay 5 is in the closed state, so both the incoming ring and the bell of telephone 1 resonate as before. Begins to slurp.

In the above embodiment, a relay 5 having a coil 7 as a DC current detection means and a normally closed contact 6 as a switching means operated by excitation of the coil 7 was used, but a transistor or the like may be used instead. Even if the electronic type used is used, the same effect can be obtained.

As described above, the bell circuit according to the present invention is a circuit in which a telephone set and an incoming bell circuit are connected in parallel to a set of telephone lines, in which a direct current detection means is connected to the telephone line to which the telephone set is connected, and the above-mentioned The incoming bell circuit is connected to a switching means which is opened when the detection means detects a direct current.

Therefore, not only can resonance be reliably prevented, but also the structure can be simplified, making it possible to realize a small size and low cost.

[Brief explanation of drawings]

The figure is a circuit diagram showing one embodiment of the present invention. ■...Telephone, 2...Incoming bell, 3...Capacitor, 4...Telephone line, 5...Relay, 6...Normally closed contact, 7...Coil. Patent applicant: Nippon Telegraph and Telephone Public Corporation Ll Δ

Claims (1)

[Claims] (l) In a circuit in which a telephone set and an incoming bell circuit are connected in parallel to a set of telephone lines, a direct current detection means is connected to the telephone line to which the telephone is connected, and the detecting means is connected to the incoming bell circuit. A bell circuit characterized by connecting a switching means that is opened by detecting a direct current.