JPH0310275B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is capable of detecting incoming calls from a central office line and displaying visually and audibly that the call is arriving at a telephone set, and which can be used without leaving the handset of the telephone set. The present invention relates to a button telephone device that can hold and hold a call to a central office line even when the telephone call is made to a central office line, and further has a direct current connection between the central office line and a telephone communication circuit during a telephone call.

Configuration of conventional example and its problems FIG. 1 shows a conventional key telephone device.
The configuration of this conventional example will be explained below with reference to FIG. 1.

In FIG. 1, 1 is an incoming call detection circuit that detects incoming calls from a central office line, 2 is a hold monitoring circuit that detects direct current during hold, and 3 is a button telephone. Next, the operation of this conventional example will be explained. When an incoming signal comes from the central office line, the DC component is removed by the capacitor _C1 , and then it is rectified by the diode bridge _DB1 and enters the incoming call detection circuit 1, where this rectified signal is detected. By detecting an incoming call, an incoming call can be displayed on the button telephone set 3. Further, when the button telephone 3 presses LK to capture the central office line, the relay contact d _i closes and the communication circuit is connected to the central office line. Here, when telephone 3 performs a hold operation, relay contacts h ₀ and h ₁ close, and even if the telephone releases LK, the central office line call continues as d _i →DB ₂ →h ₀ →resistance R _H →2→h ₁ →
A DC loop is maintained through DB ₂ . This direct current is detected by a hold monitoring circuit 2, and if there is a momentary interruption in the central office line when the other party ends the call while on hold, it is detected and relay contacts h ₀ and h ₁ are opened to open the central line.

As described above, in the above conventional example, a circuit for detecting an incoming call and a circuit for detecting direct current when a call is on hold are required separately.

Purpose of the Invention The present invention replaces the two circuits, the incoming call detection circuit and the on-hold DC detection circuit, which were required separately in the conventional example, by combining them into a single circuit by focusing on the fact that the two circuits do not work at the same time. This is what I am trying to do.

Structure of the Invention In order to achieve the above object, the present invention provides a relay contact
A two-circuit relay is used as d _i in place of the conventional one-circuit relay, and the central office line is AC-connected to the incoming call detection circuit through the break side of the relay contact d _i in the normal standby state, and when on hold. Since the relay contact d _i is closed and captures the station line, the above loop is opened, and the same circuit enters the middle of the DC loop for holding, and serves as a holding DC detection circuit to detect the state. It is designed to work, and can detect two states with one detection circuit.

DESCRIPTION OF EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, 4 is a DC detection circuit, and 5 is a communication circuit network of the button telephone. Also, d _i0 and d _i1 are two contacts of the same relay. The operation of this embodiment will be explained below. When an incoming signal comes from the central office line while the telephone is in standby mode and the central office line is open, the incoming signal has its DC component removed by capacitor C ₃ and passes through resistor R ₃ to the diode bridge. The signal is rectified by DB, passes through relay contact d _i0 and resistor R ₄ and enters DC detection circuit 4, where the incoming call is detected. When the button telephone presses LK, both contacts d _i0 and d _i1 are made, the office line is connected to the telephone communication network 5, and the incoming call detection loop passing through the resistor _R4 is opened. When the key telephone performs a hold operation here, the relay contacts h 0 and h ₁ are closed while the d _i0 and d _i1 contacts are closed, and _a central office line DC loop is formed through the resistor R _H , and the key telephone terminates the call. However, the central office line remains unchanged. Here, the DC detection circuit 4 is inserted in the middle of this DC loop and detects the DC current that is on hold, and detects when the other party ends the call while on hold and a momentary interruption occurs in the DC loop. to break connections h ₀ and h ₁ and open the central line.

Effects of the Invention The present invention has the above-described configuration, and contributes to circuit simplification and cost reduction by configuring two DC detection circuits, which were conventionally required separately, into one circuit. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a central office line system of a conventional key telephone device, and FIG. 2 is a block diagram of a central office line system according to an embodiment of the present invention. 4...DC detection circuit, 5...Telephone circuit network.

Claims (1)

[Claims] 1 Rectify the incoming signal applied to the above-mentioned office line connection terminal through a relay contact at the office line connection terminal that turns off when in standby and turns on when talking, and a series circuit of a capacitor and a resistor connected in parallel to this relay contact. A DC detection circuit is connected to the rectifier circuit and detects the DC current flowing to the output end of the rectifier circuit through a series circuit of a relay contact that is turned on during standby and turned off during a call and a resistor. is connected in series to the DC detection circuit, and in parallel to the series circuit of the relay contact that turns on during a call and the above resistor, through the call circuit network through the contact that turns on during a call, and through the contact that turns on when on hold. A button telephone device consisting of a holding resistor connected to each terminal.