JPH0444477B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polarity detectable switching center line circuit.

(Prior art and problems to be solved by the invention) The conventional station line circuit uses a rectifier as shown in Figure 4.
An incoming call detection circuit D is connected via REC, and when an incoming call is detected, contact b operates via a signal circuit (not shown), and is composed of a transistor _Q3 , a transformer _T2 , a resistor _R3 , a photocoupler _PHC3 , and a capacitor C. A current sinking circuit IS ₂ is connected to the device to suck the current during communication and maintain the communication state. As shown in Figures 5 and 6, in this circuit, the communication current is rectified by the rectifier REC, and the communication current is passed through the transistor _Q3 and the transformer _T2 .
There is a drawback that call loss occurs due to the current flowing through the REC.

Furthermore, it is impossible to identify the polarity of the signal S ₃ output from the photocoupler PHC ₃ of the communication current I ₊ shown in FIG. 5 or the communication current _I - shown in FIG. 6. In other words, there is a drawback that the polarity of the chip terminal T and ring terminal R cannot be detected during a call.

(Object of the Invention) In order to solve the above problems, the present invention aims to eliminate call loss due to the rectifier REC during a call;
Another object of the present invention is to provide an exchange office line circuit that can detect the polarity of the office line during a call using a simple circuit configuration.

(Means for Solving the Problems) The present invention was proposed to achieve the above object, and a capacitor C _A is connected to the chip terminal T side of the central office line via one break circuit of a two-circuit switch a. The other break circuit of the two-circuit switch a connected to the ring terminal R side of the station line and the capacitor C _A
Connect the input terminal of the rectifier REC between the rectifier
Connect the incoming call detection circuit D to the output end of REC, and on the other hand,
The circuit configuration of the current sink circuit IS ₁ is that the chip terminal T side of the station line is connected to one end of a transformer T ₁ having a capacitor C _B via one make circuit of a two-circuit switch a, and the ring terminal R side is connected to a two-circuit switch. A is connected to the other end of the transformer T ₁ through another make circuit, and a capacitor C ₁ is connected between the chip terminal T side and the ring terminal R side, a resistor R ₁ and a diode so that the anode is on the resistor R ₁ side. Connect D ₁ in series, connect the base of transistor Q ₁ to the connection point of capacitor C ₁ and resistor R ₁ , and connect the collector of transistor Q ₁ to the photocoupler.
The anode of PHC ₁ , the cathode of Hola coupler PHC ₁ , the anode of diode D ₁ , and the transistor
Connect the emitter of Q ₁ to the chip terminal T side through a resistor, and symmetrically connect the capacitor C ₂ between the ring terminal R side and the chip terminal T side, so that the resistor R ₂ and the anode are on the resistor R ₂ side. Connect the diode D ₂ in series with the transistor Q 2, and connect the base of the transistor Q ₂ to the connection point of the capacitor C ₂ and the resistor R _{2 .}
collector to photocoupler PHC ₂ anode,
Connect the cathode of PHC ₂ to the anode of diode D ₂ ,
The emitters of transistor Q ₂ are connected to the ring terminal R side via a resistor, and the resistor R ₁
and diode D ₁ connection point with resistor R ₂ and diode
The gist is an exchange center line circuit characterized by being connected to the connection point of _D2 .

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the embodiments are merely illustrative, and it goes without saying that various changes and improvements can be made without departing from the spirit of the present invention.

FIG. 1 is a circuit diagram showing one embodiment of the present invention. In the figure, a rectifier REC is connected between the chip terminal T and the ring terminal R through the break contact of a two-circuit switch a and a capacitor C _A.
An incoming call detection circuit D is connected to REC. When a call arrives, the incoming signal is detected by the incoming call detection circuit D, and the switching device displays the incoming call status.

Upon detection of this incoming call, the two-circuit switch a is switched and the central office line becomes compatible. Therefore, the chip T side and the ring R side are directly connected to the current sink circuit _IS1 and hold the communication current, so there is no communication loss due to the rectifier REC in the conventional example.

Further, since the capacitor C _B is connected in series with the transformer T ₁ , the magnetic permeability of the transistor T ₁ does not change due to direct current, and a good communication state can be maintained.

The current sink circuit IS ₁ , which maintains the office line in the talking state, is
The base of transistor Q ₁ is connected to the connection point between capacitor C ₁ and resistor R ₁ in a series circuit of capacitor C ₁ , resistor R 1 , and diode D ₁ , and transistor _{Q 1}
Collector is diode through photocoupler PHC _1
D1 , the emitter of the transistor _Q1 is connected to the chip terminal T in common with the capacitor _C1 through the emitter resistor, the diode _D1 is connected to the ring terminal R, while the capacitor _C2 , the resistor _R2 , Diode D ₂
The base of transistor Q ₂ is connected to the connection point of capacitor C ₂ and resistor R ₂ in the series circuit of , the collector of transistor Q ₂ is connected to diode D ₂ through a photocoupler PHC ₂ , and the emitter of transistor Q ₂ is The capacitor C ₂ is connected to the ring terminal R through a resistor, the diode D ₂ is connected to the chip terminal T, and the resistor R ₁ and the diode
The connection point of D ₁ is connected to the connection point of resistor R ₂ diode D ₂ , and in addition the transformer T ₁ with capacitor C _B
is connected to the chip terminal T and the ring terminal R via a two-circuit switch a.

As shown in Figure 2, for example, if the chip T side has positive polarity (hereinafter referred to as +), the emitter resistance → emitter of transistor Q ₁ → transistor
The base current of transistor Q ₁ flows in the order of base of Q ₁ → resistor R ₁ → diode D ₁ , as a result, transistor Q ₁ becomes conductive, and the direct current I ₊ flows through emitter resistor → transistor Q ₁ → photocoupler PCH ₁ → The current flows through diode _D1 , and the call state is maintained. At this time, diode D ₁ is connected to PHC ₂ and transistor Q ₂
Protects against excessive reverse bias by shorting.

The above explanation is regarding DC voltage, but in terms of AC, capacitor C ₁ short-circuits the emitter and base of transistor Q ₁ , so it is a current sink circuit.
The impedance of IS ₁ is approximately R ₁ , and if R ₁ is sufficiently large compared to the impedance of the communication circuit, there is almost no loss.

As shown in Figure 3, if the ring R side is positive, the DC current I _- flows from the emitter resistor to the transistor Q ₂ to the photocoupler PCH ₂ to the diode D ₂ .
The call state is maintained.

As is clear from the above explanation, the circuit configuration of the transistors etc. in the current sink circuit IS ₁ is symmetrical on the chip terminal T side and the ring terminal R side, and the polarity of the chip terminal T and ring terminal R is ₁ and
Detection can be performed by sending out a signal S ₁ or a signal S ₂ depending on the energization state of the PHC ₂ . Also, the primary side of transformer _T1 is a bipolar electrolytic capacitor.
C Connect in series with _B to output a signal to the secondary side.

(Effects of the Invention) As explained above, the exchange central office line circuit according to the present invention has two circuit switches on the chip terminal T side of the central office line.
Connect capacitor C _A through a1 break circuit,
The input terminal of the rectifier REC is connected between the other break circuit of the two-circuit switch a connected to the station ring terminal R side and the capacitor C _A , and the incoming call detection circuit D is connected to the output terminal of the rectifier REC. The circuit configuration of the current sink circuit IS ₁ is that the terminal T side of the central line is connected to the capacitor via one make circuit of the two-circuit switch a.
The ring _terminal R side is connected to the other end of the transformer T ₁ through the other make circuit of the two-circuit switch a, and the chip terminal T side and the ring terminal R side are connected to one end of the transformer T ₁ having C B. capacitor C ₁ between,
Connect the diode D ₁ in series so that the resistor R ₁ and the anode are on the resistor R ₁ side, connect the base of the transistor Q ₁ to the connection point of the capacitor C ₁ and the resistor R ₁ , and connect the collector of the transistor Q ₁ to the photocoupler PHC _1. The cathode of the photocoupler PHC ₁ is connected to the anode of the diode D ₁ , the emitter of the transistor Q ₁ is connected to the chip terminal T side via a resistor, and symmetrically, the ring terminal R side is connected to the chip terminal T side. capacitor C ₂ , resistor R ₂ and anode are resistors
Connect diode D ₂ in series so that it is on the R ₂ side,
Connect the base of transistor Q ₂ to capacitor C ₂ and resistor
At the connection point of _R2 , connect the collector of transistor _Q2 to the anode of photocoupler _PHC2 , the cathode of _PHC2 to the anode of diode _D2 , and the emitter of transistor _Q2 to the ring terminal R side via a resistor. Furthermore, since the connection point of resistor R ₁ and diode D ₁ is connected to the connection point of resistor R ₂ and diode D ₂ , the symmetrical and simple circuit configuration reduces communication loss due to communication current, and the chip terminal It is possible to provide an exchange center line circuit that enables polarity detection of a ring terminal.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
3 and 3 are diagrams explaining the communication current in FIG. 1,
FIG. 4 is a circuit diagram of a conventional office line circuit, and FIGS. 5 and 6 are diagrams explaining the communication current in FIG. 4. a...Switch, C _A ...capacitor, REC...rectifier, D...incoming call detection circuit, IS ₁ ...current sink circuit.

Claims (1)

[Scope of Claims] 1. A capacitor C A is connected to the chip terminal T side of the office line via one break circuit of a two-circuit switch a, and a capacitor C _A is connected to the chip terminal T side of the office line through one break circuit of the two-circuit switch a, which is connected to the ring terminal R side of the office line. Other break circuit and capacitor C _A
The input terminal of the rectifier REC is connected between the terminals, and the incoming call detection circuit D is connected to the output terminal of the rectifier REC.On the other hand, the circuit configuration of the current sink circuit _IS1 is such that the chip terminal T side of the office line is connected to the above-mentioned two-circuit switch a. A transformer with capacitor C _B through one make circuit of
The ring terminal R side is connected to the other end of the transformer T ₁ via the other make circuit of the two-circuit switch _a , and a capacitor C is connected between the chip terminal T side and the ring terminal R side. _1. Connect the diode D ₁ in series so that the resistor R ₁ and the anode are on the resistor R ₁ side, connect the base of the transistor Q ₁ to the connection point of the capacitor C ₁ and the resistor R ₁ , and connect the collector of the transistor Q ₁ to the photocoupler. A photocoupler is attached to the anode of PHC ₁ .
The cathode of PHC ₁ is the anode of diode D ₁ ,
The emitter of transistor _Q1 is connected to the chip terminal T side through a resistor, and symmetrically, between the ring terminal R side and the chip terminal T side, a capacitor _C2 , a resistor _R2 , and an anode are connected to a resistor _R2.
Connect the diode D ₂ in series so that it is on the side, connect the base of transistor Q ₂ to the connection point of capacitor C ₂ and resistor R ₂ , the collector of transistor Q ₂ to the anode of photocoupler PHC 2, and the cathode of PHC ₂ to the connection point of capacitor C 2 and resistor R ₂ . At the anode of diode D ₂ , a transistor
The emitter of Q ₂ is connected to the ring terminal R side through a resistor, and the connection point between resistor R ₁ and diode D ₁ is connected to the connection point between resistor R ₂ and diode D ₂ . Exchange central line circuit.