JPH0318797B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a key telephone device and a central office line circuit of an exchange. Conventional configuration and its problems The central office line circuit is an interface circuit between the central office line and the key telephone device or exchange, and is a circuit that performs network control such as detecting incoming calls, controlling calls, sending dialing, and holding calls. . FIG. 1 shows a conventional office line circuit used in a button telephone device. L1 and L2 are office lines, 1 is the office line circuit, 2 is the telephone circuit, 3 is the office line control circuit, 4
5 is a telephone circuit network for making calls, and 5 is a central office line control circuit 3 that transmits telephone switch/dial information.
Di is a relay that controls the direct current loop of the office line by turning off (OFF) when in standby, on (ON) when talking, and intermittently when sending out dials.
T is a relay for detecting a called party response, T1 is a transformer for passing current through the telephone circuit network 4, and D1 to D6.
is a diode, C1 is a capacitor, R1 is a resistor,
t is a switch. Next, the operation of the above conventional example will be explained. 1st
In the figure, when there is an incoming call from central office lines L1 and L2,
Incoming current is L1-C1-D1~D4-PH1-D
1~4-R1-L2 route, photocoupler
PH1 turns on. When PH1 is turned ON, the signal is inputted to the central office line control circuit 3 from the terminal 6, and the arrival of a central office line call can be detected. To detect the called party's response, the direction of the current in the office lines L1 and L2 is reversed when the other party answers after sending the dial, so the station line control circuit 3 detects whether the relay T changes from ON to OFF or from OFF to ON. input and detect. In the above-mentioned conventional example, each circuit for incoming call detection and callee response detection is independent, which has the drawback of complicating the circuit and increasing cost. OBJECT OF THE INVENTION The present invention eliminates the drawbacks of the above-mentioned conventional examples.
The purpose of this system is to connect a current detection element in series with the office line, and use the current detection element to detect incoming calls and the response of the called party. Structure of the Invention In order to achieve the above object, the present invention uses one current detection element connected in series with the office line so that only current in a certain direction is detected, and when in standby, an incoming call is received by that element. When making a call, it detects the called party's response by reading the reversal of the station line current after dialing. One current detection element can perform two functions: receiving a call and responding to the called party. This provides benefits that can be achieved at low cost. DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In Figure 2, L1 and L2 are office lines, 1 is an office line circuit, 2 is a telephone circuit, 3 is an office line control circuit, 4 is a telephone circuit network for making calls, and 5 is a telephone switch, which transmits dialing information to the station. Telephone control circuit for sending data to line control circuit 3. Di is a relay that controls the direct current loop of the office line by turning it off when in standby, turning on when talking, and intermittent when dialing. PH2 is a relay that controls the direct current loop of the office line when receiving a call from the office line and the called party. A photocoupler for detecting a response, D7 is a diode that is bypassed when no current flows through the photocoupler PH2, R3 and C3 are resistors and capacitors for passing alternating current when a call is received, and T2 is passing direct current to telephone circuit network 4. This is a transformer for Next, the operation of the above embodiment will be explained. Second
In the figure, when there is an incoming call on the central office line during standby, the incoming call D7 current flows through the route L1-R3-C3-T2-PH2-L2, and photocoupler PH2 turns on. When the photocoupler PH2 is turned ON, the signal is input from the terminal 6 to the central office line control circuit 3, and the arrival of a central office line call can be detected. Next, in the case of a call, a switch signal is sent from the telephone control circuit 5 to the office line control circuit 3, the relay Di is turned on, and a DC loop is formed by the D7 route of L1-di-T2-PH2-L2. At this time, photocoupler PH2 is turned on depending on the polarity of station lines L1 and L2.
Or it is turned off. When station line L1 is positive
When it is ON and the station line L1 is negative, current flows through diode D7 and photocoupler PH2 is OFF. Subsequently, the dial information is sent from the telephone control circuit 5 to the office line control circuit 3. Based on this information, the relay Di is turned on and off and the dial is sent to the central office line. When the called party answers after completion of the dial transmission, the polarity of the central office lines L1 and L2 is reversed by the telephone exchange, and the photocoupler PH2 changes from ON to OFF or from OFF to ON. By reading this change, the called party's response can be detected. This embodiment has the advantage that it is possible to detect both the incoming call on the central office line and the called party's response using the output of one photocoupler PH ₂ , and that the circuit is simple and can be realized at low cost. Effects of the Invention The present invention has the above-described configuration, and since the same current detection element performs reception of a call on the central office line and response to the called party, the circuit is simple and can be realized at low cost.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional office line circuit used in a button telephone device, and FIG. 2 is a configuration diagram of an office line circuit according to an embodiment of the present invention. 1... Office line circuit, 2... Telephone circuit, 3... Office line control circuit, 4... Telephone circuit network, 5... Telephone control circuit, PH2... Photocoupler, T2... Transformer, Di... Relay.

Claims (1)

[Claims] 1 Connect a dial contact and a diode in series to the central office line, connect a capacitor in parallel to the dial contact for passing an alternating current when an incoming call is received,
A photocoupler is connected in parallel to the above diode so that the polarity is opposite to that of the diode, and an incoming call is detected by the photocoupler outputting a signal based on the alternating current.When making a call, the photocoupler is activated by reversing the station line current. A central office line circuit configured to detect a called party response by detecting a change in output.