JPH021952U - - Google Patents

Description

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a telephone equipped with a telephone line control signal transmitting/receiving device as an embodiment of the present invention;
Figure 2 is a connection configuration diagram of a telephone system in which three telephones shown in Figure 1 are connected to a telephone line in parallel;
The figure shows three telephones shown in FIG. 1 connected in parallel to a telephone line from a main unit having a telephone line control signal transmitting/receiving device provided in the telephone shown in FIG. A connection configuration diagram of a telephone system in which interphones each having a call line control signal transmitting circuit are connected in parallel, and FIG. 4 shows each call from a PBX equipped with a call line control signal transmitting/receiving device provided in the telephone set shown in FIG. 1 is a connection configuration diagram of a telephone system in which a plurality of telephones shown in FIG. 1 are connected in parallel to a line; FIG. Explanation of main drawing numbers, 2 ... Call line control signal transmitting circuit, 3 ... Call line control signal receiving circuit, 4...
Call line, 7 ... DC impedance circuit, 20
...Second DC impedance circuit, 26...Control signal generation circuit, 31 ...Trapezoidal signal generation circuit, 37
... Variable circuit, 48 ... Input signal averaging circuit, 5
0...Identification circuit.

Claims (1)

[Scope of utility model registration request] In the first and second telephones that are connected in parallel to the same line, the first telephone has at least a group of switches for operating control signal sending operations, and a set of switches activated and coded by the operation of the group of switches for operating control signal sending operations. a control signal generation circuit that sends out a pulse signal as a control signal; a DC impedance circuit having a DC impedance that changes the voltage of the line to an off-hook voltage value; and a control signal generation circuit that integrates the control signal from the control signal generation circuit to generate a constant voltage value. A trapezoidal signal generation circuit that slices the signal and converts it into a trapezoidal control signal, and according to the waveform of the trapezoidal signal from the trapezoidal signal generation circuit,
The second telephone includes a control signal transmitting means consisting of a variable circuit for varying the DC impedance value of the DC impedance circuit, and the second telephone includes a protection circuit that is always connected to at least the line and prevents the application of a voltage value exceeding a certain value. an input signal averaging circuit that instantaneously averages the signals that have passed through the protection circuit and outputs an averaged output; control signal receiving means comprising an identification circuit that performs an operation of identifying a signal that has passed through the identification circuit; and a telephone auxiliary circuit that is controlled according to the identification output of the identification circuit; A telephone line control signal transmitting/receiving device characterized in that a telephone auxiliary circuit of a second telephone can always be controlled by operating a signal sending operation switch, regardless of the operating state of the second telephone.