Telephonic communications – Terminal – Switch or switch actuator structure
Patent
1991-12-31
1994-06-28
Dwyer, James L.
Telephonic communications
Terminal
Switch or switch actuator structure
379250, H04M 100, H04M 300
Patent
active
053254287
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an automatic switching-back device for a telephone circuit, and more particularly to the automatic switching-back device for a four-wire phone circuit including wires for an audio signal and a control signal and manipulating a control signal containing d.c. components and another control signal not containing d.c. components.
TECHNICAL BACKGROUND
A normal phone device installed in office is connected to four-wire line arrangement including audio signal wires led from an NTT (Nippon Telegram and Telephone Corporation) circuit and wires for transferring control signals between an exchanger and a terminal phone. The four-wire line arrangement has a normalized connector. In actual, however, each manufacturing company has made the corresponding connector providing each arrangement of pin locations, because each manufacturing company may specify a signal for each pin of the connector at its own discretion.
Hence, when any terminal including a phone, a facsimile, and a cordless phone is connected to an already-installed exchanger, an operator cannot grasp which one of the four lines corresponds to audio signals or control signals at a glance and is required to do troublesome operation for specifying it.
In order to overcome the shortcoming, there is provided a phone circuit switching device disclosed in Japanese Patent Application No. Hei 1-42596 (42596/1989), for example. The phone circuit switching device is arranged to use a 8-circuit and 6-contact switch and to switchably connect four wires on the exchanger side to four wires on the phone side through the switch.
This phone circuit switching device is designed to select two wires for audio signals as searching the four wires. Hence, the switching device provides a terminal for picking up an audio signal so that an auxiliary terminal such as a facsimile is switchably connected to the switching device, resulting in allowing a single line to be used for two or more uses.
In case of connecting the auxiliary terminal, when the auxiliary terminal such as a facsimile is stopped, it is desirous to automatically switch back from the facsimile to the phone. The arts disclosed in the Japanese Patent Application Nos. Hei 1-299289 and Hei 1-336916 have been proposed for automatic switching-back operation.
Those automatic switching-back devices are arranged to operate with d.c. power supplied from the control line as a power supply. The energy-saving type exchangers are commercially available so that only alternate current is flown through a control wire without flowing direct current.
Such an automatic switching-back device cannot be applied to those energy-saving type exchangers.
DISCLOSURE OF THE INVENTION
The present invention is designed to overcome the foregoing shortcoming and it is an object of the present invention to provide an automatic switching-back device for a phone circuit which is adapted to even an exchanger not flowing direct current through a control wire.
In carrying out the object in a preferred mode, according to a first aspect of the invention, an automatic switching-back device being adapted to a four-wire phone circuit containing audio signal wires and control signal wires, includes an 8-circuit and 6-contact switch having four circuits on an input side and the other four circuits on an output side, the four circuits on the input side respectively having movable contacts connected to four input wires, the four circuits on the output side respectively having interlocked movable contacts connected to four output wires, six fixed contacts of the four circuits contained in each of the input and output side being connected to select two wires of the four wires in sequence for forming six combinations of the four wires, and picking up input audio wires generally connecting audio signal wires on each of the input-side circuits and output audio wires generally connecting audio signal lines on each of the output-side circuits, and
an automatic switching circuit having an input terminal connected to th
REFERENCES:
patent: 4987586 (1991-01-01), Gross et al.
patent: 5003581 (1991-03-01), Pittard
patent: 5048073 (1991-09-01), Weiser et al.
patent: 5151972 (1992-09-01), Lorenz et al.
Iwai Seizo
Iwai Tsuneko
Iwai Yukiko
Iwai Yumiko
Chiang Jack
Dwyer James L.
Meller Michael N.
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