Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The invention relates to a device for coupling
either a telephone instrument or a telefacsimile terminal to
a single telephone line. More specifically, the invention
relates to such a device wherein a coded signal couples the
telephone line to the telefacsimile terminal, and an uncoded
signal couples the telephone line to the telephone
instrument.
Devices exist which allege to permit facsimile
terminals to share a telephone line with other uses, for
example, with a telephone instrument. However, these
devices do not provide a second telephone number.
Typically, the prior art devices depend on the presence of a
"fax tone" which is actualiy a "calling non-speech device"
tone and is missing in a substantial number of facsimile
terminals presently in use. Other devices rely on delay,
and assume that a human will pick up a telephone receiver
after three to five rings, and, after a delay, switch to the
telefacsimile terminal.
There are, however, systems which do share a
single line between at least two telephone devices such as,
for example, a telephone instrument and a telefacsimile
terminal. Two such systems are described in ~.S. Patent
4,578,534, Shelley, March 25, 1986 and 4,825,465, Ryan,
April 25, 1989.
In the '534 patent, the non-dedicated telephone
line 20 can be connected either to a data set 10 or a tele-
phone instrument 40 through contacts a, b and c of relay 61.
When a computer is to access the data set 10, it sends a
single ring burst. On receipt of this single ring burst,
contacts a and b remain connected and the system dials the
telephone number of the computer. When an external party
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wishes to reach the telephone instrument, the telephone
number of the instrument is dialed. On the second ring
burst, contact b will mate with contact c by action of the
relay 61 so that the telephone instrument is connected to
the telephone line 20. The system does not use two tele-
phone numbers, including the coded telephone number, as in
the inventive system.
In the '465 patent, a controller 10 consists of
two parallel circuits 26 and 28 (see Figure 2 of the
Patent). Circuit 26 comprises a relay Ll having coils 30
and 32 and operating contacts 38 and 40. Circuit 28 com-
prises a relay L2 having coils 34 and 36 which operate
contacts 42 and 44. Circuit 26 connects a telephone line to
a device 12 (a PBX), while circuit 28 connects the same
telephone line to a device 14 (a telefax machine). When one
of these devices is in the off hook condition, current will
flow thrugh the coils of its relay to thereby disconnect the
other device from the telephone line so that only one device
is connected to the telephone line at a time. For example,
if the telephone receiver of the PBX is lifted off the hook,
current will flow through coils 30 and 32 so that contacts
38 and 40 will disconnect. Thus, only the telephone device
will be connected to the line 18.
In both of the patented devices, only a single
telephone number is used to access either the telephone
instrument or a second telephone device. Thus, the feature
of automatically being connected to the telefax or the
receiver as a function of the telephone number dialed is not
included in, nor would it be obvious from, the teachings of
the selected references.
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It is therefore an object of the invention to
provide a device for the above-stated-purpose whic~, over-
comes the disadvantages of prior art devices.
It is a further object of the invention which is
based on a coded ringing signal.
In accordance with the invention there is provided
a device for coupling either a telephone instrument, on
receipt of an uncoded telephone number ringing signal, or a
telefacsimile terminal, on receipt of a coded telephone
number ringing signal, to a telephone line, comprising:
first coupling means for coupling said telephone
line to said telephone instrument;
switch means which, when activated, decouple said
first coupling means and couple said telephone line to said
telefacsimile terminal;
code detector means for detecting said coded
telephone number ringing signal and, on detection of said
coded telephone number ringing signal, activating said
switch means;
wherein, when said device receives said uncoded
telephone number ringing signal, said first coupling means
couples said telephone line to said telephone instrument to
cause ringing of said telephone instrument; and
when said device receives said coded telephone
number ringing signal, said first coupling means is
decoupled and said telephone line is coupled to said
telefacsimile terminal;
whereby, when said telephone line is coupled to
said telephone instrument, said telefacsimile terminal is
isolated from said telephone line; and
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when said telephone line is coupled to said tele-
facsimile terminal, said telephone instrument is isolated
from said telephone line.
The invention will be better understood by an
examination of the following description, together with the
accompanying drawing which illustrates a preferred embodi-
ment of the invention.
Referring to the drawing, an input telephone line
1 is connectable either, via telephone instrument line 3 to
a telephone instrument 5, or, via telefacsimile terminal
line 7 to a telefacsimile terminal 9. A rectifier bridge
11, comprising diodes Dl, D2, D3 and D4, is connected across
the line 3 and presents a rectified signal to the telephone
instrument on receipt of an uncoded telephone number.
Relay 13 comprises movable switches 15 and coils
17 and 19. When current runs through either coil 17 or coil
19, the switches 15 will move to their closed position.
Detector 21 detects a coded telephone number and,
on detection of the coded telephone number, causes current
to flow through the coil 19.
In operation, the telephone circuit of line 3 used
for normal telephone operation is not interrupted. The
device is attached to the circuit in parallel and the fac-
simile terminal is attached to the device. The device
requires no external power other than that provided by the
telephone line, and it does not require a battery.
In the idle condition,~ there is no alternating
voltage on the line, and therefore the ringing detector
circuit 21 is isolated by capacitor 23 and is not activated.
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The rectifier bridge extends the normal supervisory voltage
to the facsimile terminal so that the placing of a call from
the facsimile terminal can be detected.
When a standard telephone ringing signal is
detected, the device rectifies the alternating current ring-
ing signal of the telephone number to the facsimile terminal
so that only direct current reaches it, and therefore the
ringing detector of the fax terminal is not activated, but
the called telephone instrument rings in its normal manner.
If a call is placed from the telefacsimile
terminal, to send out a telefacsimile signal, current flows
in coil 17 so that contacts 15 short out the rectifier
bridge 11. Accordingly, the telephone line 1 is connected
directly to line 7 of the telefacsimile terminal 9 except
for the small resistance of the coil Kl. When the tele-
facsimile terminal completes its transmission, coil 17
releases some 75 milliseconds later and the device returns
to its idle condition.
The ringing detector 21 is set to detect the
presence of 40 to 130 volts alternating current at approxi-
mately 20 Hz. If, and only if, ringing is present for, for
example, more than 0.75 seconds but less than 1.5 seconds,
ringing detector 21 sends a current through coil 2 so that
once again switch elements 15 of the relay 13 are closed.
In the above example, with a normal telephone ring of 2
seconds duration and 4 seconds pause between rings, the
ringing detector 21 does not operate, i.e., it does not
provide a current to the coil 19.
However, with a coded telephone number, the first
burst of a "coded" ring is 1 second, for example, followed
by one-half second of silence, followed by a second burst of
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1 second. Therefore, during the silent period, current is
provided to coil 19 so that the second burst is applied to
the facsimile terminal causing it to answer. The connection
will then be held by the direct line current flowing in coil
19 until the call is cleared.
With the device, there is provided a separate
telephone number for both the telephone instrument and the
telefacsimile terminal but utilizing only a single telephone
line. Accordingly, the cost of an extra telephone line is
avoided.
When the telephone instrument is in operation, the
telefacsimile terminal is decoupled from the telephone line.
In the same way, when the telefacsimile terminal is in
operation, the telephone instrument is decoupled from the
telephone line. Accordingly, the decoupled element is
isolated from the telephone line when it is decoupled.
The inventive system is not similar to "party
line" ringing, which is no longer practical now that most
equipment on premises is provided by the customer himself.
With the novel device, it can be seen that calls to the
telephone instrument are automatically separated from calls
to the telefacsimile terminal, and calls to the tele-
facsimile terminal are automatically separated from calls to
the telephone instrument. This is, of course, because two
separate telephone numbers are used.
In addition, it is possible to use both a tele-
phone instrument and a telefacsimile terminal on the same
telephone line without one degrading the performance of the
other.
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In the above embodiment, Applicant has described a
time duration code. It will be obvious to one skilled in
the art that a different type of code could be used. In
addition, Applicant has described specific time durations.
Obviously, different time durations could be used in a time
duration code.
Further, the illustrated embodiment shows two
separate coils on a single relay. Obviously, two relays
could be used wherein each coil would have a separate set of
switches.
Thus, although only a single embodiment has been
described, this was for the purpose of illustrating, but not
limiting, the invention. Various modifications, which will
come readily to the mind of one skilled in the art, are
within the scope of the invention as defined in the appended
claims.
