Note: Descriptions are shown in the official language in which they were submitted.
3i~3~
BACKGROU~D O~ THE I!~NTION
This invention relates to hands-free telephone systems,
and more particularly, to a wireless hands-free conference
telephone system adapted forsiqnal connection to a conventional
telephone unit.
Heretofore, hands-free type telephone systems have
utilized wired transmission means to send a signal from a micro-
phone or transducer into the conventional telephone transmission
system. TZireless transmitting units have previously been used
in mobile telephone systems for boats, automobiles and air-
planes, and more recently, in portable personal phones. None
of the mobile or personal telephone systems have been adopted
for multi-person conference type sound pick up, but have been
limited to close range, single person use.
Conventional conference type telephone systems havina
a hands-free sound pick-up unit with a microphone adapted for
receiving voice or other transmission generated a substantial
distance from the microphone have all been "wired" from the
microphone to the conventional telephone circuitry. Patents
directed to wired conference telephone systems and mobile
radio telephone systems include U.S. Patent Nos. 3,889,059;
4,225,754; 4,291,197; 4,319,086; and 4,363,935.
Existing wired conference telephone systems include
a transducer-microphone which is adapted to pick up voice and
other signals aenerated at a distance of about 5-15 feet from
the microphone. But such units, by being wired to the "hands-
free unit", are designed to be positioned on a credenæa or
other piece of furniture, preferably at the side of a room where
the wire can be "out of sight".
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Other placement of a conference phone on desks, tables or the
like, must conten~ with exposure of the wiring bet~een the
microphone and the hands-free control unit telephone. Such
devices do not len~ themselves to placement in the middle of
a large conference table or other piece of furniture positioned
l'out in the open" in a room. If what may be considered an
unsightly wiring placement is to be avoided, positioning a
wired conference telephone microphone in the center of a con-
ference table has heretofore necessitated the placement Of a
hole through the table top.
Heretofore, it was also believed that the use of
microphones and speakers positioned in separate chasses
facing each other ~.ould present feedback problems.
A need has arisen for a wireless microphone-transmitter
which can be positioned in the middle of a conference table
or on other types of furniture ~ithout the interference
of exposed connecting wires, particularly for use in larqe
conference rooms such as corporate board meeting rooms, and
the like.
~t is th~refore an object of the present invention,
generally stated, to provide an improved hands-free conference
telephone system wherein the voice pick-up apparatus is remotely
~irelessly positioned from the remainder of the conference
telephone system.
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BRIEF SI~ Y OF THE I~JVE~'l rON
The invention is directed to a wi~reless hands~free
conference telephone sys~em adapted for use in connection
with a conventional telephone. The system comprises a wireless
transducer/transmitter circuit for converting sound received
into a first corresponding signal and radiating that sound
from a position remote from the remainder of the telephone
system. The system further includes a unitary control module
including a receiver circuit for receiving the r~mo~ly radiated
first corresponding signal and transferring it via a first
signal path to an output adapted for connection to the telephone.
The unitary control module further includes a loudspeaker
circuit for producing sound fro~ a secona corresponding signal
via a second signal path from an input adapted for connection
to the telephone. Lastly, the unitary control module includes
a voice switching circuit acting between the telephone and
both the loudspeaker circuit and the receiver circuit on the
first and second signal paths for increasing the gain in the
loudspeaker circuit when the second correspondin~ signal is
greater than the first corresponding signal,and for increasing
the gain in the receiver circuit when the first corresponding
signal is greater than the second corresponding signal.
BRIEF DESCRIPTION OF THE DRA~JINGS
The features of the present invention, which are
believed to be novel, are set forth with particularity in the
appended claims. The invention may best be understood by
reference to the following description of a currently preferred
embodiment thereof taken in connection with the accompanying
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:1~136~3~
drawings in the several figures of which like references numerals
identify like elements, and in which:
FIGURE 1 is a perspective view of the wireless hands-
free conference telephone system, constructed in accordance
with the present invention, wherein the transmitter unit is
positioned on a conference table in one room, and the base or
control module is positioned in an ad~oinin~ room having a wall
therebetween on which is mounted a loudspeaker for the in-
cominc3 signal.
FIGURE 2 is an elevational view of the microphone/
transmitter unit.
FIGURE 3 is a diagramatic view of the microphone/
transmitter and unitary base-control module.
DETAILED DESCRIPTION O~ THE P~EFERRED ~.~BODIr5ENT
Referring to FIGURE 1, the wireless hands-free con~
ference telephone system, generally indicated at 10, includes
a remotely positionable, self-powered microphone/FM transmitter,
generally indicated at 11, for picking up voice signals and
transmitting same to a control or base unit 12 which is con-
nected in wired relation to a commercial telephone line, in-
dicated in FIGURE 1 by a commercial telephone 13. A loud-
speaker 14 is positioned in wired relation to the control unit
12 for braodcastin~ the incoming signal from the co~mercial
telephone line. In the embodiment shown in FIGURE 1, the
control unit 12 and commercial telephone 13 are positioned
in a separate room adiacent the room in which the remote trans-
mitter 11 and loudspeaker 14 are positioned. Loudspeaker 14 is
positioned on the dividinc3 wall 15. The microphone/transmitter
12136~34
11 is preferably positioned centrally on a conference table
16 or other flat surface ~here it may pick up sound both
directly and as reflected from the table top. Control unit
12 includes an FM receiver, a portion of the loudspeaker circuit
including an amplifier 34, and a voice switching circuit 30,
all to be discussed in greater detail below. lhe voice
switching circuit monitors the inco~ing voice signal and the
outgoing voice signal and increases the gain on the strongest
signal while decreasing the gain on the weaker signal in order
to avoid feedback problems as well as to provide enhanc~d
communication capabilities between the conversing parties.
Referring to FIGURES 1,2 and 3, the micro~hone/
transmitter ~1, constructed in accordance with the present
invention, is positioned in a housing 12 which, in this em-
bodiment, has the outline, as seen in an elevational view,
of a regular hexagon definin~ 6 rectangular siae surfaces
and a hexagon shape top surface. The hexagon shaped housing
12 allows equal spacea 120 positioning of 3 accoustical
transducers or microphones 18-18, thus ~rovidlng efficient
pick up of voices or other sounds aenerated from within about
15 feet anywhere around the unit. In a preferred embodiment
3 electret condenser microphones are utilized as theirclarity
of reception a~pears su?erior to other presently available
microphones. As shown most clearly in FIGURE 2, the microphone
axis A--A is slanted downward toward the conference table top
16 or other horizontal surface on which the unit will be
sitting at an angle ~approximating 30 from the vertical.
At this downward ansle, the microphone is positioned to re-
cei~e not only a direct wave from the voice or other signal
source, but also a reflected wave off of the horizontal surface
lZ~3t~
on which the unit is positioned~ In the preferred e~bodi~ent
the microphone is positioned a distance D ~rom the floor
which is as close as possible without contact, i.e. approxi-
mately 1/8 inch as a practical limit. The closeness of the
microphone to the surface from which the reflected wave is
received is important s~ that the reflected wave is not
out of phase with the direct wave recei~ed by the microphone.
Microphone reception is enhanced by receiving both direct
wave sounds and reflected wave sounds which are in phase
~ith each other. Out of phase sound reception tends to cause
cancellation of parts of the sound.
As shown in FIGURE 3I the transducer/transmitter
unit 11 includes an F~ transmitter 20 which transmits signals
received from microphones 18-18 by radiating same from antenna
21. FM transmitter 20 is powered by battery 22, ?referably
a conventional 9-volt NEDA 1604 type batterv. An on/off toggle
switch 23 provides for selective energization of the trans-
mitter and also includes a light emitting diode 2~, which informs
users that the transmitter is on and o~erating.
Referring to FIG~RES 1 and 3, the signal which is
radiated from antenna 21 of the transducer/transmitter 11 is
received by the control or base unit 12 through antenna 25.
Antenna 25 is mounted, in this embodiment, on the top of a
housing or chassis 26, containLn~ an FM receiver 27, which is con-
nected to the telephone line 28 through a voice switching
circuit 30 and a relay 31. Receiver 27 is driven by conventional
llO-volt AC current~and the voice switching circuit 30 is
driven by direct curxent po~er supply 32 receiving direct
current from transformer 33 which, in turn, is connected to a
121368A
conventional 110-volt AC power source at 29. Signals incoming
from the telephone line are passed through relay 31 and voice
switching circuit 30 into amplifier 3~ and thence to speakers
14 which, in this embodiment, are positioned in re~ote "wired"
relation to the control unit chassis 26. In the embodiment
sho~Jn in FIGURE 1, the telephone 13 and control unit 12 are
positioned in a roo~ separated from the conference or other room
where the loudspeakers 14 and microphone/transmitter 11 are
positioned, such as at a receptionist's station, or the like;
although the system may be positioned all in one area i~ de-
sired.
It should be noted that the frequency at which FM
transmitter 11 radiates signals to receiver 27 in control
unit 12 may change from locality to locality as the frequency
must be on an issued frequency which is part of a "business
band" regulated by the Federal Communications Commission.
Hence, each unit is somewhat custom tailored during installation
as to antenna height, recei~Jer and transmitter freauency
settings, etc.
The ~arious sub-assemblies including the transmitter
20, receiver 27, voice switching circuit 30, amplifier 34,
and louspeaker 14 ~ay be of commercially available manufacture.
For example, a microphone transmitter such as sold under the
trademark COM-TEK 1~1-72 and its companion recordor M~-72
may be utilized within the scope of the present invention.
Any number of amplifiers, loudspeaXers and direct current
power supplies are usable, and the power output of the am-
plifier may vary depending on the number of speakers to be
driven. Voice switching circuits similar to those used in existin~
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"~ired" hands-free conference telephone units may be utilize~,
including the PC-4B model of Precision Components, Inc., the
K~-T1020 B9 Panasonic, and the QUSlB by Northern Telecom
Limited.
Voice switching circuits are signal intensity des-
criminators which monitor background noise, and identify
the loudest voice-like signal, whether it is a part of the re-
ceived signal or the transmitted signal in the telephone system,
the circuit then increases the gain or power of that stronger
signal while decreasing the gain or power of the ~eaker of
the signals, in order to provide a clear single signal sound
in the system. As the stren~th of the received and transmitted
signals varies, the voice switching circuit responds accord-
ingly. ~uch circuitry is shown in U. S. Patent No. 3,889,059.
Further, the advent of field effect transisters ~FET) with
rapid switching characteristics have enhanced or shortened
the response time of voice switching circuits, as shown in
U. S. Patent No. 4,319,086.
Referring to FIGURE 3, the sub-assemblies, excludin~
the transmitter 11, and the speaker 14 if desired, may be
mounted together in the unitary chassis 26 with a sin~le on/off
switch 35 and volume rheostat 36 controlling the unit. The
speaker 14 may be mounted on the chassis 26 (not shown) or
located remotely as shown in FIGURE 1 with wired connection
at conventional -jacks 37 positioned at the rear of the chassis.
~or large conference rooms where speaking individuals may be
located more than approximately 15 feet from the microphone/
transmitter unit 11, two or more such units may be utilized
and positioned in spaced relation, for example, along the length
of a long conference table. Chassis 26 in ~IGURE 3 s}-ows an
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lZ~3684
additional receiver 38 in dotted line as it would be positioned
in the chassis to recei~e F~ transmission from a second micro-
phone/transmitter unit (not shown).
Thus, a wireless hands-free conference telephone
system has been sho~n and described which provides state-of-
the-art hands-free telephone capability without the need for
cumbersome wiring connections between the microphone source
and the commercial telephone system.
While one preferred embodiment of the hands-free
conference telephone system of the present invention has been
shown and described, it will be understood by those skilled
in the art that changes and modifications may be made without
departing from the invention in its broader aspects. There-
fore, the aim in the appended claims is to cover all such
changes and modifications as fall within the true spirit and
scope of the in~ention.
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