U.S. patent number 3,665,116 [Application Number 04/886,467] was granted by the patent office on 1972-05-23 for apartment house intercom system.
This patent grant is currently assigned to Fasco Industries, Inc.. Invention is credited to Allan Holstrom.
United States Patent |
3,665,116 |
Holstrom |
May 23, 1972 |
APARTMENT HOUSE INTERCOM SYSTEM
Abstract
With this system only two wires are needed to transmit audio
signals between a speaker-microphone unit located at a central or
foyer station, and any one of a plurality of such units located at
apartments remote from the foyer station. A transistorized relay at
the central station normally connects the foyer unit for
transmission to the remote units, but is responsive to a manually
operable switch at each remote station to connect a selected remote
unit for transmission to the foyer speaker. The same two wires are
used to transmit a door unlatching signal from any remote unit to a
release mechanism at the foyer station. Also, a buzzer energizing
signal may be transmitted from the foyer station over a single line
selectively to one of two of the remote apartment stations.
Inventors: |
Holstrom; Allan (Rochester,
NY) |
Assignee: |
Fasco Industries, Inc.
(Rochester, NY)
|
Family
ID: |
25389085 |
Appl.
No.: |
04/886,467 |
Filed: |
December 19, 1969 |
Current U.S.
Class: |
379/167.07;
379/102.06 |
Current CPC
Class: |
H04M
11/025 (20130101) |
Current International
Class: |
H04M
11/02 (20060101); H04m 007/10 () |
Field of
Search: |
;179/1H,37,2A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Cooper; William C.
Assistant Examiner: Kundert; Thomas L.
Claims
Having thus described my invention, what I claim is:
1. An intercom system for communicating selectively between a
central station and one or more of a plurality of stations remote
from said central station, comprising
a combination speaker-microphone unit at each of said stations,
a pair of conductors forming part of an audio signal circuit
extending from said central station to each of said remote stations
to convey audio signals from the unit at said central station to
the unit at one of said remote stations, and vice versa,
an audio amplifier at said central station,
a direct current power supply for energizing said amplifier to
enable transmission of audio signals therefrom,
a first plurality of switches normally disposed in first positions
in which they connect the output of the speaker-microphone unit at
the central station to the input of said amplifier, and the output
of said amplifier to one of said conductors, and
a manually operable switch movable selectively to first and second
positions, respectively, at each of said remote stations for
selectively connecting the associated speaker-microphone unit
between said pair of conductors for energization thereby,
said amplifier being operative, when the manually operable switch
at one of said remote stations is in its first position, to
transmit audio signals from said unit at said central station to
the input of the unit at said one remote station,
means operative upon movement of the last-named switch to its
second position to move the first-named plurality of switches to
second positions in which they connect the output of the unit at
said one remote station to the input of said amplifier, and connect
the output of said amplifier to the input of said unit at said
central station, and
a relay coil operative, when energized, to move said first-named
plurality of switches to their second positions,
an electronic valve connected in series with said coil across said
power supply and operative to block the flow of current through
said coil, when the manually operable switch at each of said remote
stations is in its first position, and
means operative, upon the movement of the manually operable switch
at any one of said remote stations to its second position, to
render said valve conductive, thereby to energize said coil,
a second relay coil connected at one end to the positive side of
said power supply, and at its opposite end to said one conductor,
and operative to control a circuit independent of the audio signal
circuit,
a second, normally open, manually operable switch connected between
said pair of conductors at each of said remote stations and
operative upon being closed to energize said second coil, and
means for preventing energization of said second coil, when either
of the first-named manually operable switches is in either its
first or second operative position, and said second manually
operable switch is open.
2. An intercom system for communicating selectively between a
central station and one or more of a plurality of stations remote
from said central station, comprising
a combination speaker-microphone unit at each of said stations,
a pair of conductors forming part of an audio signal circuit
extending from said central station to each of said remote stations
to convey audio signals from the unit at said central station to
the unit at one of said remote stations, and vice versa,
an audio amplifier at said central station,
a direct current power supply for energizing said amplifier to
enable transmission of audio signals therefrom,
a first plurality of switches normally disposed in first positions
in which they connect the output of the speaker-microphone unit at
the central station to the input of said amplifier, and the output
of said amplifier to one of said conductors, and
a manually operable switch movable selectively to first and second
positions, respectively, at each of said remote stations for
selectively connecting the associated speaker-microphone unit
between said pair of conductors for energization thereby,
said amplifier being operative, when the manually operable switch
at one of said remote stations is in its first position, to
transmit audio signals from said unit at said central station to
the input of the unit at said one remote station,
means operative upon movement of the last-named switch to its
second position to move the first-named plurality of switches to
second positions in which they connect the output of the unit at
said one remote station to the input of said amplifier, and connect
the output of said amplifier to the input of said unit at said
central station,
electrically operable signal means at each of said remote
stations,
a plurality of manually operable signal switches at said central
station,
a further plurality of conductors extending between said central
station and said remote stations, each of said further conductors
connecting one of said signal switches to the signal means at one
of said remote stations, and
means operative, when said one signal switch is closed, to energize
the associated signal means,
each of said further conductors being connected at one end at said
central station to two of said signal switches, and at its opposite
end to the signal means at two different remote stations, and
means operative, upon the closing of one of said two signal
switches, to energize the signal means at one of said two stations,
and operative upon the simultaneous closing of said two signal
switches alternately to energize the associated signal means at
said two remote stations.
Description
This invention relates to communication systems, and more
particularly to an apartment house loud speaking intercom system
which permits audio communication from any of the several apartment
suites to the main entrance or foyer of the apartment house with a
minimum number of low voltage and low current interconnecting
wires.
Most apartment house intercom and/or door answering systems
comprise a buzzer operable by a switch located in the entrance
foyer to signal the presence of a caller, a combination
speaker-microphone unit in each apartment, a control switch with
OFF, LISTEN, and TALK positions, and a pushbutton to release the
lock on the door at the entrance from the foyer to permit a caller
to enter the apartment house. This equipment is connected by a
plurality of conductor wires or lines to a power supply, a central
amplifier, and to a loud speaker unit installed in the main
entrance foyer.
Such intercom installations traditionally have required between
each apartment, and the central or foyer amplifier usually, two
lines for producing an audio signal, two wires for controlling a
talk/listen relay located at the central amplifier, two wires for
completing the door release circuit, and two wires for connecting
the buzzer in each apartment station to the foyer pushbutton panel
and power supply.
The obvious way of reducing the number of wires in such an intercom
system is to have one wire common for each of the four circuits,
thereby making a total of five wires including one for the
signalling buzzer, instead of the eight wires.
It is an object of this invention to reduce the amount of wiring
needed for an apartment house intercom system even beyond this
obvious reduction.
A further object of this invention is to provide an improved
apartment house intercom system, which is substantially more
compact, inexpensive, and is easier to install than prior
systems.
Other objects of the invention will be apparent hereinafter from
the specification and from the recital of the appended claims,
particularly when read in conjunction with the accompanying
drawings.
In the drawings:
FIG. 1 is a wiring diagram illustrating schematically an apartment
house intercom system wired in accordance with one embodiment of
this invention; and
FIG. 2 is a wiring diagram illustrating a modification of part of
this system.
Referring now to the drawings by numerals of reference, and first
to FIG. 1, 10 represents generally a central amplifier station
located, for example, in the vestibule or central entrance foyer of
an apartment house; and 12 represents a typical station installed
in each apartment for operation in conjunction with the central
amplifier station 10.
Station 10 comprises a pair of alternating current (AC) input
terminals T1 and T2, which are connected to an AC power supply (not
illustrated), and two further terminals T3 and T4, which are
connected to a direct current (DC) power supply (not
illustrated).
The DC power supply is used to energize a conventional audio
amplifier 14 and for this purpose the positive terminal T3 is
connected by a line L3, and a line 15 to one side of the amplifier,
and the negative terminal T4 is connected through a ground line L4
and a line 16 to the opposite side of the amplifier. Line L4 also
extends to apartment stations 12 in the associated apartment
building in a manner which will be described in more detail
below.
Station 10 further includes a combination speaker-microphone unit
18, the operating coil 19 of which is connected at one end to the
line L4, and at its opposite end by a line 20 to a movable relay
contact or switch arm 21, which is one of two movable switch
contacts or arms 21 and 22 that are controlled by a relay coil K1.
Arm 21 is engageable with spaced stationary contacts 23 and 27; and
arm 22 is engageable with spaced stationary contacts 29 and 30.
Contact 23 is connected by lines 24 and 25 to the input of
amplifier 14; and the output of the amplifier is connected by a
line 26 to contact 27, and line 28 to contact 29. Contact 30 is
also connected to the input of the amplifier through line 25.
Normally, that is when the relay coil K1 is deenergized, the switch
arm 21 is engaged with a stationary contact 23, and switch arm 22
is engaged with the stationary contact 29, thus connecting the
output of the amplifier 14 through a capacitor C2 to a
communication line L5, which extends from the amplifier station 10
to each of the apartment stations 12. At the amplifier station 10,
the line L5 is also connected by a line 32 to the base of a
transistor 34, the collector of which is connected through a line
35 and the relay coil K1 to the ground line L4. The emitter of the
transistor 34 is connected to the positive terminal T3 of the DC
power supply by the line L3.
Also connected at one end to the line L3 and at its opposite end to
the line L5 is a further relay coil K2, which controls a normally
open switch arm 37. Switch arm 37 is adapted to control a
conventional door-release mechanism, which, by way of example, is
illustrated in the drawing as being a solenoid 38. Solenoid 38 is
connected at one end through a further terminal T6 and lines 39 and
L2 to the AC input terminal T2. The other AC terminal T1 is
connected by lines L1 and 40 to a stationary relay terminal 41,
that is engageable by the switch 37, when the latter is closed,
thereby to energize the solenoid 38. The solenoid 38, when
energized, operates to release a conventional door latching
mechanism such as employed in the entrances of apartment
houses.
The terminal T1 is also connected by the line L1 to one contact 43
of a normally open pushbutton type switch, which is operable in the
foyer by a visitor to signal his or her presence to the resident of
an apartment in the apartment house. The other terminal 45 of this
switch is connected by a line L6 to a conventional buzzer 46, which
is mounted in an apartment station 12. The opposite side of the
buzzer 46 is connected to the line L4.
At the typical apartment station 12 a combination
speaker-microphone unit 48 has its operating coil 49 connected at
one end to the ground line L4, and at its opposite end through a
capacitor C1 to a movable, three-position switch arm 50. Also
connected at one end to the line L4 at the apartment station 12,
and at its opposite end to a further pivotal or movable switch arm
51, is a resistance R1. Switches 50 and 51 form part of a
conventional, manually operable, three-position control switch 52,
which is mounted at the apartment station 12 for movement
selectively between three different positions identified as LISTEN,
OFF and TALK, respectively. The switch 52 is spring-loaded so that
it normally is disposed in its OFF position.
When this switch 52 is in its OFF position, the movable switch
contacts 50 and 51 register with dead-ended contacts 60 and 53,
respectively, and coil 49 and resistor R1 are deenergized. When the
switch 52 is moved to its LISTEN position, contact 51 is swung into
engagement with a further dead-ended contact 54; and switch arm 50
is swung into engagement with a contact 55, which is connected by
lines 56 and 61 to the line L5, and by lines 56 and 57 to one side
of a normally open, manually operable pushbutton switch 58, the
opposite side of which is connected by a line 59 to line L4.
In use, a visitor signals the resident of the apartment by pushing
the button 44, which is located in the foyer. This completes a
circuit from the AC terminal T1 through line L1, switch 44, line
L6, buzzer 46 in the apartment, and line L4 back to station 10
where line L4 is connected to terminal T2 by line L2. The buzzer 46
is thus energized across the AC power supply, when the switch 44 is
closed.
When the resident of the apartment hears the buzzer 46, he or she
moves switch 52 to its LISTEN position, thus completing the circuit
from negative terminal T4 of the DC power supply through line L4,
foyer speaker coil 19, line 20, switch 21, contact 23, and lines 24
and 25 to the input of amplifier 14. At this time the output of the
amplifier is connected through lines 26 and 28, contact 29, switch
arm 22, capacitor C2, lines L5, 61, 56, contact 55, switch arm 50,
capacitor C1 and the apartment speaker coil 49 to ground line L4.
The foyer speaker thus functions at this time as a microphone, its
input being applied to the amplifier 14; and the apartment speaker
48 functions as a speaker, its input being received from the output
of the amplifier 14. The capacitors C1 and C2 operate to isolate
the relay coil K2 from any direct current flow, so that the coil K2
remains deenergized at this time. Also, the base and the emitter of
the transistor 34 are at the same potential, so that the transistor
is in its normal blocking or essentially non-conductive state, so
that the relay coil K1 is also deenergized at this time.
After the visitor has been identified, the resident of the
apartment may shift switch 52 to TALK position, thereby connecting
the movable switch arms 50 and 51 with contacts 63 and 64, both of
which are connected to the line 56. This operates to connect the
resistance R1 in parallel with the speaker coil 49 and the
capacitor C1, and also completes the circuit from the positive DC
input terminal T3 to line L3, relay coil K2, lines L5, 61 and 56,
switch arm 51 and resistance R1 to ground line L4. The resistance
R1, however, has an ohmic resistance at least 10 times that of the
coil K2, so that only a very slight amount of current is allowed to
flow through the coil K2 and resistance R1. Although this quantity
of current is not sufficient to energize the coil K2 to close the
switch 37, it does create a potential difference between the
collector and base of transistor 34, whereby the latter is switched
to its conducting state, thereby energizing relay coil K1 from T3,
through line L3, the collector circuit of transistor 34, line 35,
and coil K1 to ground line L4 and terminal T4. Coil K1 then
operates to swing switch contacts 21 and 22 into engagement with
stationary contacts 27 and 30, respectively, thereby connecting the
apartment speaker 48 to the input of amplifier 14, and connecting
the output of the amplifier to foyer speaker 18. Signals developed
in the coil 49 are thus connected through capacitor C1, switch 50,
lines 56, 61 and L5, capacitor C2, switch 22, contact 30 and line
25 with the input of the amplifier 14. The amplifier output is
connected at this time through line 26, contact 27, switch 21 and
line 20 with the coil 19 in foyer speaker 18. The apartment speaker
48 now operates as a microphone to permit the resident of the
apartment to speak to the visitor through foyer speaker 18.
If the resident of the apartment, after identifying the visitor,
wishes to admit the visitor to the apartment house, the resident
pushes pushbutton 58 at station 12, thereby completing the circuit
from the positive DC terminal T3 through line L3, relay coil K2,
lines L5, 61 and 57, switch 58, and line 59 to ground line L4. This
circuit connects coil K2 directly across the DC power supply, so
that the coil is fully energized, thereby closing switch 37, and
energizing solenoid 38. As noted above, this releases the latching
mechanism on the door at the main foyer entrance.
From the foregoing it will be apparent that only two wires L4 and
L5 are required for connecting the amplifier station 10 to the
typical apartment station 12 in order to enable the transmission of
audio signals back and forth between the main station and any one
of the remote apartment stations, and also to permit operation of
the door unlatching mechanism from any of the apartment stations.
Furthermore, by adding a third wire L6, applicant's novel system is
capable of performing all of the numerous functions required of an
apartment house intercom and signalling system of the type
described. In addition, the same two lines L4 and L5 can be used
for a plurality of apartment stations 12, thereby considerably
reducing the amount of wiring, as compared to prior systems.
While in the embodiment of FIG. 1 there must be at least one
different line L6 for each apartment station 12, FIG. 2 illustrates
a novel system in which a single such line L6 can be employed for
selectively operating the buzzers or signalling devices of at least
two separate apartments or stations 12. In this embodiment, wherein
like numerals are employed to denote elements similar to those
employed in the embodiment of FIG. 1, the buzzers or signalling
devices 46-1, 46-2, 46-3 and 46-4 denote the buzzers of four
different apartments or stations similar to the station 12 of FIG.
1. Also, 10' denotes a central or foyer amplifier station similar
to station 10 of FIG. 1, but including four, manually operable
pushbuttons 44-1, 44-2, 44-3, and 44-4 for activating the buzzers
46-1, 46-2, 46-3 and 46-4, respectively.
As in the preceding embodiment, the input terminal T2 of the AC
power supply is connected through line L2, and the line L4 to one
side of each of the four different apartment buzzers 46-1, 46-2,
46-3 and 46-4. The other AC input terminal T1 is connected by the
line L1 and a diode 70 to a first trunk line L7 at the foyer
station, and through a second diode 71, to a second trunk line L8
at station 10'. The two switches 44-1 and 44-2 are connected at one
side to line L6, and at their opposite sides are connected to lines
L7 and L8, respectively. Line L6 extends from foyer station 10' to
a terminal 73 located adjacent the two apartment stations
represented by the buzzers 46-1 and 46-2, respectively. The
terminal 73 is connected through diodes 74 and 75 to the buzzers
46-1 and 46-2, respectively.
Similarly the switches 44-3 and 44-4 are connected at one side to a
line L6-1, and at their opposite sides are connected, respectively,
to the lines L7 and L8. The line L6-1 extends from foyer station
10' to a terminal 76 located adjacent the apartment stations
represented by the buzzers 46-3 and 46-4, respectively. Contact 76
is connected through diodes 77 and 78, respectively, with buzzers
46-3 aNd 46-4.
The diodes 70 and 71 are connected in opposition to one another
with respect to the terminal T1, as are the diodes 74 and 75 with
respect to their common terminal 73. Similarly the diodes 77 and 78
are connected in opposition to one another with respect to the
common terminal 76. On the other hand, the diode 70 is oriented in
the same direction as the diodes 74 and 77, while the diode 71 is
oriented in the same directions as the diodes 75 and 78.
When the switch 44-1 or 44-3 is closed, diode 70 conducts only on
the positive half cycle of the AC voltage appearing at terminal T1,
thereby developing in line L6 or L6-1 a positive signal, depending
on whether switch 44-1 or switch 44-3 is closed, which causes diode
74 or 77 to conduct to energize either buzzer 46-1 or 46-3. During
this period, the positive signal appearing on line L6 or L6-1
maintains the diode 75 or 78 non-conductive to prevent energization
of buzzer 46-2 or 46-4. As the potential on the terminal T1 grows
negative, while the switch 44-1 or 44-3 is still closed, the diode
70 stops conducting, and blocks a negative signal from appearing on
line L6 or L6-1, thus preventing energization of the associated
buzzer 46-2 or 46-4.
On the other hand if either switch 44-2 or 44-4 is closed, diode
71, and hence diode 75 or 78, would conduct only on the negative
cycle of the AC voltage to energize either the buzzer 46-2 or 46-4,
depending on which of the associated switches is closed. If, for
example, the switches 44-1 and 44-2 are closed simultaneously, the
diodes 70 and 74 would conduct for one half cycle, and the diodes
71 and 75 would conduct for the other half, thereby alternately
energizing buzzers 46-1 and 46-2. Simultaneous closing of the
switches 44-3 and 44-4 will in a like manner produce alternate
energization of buzzers 46-3 and 46-4, respectively. Thus, a single
signal line L6 or L6-1 can be used selectively to control two
different buzzers at two different apartments. As compared to the
first embodiment (FIG. 1), the system illustrated in FIG. 2 thus
reduces by 50 percent the number of signal lines L6 that are
necessary for operating the buzzers of a plurality of different
apartments.
From the foregoing it will be apparent that the novel apartment
house intercom and signalling systems disclosed herein considerably
reduce the amount of wiring necessary to operate an intercom system
as compared to prior such systems. It will be apparent, that if
desired, the signalling system of FIG. 2 can be substituted for the
corresponding signalling system illustrated in the first embodiment
(FIG. 1).
* * * * *