U.S. patent number 3,750,131 [Application Number 05/169,671] was granted by the patent office on 1973-07-31 for silent emergency alarm system for schools and the like.
Invention is credited to James C. Administrator of the National Aeronautics and Space Fletcher, N/A, William S. Read, Vasel W. Roberts.
United States Patent |
3,750,131 |
Fletcher , et al. |
July 31, 1973 |
SILENT EMERGENCY ALARM SYSTEM FOR SCHOOLS AND THE LIKE
Abstract
In a school each classroom (or other area) is instrumented with
a hidden microphone and receiver tuned to a non-audible frequency.
The receivers' outputs are connected to a central display unit in
the school's administrative office. Each instructor is provided
with a small concealable transmitter which, when hand activated by
the instructor upon the occurrence of any emergency, generates a
non-audible signal at the receiver's tuned frequency.
Inventors: |
Fletcher; James C. Administrator of
the National Aeronautics and Space (N/A), N/A (Glendale,
CA), Read; William S. (Glendale, CA), Roberts; Vasel
W. |
Family
ID: |
22616679 |
Appl.
No.: |
05/169,671 |
Filed: |
August 6, 1971 |
Current U.S.
Class: |
367/135; 340/574;
340/531 |
Current CPC
Class: |
G08B
25/016 (20130101) |
Current International
Class: |
G08B
25/01 (20060101); G08b 007/06 () |
Field of
Search: |
;340/312,148,15,277,412,279,311,287,332 ;35/1 ;109/21,38 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Caldwell; John W.
Assistant Examiner: Swann, III; Glen R.
Claims
What is claimed is:
1. In a stationary structure defining a plurality of discrete
stationary locations and a central stationary location, a method of
indicating at said central location the existence of an emergency
in any of said discrete locations, the method including the steps
of:
providing in each of said discrete stationary locations fixedly
located detection means for detecting a supersonic signal generated
therein;
providing in said central location display means, which are
directly connected by means of continuous wires to the detection
means in the various discrete locations, and which include a
plurality of indicators, each associated with a different detection
means and energized when the detection means with which it is
associated detects a supersonic signal;
generating in each discrete stationary location at which an
emergency exists a supersonic signal which is detected by the
detection means in the discrete location;
providing audio means in at least one of said discrete stationary
locations, said audio means including a variabe gain audio
amplifier; and
automatically increasing the gain of said amplifier when the
detection means in the stationary location detect a supersonic
signal which is generated therein.
2. In combination with a stationary structure defining a plurality
of discrete stationary chambers each adapted to be occupied by a
plurality of individuals and a stationary control location, a
system for indicating at said control location the existence of an
emergency in any of said chambers, the system comprising:
separate detection means installed in each stationary chamber for
detecting a non-audible signal generated therein;
control means located in said control location, directly coupled to
said separate detection means and including a separate energizable
indicator for each separate detection means installed in each
chamber, said control means further including means for energizing
each indicator associated with a detection means which detects a
non-audible signal;
signal generating means in each discrete stationary location for
generating a non-audible signal therein; and
audio means associated with at least one of said stationary
chambers, said audio means including a variable gain audio
amplifier, and means for coupling said amplifier to the detection
means in said chamber with the gain of said amplifier increasing
when the detection means detect a non-audible signal in said
chamber.
Description
ORIGIN OF INVENTION
The invention described herein was made in the performance of work
under a NASA contract and is subject to the provisions of Section
305 of the National Aeronautics and Space Act of 1958, Public Law
85-568 (72 Stat. 435; 42 USC 2457).
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an emergency alert system and,
more particularly, to a system for, and a method of, indicating the
presence of an emergency in any chamber of a multichamber facility,
such as a school or the like.
2. Description of the Prior Art
There are many multichamber facilities in which a particular
condition, such as an emergency may arise in any of the chambers.
In such a facility it is often desirable to communicate the
existence of the emergency in the particular chamber to a central
location for summoning aid, speedily. In some cases it is desirable
to communicate the existence of the emergency in a manner which is
not noticeable by persons in the chamber. For example, in some
schools extreme disturbances have occurred in classrooms. Such
disturbances have resulted from an attack on the teacher or on a
student by another student or by an unauthorized person, invading
the classroom. Student walkouts have also precipitated the need for
assistance. Coping with such occurrences is sometimes beyond the
physical capability of the instructor, particularly when the
disruption is occasioned by unknown intruders.
It is desirable in such instances for the maintenance of order or
to obtain police intervention, to make it possible for the
instructor to summon help in a discreet manner. It is apparent that
this capability would be beneficial to orderly school
administration.
Similar situations may arise in different chambers or sections of a
prison or like facility in which it is desirable to alert and
request help to cope with an emergency in any compartment of the
facility in such a manner that those in the compartment or room are
not aware that aid is being requested. Although various emergency
alarm systems are in existence in various facilities none exhibits
such capabilities.
OBJECTS AND SUMMARY OF THE INVENTION
It is a primary object of the present invention to provide a new
improved emergency alarm system for a multichamber facility to
enable the indication of an emergency in any of the chambers.
Another object of the present invention is to provide a method of
indicating at a central location the existence of an emergency in
any chamber of a multichamber facility and the particular chamber
in which the emergency exists.
A further object of the present invention is to provide a new small
manually activatable transmitter of non-audible signals.
The invention will be described in connection with a school
although it is equally applicable to other facilities in which
similar requirements exist. The aforementioned and other objects
are achieved by concealing one or more sensors, hereafter also
referred to as microphones, capable of sensing a non-audible signal
in each of the classrooms or other instrumented areas, e.g., school
cafeteria and gym. The sensor in each room is connected to a
receiver, which is in turn connected to a central unit at a central
location. Each instructor is provided with a small and
inconspicuous hand-operated non-audible signal generator. The
non-audible signal will hereafter also be referred to as a
supersonic signal. When an emergency arises in a room the
instructor impulses the generator to produce the supersonic signal
which is picked up by the sensor in the room. Its output activates
the receiver, which in turn activates in a display unit at a
central location a buzzer as well as illuminates an indicator, such
as a lamp, indicating the particular room in which the emergency
exists. The output of each receiver may also be used to activate a
two-way communication system to enable supervisory personnel at the
central location to communicate audibly with the instructor in the
room in which the emergency exists.
The novel features of the invention are set forth with
particularity in the appended claims. The invention will best be
understood from the following description when read in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial diagram of a school instrumented with the
present invention;
FIG. 2 is a general block diagram of the system of the present
invention;
FIG. 3 is a schematic diagram of one embodiment of a receiver
incorporated in the present invention;
FIG. 4 is a partial schematic and block diagram of a display unit
shown in FIG. 1;
FIGS. 5 and 6 are diagrams useful in explaining a novel supersonic
signal generator; and
FIG. 7 is a partial block diagram of a two-way communication
system, controlled in accordance with the teachings of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The implementation of the teachings of the present invention in a
school may best be explained in conjunction with FIG. 1. Therein
numeral 10 designates a classroom in a school 12, which includes an
administrative office 14. In the classroom 10 a sensor or
microphone 16, designed to pick-up acoustic energy is installed
such as in ceiling 18. The microphone is connected to a receiver 20
by means of wires 21. The receiver in turn is connected by wires 22
to a display unit 24, located in the administrative office 14. The
receiver, which is preferably located adjacent the microphone, is a
narrowband receiver and amplifier, and is tuned to provide an
activating signal only when an acoustic signal within the
narrowband is sensed by the microphone. In practice the receiver is
tuned to a supersonic frequency above the audio range, e.g., 40-45
kHz.
When a signal of the tuned frequency is received, the receiver
provides the activating signal which, when received by the display
unit, causes the illumination of an indicator, e.g., a lamp, to
indicate the room in which the supersonic signal was detected. The
display unit includes one lamp for each area (such as the
classroom) that is instrumented with a microphone and a receiver,
and the designation of the lamp in the display unit corresponds to
the location whereat a supersonic signal was detected. In a
preferred embodiment, the display unit includes a buzzer which is
activated whenever any of the receivers provides an activating
signal. The buzzer is used to alert administrative personnel to
view the display unit and determine the room in which the
supersonic signal was detected. Preferably, the buzzer and the
illuminated lamp remain activated until they are reset by an
operator.
The instructor, designated in FIG. 1 by numeral 30, in each
classroom or other instrumented area is provided with a
hand-activatable transmitter 32. The latter when activated by the
instructor produces a supersonic signal represented by line 26
which is picked up by the microphone 16. As will be pointed out
hereafter, the transmitter operates from mechanical energy that is
stored by manually compressing a spring. When the spring is
released by the instructor, a tuned bar of the transmitter is
struck, and the bar vibrates at its resonant frequency. The latter
is selected to correspond to the receiver's tuned frequency.
In the transmitter, contemplated herein, the bar is undamped except
for the friction provided by its mounting arrangement. Thus the bar
vibrates for an appreciable period to insure proper signal
detection by the microphone. This is unlike prior art television
remote control units in which bar vibration is damped so that each
vibrating bar produces single pulse supersonic (or subsonic)
television activating signals. Thus whereas in the prior art each
transmitter activation produces a single pulse of supersonic energy
at the vibrator's resonant frequency, in the present transmitter
each transmitter activation results in a ringing effect of
supersonic energy.
Attention is now directed to FIG. 2 which is a simple block diagram
of the circuitry used in practicing the present invention. Therein
it is assumed that the school includes A-N instrumented areas.
Microphones 16A-16N and receivers 20A-20N are installed in the
areas A-N respectively. In the particular diagrammed arrangement,
the display unit 24 is shown including relays 40A-40N which are
enabled by the outputs of receivers 20A-20N respectively, to enable
the supply of power from an appropriate source (not shown), to
lamps L.sub.A -L.sub.N, respectively. The outputs of the relays
40A-40N are assumed to be connected to a buzzer 40 through an OR
gate 42 so that whenever any of the relays is activated or on, in
addition to enabling the illumination of the lamp with which it is
associated, it also activates the buzzer 40. The relay circuit is
designed to hold the relay ON until it is reset. The circuit may
include a reset button to reset the relay by switching it to OFF
and thereby deactivate the illuminated lamp and the buzzer. As is
appreciated, the system further includes transmitter 32A-32N which
are carried by instructors in areas A-N, respectively.
It should be apparent that various known circuit design techniques
may be used in implementing the circuitry of the present invention.
Generally, the novelty of the invention is in the combination of
circuits and the manner in which they are employed rather than in
specific circuit embodiments. Although various circuits may be
employed, for purposes of completing the description of the present
invention a specific embodiment which was actually reduced to
practice will be described.
FIG. 3 is a complete schematic diagram of of a typical receiver,
such as receiver 20A assumed to be connected at shielded terminal
S01 to microphone 16A. The receiver, which in the particular
embodiment has a narrow bandwidth of 5kHz between 40 and 45 kHz,
has an output relay 45. It is activated when the microphone detects
a supersonic signal in the 40 to 45kHz band. Relay 45 has a pair of
normally open contacts 46 connected to terminals 47 and 48. Thus
when the relay is activated terminals 47 and 48 are shorted
out.
FIG. 4, to which reference is now made, is a partial diagram of the
panel unit 24 showing only the relay 40A, lamp L.sub.A and buzzer
40. In this embodiment terminals 47 and 48 of relay 45 are
connected to the panel unit 24, by lines 51 and 52, respectively,
the latter being grounded. Power from an appropriate source such as
110V 60 is supplied to unit 24 on lines 54 and 55, the latter being
grounded. Line 54 is connected through a power switch 57 and a
reset switch 58 to a terminal 60 to which one end of lamp L.sub.A
and one end of coil 62 of relay 40A are connected. The other ends
of the lamp and coil are connected to line 51. The relay includes
two sets 64 and 65 of normally open contacts. The movable contacts
of sets 64 and 65 are respectively connected to line 51 and to
ground, while their stationary contacts are interconnected.
In operation as long as line 51 is ungrounded, the relay 40A is
deactivated. However, when a supersonic signal is received by
receiver 20A relay 45 is activated. Consequently, line 51 is
grounded through line 52 and both relay 40A and lamp L.sub.A are
energized. Thus, the lamp is illuminated and the normally open
contacts close. The relay 40A remains ON through its contacts even
though thereafter relay 45 may become deenergized. As long as the
relay 40A is ON, lamp L.sub.A remains illuminated. Since the relay
remains ON even after the activating signal from relay 45
terminates, and remains ON until reset, the relay may broadly be
thought of as a latchable relay which is held ON (until reset) by
holding currents passing through its contacts.
As shown, the buzzer 40 is connected at one end to the stationary
contacts which are grounded as long as relay 40A is ON. The other
end of the buzzer is connected to the ungrounded power line 54 at
terminal 60 through a buzzer switch 68. Thus when the latter is
closed and the relay 40A is ON, the buzzer is activated. By opening
reset switch 58 the relay 40A is deactivated or turned OFF, thereby
deenergizing both the lamp L.sub.A and buzzer 40.
The rest of the receivers (20B-20N) are similarly connected to the
unit 24, which includes the rest of the relays and lamps which are
connected in a manner identical with that described for lamp
L.sub.A and relay 40A. In this particular embodiment, when the
reset switch 58 is opened, the buzzer 40 and any activated relay
are deenergized at the same time. Clearly if desired, a separate
reset switch may be provided for each relay and the buzzer so that
any one unit can be deenergized or reset without affecting the
others.
Attention is now directed to FIG. 5 which is a cross-sectional view
of a typical transmitter, such as transmitter 32A designed to
provide a ringing rather than a pulse type supersonic signal. The
particular transmitter is shown consisting of an outer cylindrical
casing made up of two sections 71 and 72. Section 71 has a short
externally threaded step 71a and section 72 has a corresponding
internally threaded recess 72a which are mated when the device is
assembled as subsequently described. Section 71 is provided with a
central bore 71b, which a compression spring 73 fits, and an
internally threaded recess 71c, in which a spring retainer 74 may
be adjustably threaded. Reduced projection 74a of the retainer fits
into one end of spring 73. A hammer 75 which is slidably retained
in bore 71b of section 71, has a reduced projection 75a which fits
into the other end of spring 73.
Section 71 is also provided with an L-shaped slot 76 which can be
seen in plan view in FIG. 6. Slot 76 is provided for retaining
trigger 77 in position for cocking hammer 75. On of the useful
features of the lateral section 76a of slot 76 is that when the
transmitter is worn in a pocket in the manner of a pen. Should the
wearer be grabbed, the cocked hammer 75 will be released by the
jarring action of any altercation in which he may be involved.
Trigger 77 consists of finger-operable button 77a which is
connected with hammer 75 by means of threaded stud 77b, screwed
into the hammer. Hammer 75 thus can be set in cocked position by
first shifting button 77a axially in slot 76 toward detent portion
76a, and by then laterally rotating button 77a until stud 77b is
engaged in the detent. Shifting button 77a as described compresses
spring 73. The extent of this compression is determined by the
position of retainer 74 in portion 71c of section 71.
On release of trigger 77 from the detent, the free end of hammer 75
impacts one end of vibrator 78 with great force, setting the latter
into vibration at its resonant frequency in the manner of a tuning
fork. Vibrator 78 is a metallic rod which is provided near its
center with a ring groove for retaining a thin, flexible suspension
disk 79. The flange of disk 79 is retained between sections 71 and
72 in groove 72b of the latter when the sections are threaded
together in assembly. This provides a relatively free suspension
for vibrator 78.
When rod 78 is impulsed by hammer 75, after release of trigger 77,
it produces vibrations which emanate from the open end 80 of
section 72. The dimensions of vibrator or rod 78 are chosen so that
its resonant frequency is in the supersonic range, e.g., 45kHz. By
suspending the rod 78 by disk 79, once imparted by hammer 75 it is
free to resonate, or ring for a significant period, since except
for the disk friction it is effectively undamped.
The size of the transmitter is quite small, generally like a
ballpoint pen, so that it can be concealably carried and used by
the instructor without being noticed by the students. Thus the
instructor can summon help without the students becoming aware of
the request. Herebefore it was assumed that one microphone is
intalled in each instrumented area, such as a classroom or the
like. Clearly, if desired, several microphones stratigically
located in each area may be used to feed a single receiver. This is
particularly desirable in large areas such as the school cafeteria
or gym to insure that when a transmitter is activated in such an
area, the supersonic signals are detected by at least one of the
microphones.
Herebefore it was also assumed that the output of any receiver is
used to illuminate a lamp associated therewith in the display unit
and optionally further activate a buzzer. In schools equipped with
two-way communication units between the classrooms and the
administrative office, the receiver output may further be used to
activate the two-way communication unit between the particular
classroom and the office. This would enable the teacher requesting
assistance to audibly communicate with the office personnel.
The two-way communication unit between each classroom and the
office may be represented by a microphone-speaker 92 (see FIG. 7)
installed in the classroom and connected to a microphone speaker 93
in the school office by a two-way amplifier 94. The receiver output
relay 45 (see FIG. 3) may include an additional set of contacts
connected to the amplifier 94. When an emergency arises in the room
and the receiver is activated by the detection of the supersonic
signal produced by the instructor-activated transmitter, these
additional contacts may be used to control the amplifier gain
automatically, e.g., increase it and thereby enable the instructor
to audibly communicate with the office personnel. This feature may
be particularly desirable under extreme emergencies which may
prevent the instructor from directly activating the
microphone-speaker 92 in the room.
There has accordingly been shown and described herein a novel
emergency alarm system for schools or the like. The system enables
an instructor in any classroom or other instrumented area to
indicate to personnel in an administrative office the existence of
an emergency in his area and request aid without others in the area
being aware of the request. The system comtemplates the
installation of a microphone and a narrow band tuned receiver in
each instrumented area. When an emergency arises, the instructor,
equipped with a small concealable transmitter, hand activates the
latter to produce a ringing supersonic signal which is picked up by
the microphone, causing the receiver to produce an activating
output signal. The latter is supplied to a display unit in the
administrative office wherein a lamp, representing the particular
classroom, is illuminated and if desired, a buzzer is energized to
alert personnel to the existence of an emergency. By incorporating
in the display unit one lamp for each instrumented area, the
existence of emergencies in more than one area can be
simultaneously displayed. If desired, the output of the receiver of
each instrumented area can be used to activate a two-way
communication unit to enable the instructor, in case of an
emergency, to audibly communicate with the administrative
personnel.
It is appreciated that those familiar with the art may make
modifications or substitute equivalents in the arrangements
herebefore described without departing from the true spirit of the
invention. Therefore, it is intended that the claims be interpreted
to cover such modifications and equivalents.
* * * * *