Note: Descriptions are shown in the official language in which they were submitted.
ALARM CHAIN LOCK
Field of the Invention
This invention is directed to a light port-
able, self-securing alarm sounding chain lock for secur-
ing portable devices against ~heft. More particularly,
this invention is directed to a light portable locking
device which secures moveable personal belongings such
as bicycles, skis and the like, against theft by sound-
ing an alarm when the locking devi~e is disturbed ortampered with.
Background of the Invention
Theft of valuable personal portable posses-
sions has been a continuing social problem since pre-
historic times. In recent times, particularly in western societies, the incidence of theft has been increas-
ing because man has been enjoying more leisure time and
acquiring an increasing number of portable personal
possessions, conventionally classified as luxury items.
~ Items such as skis, bicycles, various other types of
sporting equipment, radios and portable television sets,
)lave been accumulated by man at an increasing rate, and
being readily resaleable, have been a prime target for
theft. To offset this increasing theft rate, there has
~5 been a strong, continuing need for a reliable, readily
portable, lightweight, easy to use securing device.
Various designs of locks and chains have been
developed but it seems that as quickly as a new device
appears on the market, thieves develop a way to defeat
the operation and purpose of the device. One example i5
6~
the well-known portable lock and chain, or steel cable,
that is frequently used to secure items suc~ as skis or
bicycles to a stationary immoveable object. These de-
vices are now easily removed because most professional
thieves carry a set of bolt-cutters which are easily
used to sever the chain or cable. There is a strong
need for a locking device that cannot be severed or
broken by cutting devices such as bolt-cutters.
Summary of the Invention
The subject portable securing device enables
an individual to reliably secure valuable personal be-
longings against theft. It can be either fastened to
the belonging to be secured and a stationary immovable
object such as a lamp standard by means of a chain lock-
ing mechanism, or simply wrapped around the object to be
secured, whereby the alarm will be sounded when the
secured object is moved or tilted. The length of the
chain is adjustable. The device incorporates a built-in
alarm which sounds loudly if the device is lifted,
tilted or jarred, once it has been set. The device con-
tains a built-in mercury switch, which when moved, jig-
gled or jarred, triggers the alarm.
The invention is directed to a portable lock-
ing device which is electrically activated and sounds an
; 25 alarm when moved or damaged. The device includes an
electrically conductive securing mechanism.
In a preferred embodiment, the locking device
comprises a housing which contains an alarm, and an
electrically conductive elongated securing mechanism
fixedly secured at one end to the housing. The device
6~
also includes means for locking the other end of the
securing mechanism in the housing so that the housing
and securing mechanism together form a continuous loop.
Further, the device includes motion sensitive switching
means, continuity sensitive switching means, and arming
means - all contained within the housing. The motion
sensitive switching means is for sounding the alarm in
response to movement of the housing. The continuity
sensitive switching means electrically connects with the
securing mechanism on the formation of the continuous
loop for sounding the alarm in response to a subsequent
interruption in the electrical continuity of the secur-
ing mechanism. The arming means is for disabling the
sounding of the alarm except when the securing mechanism
lS is locked in the housing by the locking means.
The motion sensitive switching means may in-
clude a latching feature for maintaining the sounding of
the alarm such that once sounded by the action of the
motion sensitive switching means the alarm continues to
sound until the securing mechanism is unlocked from the
housing.
A mercury switch may be suitably utilized in
the motion sensitive switching means. If a latching
~eature is not desired, the mercury switch may be placed
in a simple series path connection with the alarm. In
cases where a latching feature is desired, the mercury
switch may be placed in a series path connection between
a voltage dividing network and the gate trigger lead of
a silicon controlled rectifier, the silicon controlled
rectifier be~ng in a series path connection with the
- ~4~4~
alarm. The voltage dividing ne-twork provides a suitable
~iasing voltage such ~hat when the mercury swi-tch closes
the silicon controlled recti~ier triggers to an on con-
dition. Once the silicon controlled rectifier is turned
on, it remains on whether or not ~le mercury switch sub-
sequently opens.
The continuity sensitive switching means may
comprise a transistor switch connected in a series path
with the alarm, the securing mechanism being electrical-
ly interconnected with the transistor switch such that
the transistor is maintained in an off condition when
the securing mechanism is locked in the housing ~ but
then, only so long as there is no interruption in the
electrical continuity of the securing mechanism.
The arming means may comprise a magnet and a
magnetically activated switch, the magnet being carried
by the locking means of the device such that movement of
the locking means from an unlocked position to a locked
position brings the magnet into proximity with the mag-
netically activated switch thereby closing the magnetic-
ally activated switch. Power from a battery contained
within the housing, may be supplied to the motion sensi~
tive switching means and to the continuity sensitive
switching means upon closure of the magnetically acti-
vated switch.
Drawings
In the drawings:
FIGURE 1 represents a partially cut-away
elevation view of the securing device
v~
PIGURE 2 rapresents a schem~tlc view of ~he
electronic circuitry o~ the devlc0J
FIGURE~3a,3b and 3c repre~ent in turn a
detailed elevation view of the locking mechani~m in o~en
posit~on, an en~ 01evatlon view of ~he cyllnder and a
per~pective vi~w of ths cylinder~
FI5URE 4 repre~ents a deta~led elevation view
of the locking m~chanism in clo3ed po~ition;
FIGURE 5 represent~ a detailed elevation view
of an alternative chain-bushing connection;
FIGURE 6 repre~ents a ~etailed elevation view
of an alternative cable-bushing connection; and
FIGURE 7 represents a ~chematic view of an
alternative electronic circuit or the device.
Detailed Description of the Invention
Re~erring to FIGURE 1, the ba~ic alarm 8ecur-
ing device 1 con~i~ts of a chain 2 and a housing 3 which
contain~ a number o co-operating components. Housin~ 3
protectively hou~es a mercury switch 4, a DC battery S,
an alarm or buz~er 6, a resistor 7, a transi~tor 8 and a
reed ~witch 11, all o~ which are electrically intercon-
nected. ~he electrical connections between the~e com-
ponents are Rhown in FIGURE 2. Locking mean~ are pro-
vided by a locking bar 9 and a lock 10 ~ activated with a
key) which penetrate one side o~ hou~ing 3 ~the top ~ide
as shown in FIGURE 1~.
A ~haft 12, cylinder 13 and ehaft stopper 14
combination pen~trate~ hou~ing 3 on a ~ide ad~acent th~
bar 9 and lock 10 ( the left hand side aa shown in ~IGUR~
1), and i~ manually interconnectable with the locking
_ 5 _
. ~
. ~ ~
)64~
bar 9. Connected physically and electrically to the
shaft 12 are an insulated wire 15, a sheath 16, and
chain 2. The chain 2, wire 15, and sheath 16 combina-
tion forms an electricaly conductive securing mechanism
which can be of whatever length is required -for desired
applications. The chain, wire and sheath combination at
the other end is connected to a chain securing threaded
shaft 19, which is held in place on a side of the hous-
ing 3 opposite the shaft 12 (the right-hand side as
shown in FIGURE 1), by a pair of securing nuts 17 and
18. The wire 15 penetrates through the length of shaft
19 and is electrically connected to the alarm components
of the device.
A permanent magnet 20 is associated with lock-
ing bar 9. Housing 3 is held together at its four cor-
ners (as shown) by means of screws or bolts secured
within threaded holes 21. A nut 23 preven-ts shaft 12
from pulling out of the end of the housing.
Referring to FIGURE 2, which illustrates the
electrical circuitry of the device, SWll is a schematic
representation of magnetically activated reed switch 11
in FIGURE 1. When lock 10 in FIGURE 1 is engaged to a
locked position thereby causing magnet 20 to activate
switch 11, the result is equivalent to switching SW
from the open condition represented by solid line all
in FIGURE 2 to the closed condition represented by bro-
ken line bll.
SWls in FIGURE 2 is a schematic representa-
tion of the circuit path defined by wire 15 in FIGURE 1.
The open condition represen-ted by sol.id line a1s
)6~
prevails so long as wire 15 does not form a closed elec-
trical loop with the circuitry in box 3. Provided the
continuity of wire 15 is not broken, such a closed elec-
trical loop is formed when chain 2 is connected in a
mechanical loop with box 3 as shown in FIGURE 1. The
closed condition of SW15 is represented by broken line
bl 5 in FIGURE 2.
SW4 in FIGURE 2 is a schematic representation
of mercury switch 4 in FIGURE 1. The normally open con-
dition oE SW4 is represented by solid line a4 in FIGURE
2. ~hen a circuit pa-th through the switch is completed
by the movement oE mercury within the switch, the switch
is in a closed condition as represented by broken line
b4 in FIGURE 2.
In use, SWls will ordinarily be the first
switch to close. This event happens when chain 2 (with
wire lS) is looped with box 3. Next, SWll is closed.
This event happens when looped chain 2 is locked into
position.
Upon the closing of SWll the circuit of
FIGURE 2 becomes armed with power from battery 5.
However, no sound will emanate from buzzer 6 so long as
transistor 8 remains in an off condition and SW4 remains
in an open position as shown in FIGURE 2.
As will be readily apparent, transistor 8 will
remain in an off condition so long as SWls remains in a
closed condition. When SWls is in a closed condition,
there is no sufficient bias on the base emitter circuit
of transistor 8 to permit current to flow in its collec-
tor circuit. If SWls is now opened, a base-emitter
curren-t (limited by the resistance of resistor 7) would
flow through transistor 8 thereby biasing the transistor
into an on condition, in turn permitting current to flow
through and sound buzzer 6. This event would happen
whenever the continuity of wire 15 was broken - for
example, by the cutting of chain 2 together with wire
15.
The closure of SW4 will complete a direct cur-
rent path from battery 5, through SWll, through buzzer
6, and back to battery 5. Accordingly, buzzer 6 will
sound upon closure of SW4.
Thus, it can be seen that when the circuit of
FIGURE 2 is armed by the closing of SWll, the alarm or
buzzer 6 will sound if SWls Or SW4 is closed. The
closure of SWls is equivalent to the cutting or break-
ing of wire 15 (which will ordinarily happen if chain 2
is cut or broken). The closing of SW4 is equivalent to
the closing of mercury switch 4 which will ordinarily
happen with suitable tilting or other motion imparted to
the mercury switch.
A conventional 1.5 volt battery may be used to
energize the device. Obviously, however, other battery
voltages could be used with suitable component selection
being made dependent upon the available voltage.
FIGURE 3a illustrates a detailed elevation
view of the locking mechanism in open position. The
locking bar ~, which is pivotally attached to the lock
10, is swung away from the threaded shaft 12 and cylin-
der 13. FIGURES 3b and 3c show details of the cylinder
13. In FIG~RE 4, which illustrates the device in closed
position, the rotation of a key (no-t shown) in lock 10
has rotated locking bar 9 to a position where it and
magnet 20 are swung into a groove in shaft 12. FIGURE 4
also illustrates reed switch 11 immediately below
locking bar 9 and magnet 20. The locking device is set
for alarm sounding purposes after chain shaft 12 is
inser-ted into cylinder 13 and a key is turned to secure
lock 10.
FIGURE 5 illustrates an alternative method of
connecting the chain to housing 3. The end of the chain
is isolated from the box by means of a plastic bushing
24. The insulated wire may be replaced by a bare copper
wire 26. This enhances the chain length connection.
The copper wire 26 must also be isolated from housing 3
by the plastic bushing 24. The alarm sounds as soon as
the chain-wire is severed, or the mercury switch is
a~itated. The head of the chain and the mechanism are
left intact. A steel washer 25 holds -the bushing 24 in
place in the wall of housing 3. In turn the washer is
held in place by a pair of nuts 28 and 29 on each side
of the box-wall. The end shat 30, which can be
constructed of brass, fits within the bushing 24 and -the
steel washer 25. The end of shaft 30, opposite chain
27, can be connected to the transistor by means of a
wire 31 soldered to the end of the shaft.
FIGURE ~ illustrates another alternative em-
bodiment of the device wherein a steel cable 32 replaces
the chain 27. The advantage of a steel cable 32 is that
it is inherently electrically conducting and thus there
is no need for any connecting wire running throu~h the
3~
chain. The end of the cable 32 is electrically isolated
from housing 3 by means of a plastic bushing 33. The
steel cable is insulated by means of an exterior sheath
34.
FIGURE 7 illustrates an alternative embodiment
for the electrical circuitry. As can be seen, all
components which appear in the circuitry of FIGURE 2 are
repeated in the circuitry of FIGURE 7. However, FIGURE
7 inclu~es three additional components, namely, a
silicon controlled rectifier 35, and resistors 37 and
38.
Structurally, the circuit of FIGURE 7 .is very
similar to the circuit of FIGURE 2. One essential dif-
ference lies in the placement of silicon controlled rec-
ti~ier 35 in the position where mercury switch SW4 was
: located in FIGURE 2. However, as can be seen in FIGURE
7, mercury switch SW4 is still utili~ed; it is connec-
ted in a series path from resistors 37 and 38 acting as
a voltage dividing network to gate trigger lead 36 of
silicon controlled rectifier 35.
In operation, silicon controlled rectifier 35
will normally be in an off condition so ~ong as switch
SW4 remains in an open condition as shown in FIGURE 7.
However, when switch SW4 as shown in FIGURE 7 closes,
silicon controlled rectifier 35 will be triggered to ~n
on condition by a suitable bias determined by the volt-
age of battery 5 and the resistances of resistors 37 and
38.
When silicon controlled rectiier 35 is trig-
gered to an on condition, it provides a path or current
-- 10 --
49
to flow through buzzer 6, and thereby sound the buzzer.
However, it will be appreciated that once sounded by the
triggering of silicon controlled rectifier 35, buzzer 6
will continue to sound until the source of power is
disabled by opening switch SWl1. Once triggered by the
closing of mercury switch SW4, even by a momentary clos-
ing, silicon controlled rectifier 35 will turn on and
will remain on until forward current through the silicon
controlled rectifier reduces to zero. Thus, the motion
sensitive switching means embodied in the circuit of
FIGURE 7 includes a latching feature.
No such latching feature is embodied in the
circuit o FIGURE 2. In FIGURE 2, buzzer 6 will turn
off and on as mercury switch SW4 opens and closes.
The absence of a latching feature may be considered un-
desirable because a person tampering with the locking
device might determine a way to carefully move the de-
vice without sounding the alarm for any significant
length of time. On the other hand, it is considered
that the sounding of an alarm, even on a momentary
basis, will be sufficient to deter many persons who
tamper ~ith the locking device. Hence, the absence of a
latching feature may not be considered particularly
serious. If a latching feature is not used, somewhat
fewer electrical components are required.
The subject portable securing device enables
an individual to secure valuable personal belongings
against theft. A belonging in question is secured by
fastening it to a suitable stationary immovable item by
means of the chain locking mechanism or simply wrapping
-- 11 --
649
the chain around the possession. The leng-th oE the
chain can be adjusted to suit the situation desired.
As will be apparent to those skilled in the
art in the light of the foregoing disclosure, many
alterations and modifications are possible in the
practice of this invention without departing from the
spirit or scope thereof. Accordingly, the scope of the
invention is to be construed in accordance with the
substance defined by the following claims.
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