Note: Descriptions are shown in the official language in which they were submitted.
PORTABLE LOCKING DEVICE WITH BUILT-IN ALA~M
The present invention relates to portable locking
devices, and in particular to a cable locking device whi~h
comprises a cable lock and a battery operated alarm to warn
of tampering.
Cable locking devices are knowrl in the art,
comprising a cable wound on a spool disposed w:ithin a housing.
The free end of the cable i5 adapted to releasably engage
with a mechanism for locking the cable to the housing. With
this arrangement, the cable can be manually pulled out from
the spool, passed around the article to be protected (for
example a bicycle) and a securely fixed object tfor example
a street lamp standard), and locked back onto the housiny,
thereby securing the article against theft. Typical examples
of this type of device may be found in Canadian Patent No.
595,042 (Gossner); Canadian Patent No. 978,765 (Lyon et al);
Canadian Patent No. 1,020,765 (Hurwitt); United States Patent
No. 3,611,760 (Muther); and United States Patent No. 3,67Q,535
(Stettner et al)
Cable locking devices known in the art demonstrate
various means for extending and retracting th~ locking cable,
and for locking the free end of the cable to the housing.
With these elements, a measure of protection against theft is
afforded. However, it has been found that a cable can be cut
fairly easily with a pair of readily available cable or bolt
cutters.
In general, the response to this eventuality has
been to use some form of alarm circuit in addition to a lock.
For example, an alarm system typically used employs a motion
sensor which triggers an audible alarm when the article to be
protected is moved. This soIution suffers from frequent false
alarms resulting from inadvertent movements of the article
~such as, for example, from being bumped by passers-by)~
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Another disadvantage of the above described
arrangement lies in the fact that the lock and alarm are
typically sold as two separate units. Furthermore, the alarm
circuits are typically unsightly, since they are designed for
function rather than visual appearance, and are otherwise
unsuitable for installation on articles such as bicycles,
where the alarm circuitry itself is exposed, and therefore
vulnerable to damage resulting from tampering, accidents, or
even the weather.
It is therefore an object of the invention to
provide a portable locking device which comprises both a cable
lock and an alarm circuit within a compact unit, the housing
of which provides substantial protection for the locking
mechanism and the alarm circuitry.
It is another object of the invention to provide a
portable security device in which the alarm circuit is adapted
to detect and warn of tampering with the cable and/or the
housing of the device. ~ -
20It is further object of the invention to provide an -~ -
alarm circuit for use in a portable locking device in which ~-
the propensity for false alarms is substantially reduced.
It is yet another object of the invention that the
alarm circuit be provided with a simple battery test function
or an audible low battery warning.
The portable locking device of the invention is
provided as a locking device for securing an article against
theft, which comprisesO a spool rotatably disposed within a
housing; a cable wound on said spool, one end of said cable
being fixedly secured to said spool, and the free end of said~
cable extending out of said housing through an opening
provided therein; engaging means disposed in the side of said
housing for releasably securing the free end of said cable to
35 said housing; and battery operated alarm means disposed inside ~- -
said housing for producing an alarm signal upon detection of
tampering with either of said housing or said cable, wherein
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said alarm means comprises a normally closed circuit
comprising a tamper switch; a relay; a silicon controlled
rectifier, a resistor, a transducer, and a power supply.
The cable spool may preferably be connected to a
spring which urges the spool to rotate so as to reel in the
cable. Notches provided in the spool can be used to lock the
spool against rotation in either direction when the cable lock
is in the locked condition. By this means, the cable may be
manually pulled out from the spool, passed around the article
to be protected (such as a bicycle) and a securely ~ixed
object (for example a street lamp standard), and locked back
onto the housing, thereby securing the article against theft.
Prior to locking, the spring-loaded spool will pull excess
cable back into the casing, thereby ensuring that a minimum
amount of cable in exposed.
The housing is composed of suitable materials which
are selected to provide high resistance to impact and
corrosion, as well as light weight. Materials used to form
the housing may include, for example, plastics and aluminum.
The cable is composed of materials which are
suitably selected to provide high resistance to shear (i.e.
cutting) as well as corrosion, while providing good
flexibility and electrical conductivity. Typical examples of
the type of cable which may be used are those types of cables
commonly referred to as "Aircraft Cable".
The engaging means is disposed within a wall of
housing and may, for example, be key operated. Thus the cable
can be selectively locked and unlocked from the engaging means
by inserting and turning the key. In addition to mechanically
locking and unlocking the cable, the engaging means preferably
serves to lock the spool against rotation when in the locked
position. ~n a further preferable embodiment, placing the
engaging means in the lo~ked position also turns on the alarm
circuit.
The alarm circuit and the engaging means may
preferably be adapted to provide a simple battery test
function. In particular, by placing the engaging means into
the locked position with the free end of the cable
disconnected from the engaging means, the alarm circuit will
test the cable and detect a "cable cut" condition, thereby
triggering an alarm signal.
The preferred embodiments of the invention will be
described in detail, with reference to the appended drawings,
in which:
Figure 1 shows a general view of an embodiment of
the locking device according to the invention;
Figure 2 schematically illustrates a cross sectional
view of an embodiment of the locking device according to the
invention;
Figure 3 illustrates an enlarged view of an
embodiment of the engaging means comprised within the
embodiment shown in Figure 2;
Figure 4 is a schematic illustration of a first
embodiment of an alarm circuit according to the invention;
and
Figure 5 is a schematic illustration of a second
embodiment of an alarm circuit according to the inventionO
.
Referring to Figures 1, 2 and 3, the locking device --
of the invention generally comprises a two-part housing 5 held
together by screws 10. A cable 15 extends through a cable ~ --
opening 16 in a wall of the housing 5, and terminates wikh a
plug 20. The plug 20 is adapted to fit into a plug opening
30 in a wall of the housing 5 to be locked in place by
engaging means (generally denoted by reference numeral 40).
A pattarn of openings (generally denoted by reference numeral
35) may be disposed in a wall of the housing 5 so as to --
facilitate emission of an audible alarm signal from the ~-
device. -
The housing 5 is preferably constructed so as to be
light-weight, resistant to water and other environmental
factors, and highly resjstant to tamp~ring. To this end, the
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housing 5, may be made of impact resistant plastics such as,
for example High-Density Polyethylene. Alternatively, the
housing 5 may be metal, such as aluminum. In addition, the
screws lO, which hold the housing 5 together, may be
constructed so as to require a special tool in order to be
removed, such as, for example, Torx (tradename) screws. A
contact switch (which acts as a tamper switch) 44 is disposed
inside the housing 5 and electrically connected to the alarm
circuit 60 as described below. When the housing 5 is securely
closed, the tamper switch 44 is held in the closed position,
whereas, when the housing 5 is opened, the tamper switch 4~
opens. By this means, if the housing is opened while the
alarm circuit is armed, the opening of the tamper switch 44
will be detected, and an alarm signal triggered.
The engaging means 40 comprises a shaft 46 which is
operatively engaged, for rotation in either direction, to a
locking cylinder 25. A plug cam 41 and a spool cam 42 are
fixedly disposed on the shaft 40, and are respectively adapted
to operati~ely engage the plug 20 and the notches 54 of the
spool 50. By this means, when the key 26 is inserted into
the locking cylinder 25, the shaft 46 may be rotated in one
direction so as to simultaneously move the plug cam 41 and the
spool cam 42 into the locked position, or alternately rotated
in the opposite direction to simultaneously move the cams 41
and 42 into the un-locked position.
The plug cam 41 comprises an plug end 41a and a
switch end 41b. The plug end 41a is adapted for operative
engagement with the plug 21, such that when the plug 20 is
inserted into the plug apparature 30 and the engaging means
40 rotated to the locked position, the plug end 41a engages
with the plug 20, thereby preventing removal of the plug 20
from the plug apparature 3Q. The switch end 41b, on the other
hand, is adapted to engage a contact switch 43 when the plug
cam 41 is rotated into the locked position. The contact
switch 43 is electrically connected to the alarm circuit 60
as will be described latter.
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Disposed within the housing 5 is a spool 50
rotatably mounted on a shaft 51 fixed to the inside of the
housing 5. A cable 15 is wound around the spool 50, passes
out of the housing 5 through ~he cable opening 16, and
terminates in a plug 20. The other end of the cable 15 is
fixedly attached to the spool 50. A coil spring 52 is
attached to the spool 50 and anchored to the inside of the
housing 5 so that the spool 50 is resiliently urged to rotate
in a direction which reels in the cable. Around the perimeter
of the spool 50, there is disposed a series of evenly spaced
notches 54 (only 5 of which are shown in Figures 2 and 3),
which are engagable with the spool cam 42 mounted on the shaft
46 of the engaging means 40. By this means, when the spool
cam 42 is moved into the locked position, the spool cam 42
operatively engages ait least one of the notches 54, thereby
locking the spool 50 against rotation in either direction.
Conversely, when the spool cam 42 is moved to the unlocked
position, the notches 54 are disengaged from the spool cam 42,
and the spool 50 thereby allowed to rotate. Finally, the
spool 50 includes contact means (not shown) adapted to
maintain an electrical connection between the spool end of the
cable 15, and the ground (or low voltage side) of the alarm
system.
The size of spool 50, spring 52, and the cable 15
are selected such that a suitable length (for example between
0.3 and 1.0 meter) of cable 15 may be pulled out of spool 50;
and when the locking device is not in use, the cable 15 will
be retracted into the spool 50 until the plug 20 is in contact
with the housing 5.
As the plug 20 is inserted ~nto the plug apparature
30, the plug 20 establishes an electrical connection with the
plug contact 45. When the plug 20 is fully engaged in the
plug apparature 30, the plug cam 41 can be moved into
operative engagement with the plug 20, thereby locking the
plug 20 into the plug apparature 30. As the plug cam 41 moves
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into the locked position, the switch end 41b of the plug cam
41 operates a contact switch 43, thereby arming the alarm
circuit 60. When the plug cam 41 moves out of the locked
position, the contact switch 43 is disengaged, and the alarm
circuit 60 thereby disarmed.
Referring now to Figure 4, the alarm system
generally comprises an alarm circuit 60, a battery 62, a
transducer 64, and a series sensor loop 68. The alarm circuit
60 comprises a silicon controlled rectifier (SCR) 63, a relay
coil 65, a relay contact 66, and a resistor 67. The series
sensor loop 68 comprises the tamper switch 44, the plug
contact 45, the plug 20, the cable 15, and the spool 50
connected in series between the gate of the SCR 63 and the
alarm circuit ground.
As mentioned previously, when the housing is
securely closed, the tamper switch will be closed. In
addition, when the plug 20 is completely engaged in the plug
apparature 30, the cable portion of the series sensor loop 68
is also closed. By this means, the series sensor loop 68 can
be opened either by opening the housing 5, or by breaking the
cable connection ~i.e. by removing the plug 20, or by cutting
the cable). Power is supplied from the battery 62, via
contact switch 43, to the resistor 67, the anode of the SCR
63, and the normally open relay contact 66. The resistor 67
is connected to the gate of the SCR 63, and one end of the
series sensor loop 68. The other end of the series sensor
loop 68 is connected to ground. The cathode of the SCR is
connected to the relay coil 65, and thereafter runs to ground.
The relay contact 66 is connected to the transducer 64.
When the engaging means 40 is moved to the locked
~osition, the switch end 41b of the plug cam 41 closes contact
switch 43 and supplies power form the battery 62 to the alarm
circuit 60. In the case when the housing 5 is closed, and the
plug 20 fully engaged in the plug apparature 30, the series
sensor loop 68 wiIl be closed. Under these conditions, the
gate of the SCR 63 will be connected to ground, and the SCR
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63 will be non-conducting. Thu~ no current will flow through
the relay coil 65 and the relay contact 66 will remain open.
This condition corresponds to a "stand-by mode" for the alarm
system, wherein the alarm system is armed, and continuously
monitoring the condition of the series sensor loop 68. The
resistor 67 serves to reduce the current flowing from the
battery 62, through the switch 43, the series sensor loop 68,
and finally to groundO For example, by using a 10 k-ohm
resistor, the current drain on the battery 62 will be 1 mA in
the "stand-by" mode.
If the series sensor loop is opened while the alarm
system is in a "stand-by" mode, the gate of the SCR 63 will
be disconnected from ground, and will therefore receive a high
voltage. The SCR 63 will therefore become to conducting, and
current will flow through the relay coil 65. This will cause
the relay contact 66 to close, connecting the transducer 64
to the battery 62. In response to the supply of power, the
transducer 64 emits an audible alarm signal of, for example,
approximately 120 db, thereby warning of tampering.
It can be seen that in this embodiment, there exists
a simple method for testing the alarm system. In particular,
if the engaging means 40 is moved to the locked position,
while the plug 20 is disconnected from the plug apparature
30, then the alarm circuit 60 will become armed while the
series sensor loop 68 is in an open condition. This will
cause the SCR 63 to immediately supply power to the relay coil
65, thereby causing the transducer 64 to emit an alarm signal.
Figure 5 illustrates a second embodiment of an alarm
circuit employed in the present invention. In this case, an
"OR" gate 70 is located between the resistor 67 and the gate
of the SCR 63. One of the "OR" gate 70 inputs is connected
to the resiskor 67, while the other input is connected to a
motion detector 72 via a delay timer 74. The motion detector
70, which may comprise a vibration sensor, accelerometer, or
other means for detecting motion, supplies a "motion detected"
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signal to the delay timer 74. In response to the beginning
of a "motion "detected" signal from the motion detector 72,
the delay timer 74 begins to count a predetermined time delay,
for example 15 seconds, while monitoring the "motion detected"
signal. If the "motion detected" signal is substantially
continuous for the duration of the predetermined time delay,
the delay timer 74 transmits a signal to the "OR" gate 70.
The "OR" gate 70 responds to a high voltage signal from either
the delay timer 74 or from opening of the sensor circuit 68
(as described in connection with Figure 4), by supplying a
high voltage to the gate of the SCR 63, thereby triggering an
alarm signal. By this means, the alarm circuit 60 can be
arranged to be triggered after a predetermined time (for
example 10-15 seconds) of continuous motion in addition to
opening of the sensor circuit 68. Consecliuently any mo~entary
movements, such as for example due to wind gusts or accidental
knocking by passers-by, which are shorter in duration than the
predetermined delay will not activate the alarm.
It will be apparent to those skilled in the art that
there are numerous ways in which the embodiments described
above may be varied. For example a clamping device may be
incorporated into the housing so that the locking device can
be permanently (or semi-permanently) fixed to an article, such
as a bicycle. In this alternative embodiment, the housing
might be opened to permit the clamping device to be opened and
brought into operative engagement with a convenient portion
of the bicycle frame. Thereafter, the clamping device is
cloe~ed and locked thereby fixing the housing to the bicycle
frame. When the housing is closed, the clampiny mechanism is
protected from tampering, thereby preventing the locking
device ~rom being removed from the bicycle.
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