Alarmed cable lock

An alarmed cable lock that sounds an alarm upon an attempt to open the lock or remove the secured item while the alarm is armed. The invention includes a lock, a cable, a power source and an alarm. The lock includes a C-channel closed at one end, a switch, and a blocking pin. The cable is attached at one end to the lock. The free end of the cable terminates in a head that is formed to slide in the C-channel. The switch is exposed in the C-channel. When the lock is armed, the blocking pin extends into the C-channel to prevent the free end of the cable from sliding out of the open C-channel end. If an attempt is made to remove the end of the cable by sliding it out the C-channel, the head passes by the switch and sets off the alarm. The alarm/lock features are operated by remote control.

This invention relates generally to locks. More particularly this invention 
relates to a cable lock that sounds an alarm, before the lock is defeated, 
if an attempt is made to steal the secured item. 
BACKGROUND 
Cable locks are known in the art for securing moveable objects to 
stationary objects. Typically a cable is threaded through the object and 
secured around an immovable object, thus anchoring the item to the 
immovable object. Cable locks are also used to secure parts of moveable 
objects to each other so that they cannot be easily transported or opened. 
For example, bicycles and motorcycles are secured by threading a cable 
around the bike frame and at least one wheel and locking the cable ends 
together such that the cable prevents the bike wheels from rolling. In 
this manner the bike cannot be rolled away. The bike can be lifted and 
moved, however, if it is not secured to an immobile object. 
Service trucks often carry expensive equipment that is too large to be 
locked in a tool box, but small enough to be carried away by a thief, 
loose in the bed of truck. Pick-up owners also carry equipment and toys 
loose in the bed of the trucks. U.S. Pat. No. 5,349,834 issued to Davidge 
illustrates a cable lock adhesively secured to the bed of a pick-up truck 
to secure equipment such as a chainsaw. U.S. Pat. 5,531,082 issued to Wolk 
discloses a portable security case which contains the objects to be 
secured. A cable integral with the case is locked around an immovable 
object such as a post. 
Thieves can defeat cable locks by severing the cable, breaking the lock 
mechanism, or carting the moveable object away, as in the case of a 
bicycle. Alarmed cable locks have been developed to alert the owner if the 
lock has been defeated. For example, U.S. Pat. No. 4,057,986 issued to 
Zolke describes a portable, battery-powered cable lock that sounds an 
alarm if the cable is cut. The disadvantage of this type of alarmed lock 
is that the alarm sounds only after the lock has been defeated. Since the 
cable must have been severed for the alarm to sound, by the time the owner 
responds to the alarm the thief may have escaped with the previously 
secured item. It is desirable to have a loud alarm that sounds when a 
thief attempts to break the cable or lock, or when the object is lifted to 
be carried away. 
Tamper resistant padlocks are described in the prior art. U.S. Pat. No. 
5,404,735 issued to Hsieh discloses a battery-powered alarmed padlock. The 
device is a padlock with a large U-shaped shackle having a vibration 
switch that triggers the alarm if abnormal vibration is detected. This 
lock is unsuitable to be used in vehicles which vibrate when in motion, 
and is limited in the size and shape of articles it can secure because of 
the rigid shackle. A cable lock is desired that can secure large items and 
detect tampering, but is relatively insensitive to vibration so that it 
can be used in a vehicle. 
Therefore, it is an object of this invention to provide an alarmed cable 
lock that sounds an alarm before the lock is defeated so that potential 
thieves are warned away. It is an object of this invention to provide an 
alarmed cable lock which can detect tampering, but is relatively 
insensitive to vibration so that it can be used in a vehicle without 
giving false alarms. It is a further object of this invention to provide 
an alarmed cable lock to secure loose equipment to, or within, a vehicle. 
SUMMARY OF THE INVENTION 
The present invention is an alarmed cable lock that sounds an alarm upon an 
attempt to open the lock or remove the secured item while the alarm is 
armed. The invention includes a lock, a cable, a power source and an 
alarm. The lock includes a C-channel closed at one end, a switch, and a 
blocking pin. The cable is attached at one end to the lock. The free end 
of the cable terminates in a head that is formed to slide in the 
C-channel. The switch is exposed in the C-channel. When the lock is armed, 
the blocking pin extends into the C-channel to prevent the free end of the 
cable from sliding out of the open C-channel end. If an attempt is made to 
remove the end of the cable by sliding it out the C-channel, the head 
passes by the switch and sets off the alarm. The alarm/lock features are 
operated by remote control.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 illustrates the alarmed cable lock, indicted generally as 10. The 
lock includes a cable 11 attached at one end to the lock housing 20. 
Alternatively, the cable 11 may be permanently attached at one end to 
another sturdy base, such as a vehicle body. The free end of the cable 11 
terminates in a head 12. The lock 10 includes a channel 14 to receive the 
head 12, a switch 15, a blocking pin 16, and a pin release 17. 
The blocking pin 16 and pin release 17 work in cooperation with a solenoid 
to control whether the blocking pin is in latch mode or release mode. FIG. 
2 shows the device in latch mode wherein the blocking pin is extended into 
the channel, thereby preventing the head from being removed from the 
channel. Blocking pin 16 extends into the channel 14 and through the lock 
housing 20. Pin release 17 is connected to the blocking pin 16 and is 
spring biased in a normally extended position with spring 21. While no 
current is running through solenoid 23, arm 22 obstructs the retraction of 
blocking pin 16 from channel 14. FIG. 3 shows the device in release mode. 
When current is running through the solenoid 23, arm 22 is attracted to 
the solenoid 23, thereby pulling it out of the path of the blocking pin 
16. Pin release 17 is depressed and blocking pin 16 is retracted from the 
channel, leaving an open path for the cable head to be moved into or out 
of the channel. 
FIG. 4 illustrates the circuitry of the preferred embodiment of the 
invention. The security system 41 is connected to the power source 40, 
preferably a vehicle battery. The security system 41 has at least one 
output terminal 42 and one input terminal 43. To retract the blocking pin 
16 from the channel 14, a high is output. The high turns on the transistor 
24 and current flows through the solenoid 23. The arm 22 is attracted 
toward the solenoid 23, which allows the pin release 17 to be manually 
depressed, retracting the blocking pin 16 and opening the channel 14. To 
prevent the pin release 17 from being depressed, thereby keeping the 
channel blocked and the head in the channel, a low is output. No current 
reaches the solenoid 23 and the arm 22 stays in a position to prevent the 
blocking pin 16 from retracting. To place the head 12 in the channel 14, a 
high is output to put the lock in release mode. The pin release 17 is 
depressed and the head is inserted. Preferably the low is output 
automatically after a given delay to return the lock to latch mode. 
The switch 15 works in cooperation with the head 12 to detect tampering. If 
the head is moved past the switch 15, a low is sent to the input 43 and 
the alarm sounds. If, for example, a thief grabs the cable and tries to 
pull the head from the channel to free the object, the alarm sounds and 
the thief is deterred by the sounding alarm. The switch 15 is interposed 
between the closed end of the channel and the blocking pin, so that the 
head has some room for movement in the channel before causing the alarm to 
sound. This allows for normal lock vibration and helps prevent false 
alarms. Preferably the switch is magnetic and is triggered with a magnet 
located in the head 12. Alternately, the switch may be electrical, 
optical, or physical, with a corresponding cooperative head to trigger 
each type of switch. Cooperative heads are made of, for example, a 
conductive metal, opaque material, or durable material, respectively. 
In the preferred embodiment, the lock housing 20 is permanently attached to 
a vehicle, preferably by welds or bolts, and most preferably in the bed of 
a service truck, as shown in FIG. 5. However, the lock housing 20 can be 
secured to any heavy or immovable object which functions as an anchor to 
the locked object. The channel is preferably installed in a vertical 
position, with the closed end of the channel at the bottom. In this 
configuration, the head tends to sit in the closed end of the channel with 
the aid of gravity until manually raised along the channel to detach the 
cable from the lock, thus helping to prevent false alarms. 
The system is operated by remote control. Remote controlled vehicle 
security systems are available commercially and may be installed during 
the vehicle manufacture or as an after-market accessory. To secure an 
object, the cable 11 is threaded through the item to be secured. The 
security system is set to release mode by remote control. Preferably, the 
security system is set to release mode simultaneously with arming the 
system. In a typical example, the remote control button is depressed, a 
chirp sounds to alert the user the system is armed and the release period 
has started. The pin release is depressed during the release period and 
the head is inserted into the channel and is left to rest below the 
switch. After a predetermined delay determined by the security system, the 
system reverts to latch mode and the pin release can no longer be 
depressed, thereby preventing the head from sliding out of the channel. 
While the security system is armed, if the head is moved past the switch, 
the alarm sounds.