GB2254719A

GB2254719A - Theft alarm device

Info

Publication number: GB2254719A
Application number: GB9107499A
Authority: GB
Inventors: Ralph Lai
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-04-09
Filing date: 1991-04-09
Publication date: 1992-10-14
Also published as: GB9107499D0

Abstract

A bicycle/motorcycle theft alarm device, comprising an alarm control circuit and an alarm set in a control box and controlled to operate by a key 3. A take-up mechanism 16 is set in the control box to automatically take up a conductive fastening cord 2 which is provided for fastening a bicycle/motorcycle in place. The opposite end of the conductive fastening cord is inserted in the control box to drive the alarm into alarm mode. Alarm signal is given when the fastening cord is broken or out of place. <IMAGE>

Description

THEFT ALARM DEVICE BACKGROUND OF THE INVENTION The present invention relates to a theft alarm device which is especially, although not exclusively, suitable for use as a cycle theft alarm, for example for pedal cycles and motorcycles.

Various types of locking devices have been commonly used by bicyclists or motorcyclists to lock bicycles and motorcycles or to fasten them in place. Some people even use chain fasteners to fasten a cycle securely to a telegraph pole or supporting object so as to protect the cycle from being stolen. Although a thief may require more time to unlock or remove the cycle, the conventional devices cannot give any alarm signal to deter theft.

Accordingly, an object of the invention is to provide a theft alarm device which automatically gives an alarm signal to deter thieves when removed from the article, such as a bicycle or motorcycle.

One aspect of the invention provides a theft alarm device, comprising an electrically-conductive cord whose ends are connectable via a control means such that the cord forms part of an electric circuit, the control means being arranged to provide an alarm signal in response to the electric circuit being broken, security means being provided to permit selective activation and deactivation of the control means.

According to a preferred embodiment, a bicycle/motorcycle theft alarm device, comprises: a control box comprising a casing holding a battery set, a control circuit and a take-up mechanism, said casing having a key switch and a plug hole at one side and an alarm output port at another side, said battery set being connected to said control circuit, said control circuit comprising an alarm, a relay and a socket, said socket being disposed in alignment with said plug hole, said take-up mechanism comprising a ratchet wheel mounted on a coiled spring and controlled by a check pawl; a conductive fastening cord having one end fixedly secured to said take-up mechanism and an opposite end coupled with a conductive plug pin; and a key to control said key switch; whereby said key is insertable in said key switch and rotatable to connect said battery set to said control circuit after said conductive plug pin has been inserted into said socket through said plug hole, to drive said alarm into alarm mode so that said alarm gives an alarm signal if said conductive fastening cord is cut or disconnected from said socket.

bicycle/motorcycle automatically when it is removed from place.

RIEF DESCRIPTION OF THE DRAWINGS : Fig. 1 is a perspective view of the preferred embodiment of the bicycle/motorcycle burglar alarm device of the present invention; Fig. 2 is a schematic circuit diagram according to the present invention ; and Fig. 3 is a cross section illustrating the internal structure of tile preferred embodiment of the bicycle/motorcycle burglar alarm device of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT : Turning now to the annexed drawings in greater detail and referring first. to Fig. 1, there is illustrated a bi.cycle/motorcycle burglar alarm device constructed accorCIng to the present invention and generally comprised of a control box 1, a fastening cord 2, and a key The control box 1 is comprised of a casing having a key switch 11 and a plug hole 12 disposed at one side for inserting the key 3 and the fastening cord 2 respectively, and an alarm output port 13 disposed at another side for output of warning sound.REferring to Fig. 3, at the inside of the control box 1, there is provided a battery set 14, a control circuit board 5 and a 4 lake-up mechanism 16, wherein said battery set 14 and said control circuit 15 are respectively connected to the key switch 11 and controlled to operate by the key 3 (see the circuit diagram in Fig. 2).

The take-up mechanism 16 is set inside the control box 1 at one corner, comprising a ratchet wheel 161 controlled by a coiled spring (which is enclosed at the inside of the ratchet wheel 161) to automatically take.up the fastening cord 2; and a check pawl 162 to stop said ratchet wheel 161 from reverse rotation. The fastening cord 2 is made from conductive string having one end fixedly secured to the take-up mechanism 16 and an opposite end fixedly coupled.

with a conductive plug pin 21. By inserting the conductive plug pin 21 in the plug hole 12, the fastening cord 2 forms into a closed circuit. As indicated, the fastening cord 2 can be automatically been up by the take- up mechanism 16, the total length of the fastening cord 2 is preferably designed suitable for binding a supporting object, for example, a telegraph pole. The key 3 is made from conductive metal in shape and sine to match the key switch 11.

Referring to Fig. 2 again, the operation of the alarm device is controlled by inser4:ing the key 3 in the key switch 11. Under disarm mode, the intermediate conductive strip of the relay 152 i.s disposed in contact with the top conductive strip thereof and, the two opposite terminals of the key switch 11 are disconnected from each other. As soon as the plug pin i of the fastening cord 2 is inserted in the plug hole r2, the socket 154 which is shown in Fig. 2 is immediately connected.If the key 3 is inserted in the key switch 11 after the socket 154 is connected, the resistor 155, the coil of the relay 152 and the alarm 151 fonn a short circuit due to electric contact between the socket 154 and the relay i52, Therefore, the relay will not be excited to tv!rn on the alarm 151. Under this condition, if the plug pin 21 is removed from the socket 154 or the fastening cord 2 is cut off, the relay 152 will be immediately excited permitting the intermediate conductive strip thereof to contact the bottom conductive strip thereof so as to further turn on the alarm 151.As soon as the alarm i51 is turned on, insertion of the plug pin 21 into the socket 154 again can not stop the alarm 151 from giving warning signal. Therefore, when a bicycle or motorcycle is placed ii position, the fastening cord 2 is pulled out from the control box 1 to bind the front or rear wheel of id bicycle e or motorcycle to - supporting object. Then, the key 3 is inserted in the key switch 11 to switch it to alarm mode and then, remove the key 3 froin the control box 1. To disarm the alarm device, it i to insert the key 3 in the key switch 11 and turn tie key switch 11 to disarm mode.

It is to be understood that the drawings are designed for purposes of illustration only, various modifications could b made to the present invention without departing from the basic teachings thereof.

Claims

1. A theft alarm device, comprising an electrically-conductive cord whose ends are connectable via a control means such that the cord forms part of an electric circuit, the control means being arranged to provide an alarm signal in response to the electric circuit being broken, security means being provided to permit selective activation and deactivation of the control means.

2. A theft alarm device according to Claim 1, wherein the security means comprises a key-operated switch.

3. A theft alarm device according to Claim 1 or 2, wherein one end of the cord is permanently attached to a control box containing the control means and the security means.

4. A theft alarm device according to Claim 3, wherein the control box is provided with a take-up mechanism from which the cord may be unwound and by which it may be rewound.

5. A bicycle/motorcycle theft alarm device, comprising: a control box comprising a casing holding a battery set, a control circuit and a take-up mechanism, said casing having a key switch and a plug hole at one side and an alarm output port at another side, said battery set being connected to said control circuit, said control circuit comprising an alarm, a relay and a socket, said socket being disposed in alignment with said plug hole, said take-up mechanism comprising a ratchet wheel mounted on a coiled spring and controlled by a check pawl; a conductive fastening cord having one end fixedly secured to said take-up mechanism and an opposite end coupled with a conductive plug pin; and a key to control said key switch; whereby said key is insertable in said key switch and rotatable to connect said battery set to said control circuit after said conductive plug pin has been inserted into said socket through said plug hole, to drive said alarm into alarm mode so that said alarm gives an alarm signal if said conductive fastening cord is cut or disconnected from said socket.

6. A theft alarm device, substantially as described with reference to, or as shown in, the drawings.