BACKGROUND OF THE INVENTION Generally, a wire rope type lock includes a lock part formed with a key holder and a locking hole, a coupling part selectively inserted into and coupled to the locking hole, and a wire rope for connecting the lock part and the coupling part. Wire rope type locks are mainly used for preventing thefts of two-wheeled vehicles such as bicycles, pushcarts and the like.

In order to use wire rope type locks, a coupling part is coupled to a lock part and a separate key is used to couple an object with a wire rope while the coupling part and the wire rope are wound on the object (e. g. , wheels of bicycle). When the object is to be unlocked from the locked state, the key is used to unlock the coupling part from the lock.

However there is a drawback in the wire rope type lock thus described in that it can be easily cut off by a tool such as a cutter or the like, thereby rendering it difficult to prevent thefts.

SUMMARY OF THE INVENTION The present invention provides a wire rope type lock adapted to detect a cut- off state of a wire rope type lock and to activate an alarm when the wire rope type lock is cut off.

According to a preferred embodiment of the present invention, the alarm device for cutting off wire rope in a wire rope type lock including a wire rope secured at one end thereof to a case with the other end coupled to a coupled part, and a lock base formed with a lock part intrinsically equipped in the case for being coupled and decoupled by a separate key, the device comprises: a signal line intrinsically equipped in the wire rope; a cut-off detecting part applying voltage to the signal line to detect a voltage between both distal ends of the signal line to output a warning signal when a voltage level thus detected decreases to less than a predetermined level ; and a speaker generating an alarm in response to the warning signal outputted from the cut-off detecting part.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the nature and objects of the present invention, reference should be made to the following detailed description with the accompanying drawings, in which: FIG. 1 is an external perspective view of a cut-off alarming device for a wire rope type lock according to an embodiment of the present invention; FIG. 2 is a cross-sectional view of a wire rope of FIG. 1 ; FIG. 3 is a cross-sectional view of an inner structure of a case of FIG. 1 ; FIGS. 4 and 5 are cross-sectional views for illustrating a structure of an ON/OFF switch of FIG. 3 and an operating state thereof ; and FIG. 5 is a circuit diagram of a cut-off alarming device according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of the present invention will now be described in detail with reference to the annexed drawings, where the present embodiment is not limiting the scope of the present invention but is given only as an illustrative purpose.

Referring to FIG. 1, an alarm device for cutting off wire rope in a wire rope type lock according to an embodiment of the present invention includes a wire rope 10 coupled at one end thereof with a coupling part 11 made of a conductive material, and a case 20 secured at the other end of the wire rope 10 and formed with an inserting hole 21 for being inserted into by a coupling part 11 of the wire rope 10.

Now referring to FIG. 2, the wire rope 10 made of a plurality of twisted metal wires 10a is formed at a peripheral surface thereof with a coated layer 10b and is disposed at a core thereof with a signal line 30 wrapped by a coated layer 30a. The signal line 30 is connected at one end thereof to a contact point inside a case 20 (described later) and is connected at the other end thereof to the coupling part 11 made of conductive material.

Referring to FIG. 3, the case 20 is disposed with a lock base 40, an ON/OFF switch 50, a connector 60, a contact point 70, a printed circuit board 80, a battery and a speaker 100.

The lock base 40 includes a locking hole 41 connectible to the coupling part 11 of the wire rope 10, a key holder 42 horizontally rotatable by a key (K) that is inserted at the top thereof and a lock part 43 for coupling or decoupling the coupling part 11 coupled to the locking hole 41 by the key (K) inserted via the key holder 42.

The lock base 40 is fixed to an inner wall of the case by a plurality of fixing brackets.

The ON/OFF switch 50 openable and closeable by way of a contact point switching method is used to apply or block the power of the battery 90 to the printed circuit board 80 by switching the contact point in relation to a position of the key holder 42.

Referring to FIGS. 4a and 4b, the ON/OFF switch 50 includes a movable contact point part 51 coupled to a lateral surface of the key holder 42, a housing 52 accommodating the key holder 42, and a pair of fixed contact points 53 and 54 attached to an inner lateral wall of the housing 52 to contact the movable contact point part 51 in relation to a rotating position of the key holder 42.

The connector 60 of a ring-shaped contact point is electrically connected at one end thereof to the printed circuit board 80 and is mounted to an area between the inserting hole 21 of the case 20 and the locking hole 41 of the lock base 40, and is abutted and electrically connected to the coupling part 11 when the coupling part 11 is coupled to the locking hole 41 via the inserting hole 21.

The contact point 70 is fixed to an inner wall surface of the case 20, and is electrically connected at one side thereof to the printed circuit board 80. The contact point 70 is also coupled to the wire rope 10 to secure the wire rope 10 to the case 20 and is electrically connected to the signal line 30 buried in the wire rope 10.

The printed circuit board 80 is operated by being applied with the power from the battery 90 and detects a cut-off of the wire rope 10, and is mounted with a variety of electrical and electronic parts for generating a control signal for activating an alarm.

The speaker 100 is attached to an inner upper side of the case 20 to generate a warning sound in response to the signal inputted from the printed circuit board 80.

The warning sound from the speaker 100 is transmitted outside of the case 100 through a through hole 22 formed at an upper end of the case 100. The circuitry of the cut-off alarming device thus described according to the embodiment of the present invention is shown in FIG. 5.

Referring to FIG. 5, the battery 90 is grounded at one end thereof and is connected at the other end thereof to a fixed contact point 53 of the ON/OFF switch 50.

The fixed contact point 53 of the ON/OFF switch 50 is commonly connected to the connector 60, a base terminal of a transistor (Tr) on the printed circuit board 80, a positive (+) pole terminal of a first capacitor (C1) and a positive (+) pole terminal of a second capacitor (C2).

A negative (-) pole terminal of the first capacitor (C1) is connected to a secondary winding of a transformer (TF) arranged on the printed circuit board 80 while a negative (-) pole terminal of the second capacitor (C2) is grounded.

A resistor (R1) is connected in a series between the fixed contact point 54 of

the ON/OFF switch 50 and the connector 60. A collector terminal of the transistor (Tr) is grounded and an emitter terminal is connected to a first winding of the transformer (TF).

Furthermore, the signal line 30 is selectively connected at one end thereof to the connector 60 via the coupling part 11 and is grounded at the other end thereof via the contact point 70.

Next, the operation of the present invention thus constructed will be described in detail with the annexed drawings.

First, a user winds the wire rope 10 on an object (e. g. , a wheel of a bicycle), and inserts the coupling part 11 via the inserting hole 21 of the case 20 for coupling with the lock base 40 of the locking hole 41. The user uses the key (K) to operate the lock part 43 to allow the coupling part 11 to be coupled to the coupling hole 41.

At this time, the key holder 42 is positioned as shown in FIG. 4b to allow the movable contact point part 51 of the ON/OFF switch 50 to contact the fixed contact points 53 and 54, prompting the ON/OFF switch 50 to be switched ON.

The current of the battery 90 is applied to the signal line 30 via the ON/OFF switch 50 and the resistor (Rl) to be passed to the ground of the signal line 30 according to the turn-on of the ON/OFF switch 50.

As a result, an electrical closed circuit connecting from the battery 90 to the resistor (Rl) and the signal line 30 is formed, and a short circuit is prevented from being generated by the resistor (Rl), but the current of the battery 90 is consumed by the resistor (Rl). The amount of consumed current is very small such that the battery 90 will last for months even in the case of a commonly used dry cell.

The transistor (Tr), being higher in potential level at the base terminal than the potential level between the emitter and the collector, maintains the turned-on state, and when the transistor (Tr) maintains a turned-off state, no current flows to the secondary winding of the transformer (TF).

If theft occurs and the signal line 30 is cut off, the current of the battery 90 is

charged in the first and second capacitors (C1 and C2). When voltage charged by the first and second capacitors (C1 and C2) reaches a predetermined level or more, the potential level at the base terminal of the transistor (Tr) becomes higher than that between the emitter and the collector, thereby turning on the transistor (Tr).

When the transistor (Tr) is turned on, the current of the battery 90 flows in the first winding of the transformer (TF), which prompts the current to be induced to the secondary winding of the transformer (TF). The current induced to the secondary winding of the transformer (TF) is applied to the speaker 100 and a warning sound is generated therefrom.

When a preset period of time lapses, the voltage charged in the first and second capacitors (C1 and C2) are discharged, and the transistor (Tr) is switched off because the potential level between the emitter and the collector becomes higher than that of the base terminal.

The current cannot flow to the first winding of the transformer (TF) because of the turned-off of the transistor (Tr), whereby the current is not induced to the secondary winding of the transformer (TF) to stop generating the warning sound from the speaker 100.

When the voltage charged in the first and second capacitors (C1 and C2) reaches a predetermined level after a preset period of time, a warning sound is generated again from the speaker 100. In other words, intermittent warning sounds are generated in response to charging and discharging periods of the first and second capacitors (C1 and C2).

By way of reference, a period of generating warning sounds from the speaker 100 can be adjusted by changing CR time constants of the first and second capacitors (Cl and C2) and the resistors (R1).

When a user uses the key (K) to operate the lock part 43, decoupling the coupling part 11 coupled to the locking hole 41, the key holder 42 is changed to a position shown in FIG. 4a to separate the movable contact part 51 of the ON/OFF

switch 50 from the fixed contact points 53 and 54, and the ON/OFF switch 50 is switched off.

The current does not flow from the battery 90 in response to the switched-off state of the ON/OFF switch 50, thereby stopping the generation of the warning sounds from the speaker 100.

Meanwhile, when a user wants to use an object while the signal line 30 is not cut off, the key (K) is used to activate the lock part 43 and to decouple the coupling part 11 fastened to the locking hole 41 so that the object can be unraveled from the wire rope 10.

At this time, the key holder 42 is changed to a position illustrated in FIG. 4a to prompt the ON/OFF switch 50 to be switched off, thereby preventing the warning sound from being generated from the speaker 100.

The foregoing description of the preferred embodiment of the present invention has been presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents.

As apparent from the foregoing, there is an advantage in the alarm device for cutting off wire rope in a wire rope type lock thus described according to the embodiment of the present invention in that the cut-off state of a wire rope is detected to allow a warning sound to be generated from a speaker when the wire rope is cut off while a coupling part of the wire rope is coupled to a lock part, thereby preventing thefts from occurring and improving the security of the wire rope type lock.