P/00/011 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "WIRELESS HORN RELAY TYPE CAR ANTITHEFT SYSTEM" The following statement is a full description of this invention, including the best method of performing it known to me/us: WIRELESS HORN RELAY TYPE CAR ANTITHEFT SYSTEM FIELD OF THE INVENTION 5 The presentinvention relates toa car antitheft system, and more particularly to a wireless horn relay type car antitheft system that is associated with an original horn relay to effectively hide from a thief while.allows easy installation, and may drive an original horn to 10 sound as an alarm. BACKGROUND OF THE INVENTION A car is an indispensable traffic tool to most people 15 in the modern society. To protect a car from being stolen, most car owners would install an antitheft device on the car. However, most conventional antitheft devices involve complicate wiring and therefore must be installed by a skilled worker instead 20 ofageneraluser. Suchconventionalantitheft devices are easily found out by a thief and become useless once they are destroyed. For instance, a conventional electronic car antitheft 25 device would generally be connected to an additionally 1 mounted siren or an original car horn, so that the siren or the car horn produces warning sound when the antitheft device is triggered. To mount the additional siren in a car, it is necessary to extend a siren output line 5 througha firewalltoanengine roomofthecartoconnect to the siren. At least one hole must be drilled on the engine room to fix the siren, and the drilling must be done by a skilled worker. When the antitheft device is directly connected to the original horn, it is still 10 necessary to extend the horn output line through the firewall to the engine room to connect to the horn, or to find an original horn trigger switch by a skilled worker. 15 Moreover, for the purpose of successfully extending the horn output line, the original wiring hole on the firewall or the hole for an engine hood control line mustbeexpanded, orholesmustbedrilledon the firewall. These works would increase the installation labor and 20 time, and the expanded or the newly drilled hole would endanger the sealed firewall to admit waste gas or rainwater to the car. It is therefore tried by the inventor to develop a 25 wireless horn relay type car antitheft system to 2 eliminate the drawbacks existed in the conventional car antitheft devices. SUMMARY OF THE INVENTION 5 A primary object of the present invention is to provide a wireless horn relay type car antitheft system that is effectively hidden in an original horn relay, allows easy installation without the need of drilling and 10 wiring in a car, and may drive an original horn to sound as an alarm. To achieve the above and other objects, the wireless horn relay type car antitheft system of the present 15 invention includes a horn relay -housing internally provided with a power input and voltage regulator circuit, a radio transceiving circuit, a CPU decoding and controlling circuit, a horn relay driving circuit, a relay, and an antitheft sensor to detect any car theft 20 behavior and drive an original horn to sound. The horn relay housing has input/output (I/O) terminals the same as those of an original horn relay; and a set of power cords including a positive power cord having a positive terminal in the form of a fuse plug for plugging into 25 an original positive voltage fuse socket to obtain 3 positive power supply, and for receiving an original fuse therein, and a negative power cord connected to a car body. The antitheft system also includes a wireless remote controller for remotely controlling 5 the on and off of all circuits in the horn relay housing. The original horn may be driven by the antitheft system of the present invention to produce warning sound and therefore also functions like an alarm. The horn relay housing may be easily installed by directly mounting 10 it into an original horn relay socket in the car without the need of drilling, wiring, and mounting additional siren in the car. BRIEF DESCRIPTION OF THE DRAWINGS 15 The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and 20 the accompanying drawings, wherein Fig. 1 is a block diagram of a wireless horn relay type car antitheft system according to a first embodiment of the present invention; 25 4 Fig. 2 is a block diagram of a wireless horn relay type car antitheft system according to a second embodiment of the present invention; and 5 Fig. 3 is a plan view of an embodiment of a wireless antitheft sensor used in the car antitheft system of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 10 Please refer to Fig. 1 that is a block diagram of the wireless horn relay type car antitheft systemaccording to a first embodiment of the present invention. As shown, the car antitheft system includes a horn relay 15 housing 1, in which there are provided a power input and voltage regulator circuit 11 for supplying working power to all circuits of the car antitheft system; a radio. transceiving circuit 12 for receiving a wireless signal and amplifying and converting the received 20 signal to a digital signal; a central processing unit (CPU) decoding and controlling circuit 13 for decoding the digital signal and providing a control signal; a horn relay driving circuit 14 for amplifying the control signal to drive a relay 15, also provided in the housing 25 1, and thereby driving an original horn 8 to sound; 5 and an antitheft sensor 2 electrically connected to the CPU decoding and controlling circuit 13 for detecting any theft behavior. 5 The horn relay housing 1 is designed to have the same size and appearance as an original horn relay, so as to prevent the horn relay housing 1 from being easily found out by a thief. The horn relay housing 1 also structurally includes a set of input/output (I/O) 10 contacts 3, which have terminals the same as those provided on an original horn relay; and a set of power cords 4 having a positive terminal in the form of a fuse plug. Awireless remote controller 5isexternally provided for remotely controlling the on and off of 15 the circuits inside the horn relay housing 1, or causing the horn to sound for locating the car or looking for help. To manufacture the wireless horn relay type car 20 antitheft system of the present invention, first mount the power input and voltage regulator circuit 11, the radio transceiving circuit 12, the CPU decoding and controlling circuit 13, the horn relay driving circuit 14, the relay 15, and the security sensor 2 into the 25 horn relay housing 1, and then make the input/output 6 contacts 3 identical to the original horn relay terminals. To install the present invention, a user needs only to remove the original horn relay from the relay socket in the car and plug the present invention 5 in the original horn relay socket. The installation can be easily completed by a general user without the need of drilling, wiring or mounting additional sirens by a professional operator. The wireless horn relay type car antitheft system of the present invention is 10 easy to install, effectively hidden to provide good antitheft effect, and may use the original horn 8 as a siren to produce warning sound. It is known the horns on cars of different brands and 15 versions might be differently triggered. For instance, some cars have horns that can be actuated only by turning an engine key to ON; some cars have horns that would cause non-supply of negative voltage in negative trigger; and some cars have horns that would cause 20 non-supply of positive voltage in positive trigger. In response to these different ways of triggering the horns, the set of power cords 4 of the present invention includes a negative power cord 41 that is screwed to the car body, and a positive power cord 42 that has 25 a fuse socket connector 45 connected to an end thereof 7 for an original fuse 46 to plug thereinto. The fuse socket connector 45 is then plugged into an original positive voltage fuse socket. Thus, the present invention may be installed on a car of any type to obtain 5 positive and negative power supply and keep the protection of original fuse 46. With a car having the present invention installed thereon, a user may push a horn button 9 in an original 10 steering wheel, so that a signal is produced at a horn button input to pass the CPU decoding and controlling circuit 13, the horn relay driving circuit 14, and the relay 15 to drive an original horn 8 to sound. That is, the function of the original horn 8 is maintained. 15 The power input and voltage regulator circuit 11 functions to stabilize power voltage, so as to provide working power needed by all circuits of the present invention. The radio transceiving circuit 12 amplifies the signal received by an antenna thereof, 20 and converts the received signal into a digital signal, which is sent to the CPU decoding and controlling circuit 13 and decoded. When the decoded signal is found correct, a control signal is sent out according to the coded signal. The control signal is amplified by the 25 horn relay driving circuit 14 to drive the relay 15 8 to work, so that the original horn 8 is driven to produce sound and could therefore be used as an antitheft alarm or siren. 5 Please refer to Fig. 2 that is a block diagram of a wireless horn relay type car antitheft system according to a second embodiment of the present invention. In the second embodiment, the built-in antitheft sensor 2 is omitted, and an additional wireless antitheft 10 sensor 25 is provided. Alternatively, the present invention may include both the built-in antitheft sensor 2 and the additional wireless antitheft sensor 25, so as to provide increased detecting points for better antitheft effect. 15 The wireless antitheft sensor 25 may internally consist of different types of antitheft sensor and transmission circuit. It is possible for the wireless antitheft sensor 25 to expose only two power cords, so as to reduce 20 required wiring and simplify the installation thereof. Fig. 3 shows an embodiment of the wireless antitheft sensor 25 included in the present invention. In this embodiment, the wireless antitheft sensor 25 includes a built-in rechargeable battery 26, to which a cigarette 25 lighter terminal 27 is connected for plugging into an 9 original cigarette lighter socket, making the wireless antitheft sensor 25 more convenient for use and effectively hidden. 5 The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended 10 to be limited only by the appended claims. 10