Patent Abstract:
A car alarm apparatus includes a first horn; a second horn; an electrical source; a theft detection section; a horn switch; a first relay closed when the horn switch is operated; a first fuse connected to the electrical source in series with the first relay and the first horn; a second fuse connected to the electrical source separately from the first fuse; and a second relay connected to the electrical source in series with the second fuse and the second horn, wherein the second relay includes a first contact that connects the second horn to an electrical source through the first fuse and the first relay in parallel with the first horn and a second contact that connects the second horn to the electrical source through the second fuse, and closes the second contact when the occurrence of the theft is detected.

Full Description:
TECHNICAL FIELD 
     The present invention relates to a car alarm apparatus that gives an alarm at the time of ordinary use of a car and at the time of a theft. 
     Priority is claimed on Japanese Patent Application No. 2009-104433, filed on Apr. 22, 2009, the contents of which are incorporated herein by reference. 
     BACKGROUND ART 
     In recent years, cars and the like have been equipped with a car alarm apparatus having a function of sounding an alarm to the surroundings when the possibility of the car being stolen is detected, in addition to a function of sounding a horn (alarm) in the case of providing a warning to peripheral cars or pedestrians at the time of the ordinary use of cars which are moving or the like. 
     As disclosed in the following Patent Document 1, in this type of car alarm apparatus, it is important that an alarm reliably operates at the time of a theft.  FIG. 6  shows a configuration illustrating an electrical circuit in a conventional car alarm apparatus. 
     This conventional car alarm apparatus has two ordinary horns  81   a  and  81   b , and one exclusive horn  82  operating at the time of a theft. The ordinary horns  81   a  and  81   b  are connected to one terminal of a switch  131   a  included in a first relay circuit  131 . The other terminal of the switch  131   a  is connected to a positive terminal of an electrical source  110  through a first fuse  121 . In addition, one terminal of a coil  131   b  included in the first relay circuit  131  is connected to a first fuse  121  similarly to the switch  131   a . The other terminal of the coil  131   b  is connected to one terminal of a diode  150  and a horn switch  160 . 
     On the other hand, the exclusive horn  82  operating at the time of a theft is connected to one terminal of a switch  132   a  included in a second relay circuit  132 . The other terminal of the switch  132   a  is connected to a positive terminal of the electrical source  110  through a second fuse  122 . In addition, one terminal of a coil  132   b  included in the second relay circuit  132  is connected to the second fuse  122  similarly to the switch  132   a . The other terminal of the coil  132   b  is connected to one terminal of the diode  150  and a security control unit  170 . Meanwhile, as shown in  FIG. 6 , a system constituted by the first fuse  121 , the first relay circuit  131  and the ordinary horns  81   a  and  81   b , and a system constituted by the second fuse  122 , the second relay circuit  132  and the exclusive horn  82  operating at the time of a theft are formed in parallel to (separately from) the electrical source  110 . 
     Here, the diode  150  provided between the first relay circuit  131  and the second relay circuit  132  has a connection configuration in which the direction thereof is set so that a current flows from the first relay circuit  131  to the security control unit  170 . Thereby, when the electrical conduction is made by an operation of the horn switch  160  (that is, at the time of ordinary use), a current flows to the electrical source  110  through the first fuse  121  and the coil  131   b  of the first relay circuit  131  to the horn switch  160 . A current flows to the coil  131   b , whereby the switch  131   a  of the first relay circuit  131  is closed, and thus a current flows to the ordinary horns  81   a  and  81   b . As a result, the ordinary horns  81   a  and  81   b  operate, and an alarm sound is given as an alarm. 
     In addition, when a theft is detected by a sensor (not shown) or the like, the security control unit  170  is controlled so that the electrical potential of the input end thereof (B point in  FIG. 6 ) becomes equal to the ground potential. Then, a current flows from the electrical source  110  through the first fuse  121 , the coil  131   b  of the first relay circuit  131  and the diode  150  to the security control unit  170 , and flows from the electrical source  110  through the second fuse  122  and the coil  132   b  of the second relay circuit  132  to the security control unit  170 . Thereby, the switch  131   a  of the first relay circuit  131  and the switch  132   a  of the second relay circuit  132  are simultaneously closed, all the horns of the ordinary horns  81   a  and  81   b  and the exclusive horn  82  operate at the time of a theft, and an alarm regarding the theft is issued. 
     Incidentally, it is often the case that the ordinary horns  81   a  and  81   b  are disposed at the front end portion of a car in order to satisfy a sound pressure as an alarm stipulated by law. When a person committing a theft performs machining from the outside of the car on the ordinary horn disposed on this area and grounds an A point in  FIG. 6 , an excessive current flows in a path that connects the electrical source  110 , the first fuse  121 , the switch  131   a  and the A point by the electrical conduction of the switch  131   a  of the first relay circuit  131  through the control of the security control unit  170 , and thus the first fuse  121  is blown. As a result, the ordinary horns  81   a  and  81   b  become inoperable. However, when the exclusive horn  82  operating at the time of a theft is disposed at a location that is out of reach from the outside, for example, the engine compartment, the ordinary horn and the exclusive horn operating at the time of a theft become separate from each other. For this reason, even when the above-mentioned A point is grounded, the second fuse  122  is not blown, and the exclusive horn  82  operating at the time of a theft can continue to sound an alarm. 
     PATENT DOCUMENT 
     
         
         [Patent Document 1] Japanese Utility Model Application, First Publication No. 4-31059 
       
    
     DISCLOSURE OF THE INVENTION 
     Problem that the Invention is to Solve 
     However, in the above-mentioned conventional car alarm apparatus, since it is necessary to provide an exclusive horn operating at the time of a theft separately from an ordinary horn used in normal operation, there is a problem in that the number of required horns becomes larger and thus costs increase, and further a space for installing the exclusive horn operating at the time of a theft also has to be secured. 
     The present invention is contrived in view of such circumstances, and an object thereof is to provide a low-cost and space-saving car alarm apparatus capable of reliably issuing an alarm at the time of a theft. 
     Means for Solving the Problem 
     The present invention adopts the followings in order to solve the above-mentioned problem and achieve such an object. That is: 
     (1) A car alarm apparatus of the present invention includes: a first horn provided in a car; a second horn provided in a place inaccessible from an outside of the car; an electrical source that supplies power to the first horn and the second horn; a theft detection section that detects an occurrence of a theft of the car; a horn switch that receives an operation of an operator; a first relay closed when the horn switch is operated; a first fuse connected to the electrical source in series with the first relay and the first horn; a second fuse connected to the electrical source separately from the first fuse; and a second relay connected to the electrical source in series with the second fuse and the second horn, wherein the second relay includes a first contact that connects the second horn to an electrical source through the first fuse and the first relay in parallel with the first horn and a second contact that connects the second horn to the electrical source through the second fuse, and closes the second contact when the occurrence of the theft is detected. 
     According to the car alarm apparatus of the above (1), at the time of the operation of the horn switch, the electrical conduction is made from the electrical source through the first fuse and the first relay to the first horn, and the electrical conduction is made from the electrical source through the first fuse and the first contact of the second relay to the second horn. On the other hand, when the occurrence of the theft is detected, the electrical conduction is made from the electrical source through the second fuse and the second contact of the second relay to the second horn. Consequently, at the time of the operation of the normal horn switch, it is possible to sound both the first horn and the second horn. In addition, when the occurrence of the theft is detected even in the case in which the first fuse is blown by the theft or the like, it is possible to reliably sound the second horn through the second fuse. For this reason, it is possible to realize a reduction in cost by preventing the number of parts from increasing and to achieve an improvement in security. 
     (2) In the car alarm apparatus of the above (1), at least one of the first fuse and the second fuse may double as a fuse provided between a lighting appliance mounted in the car and the electrical source. 
     According to the car alarm apparatus of the above (2), when the first fuse or the second fuse is blown, a predetermined lighting appliance mounted in the car is not turned on, and thus it is possible to easily perceive fuse blowing. Therefore, it is possible to reliably sound the first horn and the second horn at the time of the operation of the horn switch by resolving the fuse blowing state, and to reliably sound the second horn when the occurrence of the theft is detected. 
     Effects of the Invention 
     According to the car alarm apparatus of the present invention, it is possible to achieve a reduction in cost and space and to reliably sound an alarm at the time of a theft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating installation positions of a low-pitched horn and a security horn of a car alarm apparatus according to an embodiment of the present invention. 
         FIG. 2  is an electrical circuit diagram illustrating the car alarm apparatus according to the embodiment. 
         FIG. 3  is an electrical circuit diagram schematically illustrating a current flowing to a brake light load and a small light load according to the embodiment. 
         FIG. 4  is an electrical circuit diagram schematically illustrating a current flowing at the time of ordinary use according to the embodiment. 
         FIG. 5  is an electrical circuit diagram schematically illustrating a current flowing at the time of a theft according to the embodiment. 
         FIG. 6  is an electrical circuit diagram illustrating a conventional car alarm apparatus. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A car alarm apparatus according to an embodiment of the present invention will be described below with reference to the drawings. 
     A car alarm apparatus  1  according to an embodiment of the present invention is an apparatus that drives an antitheft alarm in addition to a horn, and includes a low-pitched horn (LOW HORN, first horn)  41  giving a relatively low-pitched and a security horn (SCTY HORN, or second horn)  42  giving a relatively high-pitched, as shown in  FIGS. 1 and 2 . The low-pitched horn  41  is disposed in the vicinity and the like of a grill opening  101  of the car front end portion in order to satisfy the sound pressure as a horn stipulated by the laws in force. In addition, the security horn  42  is disposed in a position incapable of being easily contacted from the outside of the car, particularly the inside and the like of a bumper  102  of the car front side. The security horn  42  gives an alarm sound at the time of the detection of a theft, and is sounded together with the low-pitched horn  41 , as a high-pitched horn which takes charge of a high-pitched range at the time of the operation of the horn. 
     As shown in  FIG. 2 , one end side of the low-pitched horn  41  is connected to an electrical source (+B)  10  through a first relay circuit  31  and a first fuse  21 , and the other end side of the low-pitched horn  41  is connected to an earth E of a car body and the like. The first relay circuit  31  includes a coil  31   a , a contact  31   b  constituting a contact closed by the electrical conduction to the coil  31   a , and a movable contact piece  31   c . One end of the low-pitched horn  41  is connected to a ground-side terminal of the contact  31   b , and the first fuse  21  is connected in series with an electrical source-side terminal of the contact  31   b . In addition, an electrical source-side terminal of the coil  31   a  is connected to the electrical source-side terminal of the contact  31   b , and the brake light load (stop LT load)  35  of the car is branched and connected thereto. Thereby, when a user stomps on a brake pedal, as shown in  FIG. 3 , the electrical conduction is made from an electrical source  10  through the first fuse  21  to the brake light load  35  and thus a brake light and the like are turned on. 
     In addition, a horn switch (HORN SW)  60  is interposed between the coil  31   a  and the earth E. The horn switch  60  is provided in a hub portion of a steering wheel (not shown) and the like. The horn switch  60  is pressed by a user, whereby a current flows to the coil  31   a  and thus the contacts  31   b  are closed therebetween. 
     On the other hand, the electrical source-side terminal which is one end side of a pair of terminals of the security horn  42  is connected to the electrical source  10  through a second relay circuit  32  and a second fuse  22 . The ground-side terminal which is the other end side of a pair of terminals of the security horn  42  is connected to the earth E of the car body and the like. 
     The second relay circuit  32  includes a coil  32   a , a first contact  32   b  constituting a c contact which switches two contacts by the electrical conduction to the coil  32   a , a second contact  32   c , a common contact  32   d  and a movable contact piece  32   e . At the time of the electrical non-conduction to the coil  32   a , the first contact  32   b  and the common contact  32   d  are closed therebetween by the movable contact piece  32   e . On the other hand, at the electrical conduction to the coil  32   a , the second contact  32   c  and the common contact  32   d  are closed therebetween by the movable contact piece  32   e.    
     The second relay circuit  32  is configured such that the electrical source-side terminal of the low-pitched horn  41  mentioned above is connected to the first contact  32   b , and the electrical source  10  is connected to the second contact  32   c  through the second fuse  22 . In addition, the electrical source-side terminal of the security horn  42  is connected to the common contact  32   d . Further, the electrical source-side terminal of the coil  32   a  is connected to the second contact  32   c . In addition, a small light load (small LT load)  36  is branched and connected to the second contact  32   c . Thereby, when the small light is turned on by a user, as shown in  FIG. 3 , the electrical conduction is made from the electrical source  10  through the second fuse  22  to the small light load  36  and thus the small light and the like are turned on. 
     In addition, a security control unit  70  that controls the electrical conduction to the coil  32   a  is connected between the coil  32   a  and the earth E. The switching control between the first contact  32   b  and the second contact  32   c  mentioned above is performed by the control of the electrical conduction to the coil  32   a  through the security control unit  70 . Meanwhile, for the configuration mentioned above, four terminals are provided in the first relay circuit  31 , and five terminals are provided in the second relay circuit  32 . 
     The security control unit  70  determines the presence or absence of the occurrence of a theft based on an input from a sensor (not shown) that detects the theft of the car in which the car alarm apparatus  1  is installed. When it is determined that the theft occurs, control in which a sound is made and a sound alarm sound is output is performed by the electrical conduction to the security horn  42 . A method of the electrical conduction to the security horn  42  includes, for example, a method of turning on a switching element or the like, and connecting the security horn  42  grounded previously to the electrical source  10 , or the like. More specifically, when the occurrence of a theft is detected, the security horn is connected to the electrical source  10  through the second fuse  22  by switching from the first contact  32   b  of the second relay  32  to the second contact  32   c  thereof. The first contact  32   b  is configured to form a path in which the security horn  42  is connected to the electrical source  10  through the first fuse  21  by turning on the horn switch  60  in a normal state where the theft is not detected. 
     Here, as the sensor that detects the theft mentioned above, for example, a door lock sensor that detects a door lock state or a hood lock sensor that detects a hood state and the like may be used. In the case of the door lock sensor, an illegitimate release of the door lock by a third party can be determined based on the output thereof. In addition, in the case of the hood lock sensor, the opening of a hood which is not based on a regular procedure can be determined based on the output thereof. 
     For example, in the detection of the theft based on the door lock state, a state in which the door is locked from the outside of the car by the regular method is stored in a memory (not shown) of the security control unit  70 . Thereafter, when the door lock sensor detects a state in which the door lock is released from the interior of the car at the time of maintenance of the locked state, the occurrence of theft is detected. In addition, similarly to the door lock state, also with respect to the detection of the theft based on the hood state, when the forcible opening of the hood or the release of the hood lock by an operation of a hood release lever provided within the car interior is detected, for example, in the state where the door of the car is locked, the occurrence of a theft is detected. 
     Meanwhile, the case in which the theft is detected based on the door lock sensor or the hood lock sensor as the security control unit  70  has been described. The contents of the theft and the detection method are not limited only to the contents mentioned above, but various actions in which there may be a concern that the theft of the car other than mentioned above is occurring may be detected to thereby sound the security horn  42 . 
     Next, the operations of the car alarm apparatus  1  according to the embodiment, particularly each of the operations at the time of ordinary use and at the time of the theft will be described below. 
     First, at the time of the ordinary use such as car moving, the first relay circuit  31  which is an a contact is in a state where the contacts  31   b  are opened therebetween, and the second relay circuit  32  which is a c contact is in a state where the first contact  32   b  and the common contact  32   d  are closed therebetween. Thereafter, when the horn switch  60  is pressed, as shown in  FIG. 4 , two contacts  60   a  of the horn switch  60  are short-circuited therebetween, and thus the electrical conduction is made from the electrical source  10  through the first fuse  21 , the coil  31   a  of the first relay circuit  31 , and the horn switch  60  to the earth E. At this time, since the electrical conduction to the coil  31   a  of the first relay circuit  31  is made, the contacts  31   b  of the first relay circuit  31  are closed therebetween by the movable contact piece  31   c , and thus the electrical conduction is made from the electrical source  10  through the first fuse  21 , the contacts  31   b  of the first relay circuit  31 , and the low-pitched horn  41  to the earth E. Further, the electrical conduction is made from the electrical source  10  through the first fuse  21 , the contacts  31   b  of the first relay circuit  31 , and the first contact  32   b  of the second relay circuit  32 , and the common contact  32   d , and the security horn  42  to the earth E. That is, since the electrical conduction to the low-pitched horn  41  is made and the electrical conduction to the security horn  42  is made, the low-pitched horn  41  and the security horn  42  are simultaneously sounded, and thus a low-pitched sound of the low-pitched horn  41  and a high-pitched sound of the security horn  42  are simultaneously sounded as an alarm. 
     On the other hand, the security control unit  70  detects a theft in the case in which the door of the car is in a locked state, as shown in  FIG. 5 , the ground-side terminal of the coil  32   a  of the second relay circuit  32  is short-circuited to the earth E, and thus the electrical conduction is made from the electrical source  10  through the second fuse  22 , the coil  32   a  of the second relay circuit  32 , and the security control unit  70  to the earth E. Switching is performed from the state where the movable contact piece  32   e  of the second relay circuit  32  closes the first contact  32   b —the common contact  32   d  to the state where it closes the second contact  32   c —the common contact  32   d , by the electrical conduction to the coil  32   a  of the second relay circuit  32  at this time. Thereby, the electrical conduction is made from the electrical source  10  through the second fuse  22 , the second contact  32   c  of the second relay circuit  32 , the common contact  32   d  thereof, and the security horn  42  to the earth E. The security horn  42  is sounded and the high-pitched alarm sound is issued by the electrical conduction to the security horn  42  at this time. 
     Here, when a large current exceeding the rating flows to the first fuse  21  due to the theft or the like, the first fuse  21  is blown and the electrical circuit is broken, the contacts  31   b  of the first relay circuit  31  are not closed even by the pressing of the horn switch  60  and thus the low-pitched horn  41  is not sounded. 
     However, when the theft is detected in the state where the electrical circuit to the low-pitched horn  41  is broken by the first fuse  21 , the closed state of the movable contact piece  32   e  of the second relay circuit  32  is switched from the state of the first contact  32   b  —the common contact  32   d  to the state of the second contact  32   c —the common contact  32   d . Therefore, the electrical conduction to the security horn  42  inaccessible from the outside of the car is made and thus the alarm sound is issued. 
     The security horn  42  is inaccessible from the outside of the car, whereby the sounding of the security horn  42  is not stopped because a theft performed by bypassing the security horn  42  and melting down the second fuse  22  is not possible. 
     Therefore, according to the car alarm apparatus mentioned above, at the time of the operation of the horn switch  60 , the electrical conduction is made from the electrical source  10  through the first fuse  21  and the first relay circuit  31  to the low-pitched horn  41 , and the electrical conduction is made from the electrical source  10  through the first fuse  21  and the first contact  32   b  of the second relay circuit  32  to the security horn  42 . On the other hand, when the occurrence of the theft is detected, the electrical conduction is made from the electrical source  10  through the second fuse  22  and the second contact  32   c  of the second relay circuit  32  to the security horn  42 , and thus both the low-pitched horn  41  and the security horn  42  are sounded at the time of the operation of the normal horn switch  60 . In addition, when the occurrence of the theft is detected even in the case in which the first fuse  21  is blown by the theft or the like, the security horn  42  is reliably sounded through the second fuse  22 . Therefore, it is possible to realize the reduction in cost by preventing the number of parts from increasing, and to improve security. 
     In addition, since the stop light of the car is not turned on when the first fuse  21  is blown and the small light of the car is not turned on when the second fuse  22  is blown, it is possible to easily perceive the fuse blowing of the first fuse  21  and the second fuse  22 . As a result, it is possible to reliably sound the low-pitched horn  41  and the security horn  42  at the time of the operation of the horn switch  60  by rapidly resolving the fuse blowing state, and to reliably sound the security horn  42  when the occurrence of the theft is detected. 
     Further, there is a possibility that the first fuse  21  may be blown when the stop light is not turned on, and it is possible to cause a user to perceive that there is a possibility that the second fuse  22  may be blown when the small light is not turned on. For this reason, particularly, when any one of the first fuse  21  or the second fuse  22  is blown, it is possible to make the checkup time shorter than that in the case where both the first fuse  21  and the second fuse  22  are checked. 
     Meanwhile, in the car alarm apparatus  1  of the embodiment mentioned above, the cases in which the stop light load  35  is branched and connected between the first fuse  21  and the first relay circuit  31  and the small light load  36  is branched and connected between the second fuse  22  and the second relay circuit  32  have been described. In these connections, the small light load  36  may be branched and connected between the first fuse  21  and the first relay circuit  31 , and the stop light load  35  may be branched and connected between the second fuse  22  and the second relay circuit  32 . In addition, in the embodiment, the states of the first fuse  21  and the second fuse  22  can be perceived depending on the turn-on states of the stop light and the small light. A light source used in the perception of the turn-on state is not limited to the stop light and the small light, but is not particularly limited as long as it is a light source or the like capable of being turned on by a simple operation by a user. 
     INDUSTRIAL APPLICABILITY 
     According to the car alarm apparatus of the present invention, it is possible to achieve the reduction in cost and space saving, and to reliably sound an alarm at the time of a theft. 
     DESCRIPTION OF REFERENCE NUMERALS AND SIGNS 
     
         
         
           
               10 : ELECTRICAL SOURCE 
               21 : FIRST FUSE 
               22 : SECOND FUSE 
               31 : FIRST RELAY CIRCUIT (FIRST RELAY) 
               32 : SECOND RELAY CIRCUIT (SECOND RELAY) 
               32   b : FIRST CONTACT 
               32   c : SECOND CONTACT 
               41 : LOW-PITCHED HORN (FIRST HORN) 
               42 : SECURITY HORN (SECOND HORN) 
               60 : HORN SWITCH

Technology Classification (CPC): 1