JPH0587417B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automobile theft prevention device for preventing automobile theft.

[Conventional technology]

Conventional car theft prevention devices include, for example, those that detect the opening and closing of a door and issue an alarm when the door is opened illegally, and those that detect when a magnetic metal such as a screwdriver or wire harness approaches the keyhole of the door. Some systems have a detection device installed near the keyhole, and use this detection device to issue an alarm when a driver or the like is inserted into the keyhole of the door and an attempt is made to open the door.

In addition, a configuration has been proposed in which an infrared sensor, an ultrasonic sensor, a vibration sensor, etc. are installed, and the sensor detects whether the key is inserted or the door is locked, or theft is detected by detecting vibrations when the door is opened or closed. .

[Problem that the invention seeks to solve]

In such conventional devices, which detect the opening and closing of a door, an alarm is generated only when the door is open, so although installation is easy and the cost is low, the anti-theft effect is small. Furthermore, in the case of a device that detects metal near the door keyhole or a device that uses various sensors, the anti-theft effect cannot be improved unless the device is installed on all doors. Therefore, there is a problem in that the work time required to install the device on the vehicle becomes longer, leading to higher costs.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, it is therefore an object of the present invention to provide an automobile theft prevention device that can be easily attached to an automobile and that can reliably prevent automobile theft.

[Means for solving problems]

In order to achieve the above object, the automobile theft prevention device according to the present invention includes a code input means for inputting a predetermined code, and a code input by the code input means is compared with a preset pin code. a comparison means for detecting a match between the two; an ignition detection means for detecting the state of the ignition switch; a parking/stop detection means for detecting whether the vehicle is parked or stopped based on the state of the handbrake and/or the shift lever; The ignition detection means detects the on state of the ignition switch,
and in a state where the comparison means detects a match,
When the parking/stopping detection means detects parking or parking, it starts counting a certain period of time, and when the parking/stopping detecting means no longer detects parking or parking during the counting of the certain period of time, the timing is stopped to set the initial state. A timer means is connected via a signal line to a horn drive device that sounds the horn when the horn switch is turned on and/or a headlight drive device that turns on the headlight when the headlight switch is turned on. When the ignition switch is in the ON state by the detection means, or when the comparison means does not detect a match between the code input from the code input means and the preset password code within a certain period of time from the detection, or a driving means for outputting a signal to the horn driving device and/or the headlight driving device to operate the horn and/or the headlight when the timer means finishes counting a certain period of time; The means includes a switching element that is always on and turned off when operating the horn and/or the headlight, and a switching element that is connected in series with the switching element via the signal line and that drives the horn drive device and/or the headlight. The present invention is characterized in that it includes a switch means provided in parallel with the horn switch and/or the headlight switch on the apparatus side and turned on when current stops flowing through the signal line.

[Effect]

In the above configuration, when the operator inputs a code using the code input means, the comparison means compares this code with a preset personal identification code and detects a match between the two. The ignition detection means detects the state of the ignition switch, and the parked/stopped detection means detects whether the automobile is parked or stopped based on the state of the handbrake and/or the shift lever. When the ignition detection means detects the ON state of the ignition switch and the comparison means detects a match, when the parked/stopped detection means detects a parked/stopped state, the timer means starts counting a certain period of time;
When the parking/stopping detecting means no longer detects parking or stopping during this fixed period of time measurement, the above-mentioned timekeeping is stopped and the initial state is restored.

A driving means connected to the horn driving device and/or the headlight driving device via a signal line,
When the ignition detection means detects an on state and the comparison means does not detect a match, or when the timer means finishes counting a certain period of time, a signal is output to the horn drive device and/or headlight drive device. to operate the horn and/or headlight.

Therefore, the only components connected to the automobile are the ignition detection means for detecting the state of the ignition switch and the parking/stopping detection means for detecting whether the motor vehicle is parked or stopped based on the state of the handbrake and/or shift lever. The installation work is simple, as it is only necessary to pull out the signal line from the switch related to the ignition switch, handbrake and/or shift lever.

Furthermore, when the ignition switch is turned on or when the correct password code is not input within a certain period of time, the horn and/or headlight will sound and/or turn on, making it possible to prevent theft. Furthermore, this horn and/or headlight will sound and/or turn on even if the handbrake is pulled or the shift lever is set to park while the engine is running, and a certain amount of time has elapsed. This can help prevent theft by alerting people to be careful not to leave their cars.

Further, a driving means is connected in series with the switching element via a signal line and is provided in parallel with the horn switch and/or the headlight switch on the side of the horn driving device and/or the headlight driving device, Since the switch means is turned on when current stops flowing through the signal line, when the switching element is turned off by disconnection of the power supply line or when the signal line is disconnected, the horn switch and/or
Alternatively, a switch means provided in parallel with the headlight switch is turned on to sound and/or turn on the horn and/or the headlight, thereby making it possible to reliably prevent theft.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes an anti-theft device according to the present invention, which is composed of the following main parts. That is, 2 is a microcomputer (hereinafter referred to as MPU), which inputs/outputs predetermined data and performs arithmetic processing. Reference numeral 3 denotes a keyboard as a code input means, which is composed of numeric keys "0" to "9", a clear key, and the like. 4 is a memory that stores a preset password code; PROM,
It consists of non-volatile memory such as EPROM or a deep switch. 5 and 6 are drive circuits each consisting of a transistor, etc.; 7 and 8 are output circuits each consisting of a relay, a power transistor, etc. driven by the drive circuits 5 and 6; and 9 is a side brake, and the output of the parking detection device 13 is connected to the MPU 2. 10 is an interface circuit for inputting a detection signal from the ignition detection device 14 to the MPU 2.

The output circuit 7 is an external circuit of the anti-theft device 1.
A horn driving device 11 for driving a horn to sound a horn is coupled to the output circuit 8, and a headlight lighting device 12 for lighting a headlight is coupled to the output circuit 8. Further, as described above, the detection output of the handbrake/parking detection device 13 is input to the interface circuit 9, and the detection signal of the ignition detection device 14 is input to the interface circuit 10.

The handbrake/parking detection device 13 detects when the handbrake is applied and/or when the shift lever is moved to the parking position in an automatic vehicle, and the ignition detection device 14 detects when the ignition switch is turned on. It detects on/off status.

FIG. 2 shows an example of the configuration of the horn drive device 11 and headlight lighting device 12 that are combined with the anti-theft device 1. In the figure, the horn drive device 11 is provided with a horn H, and the horn H and battery V _B
The contacts of relay RL ₁ are connected between them. Furthermore, the excitation winding of relay RL ₁ and horn switch SW ₁ are connected in series between battery V _B and ground, and the connection point between the excitation winding and horn switch SW ₁ is connected to output circuit 7 via signal line l ₁ . Connected. On the other hand, the headlight lighting device 12 is provided with a headlight LP,
Relay RL ₂ between the headlight LP and battery V _B
contacts are connected. In addition, the excitation winding of relay RL ₂ and headlight switch SW ₂ are connected in series between battery V _B and ground, and the connection point between them is signal line l _2.
It is connected to the output circuit 8 by.

Both the horn driving device 11 and the headlight lighting device 12 have conventionally known configurations, and when the horn switch SW ₁ is turned on, the relay RL ₁ is turned on.
is excited, its contact closes, and battery V _B is supplied to horn H, acting to drive it. Similarly, by turning on the headlight switch _SW2 , the relay _RL2 is energized and the headlight LP is turned on.

An overview of the operation in this configuration will be explained. The anti-theft device 1 is constantly supplied with power by the battery _VB and is in an operating state. First, when the user is an authorized operator (for example, a driver), before starting the engine, the operator inputs a password (for example, a 4-digit number) previously set in the memory 4 using the keyboard 3 using the numeric keypad. The MPU 2 compares this input code with the PIN code in the memory 4, and if they match, lights up an OK lamp such as an LED (not shown) to notify the driver that the input code and PIN code match. . The driver then starts the engine and drives.

On the other hand, if a person attempting to commit fraud does not enter the specified code using the keyboard 3 or enters a code different from the password set in the memory 4, the MPU 2 will recognize this and turn off the OK lamp. Continue to. Thereafter, when an unauthorized person starts the engine, the ignition detection device 14 detects the on state of the ignition, and the detection signal is input to the MPU 2 through the interface circuit 10. When the MPU 2 receives this ignition-on detection signal, its internal timer operates and starts measuring time. On the other hand, a set time is stored in the memory 4, and when the measured time reaches the set time, a drive signal is output to the drive circuits 5 and 6, which are driven to operate the output circuits 7 and 8. As a result, drive signals are supplied from the output circuits 7 and 8 to the horn drive device 11 and the headlight lighting device 12 through the signal lines l ₁ and l ₂ . Therefore, the output potential of the output circuit 7 becomes the ground potential due to this drive signal, and even if the horn switch SW ₁ is off, the output circuit 7 of the signal line l ₁
Since the side is grounded, an exciting current flows through relay RL ₁ and the contacts close. This drives the horn H and sounds the horn. Similarly, in the headlight lighting device 12, the output potential of the output circuit 8 becomes the ground potential, so the headlight switch
Relay RL ₂ is activated by signal line l ₂ even if SW ₂ is off.
is excited and the headlight LP lights up.

Driving signals outputted from the MPU 2 to the horn driving device 11 and headlight lighting device 12 are outputted intermittently or continuously, and the horn H and headlight LP sound and light up intermittently or continuously. This not only frightens fraudsters, but also alerts outsiders to the fact that fraud is being committed. In addition, when the input code and the password do not match, the time from when the ignition detection device 14 detects the ignition on state until the signal is output to the drive circuits 5 and 6 and the horn H and headlamp LP are driven. is preset in the memory 4, but this time may be changed externally. To stop the horn H or headlight LP after driving, set a stop time in advance in the memory 4, activate an internal timer when driving, and stop sending out the drive output when this stop time is reached. Make it. Alternatively, this alarm can be stopped by inputting a regular code that matches the password from the keyboard 3, or by turning off the ignition switch 14. That is, the MPU 2 stops sending drive signals to the drive circuits 5 and 6 by determining this state. At this time, if a regular code is entered from the keyboard 3, the alarm will be canceled and the OK lamp will light up.

Here, the input code and pin code match,
When parking with the engine running and the OK lamp is on, if the handbrake is applied or the shift lever is in the parking position, the shift lever/parking detection device 13
A detection signal is output from the MPU 2 and is input to the MPU 2 through the interface circuit 9. This signal input activates the internal timer of MPU 2, and when the time t ₁ preset in memory 4 is reached,
From there, the MPU 2 measures time until another preset time t ₂ is reached, and the MPU 2 measures the time until reaching another preset time t ₂ .
When this is reached, the mode becomes the same as when the engine is started due to mismatch of the PIN code or no code input by an unauthorized person as described above, and the OK lamp goes out, and the horn driving device 11 and headlight lighting device 12 are turned on intermittently or continuously. drive and give a warning. This function is intended to prevent theft from occurring when the driver is away from the vehicle with the engine running.

Furthermore, if you release the handbrake or shift the shift lever to a position other than parking within the predetermined time t1 set in memory ₄ , the handbrake
The detection signal from the parking detection device 13 is no longer output, and the MPU 2 determines this state, stops the operation of the internal timer, and returns to the initial state. Furthermore, if the predetermined time _t1 has elapsed, the operation will not return to the initial state, and the initial state will not be achieved unless the password is entered.

The password code set in the memory 4 may be any number of digits, but approximately four digits is appropriate. This password code is set in a non-volatile memory such as a dip switch, PROM or EPROM, or a RAM backed up by a backup battery or a large capacity capacitor. For example, to set a PIN code using non-volatile memory and the keyboard 3, press any two keys (for example, "1" and "3") on the keyboard 3 at the same time for a few seconds to several tens of seconds. The system enters the PIN code setting mode and notifies the operator of this mode by lighting an LED (not shown) or sounding a buzzer. When the MPU 2 enters the setting mode, the operator inputs an arbitrary password sequentially from the high-order digits using the numeric keypad. (For example, if the PIN code is "1234", enter "1" → "2" → "3" → "4")
After entering the PIN code, set it in advance so that one of the keys on the numeric keypad becomes the set key, and by pressing the set key, the entered code will be set in the memory 4 as the PIN code. . After that, the MPU2 cancels the setting mode and enters the normal mode. Further, this setting mode is not a state in which the device 1 issues a warning to a person attempting to commit fraud, but is effective only in the normal state in which the OK lamp is lit as described above. In addition, as mentioned above, the memory 4 stores information about the time from input code mismatch to issuing a warning, or from the time when the engine is running.
The time from when a detection signal is output from the parking detection device 13 to when an alarm is issued is set, and this time is also set by the same operation as the above-mentioned password code setting.

If the person attempting to commit fraud is aware of the setting method described above, the password code can be changed arbitrarily, so that the MPU 2 may not go into an alarm state. Therefore, when a manufacturer manufactures and ships the anti-theft device 1, a predetermined password code is set in the memory 4 in advance, and this password code is written in the instruction manual of the device 1 or the like.
The purchaser of the anti-theft device 1 puts the MPU 2 into the setting mode as described above and sets an arbitrary PIN code in the memory 4, but at this time, in order to prevent unauthorized setting, it is necessary to first set a new PIN code. Then, input the password already set in the memory 4 from the keyboard 3. The MPU 2 compares the input code and the PIN code, and if they match, enters a setting mode, allowing the operator to set a desired PIN code.

That is, at the time of purchase, the PIN code written in the instruction manual or the like at the time of shipment is inputted from the keyboard 3, and after transitioning to the setting mode state, the PIN code is changed to an arbitrary PIN code. According to this setting means,
Even if the password needs to be changed after that, only an authorized operator can do so.

Next, the processing of the MPU 2 for performing the above operation will be explained with reference to the flowchart of FIG.

First, initialize MPU2 in step _S1 ,
Clears the internal RAM, etc., and returns to subroutine A.
process. In subroutine A, in step _S2 , the state of the ignition detection device 14 is determined based on the data input from the interface circuit 10,
If the ignition is off, the OK lamp is turned off in step _S7 . Next, in step _S8 , all internal timers of the MPU 2 are made inactive, the timer counter is cleared, and the process returns to subroutine A.
In subroutine A, the ignition detection device ₁₄ determines in step S2 that the ignition is on.In step _S3 , the code entered by the operator from the keyboard 3 and the password code (for example, a number) set in the memory 4 are determined. Compare. If the two codes do not match, or if no code is input, the internal timer A starts operating and measures time in step _S4 . Next step
In step _S5 , the time measured by timer A is compared with the set time Ta set in the memory 4, and it is determined whether the measured time has reached the set time Ta. If the measured time of the internal timer A has reached the set time Ta, the timer A is made inactive in step _S6 , and the measured time is cleared, and then subroutine B is processed. In subroutine B, the OK lamp is turned off in step _S13 , and internal timer B is operated in step _S14 . Next, in step _S15 , the drive circuit 5,
The horn drive unit 11 and the headlight lighting unit 12 are outputted through the output circuits 7 and 8 to drive the horn drive unit 11 and the headlight lighting unit 12 intermittently or continuously.
The headlight LP is turned on and the horn is sounded. And step S ₁₆
It is determined whether the measured time of internal timer B has reached the set time Tb set in the memory 4, and when the set time Tb has been reached, all internal timers are made inactive and the contents are cleared in step _S17 . If the set time Tb has not yet been reached, the process returns to subroutine A. After processing step _S17 , the drive signal output to the drive circuits 5 and 6 is stopped in step _S18 , and the horn drive device 11 and headlight lighting device 12 are stopped.
deactivate and stop the alarm. The step S ₁₈
After processing, the process returns to subroutine A.

In the password code comparison process of step _S3 , if the input code matches the password, the OK lamp is lit in step _S9 and the MPU 2 enters the setting mode. That is, in this state, it is possible to change the password code and set time set in the memory 4, and in step _S10 it is determined whether the password code or set time is about to be changed. This determination process is performed by detecting that any key on the keyboard 3 is pressed. memory 4
If the contents have not been changed, subroutine C is processed. In subroutine C, the detection signal from the handbrake/parking detection device ₁₃ is input through the interface circuit 9 in step S19, and when the handbrake is applied and/or the shift lever is in the parking position, step _{S20 is} performed.
This causes internal timer C to operate. Next step
Step _S21 determines whether the timer C's measurement time has reached the set time Tc set in the memory 4. If it has, step _S22 clears the timer C's measurement time and then processes subroutine B. . If the set time Tc has not yet been reached, the process returns to subroutine A. If the handbrake is released in step _S19 and the shift lever is in a position other than parking, the internal timer C is deactivated in step _S23 , and after clearing the measured time, the process returns to subroutine A.

When the contents of the memory 4 are about to be changed in the setting change determination process in step _S10 , it is checked in step _S11 whether the code input from the keyboard 3 matches the previous password code in the memory 4. Discern. If the two codes do not match, or if no code is input from the keyboard 3, the process returns to subroutine A. If both codes match, the internal timer D is operated in step _S12 to start time measurement, and then subroutine D is processed. In subroutine D, it is determined in step _S24 whether changes to the password code and set time from the keyboard 3 have been completed.
At this time, the password code and set time are arbitrary codes and times set by the operator as described above, and the end of this setting change is performed by determining, for example, the press of the set key set in association with the numeric keypad in the above embodiment. . If the setting change is completed, return to subroutine A, otherwise go to step
Step _S25 determines whether the timer D's measurement time has reached the set time Td set in the memory 4. If the timer D has reached the set time Td, the timer D is reset at step _S26 .
is made inactive and cleared, the data input from the keyboard 3 up to that point is ignored, and the process returns to subroutine A. If the set time Td has not yet been reached, the process returns to step _S24 and subroutine D is processed. That is, in subroutine D, even if the MPU 2 is in the setting mode, if the setting change processing is not completed within a predetermined time Td, the data input so far is ignored.

Here, in the anti-theft device 1, even if the driver is an authorized driver, it is necessary to first input a code that matches the personal identification code using the keyboard 3 before driving. Therefore, since the device 1 is usually installed near the driver's seat, even a person attempting to commit fraud can easily discover the anti-theft device 1. At this time, the unauthorized person operates the keyboard 3 and enters an incorrect code, but the MPU 2 detects this and controls the horn drive device 11 and headlight lighting device 12.
make it work.

Therefore, in such an alarm state, a person attempting to commit fraud may use the power supply line that supplies the battery for the anti-theft device 1, or the signal line connected to the horn drive device 11, headlight lighting device 12, ignition detection device 14, etc. may be severed. There is also a possibility that the device 1 may be destroyed.
Possible countermeasures include, for example, protecting these power supply lines and signal lines, and structuring the casing that houses the device 1 firmly. However, such countermeasures increase the cost.

Therefore, FIGS. 4 and 5 show a configuration that takes measures against the wire being cut by an unauthorized person as described above. FIG. 4 shows a configuration that takes measures against disconnection of the power supply line and signal line supplied to the horn driving device 11 and the headlight lighting device 12. In the figure, the output of the anti-theft device 1 is connected to the power transistor Q ₁
The collector is connected to the excitation winding of the relay RL ₃ through the signal line l ₁ . the relay
The other end of RL ₃ is connected to battery V _B. Further, the fixed contact a is opened, and the fixed contact b is grounded. Furthermore, the movable contact is connected to the connection point between the excitation winding of relay RL ₁ and horn switch SW ₁ in horn drive device 11 through electric wire l ₄ .

When the relay RL ₃ is not energized, its movable contact is connected to the fixed contact b side, and when it is energized, it is switched to the fixed contact a side. The relay RL ₃ and the electric wire L ₄ are installed at a location that is difficult to be easily discovered from the outside.

Also, the power transistor Q ₁ of the output circuit 7 is
It is off when the MPU 2 is giving an alarm, and it is on when it is in a normal state. (The embodiment in FIG. 4 has a reverse relationship to the embodiment in FIG. 2.) The anti-theft device 1 is supplied with a battery _VB through a power supply line _l3 .

In this configuration, since the transistor _Q1 is in an on state in a normal state, its collector is at approximately ground potential. Therefore, since relay RL ₃ is energized and its movable contact is connected to side a, if horn switch SW ₁ is off, relay RL ₁ is not energized and horn H is not driven. On the other hand, in the alarm state, transistor Q ₁ is turned off, so relay RL ₃
The excitation current no longer flows to and the movable contact switches to the fixed contact b side. Therefore, one end of the excitation winding of relay RL ₁ is grounded and an excitation current flows, so that the contact is closed and a drive current flows through the horn H.

If an unauthorized person cuts the signal line _l1 ,
Even if transistor Q ₁ is on during normal operation, one end of relay RL ₃ is in a floating state and no excitation current flows. Therefore, the movable contact is switched to the fixed contact b side, and the excitation current flows through the relay RL ₁ , so that the driving current flows through the horn H. Further, when the power supply line _l3 is disconnected, the battery _VB is no longer supplied to the anti-theft device 1, and the transistor _Q1 of the output circuit 7 is forcibly turned off. Therefore, relay RL ₃ is no longer energized, and as described above, an energizing current flows through relay RL ₁ , causing horn H to sound.
Incidentally, the same configuration is applied to the headlight lighting device 12 as well.

As a result of the above operation, when the power supply line _L3 or the signal line _L1 is disconnected, even if the anti-theft device 1 is in a normal state and the code entered on the keyboard 3 matches the password code, the horn drive device 11 and the headlight The lighting device 12 is activated and enters an alarm state. Furthermore, the signal line _l4 and the relay _RL3 are installed in locations that cannot be easily seen from the outside, so they will not be cut or destroyed.

Figure 5 shows the ignition detection device 14 and device 1.
In the figure, an ignition switch _SW3 constituting the ignition detection device 14 is connected to the battery _VB , and the signal line _l5 is connected to the battery VB. ₅ to the device 1. ignition switch
A resistor _R1 is connected between the signal line _l5 side of _SW3 and the ground, and this resistor _R1 is connected to the ignition switch.
Installed near SW ₁ . Further, within the device 1, the signal line _l5 is connected to the positive phase input of the comparator _CP1 , and is connected to _a resistor _R2 , which is pulled up by a battery _VB . On the other hand, a reference voltage V _vef is applied to the negative phase input of the comparator CP ₁ , and the output of the comparator CP ₁ is used as a detection signal from the ignition detection device 14.

In such a configuration, the ignition switch
When SW ₃ is in the off state, a voltage obtained by dividing the voltage of battery V _B by resistors R ₁ and R ₂ is applied to the positive phase input of comparator CP ₁ . The reference voltage V _ref is set higher by this divided voltage, and therefore, in this state, the output of the comparator CP ₁ is at L level. When the ignition switch _SW3 is turned on, the positive phase input voltage of the comparator _CP1 becomes higher than the negative phase input voltage, so its output is inverted to H level. Accordingly, the MPU 2 determines the detection state of ignition on/off in the ignition detection device 14. That is, the output of the comparator _CP1 is at L level when the ignition is off, and at H level when the ignition is on.

When a person attempting to commit fraud disconnects the signal line _L5 of the ignition switch _SW3 , the voltage of the battery _VB is applied to the positive phase input of the comparator _CP1 through the resistor _R2 . It becomes higher than the reference voltage V _vef applied to the negative phase input. Therefore, the output of the comparator _CP1 becomes H level, which is the same state as when the ignition switch _SW3 is turned on, and the MPU 2 determines that the ignition detection device 14 is in the ignition on state.
Therefore, when the code inputted from the keyboard 3 does not match the password code, or when the handbrake is applied and/or when the shift lever is in the parking position, an alarm condition occurs as described above.

Note that this configuration can also be applied to the handbrake/parking detection device 13.

〔Effect of the invention〕

As described above, according to the present invention, even if an alarm is not given for some reason when the door is opened by unauthorized persons, if the ignition is turned on unless a code that matches the preset password is entered, the alarm will be activated. Therefore, theft can be reliably prevented. Further, this device does not need to be provided for each door, does not require special sensors such as infrared sensors, and can be constructed at low cost since the alarm is generated from a horn. Furthermore, if the power supply line or signal line is cut, the ringing or lighting will occur, so even if you try to stop the ringing or lighting, it will be impossible, and this will have a great effect on theft prevention.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the device according to the present invention, FIG. 2 is a circuit diagram showing an example of the structure of the horn driving device and headlight lighting device in FIG. 1, and FIG. 3 is the microcomputer in FIG. 1. FIGS. 4 and 5 are circuit diagrams showing an example of a structure in which measures are taken against wire breakage in the horn drive device and ignition detection device shown in FIG. 1, respectively. 1... Anti-theft device, 2... Microcomputer (comparison means, timer means), 3... Keyboard (code input means), 4... Memory, 5, 6...
...Drive circuit, 7, 8... Output circuit (drive means, swing element), 9, 10... Interface circuit,
11...Horn drive circuit, 12...Headlight drive device, 13...Handbrake/parking detection device (parked/stop detection means), 14...Ignition detection means, H...Horn, LP...Headlight, l ₁ ... ...Signal line, L ₃ ...Power line, RL ₃ ...
Relay (switch means), SW ₁ ...horn switch, SW ₂ ...head light switch.

Claims (1)

[Claims] 1. A code input means for inputting a predetermined code; a comparison means for comparing the code inputted by the code input means with a preset password to detect a match between the two; ignition detection means for detecting the state of the ignition switch; parked/stopped detection means for detecting whether the vehicle is parked or stopped based on the state of the handbrake and/or the shift lever; and the ignition detection means detects whether the ignition switch is on or off. When the parking/stopping detecting means detects a parking/stopping while the comparing means detects a match, the parking/stopping detecting means starts counting a certain period of time, and during the counting of the certain period of time, the parking/stopping detecting means detects a parking/stopping. a timer means that stops the time measurement and returns to the initial state when parking or stopping is no longer detected by the system, and a horn drive device that sounds the horn when the horn switch is turned on and/or a headlight switch that is turned on. It is connected via a signal line to the headlight drive device that turns on the headlight.
When the ignition detection means detects that the ignition switch is on, or within a certain period of time after the detection, the comparison means detects a match between the code input from the code input means and a preset pin code. driving means for outputting a signal to the horn driving device and/or the headlight driving device to operate the horn and/or the headlight when the timer is not in use, or when a certain period of time has been counted by the timer means; The driving means includes a switching element that is always on and turned off when operating the horn and/or the headlight, and a switching element connected in series with the switching element via the signal line and connected to the horn driving device and the switching element. /or provided in parallel with the horn switch and/or the headlight switch on the headlight drive device side,
An automobile theft prevention device comprising: a switch that is turned on when current stops flowing through the signal line.