JPH09240430A - Burglary preventive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an error deciding to be 'Burglary' not with standing non burglary generating condition, resulting from the battery voltage made less than the lowest operative voltage. SOLUTION: An engine control device 3 decides whether the voltage of a battery 6 is made less than the lowest operative voltage or not. And when it decides the voltage is not made less than the lowest operative voltage, the time to collate the cipher code of a key 1 received from a reading device 2, and a cipher code stored in an EEROM 13 is made at the first specific time, and when it is made less than the lowest operative voltage on the contorary, the above collating time is made at the second specific time longer than the first specific time. By making the collating time at the second specific time, the above collating is carried out even after the battery voltage is restored more than the lowest operative voltage, and the collating result at that time is made 'coincident', so as to confirm that the burglary deciding result is 'No burglary'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antitheft device for a mobile body, and more particularly, it is effective as an antitheft device for a vehicle.

[0002]

2. Description of the Related Art As a prior art of the above-mentioned antitheft device, there is one disclosed in, for example, Japanese Utility Model Laid-Open No. 63-24066. According to this, when a key as an instruction member for instructing the start of the engine is inserted into the key cylinder and an engine starting operation is performed, the personal identification code stored in the key is read by the reading device in the key cylinder, and the control computer makes By comparing the personal identification code read by the reading device with the personal identification code stored in the control computer, it is determined whether or not the engine is started by the regular key.

If the engine is not started with the proper key, the vehicle is determined to be stolen and the engine is stopped to prevent the vehicle from being stolen.

[0004]

By the way, the engine is started by energizing the starter from the battery, but the battery voltage greatly drops when the starter is energized. Therefore, depending on the degree of deterioration of the battery, as shown in FIG.
As shown in (a) and (b), when the starter (STA) is energized, the battery voltage (BAT) is the minimum operating voltage (minimum for the control computer to normally perform the collation of the two identification codes). It may drop below the required voltage).

As described above, when the battery voltage (BAT) becomes equal to or lower than the above-mentioned minimum operating voltage, as shown in FIG. 9 (c), the communication data of the personal identification code received by the control computer from the reading device may be destroyed. Alternatively, there is a problem that the communication until the control computer is reset and the theft determination result is output is interrupted on the way.
In this case, as a matter of course, the result of the theft determination is "theft" even if the engine is started with the regular key, and the engine is stopped.

In view of the above problems, the present invention prevents the erroneous determination of "theft" even though the battery is not stolen because the voltage of the battery becomes the minimum operating voltage or less. With the goal.

[0007]

In order to achieve the above-mentioned object, the invention according to claims 1 to 5 is provided with a voltage drop detecting means for detecting that the voltage of the battery has become equal to or lower than a predetermined voltage, and determines the theft. The means is characterized in that, when the voltage drop detecting means detects that the voltage of the battery becomes equal to or lower than the predetermined voltage, the code collating means performs more collation than when it is not detected. .

Here, how many times the above-mentioned matching is performed is defined until the above-mentioned matching can be performed after the voltage of the battery becomes equal to or higher than the predetermined voltage. Further, the predetermined voltage is defined as the minimum voltage required for the code collating means to normally perform the collation. According to the present invention as described above, when the voltage drop detecting means detects that the battery voltage becomes equal to or lower than the predetermined voltage, the above collation is performed more frequently than when the battery voltage is not detected. The collation is performed after the voltage becomes equal to or higher than the predetermined voltage. Therefore,
At this time, if the start of the prime mover is instructed by the regular instruction member, the above collation result will be “match”, and the determination result by the theft determination means will be “not theft” based on this collation result. It is possible to prevent erroneous determination as "theft" even if the moving body is not stolen. Further, in the case of the invention according to claim 2, the voltage drop detecting means makes the battery voltage equal to or lower than the predetermined voltage. When is detected, the matching is performed for the second predetermined time, and as a result, the matching is performed even after the battery voltage becomes equal to or higher than the predetermined voltage. Therefore, at this time,
If the start of the prime mover is instructed by the regular instruction member,
The above collation result is “match”, and based on this collation result, the determination result by the theft determination means is “not theft”. Therefore, it is erroneously determined as “theft” even though the moving body is not theft. In particular, when the voltage drop detecting means detects that the battery voltage becomes equal to or lower than the predetermined voltage, the collation is performed for the second predetermined time. As a result, if the start instruction of the prime mover is instructed by the regular instruction member, the collation result is once "coincidence", and the determination result by the theft determination means is "not theft". Therefore, it is possible to prevent the erroneous determination of “theft” even though the mobile body is not stolen.

Further, in the invention according to claim 4, when the voltage drop detecting means detects that the battery voltage becomes equal to or lower than the predetermined voltage, the collation is performed a second predetermined number of times, and as a result, The verification is performed even after the battery voltage becomes equal to or higher than the predetermined voltage. Therefore, at this time, if the start of the prime mover is instructed by the legitimate instruction member, the above collation result will be "coincidence", and based on this collation result, the judgment result by the theft judgment means will be "not theft". Therefore, it is possible to prevent erroneous determination as "theft" even if the moving body is not stolen. In particular, according to the invention of claim 5, the voltage drop detecting means determines that the battery voltage is the predetermined value. When it is detected that the voltage becomes equal to or lower than the voltage, the collation is performed the second predetermined number of times, and as a result, if the start of the prime mover is instructed by the regular instruction member, the collation result is once “matched”. Therefore, the determination result by the theft determination means is “not theft”. Therefore, it is possible to prevent the erroneous determination of “theft” even though the mobile body is not stolen.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Next, a first embodiment in which the antitheft device of the present invention is applied to a vehicle (automobile) that moves when an engine (not shown) is driven will be described with reference to FIGS. To do. In the present embodiment, when the ignition switch 4 is turned on, the engine of the automobile is started for the time being, and then the theft determination result described later is “theft”.
If this is the case, stop the started engine to prevent theft.

FIG. 1 is a diagram schematically showing the overall structure of the vehicle antitheft device of this embodiment. In FIG.
The key 1 (pointing member) is provided with a memory 1a for storing a predetermined secret code. The key cylinder 2 provided in the steering column portion of the vehicle is provided with a reading device 2a that reads the secret code in the memory 1a when the key 1 is inserted. This reading device 2
The personal identification code read in a is input to the engine control device 3.

When the key 1 is inserted into the key cylinder 2 and is rotated (engine start operation), the ignition switch 4 and the starter switch 5 are sequentially turned on. When the ignition switch 4 is turned on, the power from the battery 6 is supplied to the power supply circuit 15 of the engine control device 3, the fuel injection device 7, and the ignition device 8, and the starter switch 5
When is turned on, the electric power from the battery 6 is supplied to the starter 9.

The engine control unit 3 is mainly composed of a microcomputer, and has a CPU 10, a ROM 11 and
A RAM 12, an EEPROM 13, a backup power supply circuit 14, a power supply circuit 15, an input / output port 16 and the like are provided. The power circuit 15 has an ignition switch 4
The power from the battery 6 is supplied via the. CPU1
0 reads various sensor data relating to the engine operating state, such as engine speed data from the rotation sensor 17 and intake air amount data from the intake air amount sensor 18, based on the engine control program stored in the ROM 11, and the fuel injection amount and Ignition timing etc. are calculated, and based on the calculation result,
The fuel injection device 7 and the ignition device 8 are controlled according to the engine operating state.

The CPU 10 also reads the reading device 2a based on the theft determination processing program stored in the ROM 11.
The password code on the key 1 side is read from, and this password code is compared with the password code on the vehicle side stored in the EEPROM 13 to check whether the key 1 inserted in the key cylinder 2 is a proper one. judge. If the key is not a legitimate key, it is determined that the vehicle has been stolen, and fuel cut, ignition cut, headlight 19 blinking, horn 20 blowing, etc. are performed. This theft determination process will be described later with reference to FIGS.

Further, the CPU 10 is based on the battery voltage drop determination processing program stored in the ROM 11,
The battery voltage signal from the power supply circuit 15 is read, and it is determined whether the voltage of the battery 6 has become equal to or lower than the minimum operating voltage (predetermined voltage according to the invention of claim 1) that can normally operate the engine control device 3. Next, this battery voltage drop determination processing will be described using the flowchart in FIG.

The CPU 10 performs the interrupt process of FIG. 2 every 1 ms. When this interrupt processing is started, step S1
At 0, it is determined whether or not the voltage (VBAT) of the battery 6 input to the input / output port 16 via the power supply line 21 (FIG. 1) is equal to or higher than the minimum operating voltage (V1). Here, when the determination is YES, the routine exits without doing anything. On the contrary, when the determination is NO, the flag XB
AT is set to 1 and it is memorized that this battery voltage has become equal to or lower than the above-mentioned minimum operating voltage.

Next, referring to FIG.
This will be described using the flowchart of FIG. CPU 10
The interrupt processing of FIGS. 3 and 4 is performed every 1 ms. When this interrupt processing is started, the flag XNG is set in step S100.
It is determined whether or not the theft determination result is "theft" by checking whether or not 1 is set. Further, in step S110, it is determined whether or not the theft determination result is "not theft" by checking whether 1 is set in the flag XOK.

When YES is determined in any of the steps S100 and S110, it means that the theft determination result has already been obtained, and therefore the routine of FIGS. Further, when it is determined to be NO in both steps S100 and S110, it means that the theft determination result has not been obtained yet, so in the next step S120, the reading device 2
It is determined whether or not the secret code of the key 1 is received from a. If YES is determined here, the process jumps to step S180 in FIG. 4, and if NO is determined, the process proceeds to next step S130. Note that this step S120
Then, the received personal identification code is changed in step S18 described later.
If the processing of 0 (FIG. 4) is completed, it is determined as NO.

In step S130, the key cylinder 2
Then, it is determined whether the secret code of the key 1 has not been transmitted yet, and whether or not the transmission request from now on is the first time. Here, if it is the first time, it is determined as YES, and step S1
At 40, communication until the vehicle theft determination result is output (the engine control device 3 receives the secret code of the key 1, and collates this secret code with the secret code in the EEPROM 13,
A counter CDELY that counts the time from the start of a series of communications such as issuing a vehicle theft determination result based on the collation result is cleared.

Then, in the next step S150, the reader 2 is requested to transmit the personal identification code in the key 1, and in the next step S160, the time from the start of the transmission request is counted. Clear the counter CDELY1. Then, the process jumps to step S190 in FIG. If NO is determined in step S130, the counter CDE is determined in step S170.
It is determined whether or not LY1 has exceeded a predetermined time (K1). If YES is determined here, the predetermined time (K1) has elapsed from the previous transmission request, and it is considered that the next transmission request is made, and the process proceeds to step S150.
On the other hand, when the determination is NO, it is not the timing to issue the transmission request yet, so the process jumps to step S190 in FIG.

In step S180 of FIG. 4, the secret code transmitted by the reading device 2 in response to the transmission request and E
The personal identification code stored in the EPROM 13 is compared.
Here, if the collation result is “match”, step S
It jumps to 230, sets 1 to the above-mentioned flag XOK, and memorizes that the theft determination result is "not theft".

When the collation result is "mismatch" in step S180, it is determined in step S190 whether the flag XBAT is set to "1". If NO is determined here, it means that the battery voltage is not lower than the minimum operating voltage (V1). Therefore, the comparison result in step S180 is regarded as correct, and the counter CD is determined in step S200.
It is determined whether ELY has exceeded the first predetermined time (T1).

When NO is determined in this step S200, this routine is exited as it is, and when YES is determined, it is considered that the engine has not been started by a normal method, and the above-mentioned flag XNG is determined in step S220. To 1
Is set, and it is stored that the theft determination result is “theft”. When the flag XNG is set to 1, the fuel cut, the ignition cut, the blinking of the headlight 19 and the blowing of the horn 20 are performed as described above. Since these processes are well known, they are not shown.

When the determination in step S190 is YES, it means that the battery voltage has fallen below the minimum operating voltage (V1). At this time,
Even if the key 1 inserted in the key cylinder 2 is a legitimate one, there is a possibility that it will be determined as "mismatch" in step S180. Therefore, in step S210, the counter CDELY is set to the first predetermined time ( It is determined whether or not the second predetermined time (T2) longer than T1) has been reached.
Here, when NO is determined, the routine exits as it is, and when YES is determined, the process proceeds to step S220. The processing of steps S190 and S210 is an essential part of this embodiment.

Here, the first predetermined time (T1), the second
The length of the predetermined time (T2) is set based on the following idea. As described above, the present embodiment starts the engine for the time being when the ignition switch 4 is turned on, and then starts the engine when the result of the theft determination is “theft”. If T1) is too long, the theft judgment result will be "theft".
If so, the time until the engine is stopped becomes long, and the distance that the vehicle can be moved becomes long.

On the other hand, if the first predetermined time (T1) is shortened too much, the collation result in step S180 should be "match", but if it becomes "mismatch" due to some disturbance, the 1 predetermined time (T1)
Is short, the determination is “theft” in step S220. Therefore, the first predetermined time (T1) of this embodiment
Is set as the time to solve each of the above problems together.

The second predetermined time period (T2) is set as a time period during which the process of step S180 can be performed after the battery voltage stabilizes and becomes equal to or higher than the minimum operating voltage (V1). There is. In the above-described embodiment, when the battery voltage does not become lower than the minimum operating voltage, step S is performed during the first predetermined time (T1).
If the collation result of 180 is never “match”, the theft determination result is “theft”, and if it is “match” even once during the first predetermined time (T1), the theft determination result is “not theft”. It will be.

On the other hand, when the battery voltage becomes equal to or lower than the minimum operating voltage, if the above collation result is "match" during the second predetermined time (T2) longer than the first predetermined time (T1). If not, the theft determination result is "theft", and if the result is "match" even once during the second predetermined time (T2), the theft determination result is "not theft". According to this embodiment, when the key 1 inserted in the key cylinder 2 is normal, the ignition switch 4 and the starter switch 5 are sequentially turned on to energize the starter 9, as shown in FIG. When the battery voltage becomes equal to or lower than the minimum operating voltage, 1 is set to the flag XBAT at that time, and YES is determined in step S190.

Here, when the battery voltage becomes equal to or lower than the minimum operating voltage, data of the personal identification code output from the reading device 2 is destroyed, or communication is performed until the engine control device 3 is reset and a theft determination result is output. Is interrupted on the way, and the collation result in step S180 (FIG. 4) becomes “mismatch (NG)” where “coincidence (OK)” is originally supposed. If this state continues for the first predetermined time (T1), the collation result becomes "mismatch (NG)" during the first predetermined time (T1).

However, in the present embodiment, as described above, when the battery voltage becomes equal to or lower than the minimum operating voltage, the above-mentioned comparison is performed for the second time longer than the first predetermined time (T1).
A predetermined time (T2) is performed, and as a result, the number of times of collation is larger than that in the first predetermined time (T1). Further, since the battery voltage becomes equal to or higher than the minimum operating voltage by the second predetermined time (T2), the battery voltage becomes equal to or higher than the minimum operating voltage by performing the second predetermined time (T2). After that, the above collation is performed, and at this time, the above collation result is “match (OK)”.

Therefore, even if the "match (OK)" is not obtained even once during the first predetermined time (T1), it becomes "match (OK)" until the second predetermined time (T2) elapses.
The result of the theft determination is "not theft" and the flag XOK
Is set to 1. Thus, according to the present embodiment,
It is possible to prevent the problem that the key 1 inserted into the key cylinder 2 is legitimate and the vehicle is not stolen, but is erroneously determined as “theft”.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 6 to 8 only in a portion different from the first embodiment. In addition, in the processing performed by the CPU 10, the same processing as in FIGS.
The same reference numerals as these are given. As the theft determination process, the CPU 10 performs the interrupt process of FIGS. 6 and 7 every 1 ms. When this interrupt processing is started, steps S100 to S12
0 processing is performed. Then, in this step S120, Y
If it is determined to be ES, the process jumps to step S180 in FIG. 7, and if NO is determined, the process of step S170 is performed.

Then, if NO in this step S170, the routine exits without doing anything.
On the contrary, when the determination is YES, the counter CDELY
This means that the secret code of the key 1 is not received from the reading device 2 even if 1 exceeds the predetermined time (K1), that is, it is abnormal. Here, the cause of this abnormality may be a cause such as a thief destroying the key cylinder 2 or the like. However, in the present embodiment, the following steps S171 to S
173, and then step S172 or S173
Only when it is determined to be YES in the above, it is concluded that the cause of the abnormality is due to the destructive operation, and when that is not the case, the conclusion of the cause of the abnormality is suspended.

Specifically, first, in step S171,
It is determined whether the flag XBAT is set to 1. This flag XBAT is the same as in the first embodiment as shown in FIG.
Is set by the process of. And this step S
If NO is determined in 171, it means that the battery voltage has not fallen below the minimum operating voltage (V1). At this time, therefore, in the next step S172, the secret code transmission request to the reading device 2 is issued next. Then, it is determined whether or not it is a predetermined number of times (three times in this embodiment) or more.

If YES is determined in step S171, the battery voltage is the above-mentioned minimum operating voltage (V1
), It is determined in this step S173 whether or not the request to transmit the personal identification code to the reading device 2 is the predetermined number of times (five times in the present embodiment) or more. When YES is determined in step S172 or step S173, the cause of the abnormality is the destructive operation by the thief, so it is considered that a vehicle theft has occurred at this time, and the process proceeds to step S220 in FIG. Set 1 to the flag XNG.

In addition, step S172 or step S
When it is determined to be NO in 173, the conclusion of the cause of the abnormality is withheld and the processes of the following steps S150 and S160 are performed. The reason why the number of times in step S173 is set larger than the number of times in step S172 is that the reading device does not receive the data transmitted from the engine control ECU to the reading device even when the battery voltage becomes equal to or lower than the minimum operating voltage. Yes, because this was taken into consideration.

Then, steps S180 and S19 of FIG.
0 is performed, and when the result of the determination in step S190 is NO, the battery voltage is the minimum operating voltage (V1
), The collation result in step S180 is regarded as correct, and the theft determination result is set to "theft", and the flag XNG is set to 1 in step S220.

If YES is determined in step S190, the battery voltage is the minimum operating voltage (V1
). At this time, even if the key 1 inserted in the key cylinder 2 is a legitimate one, there is a possibility that it will be determined as "mismatch" in step S180. Therefore, in step S211, step S18
It is determined whether or not the matching with 0 has been performed three times or more.

When YES is determined in this step S211, it is considered that the cause of the "mismatch" in step S180 is not that the battery voltage is equal to or lower than the minimum operating voltage, but that there is a theft. Step S
The process of 220 is performed. On the contrary, when NO is determined,
Without issuing the theft determination result, in step S240, a request for transmitting the personal identification code is issued to the reading device 2, and in the next step S250, the counter CDELY1 is cleared and the routine exits. Note that the above steps S190 and S2
The process 11 is the main part of this embodiment.

In the above-described embodiment, when the battery voltage does not become lower than the minimum operating voltage, the theft determination result is "theft" unless the matching result of the first predetermined number (one time) is "match". If the matching result of the first predetermined number of times (one time) is “match”, the theft determination result is “not theft”. On the other hand, when the battery voltage becomes equal to or lower than the minimum operating voltage, the matching result of the second predetermined number of times (three times), which is larger than the first predetermined number of times (one time), is “match” even once.
Otherwise, the theft decision result will be "theft" and the second
If the matching result of the predetermined number of times (three times) is “match” even once, the theft determination result is “not theft”.

According to the present embodiment, when the key 1 inserted in the key cylinder 2 is normal, the ignition switch 4 and the starter switch 5 are turned on in sequence as shown in FIG. When electricity is supplied and the battery voltage becomes equal to or lower than the minimum operating voltage, 1 is set in the flag XBAT at that time, and in step S190, YE
It will be judged as S.

Here, when the battery voltage becomes equal to or lower than the minimum operating voltage, as described above, the comparison result in step S180 becomes "mismatch (NG)" where "match (OK)" is originally supposed. In this state, if the above first predetermined number of times (one time, indicated by C1 in FIG. 8) is performed, the above collation result will be "mismatch (NG)". However, in the present embodiment, as described above, when the battery voltage becomes equal to or lower than the minimum operating voltage, the above-mentioned collation is performed as the first operation.
The second predetermined number of times (3 times, FIG. 8) that is greater than the predetermined number of times (C1)
(Indicated by C2), and as a result, the number of times of collation is greater than when the first predetermined number (C1) is performed.

Further, since the battery voltage becomes equal to or higher than the minimum operating voltage until the second predetermined number of times (C2) is verified, the battery voltage is minimum operated by performing the second predetermined number of times (C2). Even after the voltage becomes equal to or higher than the voltage, the collation is performed, and at this time, the collation result is “match (OK)”. Therefore, the first predetermined number of times (C1
) Even if the match does not result in "match (OK)",
By performing the second predetermined number of times (C2) of collation, "match (OK)" is obtained once, the result of the theft determination is "not theft", and 1 is set in the flag XOK.

As described above, according to the present embodiment, it is possible to prevent the problem that the key 1 inserted in the key cylinder 2 is legitimate and is erroneously determined as "theft" even though the vehicle is not stolen. Further, in the present embodiment, even when YES is determined in step S170 of FIG. 6, when the battery voltage further becomes equal to or lower than the minimum operating voltage, compared to when the battery voltage does not become equal to or lower than the minimum operating voltage, Since the timing of conclusion of the cause determined to be YES in S170 is delayed, it is possible to prevent the problem that the above conclusion is erroneously issued due to the battery voltage becoming equal to or lower than the minimum operating voltage.

(Other Embodiments) In each of the above embodiments, when the ignition switch 4 is turned on, the engine is started for the time being, and if the theft determination result is "theft", the started engine is stopped. I explained the thing to prevent theft, but when turning on the ignition switch 4, stop the engine for the time being, and if the theft judgment result is "theft", then leave the engine as it is Is also good.

In the second embodiment, the first predetermined number of times referred to in the invention of claim 4 is one, but it may be two or more. In this case, it goes without saying that it is necessary to set the second predetermined number of times referred to in the invention of claim 4 as a number larger than the first predetermined number of times. Further, in each of the above-described embodiments, the theft determination result is set to "theft" when the matching result becomes "mismatch" continuously for the first predetermined time (T1) or the first predetermined number of times (C1). However, the theft determination result may be set to “theft” when a plurality of collations are performed and a predetermined ratio (for example, half) or more among them is “mismatch”.

In the above embodiment, the case where the code collating means, the theft determining means, and the voltage drop detecting means in the invention described in claim 1 are provided in the engine control device 3 has been described. It may be provided separately from 3. Further, in each of the above-described embodiments, the pointing member referred to in the invention of claim 1 is composed of the key 1, but it may be composed of a card, a remote controller for remote operation, or the like.

In the above embodiment, the case where the anti-theft device of the present invention is applied to a vehicle that moves when the engine is driven has been described, but it is applied to an electric vehicle that moves when the electric motor is driven, for example. May be. In this case, the prime mover according to the invention of claim 1 is composed of an electric motor. Further, in the above embodiment, the antitheft device for a vehicle has been described, but the present invention can be applied to, for example, a boat. In short, it can be applied to all moving bodies that move when the prime mover is driven.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a first embodiment of the present invention.

FIG. 2 is a flowchart of a battery voltage drop determination process performed by the engine control device 3 of the above embodiment.

FIG. 3 is a flowchart of a theft determination process performed by the engine control device 3.

FIG. 4 is a flowchart of a theft determination process performed by the engine control device 3.

FIG. 5 is a time chart after turning on the ignition switch 4 of the embodiment.

FIG. 6 is a flowchart of a theft determination process performed by the engine control device 3 according to the second embodiment of the present invention.

FIG. 7 is a flowchart of a theft determination process performed by the engine control device 3 of the second embodiment.

FIG. 8 is an ignition switch 4 according to the second embodiment.
It is a time chart after turning on.

FIG. 9 is a time chart showing the state of communication data when the battery voltage of the conventional device drops.

[Explanation of symbols]

1 ... Key (instruction member), 3 ... Engine control device, 4 ... Ignition switch, 5 ... Starter switch.

Claims (5)

[Claims] 1. A secret code on the side of an indicating member (1) used for a moving body that moves when a prime mover is driven, and for instructing the start of the prime mover when electric power is supplied from a battery (6), and A code collating means (3, S180) for collating with the secret code of the mobile body, and a theft determining means (S190) for deciding whether or not the mobile body is stolen based on the collation result of the code collating means (3, S180). ~ S230), the voltage of the battery (6) is a predetermined voltage in the antitheft device for stopping the prime mover when the theft determination means (S190 to S230) determines that the moving body is stolen. The voltage drop detecting means (S10) for detecting the following is provided, and the theft determination means (S190 to S230) is configured to detect the voltage drop by the voltage drop detecting means (S10). When it is detected that the voltage of the battery (6) is equal to or lower than the predetermined voltage, the code collating means (3, S180) performs more collation than when it is not detected. Theft prevention. apparatus. 2. The theft determination means (S190 to S23)
0) is the voltage drop detecting means (S10), when it is not detected that the voltage of the battery (6) is equal to or lower than the predetermined voltage, the code checking means (3, S180) is checked. When the voltage drop detecting means (S10) detects that the voltage of the battery (6) becomes equal to or lower than the predetermined voltage, the voltage collating means (3, S180) performs collation. The antitheft device according to claim 1, wherein the antitheft device is performed for a second predetermined time that is longer than the first predetermined time. 3. The theft determination means (S190 to S23)
0) is the voltage drop detection means (S10), when the voltage of the battery (6) has not been detected to be equal to or lower than the predetermined voltage, the matching result at the first predetermined time is the same. When it is not determined that the moving body is stolen, and the voltage drop detecting means (S10) detects that the voltage of the battery (6) is equal to or lower than the predetermined voltage, The anti-theft device according to claim 2, wherein when the collation result is not coincident with each other in two predetermined times, it is determined that the moving body is stolen. 4. The theft determination means (S190 to S23)
0) is the voltage drop detecting means (S10), when it is not detected that the voltage of the battery (6) is equal to or lower than the predetermined voltage, the code checking means (3, S180) is checked. When the voltage drop detecting means (S10) detects that the voltage of the battery (6) becomes equal to or lower than the predetermined voltage, the code collating means (3, S180) performs collation. 2. The antitheft device according to claim 1, wherein the antitheft device is performed a second predetermined number of times greater than the first predetermined number of times. 5. The theft determination means (S190 to S23)
0) indicates that, when the voltage drop detecting means (S10) has not detected that the voltage of the battery (6) has become equal to or lower than the predetermined voltage, the first predetermined number of times of the matching results match. When it is not determined that the moving body is stolen, and the voltage drop detecting means (S10) detects that the voltage of the battery (6) is equal to or lower than the predetermined voltage, 2. The antitheft device according to claim 4, wherein it is determined that the moving body is stolen when the matching result of a predetermined number of times does not match.