JPH04145846A - Backup power source switching circuit for on-vehicle electric equipment - Google Patents

Abstract

PURPOSE:To detect a set being the victim of robbery by preventing the input of a normal releasing signal to the set so that a backup power source circuit in the set can be switched to a low-impedance circuit. CONSTITUTION:When a backup power source is turned on, a timer in a microcomputer starts counting operation. The timer is set to the time required for assembling a set after the backup power supply is turned on. Then whether or not a normal releasing signal is inputted within the set time of the timer is judged and, when a result is 'Yes', a normal operating state is maintained by holding a backup current consuming circuit in a turned-off state. When the set is a stolen article, the normal releasing signal is not inputted, since the thief does not know the content of the releasing signal composed of a cipher, etc. When the normal releasing signal is not inputted within the time set in the timer, the timer turns off and the backup current consuming circuit is turned on.

Description

[Detailed Description of the Invention] [Summary] Regarding a backup power supply switching circuit for in-vehicle electrical equipment such as car audio, if the electrical equipment is stolen, the battery of the vehicle is discharged in a short period of time, and the The purpose of this invention is to detect whether or not a legitimate release signal is input within a predetermined time after turning on the backup power supply, and to detect whether the backup signal is input when the release signal is not input. The power supply circuit is configured to include means for switching from the backup power supply to a low impedance circuit consuming a large current.

[Industrial application field]

The present invention relates to a backup power supply switching circuit for in-vehicle electrical equipment such as car audio.

[Conventional technology]

Conventionally, various ideas have been devised as security functions for this type of vehicle-mounted electrical equipment against theft, such as a set that can be attached and removed, or a set that becomes inoperable in the event of theft. However, even if a set is equipped with such a function, there is a problem in that if the set is stolen, it is almost never returned to the user.

[Problem to be solved by the invention]

The present invention was made to solve such problems,
When an electrical device such as a car audio is stolen, the setting value of the set's dark current (current consumption from the battery) is automatically changed to discharge the battery of the stolen vehicle in a short period of time. In this way, the theft can be detected and the stolen set can be returned.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a means for detecting whether a regular release signal is input within a predetermined time after turning on the backup power supply, and a means for detecting whether the release signal is inputted manually when the backup power supply circuit is inputted. A backup power supply switching circuit for a vehicle-mounted electrical component is provided that includes means for switching from the backup power supply to a low impedance circuit that consumes a large current.

[Function] According to the above configuration, when a set is stolen, the backup power circuit inside the set is switched to a low impedance circuit because a regular release signal is not input to the cent, and as a result, the stolen set is stolen. Unbeknownst to the perpetrator, a large amount of current (enough to prevent the vehicle fuse from blowing) is constantly being consumed from the vehicle battery, eventually causing the vehicle battery to become dead (completely discharged). Therefore, even if a culprit who did not realize this charged the vehicle battery several times, it would be ineffective as the above operation would be repeated, and when the car was requested to be repaired by the dealer, it would be discovered that the set was stolen, and the battery would be discovered to be stolen. The set will be returned.

〔Example〕

FIG. 1 illustrates a circuit configuration for carrying out the method of the present invention. In FIG. 1, the right side from the chain line shows the vehicle part;
The left side shows a set assembled to the vehicle. B is a vehicle battery as a backup power source, and from the vehicle battery B through a vehicle fuse F and a diode D, the ports 1 to 1 of the microcomputer MC inside the set are connected.
A hook-up voltage is supplied to P2. C is a capacitor for retaining data stored in the memory even when the backup power supply is turned off (or when the backup power supply is consumed and its voltage drops to nearly 0.times.).

Also, the backup voltage of the backup power source (vehicle batch IJ-) B is detected via the baud 1-PI of the microcomputer MC.

A is a backup current consumption circuit and is connected to port P3 of the microcomputer MC.

When the release signal for the backup current consumption circuit is not input to the baud P4 of the microcomputer MC within a predetermined time after the backup power supply is turned on, the backup power supply circuit connected to the baud P2 , the backup current consumption circuit (low impedance circuit) connected to the port P3 is switched to the A side. When switching to the backup current consuming circuit in this way, the backup power source (vehicle battery)]3
A large amount of current (enough to prevent the vehicle fuse F from blowing) continues to be consumed, and the vehicle battery eventually becomes exhausted (completely discharged).

Note that the release signal to the backup current consuming circuit shall be sent within a predetermined period of time after the backup power supply is turned on.
In other words, it is inputted by an authorized person (person who did not steal) during the time it takes to assemble the set, such as a code input by key operation or a signal input by a hidden reset switch at the rear of the set.

FIG. 2 is a flowchart showing the operating procedure when carrying out the method of the present invention. In step 1, backup power is turned on by connecting the car cord, and in step 2
and the backup voltage of the backup power supply (for example, 13
■) is detected.

Next, in step 3, the backup current consumption circuit is temporarily turned off to return to a normal operating state. This allows a regular person (
When a person who did not steal the set assembles the set for the first time, current consumption through the backup current consumption circuit is prevented from flowing to the backup power source (battery). Next, at step 4, the timer in the microcomputer starts counting. Here, the timer is set to the time (for example, about 15 minutes to 1 hour) from turning on the backup power to assembling the cellars 1 to 1.

During this time, it is determined in step 5 whether or not the normal release signal has been input, and if YES, the backup current consumption circuit is kept in the OFF state and brought into a normal operating state. In other words, if an authorized person (a person who did not steal the set) assembles the set, he or she will know the contents of the release signal using the above code, etc., so the authorized release signal will be input during the timer operation time and normal operation will occur. The state is maintained.

On the other hand, if the item is stolen, the thief does not know the content of the coded release signal, so the official release signal is not input. If the normal release signal is not input within the time set by the timer, the timer is turned off in step 6, and the backup current consumption circuit is turned on in step 7. (That is, the normal backup power supply circuit is switched to the backup current consumption circuit.) As a result, the backup current consumption circuit continues to consume, for example, several amperes of current from the backup power supply.
Eventually, the backup power source (battery) will run out (completely discharged).

Therefore, if the backup voltage is detected in step 8, it will be approximately Ov, and in that case, the backup current consumption circuit is turned off in step 9.

Therefore, even if a person who steals the set charges the battery and reinstalls it in the car, the above operation will be repeated and the battery will die as described above.

[Effects of the Invention] According to the present invention, when an in-vehicle electrical component is a stolen item, the battery of the vehicle is discharged in a short period of time, so the theft is detected based on this, and the stolen item is detected. Returns are possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a circuit configuration for implementing the method of the present invention, and FIG. 2 is a flowchart showing the operating procedure when implementing the method of the present invention. (Explanation of symbols) A: Hack-up current consumption circuit, B: Hack-up power supply (vehicle battery), C: Memory holding capacitor, MC: Microcomputer.

Claims (1)

[Claims] 1. Means for detecting whether a regular release signal is input within a predetermined time after turning on the backup power supply, and a low impedance device that causes the backup power supply circuit to consume a large current from the backup power supply when the release signal is not input. A backup power supply switching circuit for automotive electrical equipment, characterized by having a means for switching the circuit.