JPH0219336Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field] The present invention relates to a vehicle anti-theft device, and more specifically, to a technology for preventing false alarms in a vehicle anti-theft device that issues an alarm when an object moves within the vehicle. It is something.

[Background technology]

In general, anti-theft devices for vehicles include those that detect the movement of an object within the vehicle (the detection area) and output a movement detection signal, and use this movement detection signal to drive an alarm means, and those that detect vibrations of the vehicle body. Some devices output a vibration detection signal and drive an alarm means using this vibration detection signal. However, regardless of the method of detecting moving objects inside the car or the method of detecting the vibrations of the car body, if a person plays a trick and shakes the car body, or if a large vehicle passes nearby and the car body shakes, When the sensor vibrates, in the former case, an object placed inside the vehicle shakes or the detection unit itself vibrates, causing a false alarm, and in the latter case, of course, a false alarm occurs. In this way, an alarm may be output even when no one is actually intruding into the vehicle, and there is a problem in that false alarms are likely to occur.

[Purpose of invention]

The present invention has been devised in view of the above points, and its main purpose is to provide a vehicle theft prevention device that prevents false alarms due to vibrations of the vehicle body.

[Disclosure of invention]

(Example) Hereinafter, an example of the present invention will be described based on the drawings. As shown in the figure, it is composed of a moving object detection means 1, a vibration detection means 2, a determination means 3, and an alarm means 4. The moving object detection means 1 is an ultrasonic sensor using the Doppler effect, and includes a transmitter 10.
The receiver 11 receives the ultrasonic waves reflected by the object and compares the transmitting frequency with the receiving frequency. It is determined that the object has moved. The transmitter 10 is composed of an ultrasonic vibrator such as a piezo element, and by inputting the output of an oscillator 13 to the transmitter 10 via an amplifier 12, an ultrasonic wave having a frequency equal to the output frequency of the oscillator 13 is generated. It is emitted from the transmitter 10. Ultrasonic waves emitted from the transmitter 10 and reflected by an object are received by the receiver 11.
The signal received by the receiver 11 is amplified by the amplifier 14 and then mixed with the output of the oscillator 13 by the mixer 15. A beat signal of the transmitting frequency and the receiving frequency is obtained as the output of the mixer 15. After this output is detected by the detector 16, it is amplified by the amplifier 17, and then passed through the bandpass filter 18 to remove noise. In this way, the signal can pass through the bandpass filter 18 only when the deviation of the reception frequency with respect to the oscillation frequency is within a predetermined range, and the signal passing through the bandpass filter 18 turns on the switching section 19. , an H level movement detection signal is sent out as an output signal of the moving object detection means 1. This moving object detection means 1 is arranged to send out ultrasonic waves into the interior of the vehicle, and outputs a movement detection signal when there is an intruder inside the vehicle so that the entire interior of the vehicle becomes a detection area. .

On the other hand, the vibration detection means 2 includes a vibration detector 20 that converts vibrations into electrical signals like a piezo element,
It outputs a vibration detection signal when vibration is detected. The output signal of the vibration detector 20 is sent to the amplifier 2.
After being amplified by the detector 1 and detected by the detector 22, the detected output is input to the switching unit 23. Therefore, when vibration is detected, an H level vibration detection signal is output as an output signal of the switching section 23. This vibration detection means 2 is disposed on the vehicle body, and outputs a vibration detection signal when the vehicle body vibrates.

The determination means 3 is composed of a two-input AND circuit 30 and an inverter 31 connected to one input terminal of the AND circuit 30, and the output of the moving object detection means 1 is connected to one input terminal of the AND circuit 30. The output of the vibration detection means 2 is inputted to the other input terminal of the AND circuit 30 via the inverter 31. Therefore, only when the output of the vibration detecting means 2 is at the L level and the output of the moving object detecting means 1 is at the H level, the output of the determining means 3 is set to the H level and a detection signal is output.

The output of the determination means 3 is input to the alarm means 4.
The alarm means 4 includes an alarm 40 such as a buzzer or an alarm lamp, and an alarm drive section 41 that drives the alarm 40 when the input becomes H level.
Therefore, when the output of the determining means 3 becomes H level, the alarm device 40 is activated and an alarm is issued.

The operation of the present invention will be explained below. First, in normal use, when there is an intruder inside the vehicle, if even a part of the intruder enters the vehicle, a movement detection signal is output, and in this case, the movement detection signal is detected by the vibration detection means 2. Since no vibration occurs, a detection signal is output from the determining means 3 and an alarm is issued. On the other hand, when a large vehicle or the like passes nearby or when the vehicle body is shaken from the outside due to a prank, the vibration detection means 2 outputs a vibration detection signal. Even if a movement detection signal is output, the determination means 3 ignores the output of the moving object detection means 1 and no detection signal is output, so that no false alarm occurs. That is, when a vibration sufficient to cause the moving object detection means 1 to output a movement detection signal is detected, the vibration detection signal prohibits the output of the movement detection signal. In this manner, an alarm is issued only when there is an intruder, thereby preventing false alarms.

[Effect of idea]

As described above, the present invention includes a moving object detection means that outputs a movement detection signal when an object moves within the vehicle, a vibration detection means that outputs a vibration detection signal when the vehicle body vibrates, and a vibration detection means that outputs a movement detection signal and generates a vibration detection signal when the vehicle body vibrates. It is composed of a determination means that outputs a detection signal when no detection signal is output, and an alarm means that outputs an alarm based on the detection signal, so even if a movement detection signal is output, it is detected when the vehicle body vibrates. No signal is output, and even if a movement detection signal is output from the moving object detection means due to vibrations of the vehicle body, the detection signal is not input to the alarm means, thereby preventing false alarms due to vibrations of the vehicle body.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. 1 is a moving object detection means, 2 is a vibration detection means, 3
4 is a determination means, and 4 is an alarm means.

Claims (1)

[Scope of utility model registration request] Moving object detection means outputs a movement detection signal when an object moves within the vehicle; vibration detection means outputs a vibration detection signal when the vehicle body vibrates; and when a movement detection signal is output and no vibration detection signal is output. 1. A vehicle anti-theft device comprising: a determining means for outputting a detection signal; and an alarm means for outputting an alarm based on the detection signal.