JPH0644040B2 - Ultrasonic security device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultrasonic security device, and more particularly, to an ultrasonic detecting device that emits ultrasonic waves and detects reflected waves to detect the presence or absence of an intruder in a vehicle. The present invention relates to an ultrasonic crime prevention device including a sound wave switch.

[Background Art] Generally, in this type of ultrasonic crime prevention device, the presence or absence of an intruder in the detection area set in the vehicle is always detected with the same sensitivity. However, there is a problem in that a false alarm is generated by being sensitive to vibrations generated outside the detection area, and conversely, if the sensitivity is set low, an alarm may not be output to an actual intruder.

[Object of the Invention] The present invention has been made in view of the above points, and its main purpose is to make the ultrasonic switch highly sensitive only when an intruder is present in the detection area. An object of the present invention is to provide an ultrasonic crime prevention device capable of surely detecting an intruder without causing a false alarm by being operated.

Disclosure of the Invention Hereinafter, embodiments of the present invention will be described with reference to the drawings. The ultrasonic switch 1 emits ultrasonic waves and detects the frequency shift of the reflected waves to detect the movement of an object in the detection area. As shown in FIG. Vibration detection unit 2 as a warning means in the power supply unit of
And a level determination unit 3 as a warning releasing unit are connected via a switch unit 4. The vibration detection unit 2 includes a vibration sensor 20 such as a piezo element. After the vibration detected by the vibration sensor 20 is amplified by the amplification circuit 21, the vibration detection unit 2 inputs the vibration to the comparison circuit 23 via the detection circuit 22, and the comparison circuit 23 receives the vibration. A vibration detection signal is output when compared with a preset reference level and when the vibration level is determined to be equal to or higher than a predetermined value. The vibration sensor 20 is arranged in or around the detection area of the ultrasonic switch 1 and detects the vibration generated by the intruder when there is an intruder in the detection area. The vibration detection signal is input to the switch unit 4. The switch unit 4 is an RS flip-flop circuit 4
0 and a switching element 41, and the vibration detection signal is input to the set input terminal of the RS flip-flop circuit 40. The output of the RS flip-flop circuit 40 is input to the switching element 41, which causes the switching element 41 to open and close. That is, the vibration sensor 2
When the vibration is detected by 0, the RS flip-flop circuit 40 is set and the switching element 41 becomes conductive. Since the switching element 41 is inserted between the ultrasonic switch 1 and the power source, when the switching element 41 becomes conductive, the ultrasonic switch 1 operates.

When the ultrasonic switch 1 is operated in this way, a reflected wave from an intruder existing in the detection area is detected, and if an intruder exists in the detection area, the level of the reflected wave becomes high. It is possible to determine whether or not to warn by operating the ultrasonic switch 1 as it is, depending on the strength of. That is, the signal corresponding to the intensity of the reflected wave extracted from the ultrasonic switch 1 is input to the level determination unit 3. The level determination unit is triggered by a comparison circuit 30 that compares the signal extracted from the ultrasonic switch 1 with a reference level, and a pulse output from the comparison circuit 30 when the intensity of the reflected wave is equal to or higher than a predetermined level. The monostable multivibrator 31 that outputs a pulse having a predetermined time width T is connected to the reset terminal of the RS flip-flop circuit 41 that constitutes the switch section 4. The comparison circuit 30 is a window comparator, and sets the output terminal to the H level when the input voltage is outside the range between the _first reference voltage Vref ₁ and the second reference voltage Vref ₂ . Since the signal input to the comparison circuit 30 is a vibration component as will be described later, if the amplitude is equal to or larger than a predetermined value, the comparison circuit 30 outputs the number of pulses twice the frequency of the input signal. It has become so. The monostable multivibrator 31 is retriggerable, and the negative logic output terminal keeps the L level during the time T determined by the capacitor Ct and the resistance Rt from the rising of the signal input last, and rises after the time T. It has become.

The configuration of the ultrasonic switch 1 will be described in detail. The ultrasonic switch 1 utilizing the Doppler effect described below operates on the same principle as that disclosed in JP-A-55-63774 and has a substantially similar configuration. There is.

The wave transmitter 10 is driven by the output of the oscillation circuit 11 that oscillates at a constant frequency, and the wave transmitter 10 radiates ultrasonic waves into the air. The ultrasonic wave radiated from the wave transmitter 10 is reflected by an object arranged around the ultrasonic wave, and the reflected wave is received by the wave receiver 12.
Is received by and is converted into an electric signal. Transmitter 10
The wave receiver and the wave receiver 12 are both configured by a piezo element, and the wave transmitter 10 radiates an ultrasonic wave that matches the frequency of the applied electric vibration, and the wave receiver 12 has the frequency of the received ultrasonic wave. The electric vibration corresponding to is output as a reception signal Ein.
The reception signal Ein received by the wave receiver 12 is frequency-converted through a pair of mixer circuits 13a and 13b. In the first mixer circuit 13a, a reference signal Et obtained by advancing the output of the oscillation circuit 11 through a phase shift circuit 14 by 90 degrees and a receiver 12 are provided.
The received signal Ein received by the second mixer circuit 13b is applied to output the intermediate signal E _{0 of the} frequency difference.
'Intermediate signal E ₀ of the frequency difference and the received signal Ein is applied from the wave receiver 12' the reference signal Et which is the output of the oscillation circuit 11 is output to. Therefore, a pair of intermediate signals E ₀ and E ₀ ′ whose phases are different from each other are obtained from the mixer circuits 13 a and 13 b. Here, since the frequency of the reflected wave when the object reflecting the ultrasound approaches the wave receiver 12 is higher than the oscillation frequency of the intermediate signal E ₀ phase leads that the phase of the intermediate signal E ₀ ' , in which the phase of the intermediate signal E ₀ from the frequency of the reflected wave is lower than the oscillation frequency when the object on the contrary away from receivers 12 is delayed with respect to the intermediate signal E ₀ '. Therefore, in the vector plane having the respective intermediate signals E ₀ and E ₀ ′ as the basic axes, the rotation vector represented by the received signal Ein rotates counterclockwise around the origin when the object approaches, and rotates clockwise when the object moves away. Rotate. The intermediate signals E ₀ and E ₀ ′ are amplified through amplifiers 15a and 15b, respectively, and further, bandpass filters 16a and 16a are provided to remove noise components.
16b is passed. This bandpass filter 16a, 16
The signal passing through b is a beat signal having an amplitude corresponding to the intensity of the reflected wave, and this beat signal is input to the level determination unit 3 described above. Further, the beat signal is input to the signal processing circuit 17, and in the signal processing circuit 17, first, the intermediate signals E ₀ and E ₀ ′ are converted into digital signals of H level or L level depending on whether the intermediate signals E ₀ and E ₀ ′ are positive or negative. Signal, and based on this digital signal both intermediate signals E ₀ , E ₀ ′
In which quadrant the rotation vector of the received signal Ein exists in the vector plane having the basic axis as the basic axis, and whether the quadrant in which the rotation vector of the received signal Ein exists moves from one quadrant to another An alarm signal is output when a quadrant transition is detected. This alarm signal is input to the notification circuit 18 to notify an alarm sound or the like. That is, the ultrasonic switch 1
Is to issue an alarm when it detects a frequency shift as a Doppler effect that occurs when an object that reflects ultrasonic waves moves within the detection area.

The operation will be described below with reference to FIG. In Fig. 2 (A)
The symbols (G) to (G) represent the signals of the respective parts in FIG. First, when there is no intruder in the detection area of the ultrasonic switch 1 and a vehicle hits a stone or the like and vibrates the surroundings, the vibration is detected by the vibration sensor 20 as shown in FIG. 2 (A). Since the vibration detection signal is output as shown in FIG.
The RS flip-flop 4 of the switch unit 4 as shown in FIG.
0 is set and power is supplied to the ultrasonic switch 1. In this way, the ultrasonic switch 1 operates, and at this time, the vibration is also detected by the ultrasonic switch 1. Therefore, a signal of a predetermined level or more is input to the level determination unit 3 as shown in FIG. The monostable multivibrator 31 is triggered as shown in FIG. Therefore, the output of the monostable multivibrator 31 is shown in FIG.
As described above, the RS flip-flop 40 of the switch unit 4 maintains the set state. However, at this time, no alarm is detected because there is no movement of the object within the detection area, and because the vibration is transient, the trigger signal to the monostable multivibrator 31 is immediately stopped and the last trigger signal rises. The output of the monostable multivibrator 31 is kept at the L level for the time width T of the time constant set to the monostable multivibrator 31 from then to the H level, and the switch unit 4
R4 flip-flop 40 is reset. When the RS flip-flop 40 is reset, the power supply to the ultrasonic switch 1 is stopped and the operation of the ultrasonic switch 1 is stopped. On the other hand, when there is an intruder, first the vibration sensor 20
Detects an intruder and activates the ultrasonic switch 1. When the ultrasonic switch 1 operates, the ultrasonic switch 1 detects an intruder in the detection area, and the reflected wave and the intensity become high. Therefore, a signal with a large amplitude is input to the level determination unit 3, and the monostable multi The output of the vibrator 31 is L
It becomes a level and the RS flip-flop 4 of the switch unit 4
0 maintains the set state. When the intruder moves in this state, the ultrasonic switch 1 detects the intruder and issues an alarm.

As described above, since the ultrasonic switch 1 is operated only when the vibration is generated in the detection area, it is possible to reduce the power consumption as compared with the case where the ultrasonic switch 1 is always operated. This leads to power saving. Further, although the vibration sensor 20 is separately provided in the above example, the output end of the wave receiver 12 of the ultrasonic switch 1 is connected to the input end of the amplification circuit 21 of the vibration detection unit 2 to vibrate the wave receiver 12. It may be used instead of the sensor 20. Here, since it is mounted on a vehicle such as an automobile,
Since vibration generated in the detection area can be detected by the wave receiver 12, if the wave receiver 12 is used instead of the vibration sensor 20,
This leads to a reduction in the number of parts.

Reference Example Below, an ultrasonic type crime prevention device configured without using the vibration sensor 20 will be shown as a reference example. As shown in FIG. 3, a pair of oscillating circuits 11a and 11b of the ultrasonic switch 1a is provided, and the output of one of the oscillating circuits 11a and 11b is selectively output by the logic circuit. Both oscillator circuits 11
a and 11b are set to have different output frequencies, and the output frequency of the first oscillation circuit 11a is set to the transmitter 10
And a value different from the resonance frequency of the wave receiver 12, and the output frequency of the second oscillation circuit 11b is set equal to the resonance frequency. Therefore, when the first oscillator circuit 11a is selected, the output intensity of the wave transmitter 10 and the receiving sensitivity of the wave receiver 12 are determined by the second oscillator circuit 11a.
It will be lower than when b is selected. The logic circuit is a two-input OR circuit 25, a pair of two-input AND circuits 26 and 27 connected to each input terminal of the OR circuit 25, and an inverter circuit connected between one input terminal of each AND circuit 26, 27. And an inverter circuit 2
The output terminal of the first oscillation circuit 11a is connected to the other input terminal of the AND circuit 26 connected to the output terminal side of 8 and the AND circuit 27 connected to the input terminal side of the inverter circuit 28.
The second oscillating circuit 11b and the output terminal are connected to the other input terminal. Further, the positive logic output terminal of the monostable multivibrator 31 of the level determination unit 3 is connected to the input terminal of the inverter circuit 28. The level determination unit 3 is the first embodiment.
The monostable multivibrator 31 is triggered when the intensity of the reflected wave received by the ultrasonic switch 1 reaches or exceeds a predetermined level, and the last pulse and a predetermined time from the rising edge. The output is set to the H level by the width T. Here, the vibration detecting section 2 is not provided, and an intruder in the detection area is detected by switching the sensitivity of the ultrasonic switch 1. That is, when the first oscillation circuit 11a is selected, the ultrasonic switch itself acts as a warning means.

The operation will be described below with reference to FIG. In Fig. 4 (A)
(D) represents the signal of each part in FIG. First, when there is no intruder in the detection area, the reflected wave detected by the ultrasonic switch 1 is below a predetermined level, so the output of the level determination unit 3, that is, the output of the monostable multivibrator 31 becomes L level. Since one input terminal of the first AND circuit 26 becomes H level, the output of the first oscillation circuit 11a is taken out from the output terminal of the OR circuit 25. Since this output frequency is different from the resonance frequency of the wave transmitter 10 and the wave receiver 12, the ultrasonic switch 1
Is set to low sensitivity. This sensitivity is set to such a level as to respond when the intruder's arm intrudes through the window. If a person passes near the detection area, as shown in FIG.
As shown in FIG. 4 (C), the output of the level determination section 3 becomes H level, and the output of the second oscillating circuit 11b is taken out from the output terminal of the OR circuit 25. Then, the ultrasonic switch 1 is set to a high sensitivity. However, at this time, a person passes by in an instant, so the intensity of the reflected wave decreases before the quadrant transition of the rotation vector of the received signal occurs, and the alarm is not notified. From the last rising edge of the trigger signal that occurs in the monostable multivibrator 3
The high sensitivity is maintained for a predetermined time T set to 1, and then the low sensitivity is restored. Next, when there is an intruder in the detection area, the reflected wave and the intensity are increased, so that the sensitivity is set to high as described above. At this time, since the ultrasonic switch 1 detects the movement of the intruder, an alarm is issued. It will be announced. In this way, the sensitivity is usually low, and the sensitivity is set to high after a person approaches the detection area. Is one that can be set with high sensitivity to ensure reliable detection.

[Advantages of the Invention] As described above, the present invention provides an ultrasonic switch that emits ultrasonic waves and detects the reflected waves to detect the presence or absence of an intruder in the vehicle, and an ultrasonic switch within the detection area. Or, a warning means to set the ultrasonic switch to the operating state when the intruder in the vicinity is warned and the intruder is detected, and the reflected wave detected by the ultrasonic switch reaches a predetermined level within a predetermined time after the operation of the ultrasonic switch. It is characterized in that it is equipped with a warning canceling means for canceling the operating state of the ultrasonic switch when it does not exceed, and the warning means is a vibration detecting section equipped with a vibration sensor for detecting an external vibration by an intruder. At this time, the ultrasonic switch is stopped and the vibration detection unit warns the intruder.When the vibration detection unit detects an intruder, the ultrasonic switch is activated to enter the detection area of the vibration detection unit. Since the intruder is detected in two stages by confirming the presence or absence of an intruder, even if the security device mounted on the vehicle is easily affected by vibrations, it is possible to detect almost the same detection area. There is an advantage that false alarms can be prevented by detecting and confirming at a stage. Especially, after the intruder is detected by the vibration detector that detects external vibration, the intruder is confirmed by the ultrasonic switch.
The intruder is detected using different kinds of physical quantities, and the intruder and the non-intruder can be identified for confirmation. Moreover, when an intruder actually exists, it can be reliably detected by the ultrasonic switch. Further, even if the ultrasonic switch is in the operating state, if the intruder is not detected within a predetermined time, a warning releasing means for releasing the operating state of the ultrasonic switch is provided. Even if is set to the operating state, if it is not an intruder, it can automatically return to the original state to prepare for an intruder and vigilance.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an operation explanatory diagram showing signals of respective parts in the first part, FIG. 3 is a block diagram showing a reference example, and FIG. 4 is in FIG. It is an operation explanatory view showing a signal of each part. 1 is an ultrasonic switch, 2 is a vibration detection unit, 3 is a level determination unit, 4 is a switch unit, 10 is a wave transmitter, 11a is a first oscillation circuit, 11b is a second oscillation circuit, and 12 is a wave receiver. Is.

Claims (1)

[Claims] 1. An ultrasonic switch for emitting ultrasonic waves and detecting the reflected waves to detect the presence or absence of an intruder in the vehicle.
After the operation of the ultrasonic switch, the alerting means to set the ultrasonic switch to the operating state when the intruder is detected inside or around the detection area of the ultrasonic switch and the intruder is detected. And a warning canceling means for canceling the operation state of the ultrasonic switch when the predetermined level is not exceeded within a predetermined time, and the warning means is a vibration detecting section having a vibration sensor for detecting an external vibration by an intruder. Ultrasonic crime prevention device featuring.