JPS61184481A - Apparatus for detecting moving matter - Google Patents

Abstract

PURPOSE:To provide only one ultrasonic vibrator to be used, by continuously transmitting an ultrasonic wave from an ultrasonic vibrator and detecting moving matter from the change in the amplitude of the current flowed to the ultrasonic vibrator. CONSTITUTION:When matter is moving, the magnitude and phase of the reflected wave R received by a vibrator 1 change and, as a result, the amplitudes of the signals generated at both terminals of a resistor 3 change corresponding to the movement of the matter. By this method, the detection signal corresponding to the change in the amplitudes of the signals generated at both terminals of the resistor 3 appears in the output of a detector 5 and amplified by a band amplifier 6 and, when the amplified output signal is compared with predetermined voltage by a comparator 7, the pulse line corresponding to the movement of the matter is outputted to an output terminal 8. By this method, the moving matter can be detected by using one ultrasonic vibrator.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a moving object detection device that detects a moving object using ultrasonic waves.

(Prior art) Conventionally, this type of device consists of an ultrasonic transducer dedicated to transmitting waves that continuously transmits ultrasonic waves toward a moving object, and an ultrasonic transducer dedicated to receiving and receiving waves reflected from the moving object. An ultrasonic transducer is provided to detect moving objects.

(Problems to be Solved by the Invention) However, the above method uses two ultrasonic transducers for transmitting ultrasonic waves, and has the problem of high cost.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a moving object detection device that detects a moving object using one ultrasonic transducer.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes one ultrasonic transducer and an oscillator for exciting the ultrasonic transducer and continuously transmitting ultrasonic waves. A moving object is detected from changes in the amplitude of the current flowing through the ultrasonic transducer.

(Function) In the above configuration, the ultrasonic transducer receives an excitation signal from the oscillator, continuously emits ultrasonic waves to the detection target area, and receives reflected waves from the area. If there is no moving object in that area, there will be no change in the current flowing through the ultrasonic transducer, so the moving object will not be detected. but,
When a moving object exists in the area, the current flowing through the ultrasonic transducer changes depending on the magnitude and phase of the reflected wave from the moving object, and the presence of the moving object is detected based on the amount of change.

(Effects of the Invention) Therefore, according to the present invention, a moving object can be detected using one ultrasonic transducer.

(Embodiment) In FIG. 1 showing the configuration of an embodiment of the present invention, l is an ultrasonic transducer (hereinafter referred to as a transducer) that transmits ultrasonic waves to a predetermined space and receives reflected waves from the space. ),
2 is an oscillator for exciting the vibrator 1 at a predetermined frequency;
3 is a resistor that is connected in series with the vibrator 1 and converts the current flowing through the vibrator l into voltage; 4 is an amplifier that amplifies the voltage generated across the resistor 3; and 5 is an envelope line of the output signal of the amplifier 4. 6 is a band amplifier that amplifies the output signal of the wave detector 5. 7 is a comparator that compares the output signal voltage of the band width amplifier 2ii6 with a predetermined voltage value and outputs the result to a terminal 8. , 9 is a constant voltage power supply circuit that supplies a constant voltage to the oscillator 2, the amplifier 4, the band amplifier 6, and the comparator 7.

The operation of the above configuration will be explained with reference to the signal waveform diagram shown in FIG.

The oscillator 2 outputs an excitation signal of constant amplitude (FIG. 2(a)). The frequency of this excitation signal is selected to be slightly higher than the resonant frequency of the vibrator l. When this excitation signal is applied to the vibrator 1, the ultrasonic wave T is transmitted from the vibrator 1 to a predetermined space. At this time, an alternating current ■1 flows through the vibrator 1. Now, when there is no object in the predetermined space (section t1 in Figure 2), the current I flowing through the vibrator 1 is equal to ■7, and as a result, the voltage across the resistor 3 has a constant amplitude V=rlltl.
A signal (FIG. 2(b)) is generated. When this signal is amplified and detected by the amplifier 4 and the detector 5, the output of the detector 5 (second
Figure (C)) shows a predetermined DC voltage. However, since the band amplifier 6 blocks the DC component, no signal is output from the comparator 7.

Next, when an object exists in a predetermined space and ultrasonic waves are reflected from the object, the transducer l generates mechanical displacement according to the reflected wave in addition to the mechanical displacement caused by the excitation signal, which causes resistance. A new current 1++ flows through the resistor 3, and a signal with an amplitude of V=r l it +IRl is generated across the resistor 3. now,
When the object is stationary (section 1 in Figure 2), the magnitude and phase of the reflected wave R received by the vibrator 1 do not change, so the amplitude of the signal generated at both ends of the resistor 3 also does not change. , therefore, no signal is output from the comparator 7 as in the case where no object exists. On the other hand, when the object is moving (section t3 in Figure 2), the magnitude and phase of the reflected wave R delivered to the vibrator 1 change, and as a result, the amplitude of the signal generated at both ends of the resistor 3 changes. changes as the object moves. As a result, a detection signal corresponding to the amplitude change of the signal generated at both ends of the resistor 3 appears at the output of the detector 5. This detection signal is amplified by the band amplifier 6, and this amplified output signal is converted to a predetermined signal by the comparator 7. When compared with the voltage Vr, a pulse train corresponding to the movement of the object is output to the output terminal 8 (FIG. 2(d)).

Next, a preferred application example of the present application is shown in FIGS. 3 and 4. In FIG. 3, lOO is a pine lamp, and the oscillator l
is attached near the pine plump 100. Also,
In FIG. 4, 60 is a variable gain band amplifier whose gain changes depending on an external logic value, lO is a counter that counts the pulse train signal (FIG. 2(d)), and 11 is a counter 10.
12 is a latch signal of a predetermined period and a pulse signal generator that resets the counter 10 and generates a cent signal; 13 and 14 are switches that open and close in conjunction; 15 is a battery; 16 is a D - A flip-flop circuit, 17 is a drive circuit connected to the D-flip-flop circuit 16 and lights up the pine lamp 100, 1
8 is an R-S flip-flop circuit, and 19 is a drive circuit connected to the R-S flip-flop circuit 18 to blow a horn (not shown).

That is, the embodiment shown in FIGS. 3 and 4 is an example in which the present invention is used as a lighting switch for a pine lamp and as an intruder detector of an anti-theft device that prevents intrusion by someone aiming at a vehicle.

First, switches 13 and 14, which will explain the operation of the pine lamp lighting switch, are installed inside the trunk of a car and when the driver is in the car, the switches 13 and 14 are connected to terminal 1.
Contacts 3a and 14a are respectively closed. This reduces the gain of variable gain band amplifier 60. When the driver wants to turn on the pine lamp 100, when the driver approaches the pine lamp 100 with his/her hand, the pine lamp 100 lights up.
A vibrator 1 disposed near the oscillator 1 receives the reflected wave from the hand, thereby outputting a pulse train signal from the comparator 7, which is counted by a counter 10. The counter lO counts up, and the launch circuit 11 counts up the pulse signal generator 12.
The latch circuit 11 has a logic value of "1" and is input to the clock terminal of the D-flip-flop circuit 16 via the switch 14. On the other hand, the bar terminal is connected to the data end F, and the stone terminal is “1”.
” Therefore, when the output of the launch circuit 11 rises to “1”, the Q terminal of the D-flip-flop circuit 16 becomes “1”.
1", and the Q terminal changes to O". As a result, the driver circuit 17 is activated and the pine lamp 100 is lit. Next, when turning off the pine lamp 100, when the driver brings his hand close to the pine lamp 100, the clock terminal of the D-flip-flop circuit 16 rises to 1'', and this time the Q
Since the terminal is "0", the Q terminal changes from "1' to "0" and the pine lamp 100 turns off. In this way, just by bringing your hand near the vibrator 1, you can turn on or turn off the pine lamp. can.

In other words, the gain of the variable gain band amplifier 60 is such that the voltage of the output signal of the variable gain band amplifier 60 exceeds the reference voltage Vr of the comparison 2S7 only when the hand of the vehicle occupant approaches the vibrator 1. Therefore, the pine lamp 100 will not be operated unnecessarily due to other actions of the occupant of the automobile.

Next, the operation as an anti-theft device will be explained.

If the driver wants to set up an anti-theft device when leaving the car, if the switches 13 and 14 in the trunk close the contacts at terminals 13b and 14b, the gain of the variable gain band amplifier 60 increases and the car When the top target enters the vehicle interior, the transducer l receives the reflected wave from the intruder, and since the gain of the variable gain band amplifier 60 is increasing, the output signal of the amplifier 60 changes according to the movement of the intruder. Since the voltage exceeds the reference voltage Vr, a pulse train signal corresponding to the movement of the intruder is output from the comparator 7, and the output of the launch circuit 11 rises to "L" in the same way as the activation of the pine lamp, and as a result, R-
The cent terminal of the S flip-flop circuit 18 becomes “B”.° On the other hand, the reset terminal becomes “0” via the switch 13.
'', so the R-S flip-flop circuit 18
The Q terminal becomes "L" and the drive circuit 19 is activated, and the horn is blown to notify the outside of the intruder.

In the above embodiment, the current flowing through the vibrator l was detected by the resistor 3, but as shown in FIGS. 5 and 6, the magnetic field generated by the current flowing through the wire harness 200 connected to the vibrator l is Ferrite core 31 and ferrite core 3
The same effect can be obtained even if the current detection unit 30 configured by the coil 32 wound in the same direction is used for detection.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation, FIGS. 3 and 4 are configuration diagrams showing an application example of a moving object detection device, and FIG. FIG. 6 is a partial configuration diagram showing another embodiment. DESCRIPTION OF SYMBOLS 1... Ultrasonic transducer, 2... Oscillator, 3... Resistor, 4... Amplifier, 5... Detector, 6... Bandwidth amplifier, 7... Comparator. Representative Patent Attorney Takashi Okabe Figure 1 Figure 2 tl t2 t3 Figure 5 Figure 6

Claims (1)

[Claims] The apparatus includes one ultrasonic transducer and an oscillator for exciting the ultrasonic transducer and continuously transmitting ultrasonic waves, and detects a moving object from changes in the amplitude of the current flowing through the ultrasonic transducer. A moving object detection device characterized by: