JPH0483190A - Ultrasonic sensor - Google Patents

Abstract

PURPOSE:To surely detect any object by alternately using a motion detecting method and a presence detecting method, and also storing in time series a reflection pattern from an object by the presence detecting method, and comparing the pattern to previous patterns in time series. CONSTITUTION:In a motion detecting method, ultrasonic waves reflected by a moving object are received by an ultrasonic wave receiver 4 and mixed into a transmission signal by a mixer 7 and a Doppler signal showing frequency deviation included in the reflected waves is detected and amplified and input to a detection judging circuit 12 and a detection signal is output when the Doppler signal is detected. In a presence detecting method switched from the motion detecting method, tone-burst waves produced by a transmitting circuit 2 are transmitted as pulse lines from an ultrasonic wave transmitter 3 and reflection by the object is given to the receiver 4. Then the reflection pattern of detected waveform obtained by detection of a reception signal is stored in time series in a storage circuit 17 or 18. The stored reflection pattern is compared to a previous one in time series by a comparing circuit 19 and input to the circuit 2 and a detection signal is output according to whether or not the result of comparison shows that the patterns coincide with each other.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention emits ultrasonic waves into a monitoring space and detects reflected waves from objects in the monitoring space, thereby detecting the movement or movement of objects within the monitoring space. It is connected to an ultrasonic sensor that detects its presence.

[Prior Art] This type of ultrasonic sensor uses an ultrasonic transducer to transmit ultrasonic waves of a predetermined frequency to a monitoring area, and receives reflected waves from an object using the ultrasonic transducer. , which detects the movement or presence of objects. Here, to detect the movement of an object, the movement of an intruding object is detected based on the Doppler signal included in the reflected wave, and to detect the presence of an object, a pulse train is sent from the transmitter. The presence of an object within the monitoring space is detected by transmitting ultrasonic waves and receiving reflected waves from the object using a receiver.

FIG. 8 shows the configuration of an ultrasonic sensor for detecting movement. In this conventional example, an oscillation signal oscillated from an oscillator 1 is transmitted to a monitoring area from an ultrasonic transmitter 3 via a wave transmitting circuit 2. The ultrasonic wave reflected by the moving object is received by the ultrasonic wave receiver 4, and this received signal is amplified by the amplifier circuit 6. This signal is mixed with the transmission signal by the mixer 7, and the Doppler signal indicating the frequency shift included in the reflected wave is detected by the detection circuit 8, then amplified by the amplifier circuit 9, and input to the detection circuit 15. .

The detection circuit 15 outputs a movement detection signal when detecting a Doppler signal.

FIG. 9 shows the configuration of an ultrasonic sensor for presence detection. In this conventional example, a signal oscillated from an oscillator 1 is converted into a tone burst wave by a wave transmitting circuit 2. Transmission circuit 2
The tone burst wave created by the ultrasonic transmitter 3
The pulse train is transmitted as a pulse train, reflected by an object within the monitoring area, and received by the ultrasonic receiver 4. This received signal is amplified by the amplifier circuit 11 and detected by the detection circuit 14. The detection circuit 16 outputs a presence detection signal if a received signal is detected within a certain period of time after the tone burst wave is transmitted.

[Problems to be Solved by the Invention] The movement detection method shown in FIG. 8 receives reflected waves from a moving object and detects the intruding object based on a Doppler signal indicating the frequency shift included in the reflected waves. Since the device detects movement, it performs a detection operation for moving objects that approach or move away from the ultrasonic sensor, but if the intruding object is stationary, even if it is within the monitoring area. There was a problem in that the detection operation was not performed. Further, in the presence detection method shown in FIG. 9, since a stationary object is detected, there is a problem in that the monitoring area cannot be made large enough for practical use.

The present invention has been made in view of these points, and its purpose is to use both the movement detection method and presence detection method in combination to reliably detect the entry, presence, and exit of objects. The purpose of the present invention is to provide an ultrasonic sensor that has the following characteristics.

[Means for Solving the Problems] In the present invention, in order to solve the above problems, the first
As shown in the figure, a transmitter 3 that is driven by a transmission signal output from an oscillator 1 and transmits ultrasonic waves to a monitoring space;
The ultrasonic sensor includes a receiver 4 that receives reflected waves from an object existing in the monitoring space, and detects a frequency shift component that occurs in the received signal due to the Doppler effect when the object moves. The first detection method detects the movement of an intruding object using and a second detection method for detecting the presence of the first detection method.
A first memory port l@17 stores in time series the detection signal of the second detection method before the detection signal of the first detection method is obtained, and the first memory port l@17 stores the detection signal of the second detection method before the detection signal of the first detection method is obtained. Second storage circuit 1 that stores detection signals of the second detection method in time series
8, a comparison circuit 19 that compares the memory contents of the first and second memory circuits 17 and 18, and a detection judgment circuit 12 that judges that an intruding object exists when the comparison results of the comparison circuit 19 do not match. It is characterized by this.

Here, in the case where the detection signal of the first detection method is obtained after determining that the intruding object exists, the detection judgment circuit 12 determines that the intruding object has left when the comparison result of the comparison circuit 19 matches. It is preferable to use a circuit that determines that.

In addition, in the description of the claims, the "object" may be a human body, etc. in addition to a vehicle or luggage.

[Operation] The ultrasonic sensor of the present invention alternately switches between a movement detection method that uses the Doppler effect and a presence detection method that uses detection of the presence or absence of reflection of an ultrasonic pulse train, and also uses the movement detection method to detect the movement of an object. The reflection patterns from the object using the presence detection method are stored in chronological order before and after detection, and the re-reflection patterns are compared, so the reflection pattern after movement detection matches the reflection pattern before movement detection. If not, it can be determined that the object has entered and is present in the monitoring area. In addition, in a state where an object is present, after the movement of the object is detected by the movement detection method, when the reflection pattern by the presence detection method comes to match the reflection pattern before intrusion, it is determined that the object is no longer present. can do.

[Example] FIG. 1 is a block diagram of one embodiment of the present invention.

First, a configuration for a movement detection system will be explained. A transmitting signal oscillated by an oscillator 1 is transmitted to a monitoring space from an ultrasonic transmitter 3 via a transmitting circuit 2. The ultrasonic wave reflected by the moving object is received by the ultrasonic receiver 4, and this received signal is amplified by the amplifier circuit 6 via the transmitting side switching circuit 5. This signal is mixed with the transmission signal by the mixer 7, and the Doppler signal indicating the frequency shift included in the reflected wave is detected by the detection circuit 8, amplified by the amplifier circuit 9, and input to the detection judgment circuit 12. Ru. The detection determination circuit 12 outputs a detection signal when a Doppler signal is detected.

Next, the timer circuit 10 switches to the presence detection method described below at predetermined time intervals.

When the operation time using the movement detection method reaches a predetermined time, the timer circuit 10 sends a signal to the transmission method determining circuit 13 to change to the presence detection method. The transmission method determining circuit 13 transmits the signal oscillated from the oscillator 1 to the transmission circuit 2.
In addition to sending a command signal to change to a tone burst wave,
A signal indicating that the transmission switching has been performed is sent to the transmission side switching circuit 5.

The tone burst wave created by the wave transmitting circuit 2 is transmitted as a pulse train from the ultrasonic wave transmitter 3, reflected by an object within the monitoring area, and received by the ultrasonic wave receiver 4. This received signal passes through the transmission side switching circuit 5, is amplified by the amplifier circuit 11, and is detected by the detection circuit 14. A memory circuit 17 stores the reflection pattern of the detected waveform obtained at this time in chronological order.
Or let 18 remember it. And memory circuit 17.1
A comparison circuit 19 compares the reflection patterns stored in 8 in time series. The comparison result signal is sent to the detection judgment circuit 12.
and a detection signal is output depending on whether the comparison results match or do not match.

1. Next, the operation of this embodiment will be explained with reference to FIGS. 2 to 4. As shown in FIG. 2(a), when using the above-mentioned ultrasonic sensor S as a presence sensor in a private room WC such as a toilet, first, a presence detection method is used to detect background objects that already exist in the room (for example, a toilet). Detection signals of reflected waves (see FIG. 2(b)) from floors B and F) are stored in the memory circuit 17 in time series.

This reflection pattern includes a reflected wave RB from the toilet bowl B and a reflected wave RF from the floor F. At this time, the detection signal of the movement detection method indicating the intrusion into the room (Figure 2 (c)
(see) will be in a no-signal state.

Next, as shown in Fig. 3(a), when a human body M etc. enters the room, the detection signal of the movement detection method is first detected as shown in Fig. 3(a).
detected as shown in c). When this movement detection signal is obtained, the previous presence detection signal (see FIG. 2(b) or FIG. 3(b)) is fixed in the memory circuit 17, and the memory contents of the memory circuit 17 are not updated. As shown in FIG. 4(a), when a human body M etc. is present in the room, the presence detection signal obtained by the presence detection method (see FIG. 4(b)) is stored in the memory circuit 18. be remembered. In addition to the reflected wave RB from the toilet bowl B and the reflected wave R from the floor F, the reflection pattern at this time includes the human body M.
It includes the reflected wave RM from. Therefore, by comparing and collating the reflection pattern stored in the storage circuit 17 and the reflection pattern stored in the storage circuit 18 by the comparison circuit 19, the presence or absence of the reflected wave RM from the human body M can be detected. That is, by subtracting the background pattern of the background object stored in the storage circuit 17 from the current reflection pattern stored in the storage circuit 18, the presence or absence of an intruding object can be determined. At this time, the movement detection signal changes from the large amplitude state shown in FIG. 3(e) to the small amplitude state shown in FIG. 4(c). While the reflected wave RM is being detected, it can be determined that an intruding object such as the human body M exists in the room.

The first operation example above is a presence detection operation after intrusion detection, but in the operation example 2 shown below, an exit detection operation after presence detection will be explained.

11 Takumi First, as shown in Figure 5 (a), the reflection patterns of background objects (toilet B, floor F) that already exist in the room are detected by the presence detection method (see Figure 5 (b)). ) is detected and stored in the storage circuit 17. The stored contents are updated at regular intervals. In addition, the detection signal of the movement detection method indicating the intrusion into the room at this time (see Fig. 5 (e))
is in a no-signal state.

Next, as shown in Fig. 6(a), when a human body M etc. enters the room, the detection signal of the movement detection method (Fig. 6(c)
) is obtained, the reflection pattern previously obtained by the presence detection method (see Fig. 5(a)) is fixed in the memory diagram I@17 without being updated. The detection signal (see FIG. 6(b)) is stored in another memory circuit 18, and by calculating the difference between the memory circuits 17 and 18 using one comparison circuit, the reflected wave R from the human body M is detected. It is something that This corresponds to the state described in FIG. 4 above.

Next, as shown in FIG. 7(a), when the human body M etc. leaves the room, the detection signal by the movement detection method (see FIG. 7(c)) is detected again as a large amplitude signal. In addition, the detection signal of the presence detection method (see Fig. 7(b)) includes only the reflected waves RB and RF from background objects (toilet bowl B and floor F), and the reflected waves RM from the intruding object (human body M). Therefore, the current reflection pattern stored in the storage circuit 18 (see FIG. 7(b)) and the reflection pattern before the invasion stored in the storage circuit 17 (see FIG. 5(b)) are Compare,
If the difference component is zero, that is, if the reflection pattern before the invasion matches the current reflection pattern, it is determined that the intruding object does not exist in the room, that is, it has left the room, and a detection signal is output. be.

Note that one ultrasonic transducer may serve both as the ultrasonic transmitter and the ultrasonic receiver.

[Effects of the Invention] The ultrasonic sensor according to claim 1 stores the presence detection signal before the movement detection signal is obtained, and compares it with the presence detection signal after the movement detection signal is obtained. If the two do not match, it is determined that a moving object exists, so that the presence of the object can be reliably detected after the object has entered the monitoring space.

In the ultrasonic sensor according to claim 2, the presence detection signal before the movement detection signal is obtained is stored, and the presence detection signal after the movement detection signal is obtained is compared with the presence detection signal after the movement detection signal is obtained. Since it is determined that there is no moving object, it is possible to reliably detect the exit of an object after the entry of the object into the monitoring space is detected.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Figs. 2 to 7 are explanatory diagrams of the same operation as above, Fig. 8 is a block diagram of a conventional example, and Fig. 9 is a block diagram of another conventional example. be. 1 is an oscillator, 2 is a wave transmitting circuit, 3 is an ultrasonic wave transmitter, 4 is an ultrasonic wave receiver, 5 is a wave transmitting side switching circuit, 6 is an amplifier circuit, 7 is a mixer, 8 is a detection circuit, 9 is a 10 is a timer circuit, 11 is an amplifier circuit, 12 is a detection/judgment circuit, 13 is a transmission system determining circuit, 14 is a detection circuit, 17.18 is a storage circuit, and 19 is a comparison circuit.

Claims (2)

[Claims] (1) A transmitter that is driven by a transmission signal output from an oscillator and transmits ultrasonic waves into the monitoring space, and a receiver that receives reflected waves from objects existing in the monitoring space. A first detection method detects the movement of an invading object by detecting a frequency shift component generated in a received signal due to the Doppler effect when the object moves; a second detection method for detecting the presence of an object in the monitoring space by transmitting a sound wave and receiving a reflected wave from the object by a receiver; A first storage circuit that chronologically stores the detection signal of the second detection method before the detection signal of the first detection method is obtained, and a second storage circuit that stores the detection signal of the second detection method after the detection signal of the first detection method is obtained. a second memory circuit that stores the detection signals of the detection method in time series; a comparison circuit that compares the memory contents of the first and second memory circuits; and a comparison circuit that detects an intruding object when the comparison results of the comparison circuit do not match. An ultrasonic sensor comprising: a detection/determination circuit that determines the presence of an ultrasonic sensor. (2) When the detection signal of the first detection method is obtained after determining that an intruding object exists, and the comparison result of the comparison circuit matches, the detection judgment circuit determines that the intruding object has left. The ultrasonic sensor according to claim 1, wherein the ultrasonic sensor is a circuit for: