JP2953182B2 - Ultrasonic sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic wave for emitting an ultrasonic wave into a monitored space and detecting a reflected wave from the object in the monitored space to detect the movement or presence of the object in the monitored space. It concerns a sensor.

[0002]

2. Description of the Related Art An ultrasonic sensor of this type transmits an ultrasonic wave of a predetermined frequency into a monitoring space using an ultrasonic transducer,
The movement or presence of the object is detected by receiving the reflected wave from the object by the ultrasonic vibrator. Here, in order to detect the movement of the object, the movement of the intruding object is detected based on the Doppler signal included in the reflected wave, and to detect the presence of the object, an ultrasonic pulse is transmitted from the transmitter. The presence of an object in the monitored space is detected by transmitting a wave and receiving a reflected wave from the object by a receiver. By alternately switching between these detection methods, before and after the movement of the object is detected by the movement detection method, the reflection patterns from the object by the presence detection method are stored in chronological order, and the two reflection patterns are compared. This is to determine the presence or absence of an object in the monitoring space.

FIG. 2 shows an example of the configuration. In this conventional example (Japanese Patent Application No. 2-198174), an oscillation signal oscillated from an oscillator 1 is transmitted from an ultrasonic transmitter 3 via a transmission circuit 2. The ultrasonic wave reflected by the moving object is received by the ultrasonic wave receiver 4, and the received signal is amplified by the amplifier circuit 6 via the transmission-specific switching circuit 5. This signal is mixed with the transmission signal by the mixer 7, and the Doppler signal included in the reflected wave is detected by the detection circuit 8, amplified by the amplification circuit 9, and input to the detection determination circuit 12. The detection judging circuit 12 outputs a detection signal when detecting the Doppler signal.

[0004] Next, the timer circuit 10 switches to the presence detection method described below at every predetermined time. When the operation time of the movement detection method reaches a predetermined time, the timer circuit 10 sends a signal to the transmission method determination circuit 13 to change to the presence detection method. The transmission circuit 2 receives the signal from the transmission method determination circuit 13 and transmits the signal oscillated from the oscillator 1 to the ultrasonic transmitter 3 as a tone burst wave of a pulse train suitable for the presence detection method. The transmission system determination circuit 13 sends a signal indicating that the transmission system has been switched to the transmission-specific 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 in the monitoring space, and received by the ultrasonic wave receiver 4. This received signal is amplified by the amplifier circuit 11 via the transmission-specific switching circuit 5, and is detected by the detection circuit 14.
Is detected by The reflection pattern of the detected waveform obtained at this time is stored in the storage circuit 17 or 18 in time series. Then, the reflection patterns stored in the storage circuits 17 and 18 are compared in time series by the comparison circuit 19. The presence / absence detection signal is output by the detection / judgment circuit 12 in accordance with the result of the comparison.

[0005]

In the above conventional example, if there are many stationary objects in the monitoring space and the distances from these stationary objects to the ultrasonic sensors are different, When switching to the presence detection method, the signal of the reflected wave from the intruding object to be detected overlaps with the reflected wave from the stationary object originally existing in the monitoring space. There was a problem that it became difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a super-position detection system using a movement detection system using the Doppler effect and a presence detection system using a comparison of reflection patterns. An object of the present invention is to make it possible to detect an intruding object even when a large number of stationary objects are present in a monitoring space at different distances in a sound wave sensor.

[0007]

According to the present invention, in order to solve the above-mentioned problems, as shown in FIG. 1, an ultrasonic wave is driven in a monitoring space by being driven by a transmission signal output from an oscillator 1. And a receiver 4 for receiving a reflected wave from an object existing in the monitoring space, and a frequency generated in a received signal by the Doppler effect when the object moves. The first detection method detects a shift component and detects movement of an intruding object, and transmits an ultrasonic pulse from the transmitter 3 and receives a reflected wave from the object by the receiver 4. Means for alternately switching between a second detection method for detecting the presence of an object in the monitoring space and a second detection method at predetermined time intervals,
A first storage circuit 17 that stores the detection signal of the second detection method before the detection signal of the detection method is obtained in time series,
A second storage circuit 18 that stores the detection signals of the second detection method in time series after the detection signals of the first detection method are obtained.
A comparison circuit 19 for comparing the contents stored in the first and second storage circuits 17 and 18; and a detection determination circuit 12 for determining that an intruding object exists when the comparison results of the comparison circuits 19 do not match. The ultrasonic sensor includes an in-gate pattern judging circuit 20 for judging the ratio of the detection signal of the reflected wave stored in the first storage circuit 17 in the gate. The circuit 12 generates a detection output when the comparison result of the comparison circuit 19 does not match, and sets a first off-delay time as a delay time until the detection output ends. For example, the detection judging circuit 12 generates a detection output only by the first detection method, sets a second off-delay time as a delay time until the detection output ends, OFF-delay time is characterized in that set to be longer than the first off-delay time.

[0008]

According to the ultrasonic sensor of the present invention, the movement detection method utilizing the Doppler effect and the presence detection method utilizing the presence / absence detection of ultrasonic pulse reflection are alternately switched, and the movement of the object is detected by the movement detection method. Before and after the detection, the reflection patterns from the object by the presence detection method are stored in time series and compared. When the reflection patterns do not match, it is detected that an intruding object is present. Then, even if the ratio of the detection signal of the reflected wave in the presence detection method occupying the gate is larger than the predetermined ratio, and comparing the reflection patterns before and after the movement of the object is detected,
If it is determined that it is difficult to determine the presence or absence of the presence detection signal due to the intruding object, the off-delay time is set longer than usual so that the presence of the intruding object can be detected only by the movement detection signal. As a result, reliable operation can be ensured even when used in an environment with many reflective surfaces.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. The oscillation signal oscillated from the oscillator 1 is transmitted from the ultrasonic transmitter 3 via the transmission circuit 2. The ultrasonic wave reflected by the moving object is received by the ultrasonic wave receiver 4, and the received signal is amplified by the amplifier circuit 6 via the transmission-specific switching circuit 5. This signal is mixed with the transmission signal by the mixer 7, and the Doppler signal included in the reflected wave is detected by the detection circuit 8, amplified by the amplification circuit 9, and input to the detection determination circuit 12. Detection judgment circuit 12
Is to output 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 of the movement detection method reaches a predetermined time, the timer circuit 10 sends a signal to the transmission method determination circuit 13 to change to the presence detection method. The transmission circuit 2 receives the signal from the transmission method determination circuit 13 and transmits the signal oscillated from the oscillator 1 to the ultrasonic transmitter 3 as a tone burst wave of a pulse train suitable for the presence detection method. The transmission system determination circuit 13 sends a signal indicating that the transmission system has been switched to the transmission-specific switching circuit 5. The tone burst wave generated by the wave transmitting circuit 2 is transmitted as a pulse train from the ultrasonic wave transmitter 3, reflected by an object in the monitoring space, and received by the ultrasonic wave receiver 4. This reception signal is amplified by the amplification circuit 11 via the transmission-specific switching circuit 5, and is detected by the detection circuit 1.
4 for detection. Here, the first storage circuit 17
The detection signal of the presence detection method before the detection signal of the movement detection method is obtained is stored in chronological order, and the second storage circuit 18 stores the detection signal after the detection signal of the movement detection method is obtained. The detection signal of the system is stored in time series. Then, the comparison circuit 19 compares the stored contents of the first and second storage circuits 17 and 18 in chronological order, and when the comparison results of the comparison circuits 19 do not match, the detection determination circuit 1
In 2, it is determined that an intruding object exists. In such an ultrasonic sensor, the signal amount in the gate of the reflection pattern stored in the first storage circuit 17 is determined by the in-gate pattern determination circuit 20. If the amount of signal in the gate is large, the detection determining circuit 12 extends the off-delay time in the movement detection method,
If the signal amount in the gate is small, the storage circuits 17 and 18
A detection signal is output in accordance with the match / mismatch of the comparison result of the reflection patterns of the above.

The operation of this embodiment will be described below with reference to FIGS. First, FIG. 3A shows the interior of a toilet, in which F is a floor, K is a toilet bowl, and D is a door. S is an ultrasonic sensor provided on the ceiling, and A is a monitoring space of the ultrasonic sensor S. FIG. 3 (a1) shows a detection signal according to the movement detection method. Since no moving object exists, no detection signal is generated. FIG. 3 (a2) shows a detection signal according to the presence detection method. Since no moving object exists, only a reflected wave from the background object is received. This reflection pattern is stored in the first storage circuit 17. In the figure, the horizontal axis represents the time after transmission, and the vertical axis represents the voltage value.
R is the reverberation sound after transmission, k is the reflected wave from the toilet K,
f is a reflected wave from the floor F. The gate for detecting the reflected wave starts immediately after the end of the reverberation R, and the floor F
This is a predetermined period that ends after the reflected wave f from.
In this example, the in-gate pattern judging circuit 20 judges that the ratio of the reflected signal in the gate is small, and the detection judging circuit 12 makes the storage circuits 17 and 1 the same as in the prior art.
The detection output is controlled by comparison and collation of the reflection patterns stored in 8.

Next, as shown in FIG. 4 (b), when a human body M or the like enters the room, first, a detection signal of the movement detection method is detected as shown in FIG. 4 (b1). When the detection signal of the movement detection method is obtained, the previous presence detection signal is fixed in the storage circuit 17 and the storage content of the storage circuit 17 is not updated. Thereafter, as shown in FIG. 4B, when the human body M is present in the room, the presence detection signal obtained by the presence detection method is stored in the storage circuit as shown in FIG. 4B2. 18 is stored. The reflection pattern at this time includes, in addition to the reflected wave k from the toilet K and the reflected wave f from the floor F as shown in FIG. 3 (a2), the reflection from the human body M as shown in FIG. 4 (b2). Wave m is included. Therefore, the reflection pattern as shown in FIG. 3A2 stored in the storage circuit 17 and the reflection pattern as shown in FIG. , The presence or absence of a reflected wave m from the human body 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.

Next, a case where the blind B is hung in a room as shown in FIG. At this time, since there is no intruding object in the room, the detection signal of the movement detection method is in a non-signal state as shown in FIG. In addition, the presence of the blind B causes
As shown in (a2), the detection signal of the presence detection method includes:
Many reflected waves b appear. This is because the blind B has a very large number of reflecting surfaces and the heights of the reflecting surfaces are different from each other, so that the distances from the ultrasonic sensors are different. These multiple reflected waves b are stored in the first storage circuit 17 as a time-series reflection pattern.
Next, as shown in FIG. 6A, when a human body M enters the room, a detection signal of the movement detection method is obtained as shown in FIG. As shown, the detection signal of the presence detection method is stored in the second storage circuit 18 as a time-series reflection pattern. In such a case, the reflection pattern from the background object as shown in FIG. 5A2 stored in the first storage circuit 17 and the reflection pattern as shown in FIG. Comparing with the reflection pattern including the reflected wave m from the human body M, the reflected wave m from the human body M shows a large number of reflected waves b from the blind B.
It is difficult to detect the human body M because it is buried in the inside. Therefore, in such a case, the in-gate pattern determination circuit 20 determines that the ratio of the reflection signal stored in the first storage circuit 17 in the gate is large, and
Extend off-delay time.

The operation of extending the off-delay time will be described with reference to FIG. As long as the Doppler signal obtained by the movement detection method is obtained, it can be determined that an intruding object is present.Therefore, if the Doppler signal is lost and no Doppler signal is obtained again within a predetermined off-delay time, the detection is performed. The output is turned off. This is the conventional method of setting the off-delay time. In the present invention, the off-delay time is further extended when the in-gate pattern determining circuit 20 determines that the proportion of the reflected signal occupied in the gate by the presence detection method from the background object is large.
As a result, the probability that the Doppler signal by the movement detection method can be obtained again within the off-delay time increases, and the occupancy detection determination can be made without using the presence detection method.

FIG. 8 is a control flow showing the signal processing method of the present invention. As shown in the figure, after the movement signal processing by the movement detection method, the pattern in the gate is determined, and when it is determined that the ratio of the reflection signal from the background object occupying the gate is large, the off-delay time is extended, The occupancy detection is determined by the movement detection method. When it is determined that the ratio of the reflection signal from the background object occupying the gate is small, the normal output determination similar to the conventional example is performed. In the latter case, the off-delay time is set to be short as in the conventional example, so that when the lighting control or air-conditioning control is performed by the sensor output, a power saving effect is obtained, and in the former case, the off-delay time is reduced. Although the time is set to be long, a reliable operation is guaranteed even in an environment where there is a background object having many reflective surfaces such as blinds. In this case, if the configuration is such that an environment in which presence detection is difficult is displayed, erroneous operation can be reduced and versatility can be increased as compared with a conventional ultrasonic sensor.

[0016]

According to the ultrasonic sensor of the present invention, there is provided a transmitter which is driven by a signal output from an oscillator to transmit an ultrasonic wave into a monitored space, and a reflected wave from an object existing in the monitored space. A receiver that receives the signal, stores the presence detection signal before the movement detection signal is obtained, compares it with the presence detection signal after the movement detection signal is obtained, and detects the movement if they do not match. If there is no signal, it can be determined that an intruding object is present, and when the presence detection signal before the movement detection signal is obtained has a large proportion of the reflected wave detection signal in the gate, the presence determination based on the presence detection signal is performed. Since it is determined that it is difficult and the off-delay time of the output in the movement detection signal is extended, when the intruding object is temporarily stationary in the surrounding environment including many reflective surfaces, , Transfer By the detection signal can not be obtained even existence detection signal immediately sensed output has the effect of being able to prevent a disadvantage that would exit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional example.

FIG. 3 is an operation explanatory diagram showing a first operation of one embodiment of the present invention.

FIG. 4 is an operation explanatory diagram showing a second operation of the embodiment of the present invention.

FIG. 5 is an operation explanatory diagram showing a third operation of the embodiment of the present invention.

FIG. 6 is an operation explanatory view showing a fourth operation of the embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a difference in off-delay time between the present invention and a conventional example.

FIG. 8 is a flowchart showing a signal processing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oscillator 2 Transmitting circuit 3 Ultrasonic transmitting device 4 Ultrasonic receiving device 5 Switching circuit for each transmission 6 Amplifying circuit 7 Mixer 8 Detecting circuit 9 Amplifying circuit 10 Timer circuit 11 Amplifying circuit 12 Detection judgment circuit 13 Transmission method determination Circuit 14 Detection circuit 17 Storage circuit 18 Storage circuit 19 Comparison circuit 20 In-gate pattern determination circuit

────────────────────────────────────────────────── (5) References JP-A-5-273344 (JP, A) Patent 2774186 (JP, B2) Patent 2573403 (JP, B2) Patent 2807120 (JP, B2) (58) Fields investigated (Int.Cl. ⁶ , DB name) G01S 7/52-7/64 G01S 15/00-15/95

Claims (1)

(57) [Claims] 1. A transmitter for transmitting an ultrasonic wave into a monitoring space driven by a signal output from an oscillator, and a receiver for receiving a reflected wave from an object existing in the monitoring space. A first detection method for detecting the movement of an intruding object by detecting a frequency shift component generated in a received signal by the Doppler effect when the object moves, and transmitting an ultrasonic pulse from a transmitter. Means for alternately switching the second detection method for detecting the presence of an object in the monitored space by receiving a reflected wave from the object with the receiver at predetermined time intervals, and detecting the first detection method A first storage circuit that stores a detection signal of the second detection method before the signal is obtained in a time-series manner, and a detection signal of the second detection method after the detection signal of the first detection method is obtained A second storage circuit for storing the data in a time-series manner, and first and second storage circuits. In an ultrasonic sensor including a comparison circuit that compares the contents stored in the circuit and a detection determination circuit that determines that an intruding object is present when the comparison results of the comparison circuits do not match, the reflection stored in the first storage circuit A gate pattern judging circuit for judging a ratio of a wave detection signal occupying in the gate; if the ratio is less than a predetermined ratio, the detection judging circuit generates a detection output when the comparison result of the comparison circuit does not match At the same time, a first off-delay time is set as a delay time until the detection output ends, and if the ratio is equal to or more than a predetermined ratio, the detection determination circuit generates a detection output only by the first detection method and ,
An ultrasonic sensor, wherein a second off-delay time is set as a delay time until the detection output ends, and the second off-delay time is set longer than the first off-delay time.