JPH06222140A - Ultrasonic sensor - Google Patents

Abstract

PURPOSE:To provide an ultrasonic sensor which is so excellent in reliability concerning detection of moving objects that even if there are air flows or the like with temperature differences inside a supervisory space, malfunctioning such as outputting a signal indicating detection of a moving object will not be caused by the air flows. CONSTITUTION:In an ultrasonic sensor, an ultrasonic wave transmitted from a transmitter 3 and reflected from an object present in a supervisory space is received by a receiver 4 and then predetermined unit values are sequentially integrated together through addition or subtraction according to whether the Doppler component of the input signal of the receiver 4 is positive or negative, and when this integral value exceeds a predetermined threshold, a signal that indicates detection of the moving object is outputted. An integrating circuit 7 performs integration with values greater than the predetermined unit values in executing subtraction when the integral value is positive or addition when the integral value is negative.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects the presence of a moving object in a reflective space by transmitting an ultrasonic wave of a predetermined frequency into the monitored space and detecting a reflected wave from an object in the monitored space. To an ultrasonic sensor applied to

[0002]

2. Description of the Related Art As an ultrasonic sensor of this type, there has been proposed an ultrasonic sensor capable of detecting a moving object by utilizing the Doppler effect when an ultrasonic wave is transmitted to the moving object. This conventional one continuously transmits an ultrasonic wave of a predetermined frequency from a wave transmitter, and at the time of receiving a reflected wave at a constant time interval, the received signal of the wave received signal is output from the wave receiver. The positive / negative of the Doppler component is judged according to a certain rule. And the positive of the Doppler component
Based on the negative value, a predetermined unit value that is determined in advance is sequentially added or subtracted to obtain an integrated value. If the integrated value exceeds a predetermined threshold value, the moving object is present in the monitoring space at that time. It is configured to output a predetermined moving object detection signal by determining that the object is a moving object.

[0003]

However, the above-mentioned conventional devices have the following problems. That is, when an ultrasonic sensor of this kind is installed in a room and used for human body detection, for example, an airflow having a temperature difference from room temperature flows into the monitoring space from an air conditioner or the like, or the ultrasonic wave is directly detected. It may hit the sensor. However,
The airflow has a property of affecting the Doppler effect and changing the Doppler component in the received signal. For example, in an example of an experiment conducted by the applicant of the present application, when there is cold wind with a wind speed of 40 to 80 [cm / s] at a position 0.7 m in front of the ultrasonic sensor, as shown in FIG. , The signal component having the positive Doppler component is 68.2.
[%], 19.11 [%] for the negative signal component, 11.78 [%] for the signal component for which positive / negative cannot be determined, and 10.73 [%] for the signal component determined to have no Doppler component.
Was recognized as. As is clear from such data, if an airflow having a temperature difference from the room temperature occurs in the monitoring space, there will be many signal components in the received signal for which the positive / negative of the Doppler component cannot be determined. In addition, many signal components that bias the Doppler component to either positive or negative are included.

On the other hand, conventionally, the integrated value is merely obtained by sequentially adding or subtracting a predetermined unit value based on the positive or negative of the Doppler component of the received signal. . Therefore, conventionally, when the air flow for cooling or heating is continuously generated in the monitoring space,
There is a phenomenon in which the positive or negative of the Doppler component of the received signal caused by the air flow is judged and a predetermined unit value is continuously added or subtracted, and the integrated value exceeds a certain threshold value. As a result, in the related art, a malfunction occurs in which a moving object detection signal is output even though there is no moving object in the monitoring space, which is a difficulty.

The present invention has been proposed in view of the above points, and even if an air flow having a temperature difference occurs in the monitoring space, a malfunction occurs such that a moving object detection signal is output due to the air flow. It is an object of the present invention to provide an ultrasonic sensor that is excellent in the reliability of moving object detection.

[0006]

An ultrasonic sensor according to the present invention, which is proposed to achieve the above object, comprises a wave transmitter for transmitting an ultrasonic wave in a monitoring space, A wave receiver that receives the reflected wave that is transmitted from this wave transmitter and that is reflected from an object existing in the surveillance space and outputs the received wave signal, and the Doppler component of the received wave A means for judging negative, an integration processing circuit for sequentially adding or subtracting a predetermined unit value predetermined based on the positive or negative of the Doppler component, and an integrated value calculated by this integration processing circuit An ultrasonic sensor comprising means for outputting a moving object detection signal when a predetermined threshold value is exceeded, wherein the integration processing circuit is a subtraction process when the integrated value is positive, or an integrated value. When performing addition processing when is negative, Instead of the position values, it is configured to perform the integration process with a value greater than that.

According to a second aspect of the present invention, in the ultrasonic sensor according to the first aspect of the present invention, the integration processing circuit is configured so that when the level of the Doppler component of the received signal is lower than a predetermined level. When the integrated value is positive, a predetermined unit value is subtracted from the integrated value, and when the integrated value is negative, a predetermined unit value is added to the integrated value.

The ultrasonic sensor according to a third aspect of the present invention is the ultrasonic sensor according to the first or second aspect, wherein the integral processing circuit has a positive integrated value when the integration processing circuit cannot determine whether the Doppler component is positive or negative. At this time, a value larger than the predetermined unit value is subtracted from the integrated value, and when the integrated value is negative, a value larger than the unit value is added to the integrated value.

[0009]

In the ultrasonic sensor according to the present invention as set forth in claim 1, which is characterized by the above, due to the occurrence of an air flow with a temperature difference in the monitoring space, the positive / negative of the Doppler component of the received signal Even if a negative value is determined and the integration processing circuit continues the integration processing of a predetermined unit value, if the subtraction processing when the integration value is positive or the addition processing when the integration value is negative is performed, the predetermined unit A value larger than the value is subtracted or added. That is, for example, when a large number of positive Doppler components are included in the received signal due to the influence of the air flow, a predetermined unit value “1” is added in the integration processing circuit and the integrated value is positive. When the Doppler component is converted to a negative value, a predetermined unit value "1" is not subtracted from the integrated value, but a larger value (for example, "3") is subtracted. Therefore, the integrated value based on the Doppler component generated due to the airflow has a large degree of returning to the midpoint (that is, the level where the integrated value is 0), and the integrated value easily exceeds the threshold value. Disappears. As a result, it is possible to eliminate the possibility that the moving object detection signal is unreasonably output even though the moving object does not exist.

Further, as described above, when the integrated value is returned to the midpoint to a large extent, when a moving object actually enters the monitoring space, one of the positive and negative polar thresholds is selected. The time required to reach one of the thresholds is shortened as a whole. That is, for example, in the state where the integrated value is a positive value, when the moving object actually enters the monitoring space and the integrated value is integrated in the negative direction,
It takes a long time for the integrated value to reach the negative threshold value. However, as in the present invention, when the moving object does not exist in the surveillance space and the integrated value is always near the midpoint, when the moving object actually invades, the integrated value is positive or negative. In either direction, the time required for the integrated value to reach the threshold value is shortened, and the moving object detection timing can be advanced.

In the ultrasonic sensor according to the second aspect of the present invention, the integration processing circuit, when the level of the Doppler component of the received signal is lower than a predetermined level, that is,
When there is no moving object in the monitoring space and a Doppler component larger than the predetermined level cannot be obtained, the integration processing circuit subtracts a predetermined unit value from the integration value when the integration value is positive at that time. By doing so, the integrated value approaches the midpoint, and when the integrated value is negative, a predetermined unit value is added to the integrated value, so that the integrated value also approaches the midpoint. Therefore, when there is no moving object in the monitoring space, it is possible to further prevent the predetermined unit values from sequentially accumulating due to the Doppler component in the received signal generated by the airflow having a temperature difference, False detection of a moving object can be prevented more thoroughly.

In the ultrasonic sensor according to the third aspect of the present invention, when the positive / negative of the Doppler component cannot be determined, if the integrated value is positive at that point, the integrated value is calculated from the predetermined unit value from the predetermined unit value. Also, by subtracting a large value, the convergence of the integrated value to the midpoint is accelerated. On the contrary, if the integrated value is negative, a value larger than the unit value is added to the integrated value, so that the convergence of the integrated value to the midpoint is accelerated. Therefore, unlike when the above-mentioned positive / negative of the Doppler component cannot be determined, unlike the case where an object such as a human body moves in the monitoring space, an airflow with a constant non-directional temperature difference in the monitoring space is generated. It is a peculiar phenomenon that occurs when the above occurs. Therefore, when an air flow with a temperature difference occurs,
The cumulative value of the integrated value caused by the airflow is also subtracted or added with a value larger than the unit value of the predetermined unit, so that the integrated value is easily converged and the integrated value is prevented from exceeding the threshold value. As a result, it is possible to more thoroughly prevent the false detection of the moving object due to the generation of the air flow.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of the hardware configuration of the ultrasonic sensor S according to the present invention. This ultrasonic sensor S is a wave transmitter 3 that continuously transmits an ultrasonic wave of a predetermined frequency based on an oscillation signal (wave transmission signal) oscillated from an oscillator 1 and supplied via a wave transmission circuit 2. And a wave receiver 4 that receives a reflected wave transmitted from the wave transmitter 3 and reflected from a moving object existing in the monitoring space at a constant time interval. After the wave receiver 4, the wave receiver 4
Is provided with a Doppler component detection unit 5 for detecting a Doppler component in the received wave signal output at a constant time interval, a vector rotation circuit 6, an integration processing circuit 7, a detection determination circuit 8 and the like.

Of the above, the Doppler component detector 5 is
The received signal output from the wave receiver 4 and amplified by the amplifier circuit 50 is input to the two mixers 51a and 51b. In the mixer 51a, the received signal is mixed with the transmitted signal output from the transmitting circuit 2, so that the Doppler signal E'of the received signal is detected by the detection circuit 52a and amplified by the amplifier circuit 53a. Is configured to. On the other hand, the other mixer 51
In b, the transmission signal converted by the phase circuit 54 to have a phase difference of π / 2 is mixed with the reception signal, so that the detection circuit 52b detects the Doppler signal E of the reception signal and amplifies it. It is configured to be amplified by the circuit 53b. Therefore, the Doppler component detection unit 5 detects Doppler signals E and E ′ (Doppler components) whose phases are different from each other by π / 2.

The vector rotation circuit 6 replaces the signals E and E'of the Doppler components detected by the Doppler component detecting section 5 with the x and y signals, and, for example, as shown in FIG. The received signal is represented by a vector coordinate having E'as a basic axis, and the positive or negative of the Doppler component is determined by confirming the rotation direction of the coordinate with respect to the origin. Specifically, for example, in FIG.
The vector coordinate position of the received signal rotates counterclockwise, such as the received signal located at point a in quadrant 1 transitions to point b in quadrant 2 and from point b to point c in quadrant 3 Sometimes, the Doppler component is judged to be positive. Further, the Doppler component is determined to be positive even when the vector coordinate position d point next to the point c stays in the same quadrant as the previous point c.
On the other hand, when the coordinate position of the received signal rotates in the clockwise direction with respect to the origin of the basic axis as in the case of changing from point d to point e, the Doppler component is determined to be negative. To do.

Incidentally, when the positive / negative of the Doppler component is judged, for example, there is no moving object in the monitoring space,
Further, when there is no airflow with a large temperature difference, the level of the Doppler signal in the received signal becomes 0 or a minute level. In such a case, the vector rotation circuit 6 does not make a positive / negative determination when the detection level of the Doppler signal is low and does not reach a predetermined constant level, and the signal for discriminating the positive / negative is It is configured to output different signals to the integration processing circuit 7 side.

When an air flow with a large temperature difference is generated in the monitoring space, for example, in FIG. 2, the coordinate position of the received signal is quadrant 4 which is discontinuous from the point e in quadrant 2 from this point. In some cases, a phenomenon such as a transition to the f point of may occur. In such a case, whether the coordinate position of the received signal is clockwise or counterclockwise cannot be determined, and positive / negative determination cannot be performed. Therefore, in such a case, the vector rotation circuit 6 is configured to output a signal to that effect to the integration processing circuit 7 side.

The integration processing circuit 7 performs integration processing of a predetermined unit value (for example, "1") based on the positive / negative discrimination signal output from the vector rotation circuit 6 at constant time intervals. . This integration process is basically
Each time a positive signal is received, "1" is added as a unit value (corresponding to section A in FIG. 3), and "1" is subtracted each time a negative signal is received (corresponding to section D in FIG. 3). To do. However, when the integrated value obtained by such addition or subtraction is positive, a negative signal is output from the vector rotation circuit 6, and when performing the subtraction processing, “1” as the unit value is not applied. , Arrow B in FIG.
Or larger than that, as indicated by arrow C, eg "3"
Is subtracted. Further, when the integrated value is negative, "1" as the unit value is not applied even when the addition process is performed, and "3" is added as shown by an arrow E in FIG. Has been done. However, in the present invention, the unit value "1"
It is not always necessary to use "3" as a value different from, and any value may be used as long as it is a value larger than the predetermined unit value "1".

On the other hand, the integration processing circuit 7, unlike the positive and negative signals from the vector rotation circuit 6, also integrates a predetermined unit value when receiving a signal indicating that the level of the Doppler component is below a predetermined level. Is configured to perform processing. However, in this case, if the integrated value is positive at that time, a predetermined unit value “1” is subtracted from the integrated value, and the integrated value is processed to approach the midpoint (0). Has been done. Conversely, when the integrated value is negative,
A predetermined unit value "1" is added to the integrated value, and the integrated value is processed to approach the midpoint (0).
Further, when the vector rotation circuit 6 cannot determine whether the Doppler component is positive or negative, integration processing using a value larger than a predetermined unit value "1" (for example, "3") is performed. In this case, if the integrated value at that time is positive, "3" is subtracted from the integrated value. If the integrated value is negative, "3" is added to the integrated value. In this way, the integration processing circuit 7 is configured to process the integrated value so as to approach the midpoint (0) early in any case.

If the integrated value by the integration processing circuit 7 exceeds a predetermined threshold value TH, the detection judgment circuit 8 judges that a moving object exists in the monitoring space at that time, and the moving object is detected. It outputs a detection signal.
The threshold value TH is positive or negative (+,-) as shown in FIG.
Are provided on both pole sides.

Next, the operation of the ultrasonic sensor S having the above structure will be described. In this ultrasonic sensor S, even when there is no moving object in the monitoring space, when an air flow for cooling or heating having a large temperature difference from the room air conditioner is generated in the monitoring space from the indoor air conditioner. In the received wave signal output from the wave receiver 4, the Doppler component caused by the air flow is included. Although the Doppler component caused by such an air flow has a property biased to either positive or negative, if expressed by the vector coordinates shown in FIG. 2, the transition direction is not constant, and the transition direction is successively changed. Is inverted, and positive and negative are switched irregularly. Therefore, by maintaining the positive Doppler component due to the air flow for a while, even if a predetermined unit value "1" is sequentially added in the integration processing circuit 7 as shown in section A of FIG. , In the middle of the process, a phenomenon occurs in which the Doppler component is irregularly inverted to negative. In this case, subtraction processing of the integrated value is performed as shown by arrow B.

In this subtraction process, for example, "3", which is larger than the predetermined unit value "1", is applied, so that the degree of convergence of the integrated value to the midpoint (0) becomes large. . Contrary to the above, the Doppler component remains negative for a while, and even if the predetermined unit value “1” is sequentially subtracted as in the section D of FIG. Is positively inverted, and when the addition process is performed as shown by arrow E, the value of "3" is added, and the degree to which the integrated value converges to the midpoint (0) also increases. Therefore, it is prevented that the integrated value in the integration processing circuit 7 exceeds the threshold value TH when it is generated in the airflow having a large temperature difference.

As shown in FIG. 4, conventionally, when the Doppler component of the received signal is biased positive, for example, due to the air flow in the monitoring space, and when this is sequentially accumulated, the integrated value exceeds the threshold value TH. However, in the present invention, the midpoint (0)
Since the rate of convergence to is large, the integrated value will not exceed the threshold value TH due to the air flow as in the conventional case. As a result, according to the present invention, it is possible to prevent the moving object detection signal from being output due to an error even though the moving object does not exist in the monitoring space.

Further, unlike the case where a moving object invades the surveillance space and moves, in the case where an air flow with a temperature difference occurs in the surveillance space, the vector rotation circuit 6 determines whether the Doppler component is positive or negative. There are many cases where it is not possible. In such a case, the integration processing circuit 7 of the ultrasonic sensor S subtracts a value of "3" larger than the predetermined unit value "1" when the integrated value is positive, and In order to converge the integrated value to the midpoint (0) to a large degree by adding when the integrated value is negative,
It is more thoroughly prevented that the integrated value exceeds the threshold value TH due to the presence of the air flow.

Further, the level of the Doppler signal in the received signal becomes very small when no moving object enters the surveillance space and when there is no airflow with a large temperature difference, but in this case, A predetermined unit value "1" is added or subtracted to converge the integrated value to the midpoint (0). Therefore, it is possible to more effectively prevent an increase in the integrated value when a moving object does not actually exist in the monitoring space, and it is possible to reliably prevent the moving object detection signal from being erroneously output. .

Further, as described above, in the ultrasonic sensor S, since the integrated value has a large degree of convergence to the midpoint (0), it takes time for the integrated value to return to the vicinity of the midpoint (0). It will be shortened. As a result, there is an advantage that the detection time when the moving object actually invades the monitoring space becomes earlier. That is, as shown in FIG. 5, for example, when the integrated value is positive in the section F, a moving object such as a human body actually enters the monitoring space, so that the subtraction processing of the integrated value is performed in the section G. It may be done. In such a case, conventionally,
Since the predetermined unit value "1" is subtracted by one, it takes Tb until the integrated value returns to the midpoint (0), but in the present invention, the value subtracted when the integrated value is positive is " 3 ”, the time Ta until the integrated value returns to the midpoint (0) is shorter than that. Therefore, as for the time until the integrated value exceeds the negative threshold value TH, the time T1 of the present invention is shorter than the conventional time T2.
By (Tb-Ta), the time when the moving object is detected can be advanced and the responsiveness becomes excellent.

[0027]

As can be understood from the above description, according to the ultrasonic sensor of the present invention as set forth in claims 1 to 3, it is possible to receive a wave caused by the presence of an air flow having a temperature difference in the monitoring space. Even if a predetermined integration process is performed in the integration processing circuit by detecting the Doppler component in the signal, it is possible to prevent the integration value from exceeding a predetermined threshold value by increasing the degree of convergence of the integration value to the midpoint. It is possible to avoid the problem, and it is possible to appropriately prevent the problem that the moving object detection signal is erroneously output due to the air flow, even though there is no moving object in the monitoring space. Moreover, by increasing the degree to which the integrated value converges to the midpoint, it becomes possible to shorten the time until the integrated value exceeds the predetermined threshold when a moving object actually enters the monitoring space. There is also an advantage that the responsiveness of object detection can be improved.

Particularly, according to the present invention as set forth in claim 2,
Even when there is no moving object in the monitoring space and a Doppler component larger than the predetermined level cannot be obtained, the processing to bring the integrated value closer to the midpoint is performed, so when there is no moving object in the monitoring space. In addition, it is possible to more reliably prevent the error detection of the moving object.

According to the present invention as defined in claim 3,
Even if there is a situation where the positive / negative of the Doppler component, which is peculiar to the Doppler component, cannot be determined when an air flow with a temperature difference occurs in the monitoring space, the integrated value is converged to the midpoint to a large degree. It is possible to more thoroughly prevent the false detection of a moving object due to a certain air flow.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a hardware configuration of an ultrasonic sensor according to the present invention.

FIG. 2 is an explanatory diagram showing an example of a case of determining whether the Doppler component of a received signal is positive or negative.

FIG. 3 is an explanatory diagram showing an example in which integration processing is performed by an integration processing circuit.

FIG. 4 is an explanatory diagram showing a change state of an integrated value between the present invention and a conventional example when an airflow having a temperature difference from room temperature is generated in the monitoring space.

FIG. 5 is an explanatory diagram showing a change state of an integrated value between the present invention and a conventional example when a moving object actually enters the monitoring space.

FIG. 6 is an explanatory diagram showing an example of characteristics of a Doppler component when an airflow having a temperature difference from room temperature is generated in the monitoring space.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 oscillator 2 wave transmitter 3 wave transmitter 4 wave receiver 5 Doppler component detector 6 vector rotation circuit 7 integration processing circuit 8 detection judgment circuit 51a, 51b mixer 52a, 52b wave detection circuit 54 phase circuit S ultrasonic sensor

Claims (3)

[Claims] 1. A transmitter for transmitting ultrasonic waves into a surveillance space, and a reflected wave transmitted from the transmitter and reflected from an object existing in the surveillance space to receive the reflected wave. A wave receiver that outputs a received signal, a means for determining whether the Doppler component of the received signal is positive or negative, and a predetermined unit value that is predetermined based on the positive or negative of the Doppler component is sequentially added or An ultrasonic sensor having an integration processing circuit for performing subtraction and integration, and means for outputting a moving object detection signal when the integration value calculated by the integration processing circuit exceeds a predetermined threshold value. The integration processing circuit, when executing the subtraction processing when the integrated value is positive or the addition processing when the integrated value is negative, replaces the predetermined unit value with an integration processing with a larger value. Is configured to perform Nsa. 2. The integration processing circuit according to claim 1,
When the level of the Doppler component of the received signal is lower than the predetermined level, when the integrated value is positive, a predetermined unit value is subtracted from the integrated value, and when the integrated value is negative, the integrated value is An ultrasonic sensor, which is configured to add a predetermined unit value. 3. The integration processing circuit according to claim 1, wherein the integration processing circuit determines a value larger than the predetermined unit value from the integrated value when the integrated value is positive when the positive / negative of the Doppler component cannot be determined. An ultrasonic sensor, wherein the ultrasonic sensor is configured to subtract and add a value larger than the unit value to the integrated value when the integrated value is negative.