JPH09222478A - Ultrasonic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable detection of an invading object by a method wherein an arrival time is compared between the reflected light during monitoring and the reflected light during environmental setting to judge that an object exists in a monitoring space when the former is shorter than the later and the value of the later exceeding a fixed value is assumed as the fixed value. SOLUTION: An oscillation signal of an oscillator 1 is transmitted by a transmitting circuit 2 as tone bust wave from a transmitting/receiving device 3 and the reflected wave from an object within a monitoring space is received by the transmitting/ receiving device 3. The received signal is detected by a detection circuit 5 via an amplification circuit 4 to measure the time until a detection waveform exceeds a fixed threshold after the transmission of an ultrasonic wave. In the environmental setting for a environment memory circuit 7 and a present state memory circuit 6 separately, the arrival time of the reflected wave during the monitoring is always stored to compare the individual arrival time of the circuits 6 and 7 by a comparator circuit 8. A detection judging circuit 9 determines an object to exist when the arrival time of the circuit 6 is shorter than that of the circuit 7. When the reflected wave is not received by the arrival time delayed the most within the monitoring range in the environmental setting the arrival time is judged to be such of the circuit 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an ultrasonic sensor which transmits ultrasonic waves to a monitoring space such as a parking lot and detects reflected waves to detect the presence or absence of a vehicle.

[0002]

2. Description of the Related Art An ultrasonic sensor used in a parking lot or the like transmits an ultrasonic wave of a predetermined frequency into a surveillance space by using an ultrasonic transducer, and a reflected wave from an object in the surveillance space. The presence of an object is detected by receiving a wave with an ultrasonic transducer. That is, from the difference between the arrival time of the reflected wave when there is no object in the surveillance space and the arrival time of the reflected wave when there is an object in the surveillance space, is it possible to determine whether the ultrasonic reflection target is the floor surface? , It is determined whether the object exists in the monitoring space.

Here, the monitoring space is a space where the ultrasonic sensor can receive the reflected wave when the transmitted ultrasonic wave is reflected by the intruding object, and the ultrasonic sensor detects the intruding object. Means a possible space. FIG. 3 shows a configuration example of a conventional ultrasonic sensor. This ultrasonic sensor 100
Is an oscillator 101, a transmission circuit 102, an ultrasonic wave transmitter / receiver 103, an amplification circuit 104, a detection circuit 105, a current state storage circuit 106, an environment storage circuit 107, a comparison circuit 108, and a detection determination circuit. And 109.

The oscillation signal output from the oscillator 101 is
A tone burst wave is generated in the wave transmission circuit 102, transmitted as a pulse train from the ultrasonic wave transmitter / receiver 103, reflected by an object in the monitoring space, and received by the ultrasonic wave transmitter / receiver 103. The received signal is amplified by the amplification circuit 104 and detected by the detection circuit 105. The distance to the reflected object can be obtained by measuring the arrival time until the detected waveform thus obtained exceeds a predetermined threshold value with reference to the time of transmitting ultrasonic waves.

The environment storage circuit 107 stores the arrival time of the reflected wave measured when the power is turned on or when the environment is set (when there is no object in the monitoring space) such as when the reset switch is operated. The current state storage circuit 106 stores the arrival time of a reflected wave measured at regular intervals during normal monitoring while the power is on. Then, the comparison circuit 108 includes the environment storage circuit 107 and the current state storage circuit 106.
The arrival determination time held in 1 is compared, and the detection determination circuit 109 determines the presence or absence of an object in the monitoring space based on the comparison result.

That is, when the arrival time stored in the current state storage circuit 106 is shorter than the arrival time stored in the environment storage circuit 107 at the time of setting the environment, or not only the arrival time is shorter, the difference between them is further reduced. Is longer than a predetermined time, it is determined that an object is present and a detection signal is output, while in other cases, the detection signal is not output. By installing such an ultrasonic sensor 100 on the ceiling surface of an indoor parking lot and monitoring the floor surface, it is possible to recognize whether or not a vehicle is parked in the parking lot.

The state at this time is shown in FIG. (A) shows the case when the environment is set, and (b) shows the case where the vehicle enters the monitoring space during the monitoring. The environment setting is performed in a state where no vehicle or the like enters the monitoring space, and the ultrasonic sensor 10
After transmitting ultrasonic waves from 0, the ultrasonic sensor 100 receives the reflected wave w2 from the floor surface at the arrival time t1. The arrival time t1 required here is called a detection gate and is used in the subsequent monitoring.

At the time of monitoring, the ultrasonic sensor 1 is set at regular intervals.
When the transmission wave w1 from 00 is repeated and the reflected wave w3 is received in the detection gate, it can be determined that the vehicle C or the like exists, while the same reflected wave w2 (arrival time t
If 1) is received, it can be determined that there is no object in the surveillance space. Even when the reflected wave w2 is not received after the arrival time t1, the transmitted wave w1 can be determined to be absorbed and the object can be determined to exist. This figure shows a case where the arrival time t2 of the reflected wave w3 is shorter than the arrival time t1 at the time of environment setting (t1> t2) due to the presence of the vehicle C.

[0009]

However, in the above-described conventional ultrasonic sensor, if the ultrasonic transducer (horn) is mistakenly installed while being installed on the ceiling or the like, the ultrasonic sensor may be affected by the floor surface when setting the environment. Even if the reflected wave could not be received and the monitoring state was subsequently received, the reflected wave could not be continuously received, so it was determined that there was an object in the monitored space.

Further, although it is possible to repeat the transmission of waves until the existence of the floor surface can be recognized by the reflected waves and to output an abnormal signal, in these cases, unless the installation state is returned to normal, the monitoring space The object could not be detected. The present invention has been made in view of the above circumstances, and it is possible to detect an intruder in a monitoring space even when the installation state is abnormal at the time of environment setting and reflected waves cannot be received. It is an object of the present invention to provide an ultrasonic sensor that can be installed and can instruct to restore the installation to normal.

[0011]

An ultrasonic sensor according to claim 1, which is proposed to achieve the above object, comprises a first storage means for storing the arrival time of a reflected wave being monitored, and an environment setting. Second storage means for storing the arrival time of the reflected wave at time, comparison means for comparing the arrival time of the reflected wave stored in the first storage means and the second storage means, and the result of the comparison by the comparison means A detection determination unit that determines that an object is present in the monitoring space when the arrival time of the first storage unit is shorter than the arrival time of the second storage unit, and When the reflected wave is not received by the arrival time of the latest reflected wave within the monitoring range, the arrival time is set as the arrival time of the second storage means for comparison by the comparison means. Thereby, even when the monitoring state is entered, it is possible to determine that an object exists in the monitoring space by receiving the reflected wave from the intruder.

It is needless to say that the first storage means and the second storage means may have different storage areas so as to share the same storage means.
Further, these storage means may store distance data that can be calculated from the arrival time of the reflected wave or a waveform pattern obtained by digitally converting the reflected wave after detection, so that the two can be compared and judged.

Further, the arrival time of the reflected wave which is the latest within the monitoring range is the time when the object exists within a predetermined distance (for example, 3.5 m) where the ultrasonic sensor guarantees the detection of the object. Is the arrival time of the reflected wave of. The ultrasonic sensor according to claim 2 is further provided with display means for displaying the operating state of the ultrasonic sensor according to claim 1, and the reflected wave for the ultrasonic wave transmitted at the time of setting the environment is the latest within the monitoring range. If the reflected wave is not received by the arrival time, the display means indicates an abnormal state. Here, the display means is composed of an LED or the like, and lights up or blinks to notify that the reflected wave cannot be received, and prompts confirmation of the installation state.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of the configuration of the ultrasonic sensor of the present invention. The ultrasonic sensor S is installed on the ceiling of an indoor parking lot and is used as a vehicle sensor for detecting the presence or absence of a vehicle in the monitoring space. The ultrasonic sensor S has the same configuration as the conventional ultrasonic sensor shown in FIG. , Oscillator 1, wave transmission circuit 2, and ultrasonic wave transceiver 3
An amplifier circuit 4, a detection circuit 5, a current storage circuit 6 which is a first storage means and is composed of RAM and the like, and an environment storage circuit 7 which is a second storage means and is composed of an EEPROM and the like.
And a comparison circuit 8 which is a comparison means, and a detection judgment circuit 9 which is a detection judgment means, and further, a floor surface judgment for judging the existence of the floor surface from the arrival time of the reflected wave stored in the environment storage circuit 7. The circuit 10 includes a detection gate setting circuit 11 that sets a detection gate in the comparison circuit 8 according to the determination result of the floor determination circuit 10, and a display 12 that is a display unit that indicates the operating state of the sensor S.

The oscillation signal of the oscillator 1 is converted into a tone burst wave in the wave transmission circuit 2 and transmitted as a pulse train from the ultrasonic wave transmitter / receiver 3, and the wave reflected by an object in the monitoring space is transmitted by the ultrasonic wave transmitter / receiver 3. Receive the wave. The received signal is amplified by the amplification circuit 4 and detected by the detection circuit 5. If the detection waveform obtained in this way measures the arrival time until it exceeds a predetermined threshold value when the ultrasonic wave is transmitted,
The distance to the reflected object is obtained.

The environment storage circuit 7 stores the arrival time of the reflected wave measured when the power is turned on or when the environment is set such as when the reset switch or the environment setting switch is operated. The arrival time of the reflected wave measured at regular intervals during normal monitoring while the power is on is stored. Then, the comparison circuit 8 compares the arrival times held in the environment storage circuit 7 and the current storage circuit 6, and the detection determination circuit 9 determines the presence or absence of an object in the monitoring space based on the comparison result.

That is, when the arrival time stored in the current state storage circuit 6 is shorter than the arrival time stored in the environment storage circuit 7 at the time of environment setting, or not only,
Furthermore, if these differences are more than a predetermined time,
While it is determined that an object is present and a detection signal is output, in other cases, the detection signal is not output. The storage circuits 6 and 7 store distance data that can be calculated from the arrival time of the reflected wave and waveform patterns that are digitally converted after detection, and compare and determine the presence of an object. It may be detected. In addition, in the environment storage circuit 7,
As an initial value, an arrival time corresponding to the distance from the floor surface to the ceiling (for example, 2.2 m) of a standard indoor parking lot may be set.

In the comparison circuit 8, the current state storage circuit 6 is usually used.
The arrival time of the reflected wave stored in the environment storage circuit 7 is compared with the arrival time of the reflected wave stored in the environment storage circuit 7, and the comparison result is output.
When the presence of the floor surface cannot be detected at 0, that is, the reflected wave (first reflected wave) for the transmitted ultrasonic wave is not received by the latest arrival time stored in advance in the floor surface determination circuit 10. In this case, the arrival time of the environment storage circuit 7 compared by the comparison circuit 8 is changed and set by the detection gate setting circuit 11 to this latest arrival time.

Here, the latest arrival time is the arrival time of the reflected wave which is the latest within the monitoring range, that is, the distance (eg 3.5 m) at which the ultrasonic sensor S guarantees the detection of the object. Is the arrival time of the reflected wave when there is
It is stored for each type of the ultrasonic sensor S according to a standard installation environment. FIG. 2 shows an example of the operation of the ultrasonic sensor S described above.

(A) is a case where the sensor S is installed on the ceiling while the horn remains tilted. If the environment is set in this state, the reflected wave is not received within the latest arrival time t with respect to the ultrasonic wave transmission w1, or even if the reflected wave is received, the detected waveform does not exceed a predetermined threshold value. (Reflected wave w ') In this case, after the latest arrival time t is set as the detection gate, the monitoring state is entered.

At this time, at the same time, the L of the display 12 is
An abnormal condition is indicated by lighting or blinking the ED or the like. As a result, it is possible to notify that the installation state is abnormal and to promote normal installation. (B) is the case of (a) at the time of environment setting, and then is the case of shifting to the monitoring state. Although the monitoring space is limited to some extent in the range in which the ultrasonic sensor S is tilted, when the vehicle C enters in this state, the detection gate is set to the longest time zone (t) in which the reflected wave can be received. Therefore, the arrival time is t '
It is possible to reliably detect the presence of the vehicle C (there is an object) by receiving the reflected wave w3 that is (t ′ <t). In addition,
At this time, since the object detection is not performed when there is no reflected wave in the transmitted wave w1, there is no possibility of malfunction.

(C) is a case where the ultrasonic sensor S is normally installed by looking at the display on the display 12. When re-installed, perform the environment setting operation again to set a normal detection gate. That is, with no object present,
The reflected wave w2 from the floor is received with respect to the transmitted wave w1, and the arrival time t1 at that time is used as a detection gate. At this time, object detection may be performed when there is no reflected wave in the transmitted wave w1.

[0023]

As can be understood from the above description, according to the ultrasonic sensor of the first aspect of the present invention, the reflected wave at the time of setting the environment is received even when the ultrasonic sensor is installed tilted to the ceiling. Even if the wave cannot be generated, the time period to be monitored is maximized in order to detect the reflected wave of the object, so that the presence of the object in the monitoring space can be detected when the monitoring state is set thereafter.

According to the ultrasonic sensor of the second aspect,
Since it is possible to display that the reflected wave for the ultrasonic wave transmitted at the time of setting the environment could not be received, it is possible to promptly deal with an abnormal installation or the like.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an example of the operation of the ultrasonic sensor of the present invention.

FIG. 3 is a block diagram showing an example of an internal configuration of a conventional ultrasonic sensor.

FIG. 4 is a diagram showing an example of the operation of a conventional ultrasonic sensor.

[Explanation of symbols]

S ... Ultrasonic sensor 6 ... Current state storage circuit (first storage means) 7 ... Environment storage circuit (second storage means) 8 ... Comparison circuit (comparison means) 9 ... Detection Judgment circuit (detection judgment means) 10 ... Floor surface judgment circuit 11 ... Detection gate setting circuit 12 ... Display (display means) w1 ... Wave transmission w2 ... Reflected wave by floor surface w3. .. Reflected wave by vehicle t ... Latest arrival time (arrival time of reflected wave that is the latest in the monitoring range) t '... Arrival time of reflected wave by vehicle t1 ... Reflected wave by floor surface Arrival time of C ... Vehicle

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideki Kawahara 1048 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Works, Ltd.

Claims (2)

[Claims] 1. An object in a monitoring space by comparing the arrival time of a reflected wave with respect to an ultrasonic wave transmitted at regular intervals during monitoring and the arrival time of a reflected wave with respect to an ultrasonic wave transmitted during environment setting. In the ultrasonic sensor for detecting the presence or absence of the presence of a first storage means for storing the arrival time of the reflected wave being monitored, a second storage means for storing the arrival time of the reflected wave when the environment is set, Means for comparing the arrival times of the reflected waves stored in the second storage means with the storage means, and as a result of the comparison by the comparison means, the arrival time of the first storage means is the arrival time of the second storage means. When it was shorter,
Equipped with a detection determination means for determining that there is an object in the monitoring space, the reflected wave to the ultrasonic wave transmitted at the time of environment setting is received by the arrival time of the reflected wave which is the latest in the monitoring range. If not, this arrival time is set as the arrival time of the second storage means for comparison by the comparison means. 2. The display device according to claim 1, further comprising display means for indicating an operating state of the ultrasonic sensor, wherein the reflected wave for the ultrasonic wave transmitted at the time of setting the environment is the latest reflected wave within the monitoring range. An ultrasonic sensor characterized in that an abnormal state is displayed on the display means when no waves are received by the arrival time.