JP2605335B2 - Ultrasonic array sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultrasonic array sensor in which a plurality of ultrasonic transducers for transmitting ultrasonic waves and receiving reflected waves are arranged on the same plane. It is.

[Conventional technology]

A conventional ultrasonic sensor using one ultrasonic transducer cannot detect a narrow range because the directional beam is thick and gentle.

For example, Japanese Patent Application No. 61-216266 discloses an ultrasonic array sensor in which a plurality of ultrasonic transducers are arranged on the same plane.

In this ultrasonic array sensor, a plurality of ultrasonic transducers are arranged at equal intervals. Thereby, the directional beam could be narrowed.

Here, when monitoring over a wide range using an ultrasonic array sensor having such a narrow directional beam, it is necessary to scan the directional beam over a wide range. For example, as shown in FIG. 4, the direction of the directional beam, that is, the directional angle φ may be changed by controlling the transmission time of the five ultrasonic transducers S1 to S5 by the delay circuits D1 to D5. That is, as shown in FIG.
By shifting the transmission time of S1 to S5 by Δt to align the in-phase wavefront with the direction shifted by an angle φ from the front direction, the directional beam can be scanned by the angle φ. If the distance between the ultrasonic transducers S1 to S5 is d and the distance between the in-phase wavefronts is Δl, then Δt = Δl / c = d sinφ / c (c is the speed of sound). If the transmission time is sequentially delayed from S1 to S5 by the time Δt determined by this equation, the direction of the directional beam is inclined in a direction deviated from the front direction by an angle φ as shown in FIG.

[Problems to be solved by the invention]

In the conventional example described above, the directional beam is changed as shown in FIG.
As shown in (e), if the scanning is performed in order from the direction A to the direction E, the position where the detection object P exists can be detected in the angular direction with a resolution.
There is a problem that the phase delay operation has to be performed twice and it takes time to scan the directional beam.

The present invention has been made in view of the above points, and an object of the present invention is to provide an ultrasonic array sensor having resolution in an angular direction and capable of detecting in a short time.

[Means for solving the problem]

The present invention provides a plurality of ultrasonic transducers for transmitting an ultrasonic wave and receiving a reflected wave, a delay circuit for giving a phase difference according to the timing of transmission of the ultrasonic transducer, and the ultrasonic transducer. A determination unit for determining in which direction the detection object is present based on each received signal from the ultrasonic array sensor in which the plurality of ultrasonic transducers are arranged on the same plane. The ultrasonic transducers are arranged such that a plurality of the ultrasonic transducers are formed at equal intervals, and the delay circuit has a phase difference in the timing of transmission to each of the ultrasonic transducers,
While sequentially scanning the plurality of directional beams, at least one of the plurality of directional beams in the scan when the phase difference is provided, at least one of the plurality of the directional beams in the scan before the phase difference is provided. In this case, the position of the detection object is detected based on the detection data for each scan by the determination unit.

[Action]

The ultrasonic array sensor of the present invention arranges a plurality of ultrasonic transducers at regular intervals, for example, at an interval of 1.4λ (where λ is the wavelength of the ultrasonic wave), thereby simultaneously providing directional beams in a plurality of directions. , Formed at equal intervals, and sequentially scans this directional beam by shifting the transmission time by a delay circuit,
At least one of the plurality of directional beams in the scan having the phase difference is overlapped with any one of the plurality of directional beams in the scan before providing the phase difference, and each of the scans The direction in which the object exists is detected in a short time by the determination unit from the detection signal of the object at the time of (1).

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. S1 to S5 are ultrasonic transducers for transmitting ultrasonic waves and receiving reflected waves, and are arranged at equal intervals on the same plane to constitute an ultrasonic array sensor. Ultrasonic transducer S1 ~
The interval d between S5 is 1.4λ (λ is the wavelength of the ultrasonic wave). D1
D5 is a delay circuit connected to each of the ultrasonic transducers S1 to S5, and controls the transmission time of the ultrasonic transducers S1 to S5. That is, the delay circuits D1 to D5 are for shifting the transmission of the ultrasonic transducers S1 to S5 in order and inclining the directional angles of the plurality of directional beams by φ. J is a determination unit that determines in which direction the detection object is present based on the received signals from the ultrasonic transducers S1 to S5.

FIG. 2A shows directivity characteristics in the present embodiment when there is no delay in transmission of the ultrasonic transducers S1 to S5 by the delay circuits D1 to D5. The distance d between the ultrasonic transducers S1 to S5 is 1.4λ.
Therefore, three directional beams are generated. Assume that these three directional beams are in directions of angles φ1, φ2, and φ3, respectively. The angle between the three directional beams is φ. Next, the directions of the directional beams are shifted by an angle φ by delay circuits D1 to D5 so as to be directed at angles φ4, φ5, and φ6 as shown in FIG. 2B. Here, φ1
And φ5 and φ2 and φ6 have the same angle. Also, the angle is shifted in the opposite direction from the state of FIG. 2A by an angle φ (an angle of 2φ from the state of FIG. 2B), and as shown in FIG. 2C, the angles φ7, φ8, Turn to the direction of φ9.
Here, φ2 and φ7 and φ3 and φ8 have the same angle.

In this manner, scanning is performed by the delay circuits D1 to D5 so that the direction of the directional beam is shifted by an integral multiple of the angle φ between the directional beams to be generated.

However, it is necessary that at least one or more directional beams overlap.

Therefore, the above condition is satisfied in the case of the ultrasonic array sensor having three beams as in this embodiment.
FIGS. 2A to 2C show only the three states.

FIG. 3 shows an actual directional beam. Fig. 3 (a)-
(C) corresponds to FIGS. 2 (a) to (c), respectively. The direction in which the detection object exists has resolutions of five directions A to E. P is a detection object that actually exists, and is assumed to be present in the direction of B.

Next, how the determination unit J detects the presence of the detection object P will be described.

When the directional beam is in the state shown in FIG.
There is a received signal. Next, in the state of FIG.
Again, there is a received signal.

However, in the state of FIG. 3 (c), there is no received signal.

 Here, Table 1 shown below is prepared.

Here, the circles indicate the states where there is a received signal in each of the states (a) to (c) shown in FIG. In Table 1, (a)
The existence position of the detection object P can be determined based on the location of the mark in each state of (c) to (c).

In the above example, the reception is detected in the state of (a) and the state of (b), and the reception is not detected in the state of (c). That is, it is determined that the detection object P exists in the direction of B marked with a circle only at the point ()).

In this embodiment, an example in which the number of directional beams is three has been described. However, by adjusting the interval between the ultrasonic transducers, the number of directional beams can be increased, and the resolution in the angular direction can be further improved. Is possible. Further, as shown in the conventional example, the number of phase delay operations of the directional beam can be reduced from three times to five times in the conventional example.

〔The invention's effect〕

As described above, according to the present invention, a plurality of ultrasonic transducers for transmitting an ultrasonic wave and receiving a reflected wave, and a delay circuit for giving a phase difference depending on the transmission timing of the ultrasonic transducer. ,
Having a determination unit to determine in which direction the detection object is present by each received signal from the ultrasonic transducer,
In the ultrasonic array sensor in which the plurality of ultrasonic transducers are arranged on the same plane, the ultrasonic transducers are arranged so that a plurality of directional beams are formed at equal intervals, and each of the ultrasonic transducers is arranged by the delay circuit. By giving a phase difference to the timing of the transmission to the acoustic transducer, the plurality of directional beams are sequentially scanned, and at least one of the plurality of directional beams in the scan with the phase difference is at least one of the directional beams. Since any one of the plurality of directional beams in the scan before giving the phase difference is overlapped, and the determination unit detects the position of the detection object based on the detection data for each scan. Thus, an ultrasonic array sensor having resolution in the angular direction and capable of detecting in a short time could be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram showing a directional beam according to the above embodiment, FIG. 3 is a schematic diagram showing a direction of the directional beam according to the embodiment, FIG. FIG. 5 is a block diagram showing a conventional example, FIG. 5 is a diagram for explaining the principle of the above, FIG. 6 is a schematic diagram showing an array of ultrasonic transducers and a directional beam according to the above, and FIG. It is a schematic diagram which shows the scanning body of such a directional beam. S1-S5: Ultrasonic transducer D1-D5: Delay circuit J: Judgment unit

Claims (1)

(57) [Claims] A plurality of ultrasonic transducers for transmitting an ultrasonic wave and receiving a reflected wave; a delay circuit for providing a phase difference depending on a transmission timing of the ultrasonic transducer; A determination unit for determining in which direction the detection object is present based on each of the received signals from the transducer, and an ultrasonic array sensor in which the plurality of ultrasonic transducers are arranged on the same plane. Arrange the ultrasonic transducers so that a plurality of beams are formed at equal intervals, by the delay circuit, by giving a phase difference in the timing of the transmission to each ultrasonic transducer,
While sequentially scanning the plurality of directional beams, at least one of the plurality of directional beams in the scan when the phase difference is provided, at least one of the plurality of the directional beams in the scan before the phase difference is provided. An ultrasonic array sensor, wherein the position of a detection object is detected based on the detection data for each scan by the determination unit.