JPS62277574A - Ultrasonic sensor - Google Patents

Abstract

PURPOSE:To thin an ultrasonic sensor and to easily vary the directivity by providing a transmitting and receiving means where plural ultrasonic vibrators are arrayed on the same plane of a base, a vibrator selecting means, and a signal processing means. CONSTITUTION:The transmitting and receiving means 2 is formed by arraying plural ultrasonic vibrators 1(11-16) which transmit and receive ultrasonic waves on the same plane of the base. Further, transmitted signals inputted to transmitted wave input terminals TS1 and TS2 are processed by transmitting circuits A11-A16 and applied to the vibrators 11-16 and wave reception outputs of the vibrators 11-16, on the other hand, are inputted to receiving circuits A21-A26, whose outputs are put together into one composite signal and outputted to received wave output terminals Tr1 and Tr2. Then, a vibrator selecting means 3 is so constituted to form plural combinations of vibrators 1 which operate at one transmitted wave period; and the received signal outputs of the 1st and a 2nd transmission and reception periods where transmitting and receiving operations are performed at different timing are ANDed by a signal processing means 3, which outputs a composite received wave signal, so desired total directivity covering both transmitted and received wave periods is easily realized.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Technical Field] The present invention relates to an ultrasonic sensor that transmits ultrasonic waves and receives reflected waves of the ultrasonic waves from an object to be detected [Background Art] ] Generally, the detection method of an object detection device using this type of ultrasonic sensor is to transmit an ultrasonic wave consisting of a pulse wave from a transmitter and to detect the reflected wave of the transmitted ultrasonic wave by the object to be detected. There is a presence detection method that detects the distance to the object to be detected according to the time from transmitting the ultrasonic wave to receiving the reflected wave, or detecting the distance from the transmitter to a predetermined frequency. A movement detection method that transmits a continuous wave, receives the reflected wave from a moving detected object using a receiver, and detects the movement of the detected object according to the frequency shift caused by the Doppler effect of the reflected wave. I am unknown.

By the way, foot sound waves have a shorter wavelength than sound waves in the audible range and therefore have sharp directivity, so it is possible to limit the range to be detected.For example, as shown in Figure 8. When directivity is obtained, a detection range corresponding to the half-value angle θ, /2 can be obtained.

Conventionally, in order to obtain a predetermined directivity, a truncated conical horn 5 is required to propagate the ultrasonic waves generated by the ultrasonic transducer 1 with a predetermined directivity, as shown in FIG. there was. For this reason, there was a problem in that the size in the radial direction became large, making it unsuitable for thinning. Furthermore, the directivity is uniquely determined by the shape of the horn 5, so in order to obtain a desired directivity, it is necessary to change the shape of the horn 5 or prepare multiple horns 5 with different shapes. There was a problem that the directivity could not be changed in the tube.

[Objective of the Invention 1 The present invention has been made in view of the above-mentioned points, and its purpose is to easily reduce the thickness, easily change the directivity, and achieve the desired An object of the present invention is to provide an ultrasonic sensor that can easily realize comprehensive directivity.

[Disclosure of the Invention] (Embodiment) FIGS. 1 and 2 show an embodiment of the present invention, in which a plurality of ultrasonic transducers 1 for transmitting and receiving ultrasonic waves are shown in FIG.
) As shown in (b), the wave transmitting/receiving means 2 are arranged (square arrangement or concentric arrangement) on the same plane of the base.
and a transducer selection means 3 for selecting an arbitrary ultrasonic transducer 1 from the plurality of ultrasonic transducers 1 to transmit and receive waves,
A transducer selection means 3 is provided with a signal processing means 4 for generating a transmission signal and processing a reception signal, and a transducer selection means 3 so as to form a plurality of combinations of ultrasonic transducers 1 that operate in one transmission/reception period. The signal processing means 4 is configured to perform wave transmitting and receiving operations for each set at different timings, and to output a composite received signal obtained by performing a logical operation on the received signal output of each set.

Here, the transducer selection means 3 includes wave transmitting circuits A11 to A16 and wave receiving circuits A21 to A16, as shown in the figure fj'S2.
A26, and the transmitting input terminal Ts+
The transmitting signal input to r T s 2 is sent to the transmitting circuit A1
Signal processing (oscillation of a predetermined frequency,
(processing such as amplification) and is applied to the ultrasonic transducers 11 to 16. On the other hand, ultrasonic transducers 11 to 1
The received wave output of No. 6 is input to the receiving circuits A21 to A2g which process the received wave output (processing (noise removal, amplification, etc.) The circuit configuration of the transducer selection means 3 is merely an example, and is not limited to this embodiment.

The operation of the embodiment will be explained below. Now, the directivity of this ultrasonic sensor can be arbitrarily changed by changing the arrangement pitch d of the ultrasonic transducers 1, which are the array 7 actors, and the number 11 of transducers driven in parallel. For example, as shown in FIG. 3, if the array 7 actor is d=o, 5λ, and n=5, then IjS4 (
, ), a directional beam with a half-value angle θ172 of about 29° is obtained, and when d=o, 5λ, mouth=10, d−^, n=5, and d=λ , n=10
In this case, directional beams as shown in FIGS. 4(b) to 4(d) can be obtained.

By the way, in the present invention, 4M+=7. F+IIInmglb-7-1fr)jJI
The transducer selection means 3 is formed in such a way that the wave transmitting and receiving operations are formed such that the combined directivity of the transmitting and receiving waves is different in the 'R example. tJrJl performed at different timings (first period, second period)
Since the signal processing means 4 outputs a composite received signal obtained by ANDing the received wave signal outputs of the second wave transmitting/receiving period, the directivity in each of the first and second wave transmitting/receiving periods is By appropriately designing each of them, the desired overall directivity over both transmission and reception periods can be easily achieved with a simple configuration.

For example, as shown in Fig. 5, a directional beam with a half-power angle of about 8 degrees is realized using multiple ultrasonic transducers 1 for both transmitting and receiving (the directivity during transmitting and receiving is the same). (Realized using a plurality of ultrasonic transducers 1), d=0.5λ, n=
20 elements are required.

However, in the first transmission/reception period, d=2 people,
Ultrasonic waves are transmitted and received with the directivity shown in Figure 6 (,) obtained by setting n = 5, and in the second transmission and reception period, the obtained result is obtained by setting d = λ and n = 2. The ultrasonic wave is transmitted and received with the directivity shown in FIG. 6(b).
1st. Theory of the received signal output obtained in the second transmission/reception cycle Pl! If the product is calculated, the overall directivity will be 1 as shown in FIG. 6(c), and a directivity equivalent to the directivity shown in FIG. 5 can be easily realized. That is, if the directivity of multiple transmission/reception cycles is made different, and the reception signal is obtained by performing a logical operation on the reception signal output of each transmission/reception cycle,
By diversifying the overall directivity, any directivity can be easily realized with a simple configuration (with a small number of oscillators), and miniaturization and cost reduction can be achieved. A wave transmitting/receiving means in which a plurality of ultrasonic vibrators for transmitting and receiving ultrasonic waves are arranged on the same plane of a base, and an arbitrary ultrasonic vibrator from the above ultrasonic vibrators is selected to transmit and receive ultrasonic waves. A plurality of combinations of ultrasonic transducers that operate in one transmission/reception period are formed. The transducer selecting means is formed as shown in FIG. Compared to the conventional example using a horn, the size in the radial direction can be made smaller and the thickness can be easily made thinner. Moreover, the ultrasonic transducer that operates in one transmission/reception period can be used with the transducer selection means. The directivity can be arbitrarily changed simply by changing the combination, and the directivity can be easily changed.

In addition, the desired overall directivity can be easily achieved with a simple configuration (with a small number of oscillators) by making the directivity of multiple transmission/reception cycles different, and it is possible to achieve downsizing and cost reduction. There is an effect that it can be done.

[Brief explanation of the drawing]

FIG. 1 (aHb) is a perspective view of essential parts of one embodiment of the present invention;
3 to 6 are diagrams illustrating the operation of the same as above, FIG. 7 is a schematic configuration diagram of the conventional example, and FIG. 8 is a diagram illustrating the operation of the same. 1. 11 to 16 are ultrasonic transducers, 2 is a wave transmitting/receiving means, 3 is a transducer selection means, and 4 is a signal processing means. Figure 1 (b) Figure 7 Figure 8] Figure 4 (C) (b) (d) GAIN (dB)

Claims (1)

[Claims] (1) A wave transmitting/receiving means in which a plurality of ultrasonic vibrators for transmitting and receiving ultrasonic waves are arranged on the same plane of a base, and any ultrasonic vibrator selected from the above ultrasonic vibrators is used to transmit and receive ultrasonic waves. A plurality of combinations of ultrasonic transducers that operate in one transmission/reception period are formed, including a transducer selection means for transmitting a wave and a signal processing means for generating a transmission signal and processing a reception signal. The oscillator selection means is formed as shown in FIG. An ultrasonic sensor featuring: