JPH0251155B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field of the Invention) This invention is a method for arranging a plurality of ultrasonic transducers and synthesizing the received signals of each transducer to generate a received beam having directivity in a specific direction. The present invention relates to a device for forming a directional received beam and changing the directivity direction of a directional received beam over time.

The applicant has filed patent application No. 57-121439 for this type of device.
(Special Publication No. 1-016392). This device separately mixes the received signals from a plurality of arrayed ultrasonic transducers with mixed signals prepared for each received signal, and extracts specific frequency components from the summed output of the mixed signals. It is. Then, by changing the phase of each mixed signal while maintaining a specific phase relationship, the extracted frequency signal is detected as a directional receiving beam, and the pointing direction of the directional receiving beam is determined. It changes over time.

(Object of the Invention) This invention further develops the above-mentioned device provided by the applicant (Japanese Patent Application No. 121439/1983 (Japanese Patent Publication No. 1-016392)) to sharply sharpen the directivity angle of a directional receiving beam. The purpose is to

Generally, when arranging multiple ultrasonic transducers and combining the received signals of each transducer to form a directional receiving beam, the directivity angle of the receiving beam is determined by the array length of the transducers. The directivity angle becomes sharper as the array length increases.

The purpose of this invention is to form a received beam with the same directivity angle as when a received beam is formed using a vibrator having an equivalent array length twice as long as the vibrator array length, without changing the array length of the vibrator. .

(Structure and operation of the invention) In FIG. 1, Z ₁ to Z ₇ indicate ultrasonic transducers, and an example is shown in which seven transducers are arranged at intervals d.

Each received signal of the ultrasonic transducers Z ₁ to Z ₇ is amplified by each of the preamplifiers P ₁ to P ₇ . and,
The outputs of the preamplifiers P ₁ to P ₇ are connected to the mixing circuits M ₁₁ to
At the same time as being led to M ₁₇ , the mixing circuit M ₂₁ to M ₂₇
You will also be guided to

Each of the mixing circuits M ₁₁ to M ₁₇ includes a preamplifier P ₁
Each output of _P7 to latch circuit 101 to 107
and the rectangular wave train sent from the Further, each of the mixing circuits M ₂₁ to M ₂₇ mixes the rectangular wave trains sent out from the latch circuits 201 to 207, respectively.

The outputs of the mixing circuits M ₁₁ to M ₁₇ and M ₂₁ to M ₂₇ have their respective phases influenced by the phase of the mixed signal. Therefore, the latch circuits 101 to 107
Alternatively, by changing the phase of the rectangular wave train sent out from 201 to 207, the preamplifier P ₁
The received signals of the ultrasonic transducers Z ₁ to Z ₇ transmitted from P ₇ to P 7 can be equivalently shifted in phase. Therefore, by setting the phases of the rectangular wave trains sent out from the latch circuits 101 to 107 to have a specific phase relationship, the received signals of the ultrasonic transducers Z ₁ to Z ₇ can be made equal in a specific direction. A phase wavefront can be formed. For example, when forming an equal phase wavefront in the θ direction with respect to the front direction, the ultrasonic transducer Z ₁
The phase of each received signal from _Z7 to 2nπ/λd sinθ (n=1, 2, 3...
). i.e. ultrasonic transducer Z ₄
In contrast, the received signal of the ultrasonic transducer Z ₃ should be delayed by 2π/λd sinθ, and the received signal of the ultrasonic transducer Z ₂ should be delayed by 4π/λd sinθ. Further, the phase of the reception signal of the ultrasonic transducer Z ₅ may be advanced by 2π/λd sinθ, and the phase of the reception signal of the ultrasonic transducer Z ₆ may be further advanced by 4π/λd sinθ.

Therefore, by sequentially varying the phase of the rectangular wave trains sent out from the latch circuits 101 to 107 by 2πd/λsinθ, the ultrasonic transducer Z ₁
It is possible to form equal phase wavefronts in the θ direction for each received signal from Z7 to _Z7 .

The rectangular wave sequences a to g in FIG. 2 represent the latch circuit 101.
The rectangular wave trains sent out from 107 to 107 are shown, and the phases are sequentially different by 2π/λd sinθ.

The mixing outputs of mixing circuits M ₁₁ to M ₁₇ are added to adder circuit 3.
After being added at , the signals are guided to a filter 4 and a signal of a specific frequency is extracted. Therefore, the filter 4 outputs a received signal having an equal phase wavefront in the θ direction. The direction θ of the equal phase wavefront is
As explained in Japanese Patent Publication No. 57-121439 (Japanese Patent Publication No. 1-016392), by controlling the phases of the rectangular wave sequences a to g, they can be changed in time within a predetermined range of angles.

Latch circuits 101 to 107 send out rectangular wave sequences a to g by latching the data stored in memory circuit 5. That is, as explained in Japanese Patent Application No. 57-121439 (Japanese Patent Publication No. 1-016392),
The memory circuit 5 has a 7-bit output terminal corresponding to the number of arrays of ultrasonic transducers _Z1 to _Z7 , each bit output has the same number of memory addresses, and the memory data at each memory address can be read out simultaneously. be done. Binary value storage data is written in advance at each storage address, and the storage data at the storage address corresponding to the count value of the counter 6 is read out. As a result, the latch circuits 101 to 107 output rectangular wave trains shown in FIG. 2a to g. The phases of the rectangular wave sequences a to g can be arbitrarily set and changed by storing data written in the storage circuit 5. Therefore, when reading out the data stored in the memory circuit 5 in accordance with the counted value of the counter 6, the
Similarly to No. 57-121439 (Japanese Patent Publication No. 1-016392), by controlling the phases of the rectangular wave trains a to g, the equal phases formed by the ultrasonic wave receivers Z ₁ to Z ₇ are obtained. The direction θ of the wavefront can be changed. This equal-phase wavefront, and hence the directivity direction θ of the received beam, changes as the count value of the counter 6 changes. Note that the counter 6 performs a counting operation by receiving a pulse train from a clock pulse source 7 via a frequency dividing circuit 8. Also, the latch pulse generation circuit 9 generates a latch pulse based on the input pulse and output pulse of the frequency divider circuit 8, and the latch circuits 101 to 107 perform a latch operation based on the latch pulse. As a result, the rectangles shown in FIG. 2 a to g are generated. Send out a wave train. The latch operation of the latch circuits 101 to 107 is described in Japanese Patent Application No.
As explained in No. 121439, this is to smoothly generate rectangular wave sequences a to g.

As a result of the above, a directional reception beam signal is transmitted from the filter 4, which has directivity in one direction and whose direction changes as the count value of the counter 6 changes.

On the other hand, the mixing circuits M ₂₁ to M ₂₇ are latch circuits 20
1 to 207 are mixed, and each mixed output is sent to the adder circuit 10.
After being added, the signals are guided to a filter 11 where a specific frequency component is extracted. Latch circuits 201 to 2
07 sends out rectangular wave trains similar to those shown in FIG. 2 a to g by latching the stored data in the memory circuits 201 to 207. The memory circuit 12 and the counter 13 operate in the same manner as the memory circuit 5 and the counter 6, respectively. . Therefore, like the filter 4, the filter 11 has directivity in one direction, and a directional reception beam whose directivity changes with the count value of the counter 13 is transmitted.

As is clear from the above, the directional direction of the directional received beam sent out from the filter 4 corresponds to the count value of the counter 6, and the directional direction of the directional received beam sent out from the filter 11 corresponds to the count value of the counter 13. Corresponds to numbers. Counters 6 and 13 have their counts reset by a trigger pulse from transmitter 19. At this time, the counted value of the counter 13 is preset to the preset value of the preset circuit 14. Therefore, the counters 6 and 13 perform counting operations while maintaining different values by the preset value of the preset circuit 14. Therefore, the directional receiving beam of the filter 4 and the directional receiving beam of the filter 11 also differ in direction by an angle corresponding to the set value of the preset circuit 14.

Figure 3 shows filters 4 and 1 at a certain moment.
1 shows a characteristic diagram of the directional receiving beam transmitted by No. 1,
A shows the directional received beam of the filter 4, B
indicates the directional received beam of the filter 11.

The directional receiving beam A is directed in the θ ₁ direction, and the directional receiving beam B is directed in the θ ₂ direction, which is different by Δψ. As is clear from the above, this difference angle Δψ corresponds to the set value of the preset circuit 14.

Directional receiving beams A and B of filters 4 and 11
is guided to a multiplication circuit 15, and the multiplication output of each received beam is sent out. Therefore, the multiplier circuit 15 sends out a received beam in the common area of the directional received beams A and B, as shown in FIG. 3C.

In Fig. 3, the directivity angle of the directional received beam A or B, that is, the half-reduction full angle α of the directivity characteristic is:
It is determined by the array length of the ultrasonic transducers Z ₁ to Z ₇ in FIG. On the other hand, the multiplication output C extracts the common area of the received beams A and B, and the common area is connected to the preset circuit 14 as explained above.
It can be set arbitrarily by setting the value of . Therefore,
As shown in FIG. 3C, the multiplier circuit 15 can equivalently send out a received beam represented by a directivity angle β that is sharper than the directivity angle α of the directional received beam A or B.

In the above, the setting value of the preset circuit 14 may be set in consideration of the characteristics of the received beam C sent out as the output of the multiplication circuit 15. In other words, as the setting value becomes smaller, the received beam A
Since the common area between and B becomes larger, the directivity angle β of the multiplication output C becomes larger. The output level of the received signal also increases. Conversely, if the above set value is increased, the common area of the received beams A and B becomes smaller, so that the multiplication output C has a sharper directivity angle β. As the set value increases, the output level of the multiplication output C decreases.

The received wave output (FIG. 3C) sent out from the multiplication circuit 15 as described above is amplified by the amplifier 16 and then sent to the display 17 for display. Display 1
Reference numeral 7 uses, for example, a cathode ray tube display, and the output of the multiplication circuit 15 modulates the brightness of the electron beam.

Pixel scanning is performed on the display 17 by a scanner 18, and each received signal is displayed at a corresponding position. Further, the scanner 18 performs pixel scanning based on the transmitter 19, and this pixel scanning is performed in synchronization with the change in the direction of the directional reception beam by the counter 6 or 13. Note that the transmitter 19 causes the transmitter 20 to transmit ultrasonic pulses at regular intervals. The reflected pulses are then received as ultrasonic pulses Z ₁ to Z ₇ . In addition, in this case, the transmitter 20
can also be used as the ultrasonic transducers _Z1 to _Z7 .

(Effect of the invention) As is clear from the above explanation, the directivity angle of the directional receiving beam can be sharpened without increasing the array length of the ultrasonic transducers, so the structure of the transducer can be made relatively small. A practical device can be obtained.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the invention, FIG. 2 is a waveform diagram for explaining its operation, and FIG. 3 is a diagram for explaining the characteristics of the received beam. Z ₁ to Z ₇ ... Ultrasonic transducer, P ₁ to P ₇ ... Preamplifier, M ₁₁ to M ₁₇ and M ₂₁ to M ₂₇ ... Mixing circuit, 101 to 107, 201 to 207...
...Latch circuit, 3...Addition circuit, 4...Filter, 5...Memory circuit, 6...Counter, 7...
Clock pulse source, 8... Frequency dividing circuit, 9... Latch pulse generation circuit, 10... Addition circuit, 11...
Filter, 12... Memory circuit, 13... Counter, 14... Preset circuit, 15... Multiplication circuit, 16... Amplifier, 17... Display, 18...
Scanner, 19... transmitter, 20... transmitter.

Claims (1)

[Scope of Claims] 1. Arranging the first to nth ultrasonic transducers and synthesizing the reception signals of each ultrasonic transducer to form a directional reception beam in a specific direction, and In a device for sequentially changing the directivity direction of a wave beam, n sets each of which separately mixes each received signal of the first to n-th ultrasonic transducers and a mixed frequency signal guided for each received signal; a first mixing circuit group composed of mixing circuits; a first mixed frequency signal generation circuit that sends out each of the mixed frequency signals used in the first mixing circuit group; and the first mixing circuit group. a first addition circuit that adds together the mixed outputs of each of the above; a first filter that extracts a specific frequency component from the addition output of the first addition circuit; and the first to n-th ultrasonic vibrations. a second mixing circuit group that separately mixes each received signal of the child and a mixed frequency signal that is guided for each received signal and that is different from the mixed frequency signal of the first mixing circuit group; a second mixed frequency signal generation circuit that sends out each of the mixed frequency signals used in the second mixing circuit group; and a second mixed frequency signal generation circuit that adds together the mixed outputs of the second mixing circuit group. an addition circuit; a second filter that extracts a specific frequency component from the addition output of the second addition circuit; and a multiplication circuit that multiplies the extraction signal of the first filter and the extraction signal of the second filter. The first and second mixed frequency signal generation circuits generate the received signals of the first to n-th ultrasonic transducers each mixed frequency so as to form equal phase wavefronts in one direction. The phase of the signal is determined, and each of the first to nth mixed frequency signals is generated such that the phase of the mixed frequency signal changes in conjunction with the direction of the equal phase wavefront, and further,
It is characterized in that the equal phase wavefront formed by the first mixed frequency signal generation circuit and the equal phase wavefront formed by the second mixed frequency signal generation circuit are slightly different. Directional receiving beam forming device.