JPH05281210A - Ultrasonic device - Google Patents

Abstract

(57) [Abstract] [Purpose] A small number of signal lines enable both direction control and high range resolution at the same time. [Structure] Weighting is performed in the arrangement direction of the transducers and the time axis direction of the drive signal. [Effect] With a small number of signal lines, a high azimuth resolution is achieved while improving the distance resolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring or observing an object with ultrasonic waves.

[0002]

2. Description of the Related Art As such a device, the Journal of the Acoustical Society of Japan, Vol. 31, No. 12, pp. The devices described in 716-724 (1975) are known.

[0003]

According to the conventional configuration,
Although it is possible to control the target direction with a single signal line, there is a problem in the resolution in the distance and the azimuth direction.

It is an object of the present invention to simultaneously realize direction control and high azimuth and range resolution with a small number of signal lines.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to weight a signal amplitude with respect to a time axis of a drive signal or an arrangement direction of an element array in an ultrasonic transducer in which a transmission or reception direction changes depending on a signal waveform. It is achieved by doing.

[0006]

The configuration shown in FIG. 1 is an example of a transmitter in which the transmission direction of ultrasonic waves changes depending on the signal frequency. In this configuration, since the polarization axes of the piezoelectric elements are sequentially inverted and arranged, the signal of wavelength λ advances in the direction of the arrow, and this direction changes depending on the wavelength. From this transmitter, ultrasonic waves are transmitted in the target direction and reflected signals are received as shown in FIG. However, when transmitting by this method, as can be understood from FIG. 1, the wavefront of the transmitted ultrasonic wave initially has only the signal from the element 1 as shown in FIG. 3 with respect to time. Then, a wavefront is formed by a large number of elements 1 and 2 and then elements 1, 2 and 3 successively. Therefore, as shown in FIG. 4, the spatial expansion of the wavefront at each time is initially a wide directivity due to a single element, then gradually narrows and widens again, and ends. Therefore, if the point reflector O is imaged with the configuration of FIG.
Is displayed and the resolution is reduced.

Therefore, as shown in FIG. 6, by weighting the transmission signals in correspondence with the arrangement direction, the portions indicated by 1 and 2 are suppressed and the resolution is improved as shown in FIG. Similarly, as shown in FIG. 8, even if the drive signals are weighted in the time-axis direction, the portions 1 and 2 are suppressed, and similarly, FIG. 7 is obtained. When both FIG. 6 and FIG. 8 are applied at the same time, the peripheral portion is greatly suppressed with respect to the central portion as shown by 3 and 4 in FIG. 9, so that the display image shows high resolution as shown in FIG. Become. Usually, the optimum filtering process is performed to improve the signal-to-noise ratio, but in the case of such a device in which the signal waveform differs depending on the direction, the optimum process corresponding to each direction is required.

[0008]

FIG. 11 shows the structure of a transmitter / receiver according to the present invention. Here, 5 is a sound absorbing material and suppresses the contribution of the peripheral portion. Further, 6 is a vibrating element having a different area in the arrangement direction, and similar weighting is performed. FIG. 12 shows the overall configuration of the device. 7 is the transmitter / receiver of FIG. 11, 8 is a generator of weighted drive signals, 9 is a signal processing unit for reception,
The optimum filtering process and the imaging process are performed and displayed on the display unit 10. Correlation processing is one configuration of this optimum filtering processing.

[0009]

According to the present invention, it is possible to transmit and receive ultrasonic waves whose directions change electronically while maintaining high distance resolution.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a wave transmitter in which a transmission direction of ultrasonic waves changes depending on a signal frequency.

FIG. 2 is an explanatory diagram of a transmission / reception wave configuration example.

FIG. 3 is an explanatory diagram of a transmission signal time.

FIG. 4 is an explanatory diagram of a spatial distribution of a transmission signal.

FIG. 5 is an explanatory diagram of an example of a point reflector image.

FIG. 6 is an explanatory diagram of an array direction weighting operation.

FIG. 7 is an explanatory diagram of an example of a point reflector image by weighting.

FIG. 8 is an explanatory diagram of time-direction weighting operation.

FIG. 9 is an explanatory diagram of a bidirectional weighting operation.

FIG. 10 is an explanatory diagram of an example of a point reflector image by weighting in both directions.

FIG. 11 is an explanatory diagram of a configuration example of a weighted transceiver.

FIG. 12 is an explanatory diagram of one embodiment of the overall configuration.

[Explanation of symbols]

1, 2 ... One-sided weight end signal, 3, 4 ... Two-sided weight end signal, 5 ... Sound absorbing material, 6 ... Unequal area vibration element, 7 ... Transducer, 8 ... Signal source, 9 ... Reception processing Section, 10 ... Display section, T1
-T4 ... Vibration element number.

Front Page Continuation (72) Inventor Chitose Nakatani 1-280 Higashi Koigokubo, Kokubunji City, Tokyo Inside Central Research Laboratory, Hitachi, Ltd.

Claims (6)

[Claims] 1. An ultrasonic wave transmitter / receiver in which a transmitting or receiving direction changes depending on a signal waveform, wherein signal amplitudes are weighted with respect to a time axis of a drive signal or an arrangement direction of element arrangements. 2. The ultrasonic device according to claim 1, wherein the ultrasonic wave transmitter / receiver whose transmission or reception direction changes according to the signal waveform is realized by an inverted polarization array. 3. The ultrasonic device according to claim 1, wherein the amplitude weighting in the arrangement direction is made of a sound absorbing material. 4. The ultrasonic device according to claim 1, wherein the amplitude weighting in the array direction is based on an array element area. 5. An ultrasonic device, wherein an ultrasonic wave transmitter / receiver whose transmission or reception direction changes depending on a signal waveform, performs an optimum filtering process on each reception signal waveform corresponding to a signal arrival direction. 6. The ultrasonic device according to claim 5, wherein the optimum filtering process is a correlation process.