JP2600136B2 - Ultrasound diagnostic equipment - Google Patents

Description

The present invention relates to an ultrasonic diagnostic apparatus for transmitting and receiving ultrasonic waves.

(B) Conventional technology and its problems The ultrasonic probe included in the conventional ultrasonic diagnostic apparatus is provided with an acoustic lens and a matching layer on the ultrasonic wave transmitting / receiving surface side of the vibrator. In some cases, a back layer is provided on the side facing the wavefront.

The back layer is conventionally formed by mixing tungsten or fate powder into an epoxy-based or rubber-based resin, and suppresses the ringing of the ultrasonic waves radiated from the vibrator to absorb unnecessary waveforms. This is to impart a damper effect in the vibration system. Therefore, when focusing on the role of this back layer, when transmitting ultrasonic waves, it exerts a sufficient damper effect to suppress ringing, and then reduces the damper effect when receiving ultrasonic waves. It is most desirable that the gain of the ultrasonic wave does not deteriorate.

However, the characteristics of the conventional back layer are fixed once the mixing ratio is set and attached to the vibrator, and it is impossible to change the characteristics according to the transmission and reception of ultrasonic waves. . Therefore, even if the mixing ratio of the resin and powder constituting the back layer is appropriately set,
There was naturally a limit in obtaining high resolution and high gain.

The present invention has been made in view of such circumstances, and enables to appropriately change the characteristics of the back layer according to the transmission and reception of ultrasonic waves, to effectively suppress the occurrence of ringing,
It is an object of the present invention to provide an ultrasonic diagnostic apparatus with higher performance than before.

(C) Means for Solving the Problems In order to achieve the above object, the present invention has an ultrasonic probe, and the ultrasonic probe is an ultrasonic probe that generates ultrasonic waves. An ultrasonic diagnostic apparatus having a back layer on a back side facing a wave transmitting / receiving surface, wherein the back layer includes a piezoelectric composite formed by filling a resin between columnar piezoelectric elements arranged vertically and horizontally. An electrode is formed on at least one side of the opposing surface of the piezoelectric composite.
A voltage is applied through the electrode substantially in synchronization with the ultrasonic wave transmission timing.

(D) Function When transmitting ultrasonic waves, a voltage is applied to the vibrator.
At that time, a voltage is also applied to the piezoelectric composite. Then, the piezoelectric composite acts as a mass load on the vibrator that emits ultrasonic waves, and ringing is suppressed.

When receiving ultrasonic waves, if the piezoelectric composite is left to free vibration without applying any voltage, the damper effect will be reduced as compared to when transmitting ultrasonic waves, so even weak ultrasonic echoes can be detected efficiently. You can do it.

(E) Embodiment FIG. 1 is a perspective view of a main part of a linear electronic scanning type ultrasonic diagnostic apparatus according to an embodiment of the present invention.

The ultrasonic diagnostic apparatus according to this embodiment includes a piezoelectric vibrator (hereinafter, referred to as a piezoelectric vibrator).
An ultrasonic probe 1 having a vibrator 2 is provided. The vibrator 2 has electrodes 6a and 6b formed on opposing surfaces of the respective piezoelectric substrates 4 cut at a predetermined pitch. One of the electrodes 6a serves as an ultrasonic wave transmitting / receiving surface. A first matching layer 8 and a second matching layer 10 for acoustic impedance matching are sequentially laminated thereon, and an acoustic lens 12 is further provided on the second matching layer 10.

On the other hand, a back layer 14 is attached to the other electrode 6b of the vibrator 2. As shown in FIG. 2 and FIG. 3, the back layer 14 has columnar piezoelectric elements 16 made of PZT or the like arranged vertically and horizontally, and the space between these piezoelectric elements 16 is filled with an epoxy resin 18. The piezoelectric composite 20 includes The piezoelectric composite 20 is joined to the electrode 6b of the vibrator 2 so that the column axis direction of each piezoelectric element 16 matches the vibration direction of the vibrator 2, and the electrode 24 is Are formed. The mixing ratio between the piezoelectric element 16 and the resin 18 constituting the piezoelectric composite 20 is appropriately selected in consideration of the damper effect within a range of 20 to 80% with good electromechanical coupling efficiency.

Therefore, when transmitting the ultrasonic wave, as shown in FIG. 4, the driving voltage Es of the burst wave is applied between the electrodes 6a and 6b of the vibrator 2.
Is applied, the electrodes 6 sandwiching the piezoelectric composite 20 of the back layer 14
The voltage Ed is also applied between b and 24. In this case, the voltage Ed applied to the piezoelectric composite 20 is given with a slight gradient change with respect to the output period of the drive voltage Es applied to the vibrator 2, and is then set to zero potential. By doing so, the piezoelectric composite 20 acts as a mass load on the vibrator 2 and the ringing is suppressed within a short time as compared with the case where no voltage is applied to the piezoelectric composite 20 (see FIG. 5). Is done.

On the other hand, at the time of receiving ultrasonic waves, if any voltage is not applied to the piezoelectric composite 20 and the vibration is left to free vibration, the damper effect is reduced as compared with the time of transmitting ultrasonic waves, so that the gain is not reduced. A weak ultrasonic echo can be detected efficiently.

In this embodiment, the linear electronic operation type ultrasonic diagnostic apparatus has been described.However, the present invention is not limited to this, and includes a sector type or other ultrasonic probe having a back layer. It goes without saying that any ultrasonic diagnostic apparatus can be widely applied.

(F) Effect As described above, according to the present invention, it is possible to effectively control the occurrence of ringing at the time of transmitting an ultrasonic wave while reducing the damper effect at the time of receiving an ultrasonic wave. As a result, high resolution and high gain can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a linear electronic scanning type ultrasonic diagnostic apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view showing an arrangement state of piezoelectric elements constituting a piezoelectric composite, and FIG. FIGS. 4 and 5 are plan views of the piezoelectric composite, and FIGS. 4 and 5 are waveform diagrams showing the voltage applied to the vibrator and the piezoelectric composite and the state of ultrasonic waves generated by the voltage. 1 ... ultrasonic probe, 2 ... transducer, 14 ... back layer, 16
…… Piezoelectric element, 18 …… Resin, 20 …… Piezoelectric composite.

Claims (1)

(57) [Claims] 1. An ultrasonic diagnostic apparatus having an ultrasonic probe, wherein the ultrasonic probe has a back surface layer on a back surface opposite to an ultrasonic wave receiving surface of a transducer for generating ultrasonic waves. The back layer includes a piezoelectric composite formed by filling a resin between columnar piezoelectric elements arranged vertically and horizontally, and an electrode is formed on at least one side of a facing surface of the piezoelectric composite. An ultrasonic diagnostic apparatus characterized in that a voltage is applied to the piezoelectric composite through the electrodes substantially in synchronization with ultrasonic transmission timing.