JPS6227600B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic transducer used in an ultrasonic diagnostic apparatus or the like.

The phased array type ultrasonic transducer used in conventional ultrasonic diagnostic equipment has a large number of rectangular transducer elements A ₁ , A ₂ . By arranging them in parallel with each other and sequentially applying a driving voltage to each vibrating element with a predetermined delay time, a composite wave of sound waves from the individual vibrating elements is emitted in a desired direction. The vibrating elements A ₁ , A ₂ , . . . are made of a prismatic piezoelectric material having a width of 0.4 mm and a length of 16 mm, for example, and are arranged at intervals of, for example, 0.1 mm with a common base B made of the same material. Vibration element
On the surfaces of A ₁ , A ₂ , ..., one of the pair of electrodes C ₁ ,
C ₂ , ... are provided, and lead wires D ₁ , ... are provided respectively.
D ₂ , ... are connected. The other of the pair of electrodes is provided on the back surface of the base B as a common electrode E,
A lead wire F is connected to this. Although not shown, a backing material or the like is provided on the lower surface of the electrode E to prevent ultrasonic radiation from being emitted from the lower surface. In this type of phased array type ultrasonic transducer, if a sector drive method is used in which the individual transducer elements are sequentially driven with a predetermined delay time rather than simultaneously, and the ultrasound transmission direction is set in the desired direction, adjacent transducer elements Mutual interference occurs between the two. For example, when a transducer element A ₂ is driven, a portion of the ultrasonic waves emitted in all directions, X ₂ emitted from the side surface of the element, is transmitted to the side surfaces of the adjacent transducer elements A ₁ and A ₃ as shown in Fig. 2. The vibrations Y ₁ and Y ₃ are superimposed on the original vibrations of the vibration elements A ₁ and A ₃ . Therefore, the driving order now is A ₁ ,
If A ₂ and A ₃ are in this order, the end of vibration will be delayed in element A ₁ , and the vibration will start in element A ₃ before the original operation timing, and as a result, the ultrasonic wave emitted from the ultrasonic transducer will A problem arises in that the waveform varies depending on how the delay time is given, in other words, the direction in which the composite wave is transmitted. Although this poses no particular problem when ultrasonic diagnosis is performed using the amplitude and timing of the reflected pulse, it is a problem when the reflected waveform itself is used. The method of analyzing this reflected waveform has the following advantages. In other words, by simply looking at the amplitude and timing of the reflected waves, you cannot target the reflected waves from things other than the target (ultrasonic waves are not as focused as light, so such reflected waves are quite large).
This may cause trouble in analyzing the target because it is treated completely indistinguishably from the reflected wave from an object. However, in the method that uses the waveform of the reflected wave, it is possible that the reflected wave is a reflected wave of the transmitted wave. It can be easily identified, and since the transmitted wave is emitted toward the target by adjusting the delay time described above, it is possible to separate the reflected waves from the target and those from things other than the target.
By extracting only the reflected waves of a desired waveform using a CCD filter or the like, it is possible to obtain advantages such as making the outline of an ultrasound tomographic image clearer, for example.

The present invention aims to reduce the mutual interference of the individual vibrating elements of a phased array type ultrasonic transducer and always obtain the same transmitted waveform regardless of the direction in which the composite wave is transmitted. In an ultrasonic vibrator in which a plurality of vibrating elements each having electrodes provided on two opposing sides of a piezoelectric material are arranged at a predetermined interval in a direction intersecting the longitudinal direction of the vibrating elements, at least one of the electrodes of each vibrating element is arranged. is divided into a plurality of parts in the length direction, and when emitting ultrasonic waves, divided electrode parts of adjacent vibrating elements that do not face each other are driven. The present invention will be explained in detail below with reference to the illustrated embodiments.

FIG. 3 shows an embodiment of the present invention, in which the same parts as in FIG. 1 are given the same reference numerals. This example differs from Fig. 1 in that the individual electrodes of each vibrating element A ₁ , A ₂ .
In this example, each positive side electrode is divided into two parts, and a lead wire is connected to each part. C ₁₁ and C ₁₂ are divided electrode portions obtained by dividing the electrode C ₁ of the vibration element A ₁ , and lead wires D ₁₁ and D ₁₂ are connected to them, respectively. The same applies to the other parts, and one of the divided electrode parts C ₂₁ , C ₃₁ ... of the vibration elements A ₂ , A ₃ ... is connected to the lead wire D ₂₁ ,
D ₃₁ ... is connected to the other divided electrode portion C ₂₂ ,
C ₃₂ ... is connected to lead wires D ₂₂ , D ₃₂ ....
Such a phased array type ultrasonic transducer can be used in linear scan and sector scan methods, but when transmitting these signals, the divided electrode portions on the side that do not face each other between adjacent transducer elements are selectively used. For example, if the electrode part C ₁₂ is driven (voltage is applied) with the vibration element A ₁ , the vibration element
In A ₂ , the electrode part C ₂₁ is driven, and the electrode parts C ₁₁ , C ₂₂
is in a rest state, and in the same manner, only the electrode portions C ₁₂ , C ₂₁ , C ₃₂ , C ₄₁ , C ₅₂ , . . . are driven to perform the required scan. In this way, for example, in the vibrating element _A2 , the portion where vibration occurs due to the drive signal is limited to the lower piezoelectric material of the electrode portion _C21 , and no vibration occurs in the lower piezoelectric material of the other electrode portion _C22 . Therefore, the vibration of the vibration element A ₂ is transmitted from the lower piezoelectric material of the electrode C ₂₁ to the element gap, through the lower piezoelectric material of the electrodes C ₁₁ and C ₃₁ of the elements A ₁ and A ₃ , and from the lower piezoelectric material of the electrode C ₂₂ . The degree of transmission to the voltage portions C ₁₂ and C ₃₂ of the adjacent vibrating elements A ₁ and A ₃ through the piezoelectric material and the gap between the elements is extremely small. It would be even better if grooves were made in the piezoelectric material between the divided electrodes C ₁₁ and C ₁₂ , C ₂₁ and C _{22 .} . . of each element.
In this way, the electrode parts of the vibrating elements A ₁ , A ₂ , A ₃ ...
The waveform of the ultrasonic wave generated by applying a driving voltage to C ₁₂ , C ₂₁ , C ₃₂ , . . . is much freer from inter-element interference than that shown in FIG.

As mentioned above, this ultrasonic transducer has electrode parts selected in a staggered manner to avoid mutual interference during transmission.
Although only C ₁₂ , C ₂₁ , C ₃₂ ... or C ₁₁ , C ₂₂ , C ₃₁ ... are used, the problem of mutual interference can be ignored during reception, so all electrode parts are used to expand the reception area.
C ₁₁ , C ₂₁ , C ₃₁ , ..., C ₁₂ , C ₂₂ , C ₃₂ ... are used. FIG. 4 is a diagram showing a switching circuit for these electrode portions, taking as an example an ultrasonic vibrator having 32 vibrating elements A ₁ to _{A 32} . SW is a switch group having 32 reception-only switches _SR and the same number of transmission/reception switching switches _STR , and each reception-only switch _SR has electrode portions C ₁₁ , C ₂₂ , . . . that are not used during transmission.
C ₃₁₁ , C ₃₂₂ , and each transmission/reception switching switch S _TR has an electrode portion C ₁₂ , which is used for both transmission and reception.
Connected to C ₂₁ , ...C ₃₁₂ , C ₃₂₁ . The common electrode E of the ultrasonic vibrator is grounded, but instead of being a single conductive plate common to all the vibrating elements _A1 to _A32 , it may be separated for each individual vibrating element. . When the common electrode of each vibrating element is provided independently, it is connected to the opposing electrode C ₁ ,
C ₂ ...may be divided in the same way. switch group SW
is the changeover switch control signal from the control circuit CONT
Controlled by SC. As shown in the figure, when switching to the transmitting side T, the drive signal DV passes through the delay circuits TD ₁ , TD ₂ , ... TD ₃₁ , TD ₃₂ and the switch S _TR to the electrode portions C ₁₂ , C ₂₁ , ... C ₃₁₂ , _C321
is applied to In the case of sector scan, the delay amounts of the delay circuits TD ₁ to _{TD 32} are varied by a desired degree (this is changed depending on the scan angle) in the order in which the vibrating elements are arranged. At the time of reception, the switch group SW is switched.
Both S _R and S _TR are switched to the receiving side R, and the outputs of the electrode portions C ₁₁ to C ₃₂₁ and C ₁₂ to _{C 322} are combined. In the case of sector scan, the outputs of the vibrating elements A ₁ to _{A 32} are combined through delay circuits RD ₁ to _{RD 32} , respectively, to produce the final output OUT. This delay circuit RD ₁ ~ _{RD 32}
The amount of delay is commensurate with that of the delay circuits TD ₁ to TD ₃₂ .

FIG. 5 shows another embodiment of the invention. In this example, the drive electrode of each vibration element (represented by A ₁ ) is divided into four parts, and every other divided electrode part C ₁₁ and C ₁₃ is used as the lead wire D ₁₁ , and the remaining electrode parts C ₁₂ and C ₁₄ are used as the lead wire D 11. Connect to lead wire D ₁₂ . And lead wires connected to non-opposing electrode parts between adjacent vibrating elements
D ₁₁ , D ₂₂ , . . . or D ₁₂ , D ₂₁ , . . . are selected and driven. This is similar to FIG. 3 in that all electrode portions are used during reception. In this example, the electrode part C ₁₁
Grooves G are provided by cutting the piezoelectric element between C ₁₂ and C 12 , C ₁₂ and C ₁₃ , and C ₁₃ and C ₁₄ (the same applies to other elements). This groove G reduces the degree to which vibration is transmitted in the arrangement direction of the electrode portions C ₁₁ , C ₁₂ , . . . within the same vibrating element, so as mentioned above, mutual interference between adjacent vibrating elements is further suppressed Ru. still,
When the electrodes of each element are divided into many electrode parts and the divided electrodes of each element are arranged in a matrix shape in the X and Y directions as shown in Fig. 5, each vibrating element A ₁ , A ₂ . . .
In addition to normal sector scanning in which the driving time points of This allows the ultrasonic beam to be focused in the YZ plane more than in normal sector scanning.

As described above, according to the present invention, it is possible to reduce the interference between the vibrating elements constituting the phased array type ultrasonic transducer, so there is an advantage that the same transmitted waveform can be obtained regardless of the direction in which the composite wave is transmitted. be.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a conventional phased array type ultrasonic transducer, FIG. 2 is an illustration of mutual interference between transducer elements, FIG. 3 is a perspective view showing an embodiment of the present invention, and FIG. The figure is a configuration diagram showing the electrode switching circuit, and FIG. 5 is a perspective view showing another embodiment of the present invention. In the figure, A ₁ , A ₂ ... are vibration elements, C ₁₁ , C ₁₂ ...
is a divided electrode portion of one of the pair of electrodes, E is the other electrode, and SW is a group of switches for switching between transmission and reception.

Claims (1)

[Claims] 1. In an ultrasonic vibrator in which a plurality of vibrating elements each having electrodes provided on two opposing surfaces of a piezoelectric material are arranged at a predetermined interval in a direction intersecting the length direction of the vibrating elements, each vibration An ultrasonic transducer characterized in that at least one of the electrodes of the element is divided into a plurality of parts in the length direction, and when emitting ultrasonic waves, the divided electrode parts of adjacent transducer elements that do not face each other are driven. 2. The ultrasonic transducer according to claim 1, wherein a groove is provided in the piezoelectric material between the divided electrodes.