JPS6227825B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic vibration device used in an ultrasonic diagnostic apparatus.

When transmitting an ultrasonic beam using an array of ultrasonic transducers (hereinafter simply referred to as transducers), several transducers are grouped into one group, and these several transducers are arranged with a time difference based on a certain relationship. It is known that by driving, the transmitted ultrasound beam is focused on one point. An image obtained by an ultrasonic diagnostic apparatus using such an ultrasonic beam is clear near its focal point, but unclear in other areas. This is because the ultrasonic beam is focused at the focal point, but the degree of focus of the ultrasonic beam is reduced in other areas.

The present invention aims to provide an ultrasonic diagnostic apparatus having an average depth of focus by a method of transmitting a plurality of ultrasonic beams having different depths of focus within a very short period of time.

FIG. 1 is a diagram showing the principle of focusing ultrasonic waves to one point by electronic operation. In Figure 1, PL
The pulse generator outputs a trigger pulse that causes ultrasonic waves to be transmitted. B ₁ to B ₈ are time delay elements, C ₁ to C ₈
are vibrators uniformly arranged at equal intervals d as shown in FIG. In such a device shown in FIG.
nth oscillator from the center (for example, n=1 is the oscillator
It is known that when the time delay shown in equation (1) is imposed on each transducer for C ₄ and C ₅ ), the ultrasonic waves are focused from the array to the position of focal depth r, as shown in Figure 1. ing.

τ=(n+3)・(4−n)d ² /2・V・r (1) τ: delay time V: sound speed where n・d<<r FIG. 2 is a diagram showing the principle of the present invention. In FIG. 2, C ₁ to _{C 8} are vibrators arranged uniformly at equal intervals as in FIG. 1, and P ₁₁ to _{P 38} are vibrators C _{1 to} C 8 .
A pulse waveform for driving _C8 is shown, and the horizontal axis of this pulse waveform represents the passage of time. _F1
~F ₃ represents the focal point, and the center line l of the oscillators C ₁ ~C ₈
It is located above. In FIG. 2, each transducer transmits one ultrasonic wave per drive pulse. As shown in FIG. 2, the drive pulses P ₁₁ to _{P 18} are determined to have the delay time relationship of the above-mentioned equation (1). Therefore, the driving pulses P ₁₁ to _{P 18}
The ultrasonic beam transmitted from the transducer array is focused at a focal point _F1 , as shown in FIG. Further, drive pulses P ₂₁ to _{P 28} and drive pulses P ₃₁ to _{P 38}
As shown in FIG. 2, they are determined to have the delay time relationship of equation (1) described above. Therefore, the ultrasound beam transmitted by the drive pulses P ₂₁ -P ₂₈ is focused at the focal point F ₂ and the ultrasound beam transmitted by the drive pulses P ₃₁ -P ₃₈
The ultrasound beam is focused at the focal point _F3 . The above drive pulses P ₁₁ to P ₃₈ are generated within a very short time.
In other words, by applying it to the transducers C ₁ to _{C 8} at substantially the same time, it is possible to obtain a highly directional ultrasonic beam having three focal points.

Although the number of focal points is described as three in FIG. 2, this description does not limit the number of focal points to three. Also, in Figure 2,
Although the description has been made assuming that the number of vibrators constituting one group is eight, this description does not limit the number of vibrators constituting one group. Furthermore, in FIG. 2, a group of drive pulses P ₁₁ to P ₁₈ and P ₂₁ to _{P 28} are
When applying P ₃₁ to _{P 38} , the drive pulse applied to oscillators C ₁ and C ₈ is used as the reference time, and this drive pulse
It is shown that this group of driving pulses is applied with a slight time delay to P ₁₁ , P ₂₁ , P ₃₁ , P ₁₈ , P ₂₈ , and P ₃₈ , but as is clear from FIG. It is clear that even if P ₁₁ , P ₂₁ , P ₃₁ , P ₁₈ , P ₂₈ , and P ₃₈ are applied at the same time, an ultrasonic beam having three focal points can be obtained as in FIG. 2.

Furthermore, as mentioned above, in FIG. 2, when applying a group of drive pulses P ₁₁ to _{P 18} , P ₂₁ to _{P 28} , and P ₃₁ to P ₃₈ , the drive pulses applied to the vibrators C ₁ and C ₈ are used as a reference. Although it has been explained that the oscillators are operated as the time, this description does not limit the oscillators used as the reference time to C ₁ and C ₈ . That is, for example the oscillator C ₂
Even if the ultrasonic beam is operated using C7 and _C7 as the reference time, an ultrasonic beam having three focal points can be obtained as in FIG. 2.

FIG. 3 is a block diagram showing one embodiment of the present invention. In FIG. 3, PL outputs a trigger pulse that causes a pulse generator to transmit ultrasonic waves.
B ₁₁ to _{B 38} are time delay elements, which are composed of, for example, delay lines, and have a function of shifting the phase of the applied signal. A ₁ to _{A 8} are adders, D ₁ to _{D 8}
is a drive circuit, and C ₁ to C ₈ are vibrators. The output signal of the pulse generator PL is applied in parallel to each time delay element B ₁₁ -B ₃₈ . Time delay elements B ₁₁ , B ₂₁ , B ₃₁
The output of is connected to the electrode of oscillator C ₁ through a series circuit of adder A ₁ and drive circuit D ₁ , and the output of time delay elements B ₁₂ , B ₂₂ , B ₃₂ is connected to adder A ₂ and drive circuit. D ₂
is connected to the electrode of the vibrator C 2 through a series circuit with the oscillator C ₂ . The other time delay elements are also connected to the electrodes of the vibrator through the series circuit of the adder and the drive circuit in the same manner as described above. The other electrode of the vibrator is connected to circuit ground.

The operation of the ultrasonic vibrator shown in FIG. 3 configured and connected in this way is as follows. pulse generator
A single pulse is generated from the PL and introduced into all time delay elements at the same time. The time delay element is
It is divided into three groups: _B11 to _B18 , _B21 to _B28 , and _B31 to _B38 . The delay time of the time delay elements constituting each group is set to the value shown in equation (1). Therefore, the output signals of time delay elements B ₁₁ to B ₁₈ are:
This corresponds to drive pulses P ₁₁ to P ₁₈ in FIG. Similarly, _the output signals of the time delay elements B ₂₁ to _{B 28} correspond to the drive pulses P ₂₁ to P ₂₈ in FIG.
The output signal of _B38 corresponds to drive pulses _P31 to _P38 . Each drive pulse that has passed through each time delay element is added by each adder. That is, for example, the drive pulse
P ₁₅ , P ₂₅ , and P ₃₅ are configured into a pulse train as shown in FIG. 2, and are applied to the vibrator C ₅ via the drive circuit D ₅ to transmit ultrasonic waves. In this way, an ultrasonic beam having the driving pulse and three focal points shown in FIG. 2 can be easily obtained.

In this way, according to the present invention, since ultrasound is transmitted by combining transmission pulses that are focused at several depths, the resulting ultrasound beam has sharp directivity on average. Therefore, the image projected on the cathode ray tube of the ultrasonic diagnostic apparatus can be a clear image that is entirely in focus, and the effect is extremely large.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle of focusing ultrasonic waves to one point by electronic operation, Fig. 2 is a diagram showing the principle of the present invention, and Fig. 3 is a block diagram showing an embodiment of the present invention. . PL...Pulse generator, _B11 to _B38 ...Time delay element, _A1 to _A8 ...Adder, _D1 to _D8 ...Drive circuit, _C1 to _C8 ...Resonator, _P11 ~P ₃₈ ...Drive pulse.

Claims (1)

[Claims] 1. Ultrasonic vibrations in which ultrasonic waves transmitted from a group of transducers are focused on a certain focal point by creating a delay relationship between signals that excite a group of transducers arranged in an array. The apparatus includes a pulse generator, a plurality of groups of time delay elements having the configuration described below and having different focal positions, and a plurality of adding means A ₁ , A ₂ ,... described below.
By exciting each vibrator C ₁ , C ₂ , etc. with the signal passed through each adding means A ₁ , A ₂ , etc., each time a pulse is output from the pulse generator, An ultrasonic vibration device that transmits ultrasonic waves with multiple focal points. <Group of time delay elements> A group of time delay elements B ₁₁ , B _{12 ,} . . . provided corresponding to each of the oscillators C ₁ , C _{2 , .} . . ,... A group consisting of a plurality of time delay elements with a predetermined delay amount so that when each of the transducers C ₁ , C ₂ ,... is excited by a signal passed through the oscillators C 1 , C 2 ,..., the ultrasonic waves are focused at a certain focal point <adding means> Each time delay element corresponds to the same oscillator C ₅
Adding means A ₅ for adding the output signals of B ₁₅ , B ₂₅ , and B ₃₅