JPH0346141B2 - - Google Patents

Description

[Detailed description of the invention]

Technical Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus equipped with a split transducer type ultrasonic probe, and performs adjustment by weighting the transmission drive voltage and/or reception amplification gain of a group of elements selected at the same time. The aim is to make the scanning pitch of the acoustic beam less than the arrangement pitch of the elements. Prior Art and Problems In an ultrasonic diagnostic apparatus using a linear array type probe, a group of simultaneously driven elements is sequentially changed to move an ultrasonic beam in parallel as shown in FIG. 1a or b. In the example shown in FIG.
By sequentially changing (alternating) the elements, the focused ultrasonic beam 30 is translated in the direction of the arrow. , . . . indicate the selection order of the element groups, and 30' indicates the first parallel-translated beam.
The image quality can be improved by reducing the beam scanning pitch _P1 , but in this scanning method, the minimum value of the pitch is the division interval (element width or element arrangement pitch) W.
is the limit. Therefore, in order to further improve the image quality, the division interval W must be narrowed, which causes problems such as a decrease in the mechanical strength of the element and difficulty in processing. Also, if the overall width is constant, probe 2
0, the number of lead wires increases as the number of divisions increases, making it difficult to handle the probe. In the example shown in Figure 1b, in Figure 1a, one element is added to the right end and at the same time one right end is removed, and two elements are changed at one time, whereas one element is increased or decreased at one time (for example, one element is added to the right end with respect to (by adding element 6 to , and removing element 1 at the left end of ), the beam 30 is arranged at a pitch P ₂ = half of the element arrangement pitch.
It is designed to move at w/2. In this method, a density twice as high as that in FIG. 1a can be obtained, but even in this case, a scanning pitch of less than w/2 cannot be achieved. Furthermore, since the number of driving elements changes for each scan, there is a drawback that the received temperature and pressure varies from scan line to scan line. Purpose of the Invention The present invention achieves
It is intended to enable scanning at any pitch, which may even be 1/2 or less of the pitch, regardless of the element arrangement pitch. Structure of the Invention The present invention includes an ultrasonic end contact made by arranging a large number of transmitting/receiving transducer elements, and selects and operates a plurality of elements in the array as a group to focus and scan an ultrasonic beam. In an ultrasonic diagnostic device that moves the scanning line by changing the selected element, the desired intensity distribution of the driving or receiving beam and the intensity distribution obtained by moving the distribution by an arbitrary pitch equal to or smaller than the element arrangement pitch are used. A storage means for storing weighting values to be given to each selection element in order to achieve this, and a storage means for reading the storage means at each transmission of an ultrasound beam, and weighting the transmission drive voltage and reception amplification gain of each element using the read values. This will be described in detail below with reference to the illustrated embodiments. Embodiment of the Invention FIG. 2 is an explanatory diagram showing an embodiment of the present invention, in which a solid line curve 41 is the ideal intensity distribution of the driving or receiving beam, and in order to realize it, each element 1 to
7 is given a weighting indicated by a solid line bar graph 42.
It is clear that in this way the transmitted or received ultrasound beams 30 will have the same distribution centered on the element 4 as shown. Next, dashed curve 4
When the distribution is changed to that shown by 3, the center of the ultrasonic beam 30' moves to the center of gravity of the distribution between elements 4 and 5. This amount of movement can be set at any position between elements 4 and 5 based on the value set by curve 43. The table below shows an example of weighting in which pitch P ₃ is set to w/3.

[Table] A simple way to obtain such a table is to first determine the shape of the curve 41 in FIG. It is about reading. bar graph 4
Each value of 2 is an index of the transmission drive voltage or reception amplification gain of each element in the part covered by the curve 41 of the probe (aperture surface), but in order to operate the elements at a value proportional to these, read-only values are required. It is preferable to store each value in a memory (ROM), read it out, and input it as a coefficient to the drive and amplification circuit for the in-aperture element group. If the weighting distribution curves 41 and 43 are Gaussian distribution, COS distribution, COS ² distribution, etc., the beam shape will be improved, but this is not necessarily the case. The point is that if the distribution is not uniform, the beam center can be moved to any position without the restriction of the element width w. Furthermore, the number of elements to be selected at once is not limited to the above example. FIG. 3 shows an example of application to a fan-shaped scanning probe in which the element array is curved in an arcuate manner, where 21 is a front chamber filled with an ultrasonic transmission medium, and 22 is an object to be measured. In the example of a, the ultrasonic propagation velocity v ₁ of the front chamber medium is the measured object 22.
This is the case when it is almost equal to that of v ₂ . At this time, the beam 30 scans the inside of the object to be measured 22 in a fan shape through approximately the center 23 of the curvature of the probe 20. Therefore, it is effective when observing the heart through the gap between the ribs. In the example b, the beam 30 is refracted so that v ₁ <v ₂ (θ ₂ >θ ₁ ), and the probe is made smaller in both the width of the element array and the depth of the front chamber. In this case, even if the element spacing of the probe 20 is uniform and the scanning pitch of the ultrasonic beam in the front chamber is uniform, the scanning pitch within the object to be measured 22 becomes coarser toward the periphery. The density of this scanning pitch can also be corrected. That is, the weighting etc. may be changed so that the scanning pitch in the peripheral area is denser than that in the central area. FIG. 4 shows a probe in which arc-shaped probes 20 and 20' are disposed in an intersecting manner so that two cross sections can be observed simultaneously, and the present invention can be applied to this probe. The present invention can also be applied to a two-dimensional scanning plane array type probe in which the probe 20 is divided into a matrix as shown in FIG. In this case, the weighting becomes a three-dimensional mountain shape. In this case, the number of divisions can be reduced by applying the driving method of the present invention to obtain the same scanning pitch. For example, if the number of divisions is reduced to 1/2 in both the vertical and horizontal directions, the total number of divisions will be reduced to 1/4, and the manufacturing cost will be reduced. There are advantages such as improved scanning performance due to reduced number of lead wires. FIG. 6 shows a configuration example of a weighted drive and reception circuit for the vibrator 20. A signal from the timing generation circuit 50 is guided to a drive waveform generation circuit 51, where a drive waveform is generated. This drive waveform is, for example, an impulse or one to three sine waves depending on the resonant frequency of the vibrator 20. The weighting data as shown in Table 1 above is stored in the memory (ROM) 52 as a digital value. This memory 5
The weighting data read out from RA 2 is converted into an analog value by a D/A converter 53, and is used by a gain controller 54 to adjust the gains of a receiving amplifier (RA) 55 and a driving amplifier (DA) 56. These amplifiers 55 and 56 are provided as many as the number of divided elements of the vibrator 20, respectively. 57 is a limiter that prevents excessive voltage from being input to the receiving amplifier 55 during driving; 58 is an adder that combines all the outputs of the receiving amplifier 55; 59 is a rectifier circuit that rectifies the output; 60
is a cathode ray tube (CRT). When transmitting ultrasonic waves, some of the multiple elements in the probe 20 are simultaneously selected, the selected elements are sequentially changed, and the driving voltage of each element in the selected elements is changed according to the distribution curve. These controls can be performed only by controlling the gain of the amplifier. That is, the gain of the amplifier of the non-selected element may be set to 0, and the gain of the amplifier of the selected element may be set to a value that follows the distribution curve. In this way, parallel scanning, fan scanning, etc. are performed using the ultrasonic beam as a scanning line, and the reflected waves are received by the same (although not necessarily the same) probe 20, weighted and amplified by the amplifier 55, added, After rectification, it will be displayed on CRT60. Effects of the Invention As described above, according to the present invention, a fine scanning pitch smaller than the division interval of the vibrator can be obtained.
There is no need to divide the vibrator into smaller pieces. This not only simplifies the manufacture of the vibrator and greatly improves the cost, but also has the advantage of reducing the number of lead wires and improving operability.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a conventional linear array type ultrasonic probe, Fig. 2 is an explanatory diagram of main parts showing an embodiment of the present invention, and Figs. 3 to 5 are various diagrams to which the present invention can be applied. FIG. 6 is an explanatory diagram of the probe, and FIG. 6 is a configuration diagram of the weighting drive and reception circuit of the transducer according to the present invention. In the figure, 1 to 10 are transmitting and receiving transducer elements;
20 is a probe, 30 and 30' are ultrasound beams, 4
1,43 is a distribution curve.

Claims (1)

[Claims] 1. An ultrasonic probe having a large number of transmitting/receiving transducer elements arranged, and selecting and operating the plurality of elements in the arrangement as one group to focus and scan an ultrasonic beam. In an ultrasonic diagnostic device that moves the scanning line by changing the selected element, the desired intensity distribution of the driving or receiving beam and the intensity distribution obtained by moving the distribution by an arbitrary pitch equal to or smaller than the element arrangement pitch are used. Storage means 52 for storing weighting values given to each selection element for realization
and means 53, 5 for reading the storage means each time an ultrasonic beam is transmitted, and weighting the transmission drive voltage and reception amplification gain of each element based on the read values.
4, 55, and 56. 2 A large number of transmitting and receiving transducer elements are linear,
The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus is arranged in an arc shape, a spherical shape, or a planar shape.