JPH05200028A - Ultrasonic diagnosing device - Google Patents

Abstract

PURPOSE:To provide an ultrasonic diagnosing device giving an ultrasonic tomographic image in which a delay time is quantized and the quantizing width is varied in a position of a group of receiving piezoelectric transducers to reduce circuit elements and prevent the ultrasonic image from degrading the quality. CONSTITUTION:A delay time setting circuit has a delay line 20 and input/output circuit 22. The delay line 20 is provided with 48 output taps 20-1-20-48 and the input/output circuit 22 provided in 4X8 with 48 matrix circuits 22-101-22-806. A delay time curve is quantized to approximate a quantization delay time curve 112 by setting such delay line 20. Then, the quantization delay time curve 112a on both ends of a group of vibrators having a small absolute valve of the delay time is equalized to the prior quantization delay time curve. On the other hand, the quantization delay time curve 112b in the central part is different from the prior one, while the quality of the tomographic image is not remarkably degraded since the influence of both ends of the receiving vibration group on the bundle of ultrasonic wave beams is large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus which transmits and receives ultrasonic waves to and from a subject and obtains an ultrasonic tomographic image based on the received reflected waves, and more particularly, an ultrasonic diagnostic apparatus of electronic focus control. Regarding

[0002]

2. Description of the Related Art Conventionally, in an ultrasonic diagnostic apparatus which obtains a tomographic image by transmitting and receiving ultrasonic waves by an ultrasonic probe having a plurality of transducers, one ultrasonic beam is transmitted from a plurality of transducers. Be focused on.

Explaining with reference to FIG. 3, the transducer array 10 arranged linearly has 32 transducers 10-1 to 10-32. When focusing the ultrasonic beam on the point F0 at a distance S0 from the transducer array 10, the transducers 10 near the center are
A path difference occurs between the distance S0 from -16, 10-17 to the point F0 and the distance S1 from the end vibrators 10-1, 10-32 to the point F0. By setting the difference in the arrival time of the ultrasonic waves caused by this path difference S1 -S0 as the delay time (td) of the transmission timing of the ultrasonic pulse of each transducer in advance, the phase of the ultrasonic pulse is uniform at the point F0. Are tied together. As shown in FIG. 4, the transmission timing of ultrasonic waves of the vibrator near the center is delayed with respect to the vibrator at the end portion where the distance to the focus (F0) is long, and the focus (F0 By delaying the transmission timing in accordance with the distance up to), when the ultrasonic pulse reaches the point F0, the point where the phases are aligned can be focused on the point F0. A curve showing the amount of delay time to be given to each transducer is the delay time curve 100 shown in FIG.

Further, in reception, there is a time difference in the time required for the reflected wave from the point F0 to reach each transducer. The delay time setting circuit 11 shown in FIG. 5 is provided to correct this time difference and align the phases. A curve 101 showing the delay time at this time is a delay time curve at the time of reception.

The setting of the delay time as described above is performed by, for example, the delay time setting circuit shown in FIG. The delay time setting circuit is composed of a delay line 30 and an input / output circuit 32, and the delay line 30 has a group of 80 output taps (3
0-1, 30-2, ..., 30-80) and 4 I / O circuits
It is composed of 80 × 8 matrix circuits.

Each delay line 30 has two output taps.
The delay time of 0 nsec (nanosecond) is output. In FIG. 6, the output tap 30-1 is 20 ns, and the output tap 30-2 is
, 40 ns, ..., The output tap 30-80 has a delay time of 1600 ns. That is, the quantization width in this case is 20 nsec, and the delay time curve 10 shown in FIG.
1 is quantized with this quantization width and approximated (11
1). This delay time setting circuit sets a delay time for each transducer as shown in FIG. 7 to focus the ultrasonic pulse.

[0007]

As described above, the delay time setting circuit includes the delay line 3 having 80 output terminals.
Although it has 0 and 80 matrix circuits, the delay time of each transducer in the central portion of the transducer group for reception is not much different from that of the adjacent transducer. Therefore, it is not necessary to reduce the quantization width near the center of the receiving transducer group. On the contrary, in order to reproduce the delay time curve 101 at both ends of the transducer group for reception, it is necessary to finely quantize because the difference in delay time given to each adjacent transducer is large.

That is, the quantization width required to reproduce one delay curve is different at both ends and the central portion of the receiving transducer group, and if the quantization width is set to be small, the receiving transducer group's There is a problem that the quantization width becomes unnecessarily small in the central portion, and if the quantization width is set large, the reproducibility of the delay curve is poor at both ends of the transducer group for reception.

Further, when the quantization width is reduced, there is a problem that the number of delay line output taps increases and the number of matrix circuits increases.

The present invention has been made to solve the above problems, and an object thereof is to obtain an ultrasonic diagnostic apparatus capable of reducing the number of circuit elements without degrading the image quality.

[0011]

In the ultrasonic diagnostic apparatus according to the present invention, the delay time of the ultrasonic pulse is quantized,
In addition, when quantizing, different quantizing widths are set according to the parts of the transducer group for reception.

[0012]

The circuit element corresponding to the probe can be reduced by setting a large quantization width in the portion where the slope of the delay time curve which differs depending on the portion of the probe is small.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a delay time setting circuit of the ultrasonic probe of this embodiment. Delay time setting circuit is delay line 2
0 and an input / output circuit 22, and the delay line 20 includes 48 output taps 20-1, 20-2, ..., 20-48,
The input / output circuit 22 is a 4 × 8 matrix circuit 22-101,
, 22-806, 48 matrix circuits are provided.
From the characteristics of the delay time shown in FIG. 2, it can be seen that the area where the absolute value of the delay time is large, that is, the delay time given to the transducer near the center of the transducer group for reception does not change significantly between the adjacent transducers. In other words, the change rate of the delay time curve 101 in the transducer array direction (the slope of the delay time curve) is small in this region. Therefore, the delay time curve can be quantized almost in the same manner as in the prior art, even if the quantization width is set to 40 ns by thinning out the tap with the long delay time in the output tap group of the delay line 30 shown in the prior art. In the embodiment, the output taps 20-1 to 20-16
Output taps 20-17 to 20-4 at 20nsec intervals
The delay time is set up to 8 every 40 ns. Specifically, 20-1 is 20 ns, 20-2 is 40 ns, ..., 20
-16 is set to 320 seconds, 20-17 is 360n seconds, 2
0-18 is set to 400 nsec, and 20-48 is set to 1600 nsec.

By setting such a delay line, the delay time curve 101 is approximated to the quantized delay time curve 112 by quantization. At this time, the quantized delay time curve 112 at both ends of the transducer group for reception whose absolute value of delay time is small
a becomes equal to the above-mentioned quantization delay time curve 111. On the other hand, the quantization delay time curve 11 at the center of the transducer group for reception
2b is different from the quantization delay time curve 111 described above,
Since the influence of both ends of the transducer group on reception is large with respect to the focusing of the ultrasonic beam, the image quality of the tomographic image is not significantly deteriorated.

By setting the delay time as described above, the number of matrix circuit elements is set to 80 of that of the conventional delay circuit.
It is possible to reduce the number to 48 compared to the number.

In this embodiment, the minimum delay time of reception is always corrected to the minimum time tap of the delay line. At this time, in order to make the display start position of the image constant, the sum of the maximum delay times of transmission and reception must always be constant, so the minimum time tap for reception is used. The correction delay time is distributed to the transmission delay time. Since the transmission start time only counts a certain period of time, it is easy to increase the maximum transmission delay time.

By thus dividing the delay time at the time of transmission and at the time of reception, the minimum delay time can always be set to the minimum output tap of the delay line, which improves the reproducibility of the delay time curve, and thus the quantization It is possible to prevent the error due to the error from increasing.

In this embodiment, the delay lines are thinned out by one and the quantization width is 20 nsec.
Although it was set with two types of 0 ns, the quantization width was 20 ns,
It is also possible to set three types of 40 ns and 60 ns. For example, output taps 20-1 to 20-24 are 20
Output taps 20-25 to 4 are 4 at n-second intervals.
It is also possible to set the output taps 20-41 to 20-48 at 60 ns intervals at 0 ns intervals.

Further, the case where the number of output taps is 48 is shown, but the number is not limited to this.

[0021]

As described above, since the output taps of the reception delay line are thinned out and used, it becomes possible to reduce the number of circuit elements and the end portion of the reception transducer group which greatly affects the focusing of the ultrasonic beam. Since the quantization width of is set as in the conventional case, the image quality of the ultrasonic tomographic image is not deteriorated.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a delay time setting circuit of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 2 is a diagram showing a quantized delay time curve according to the present invention.

FIG. 3 is a diagram showing a method of focusing an ultrasonic probe including a plurality of ultrasonic transducers.

FIG. 4 is an explanatory diagram of a delay time set at the time of transmission.

FIG. 5 is an explanatory diagram of a delay time set at the time of reception.

FIG. 6 is a configuration diagram of a conventional delay time setting circuit.

FIG. 7 is a diagram showing a conventional quantized delay time curve.

[Explanation of symbols]

 10 Transducer array 11 Delay line (function) 20 Delay line (element) 22 Input / output circuit

Claims (1)

[Claims] 1. An ultrasonic wave pulse is transmitted by a probe composed of a plurality of transducers, the ultrasonic wave pulse reflected from a subject is received, and further, a received signal is obtained for each of the plurality of transducers. In an ultrasonic diagnostic apparatus that sets a predetermined delay time amount and focuses an ultrasonic pulse to obtain an ultrasonic tomographic image, the delay time is quantized, and the quantization width differs depending on the part of the transducer group for reception. An ultrasonic diagnostic apparatus characterized by the above.