JPH06237930A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To provide satisfactory resolution by forming the image of a focal point inside a reagent by applying electric delay to plural ultrasonic oscillators, dividing the plural ultrasonic oscillators into groups in the case of providing the ultrasonic echo information of the reagent, and applying electric delay for each group. CONSTITUTION:A pulse signal with the prescribed number of vibrations is generated by a pulser 4, and the plural ultrasonic oscillators classified into groups inside an ultrasonic probe 1 are excited through a channel switching part 2. In this case, the channel switching part 2 changes the allocation of ultrasonic oscillators to respective channels so that the diameter of the ultrasonic probe can be changed into a desired size corresponding to the focal distance of ultrasonic waves. Then, a reflected signal reflected on the reagent and received by the probe 1 is inputted through a preamplifier 3 and a delay line 5 to an adder 6, in this case, a signal for each ultrasonic oscillator is added, envelop detection is performed to the added signal by a detection circuit 8, the signal is converted to a TV signal by a DSC 9 later, and the TV signal is displayed on a monitor 11.

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, and more particularly, to an ultrasonic diagnostic apparatus which applies an electrical delay to an ultrasonic transducer to focus on the inside of a subject to obtain ultrasonic echo information.

[0002]

2. Description of the Related Art An electronic scanning method is a typical scanning method in a subject using an ultrasonic diagnostic apparatus. First,
The electronic scanning method will be described, and subsequently, the variable focus and the variable aperture for improving the lateral resolution on the ultrasonic image will be described.

Electronic scanning methods include a linear electronic scanning method and a sector electronic scanning method.

The linear electronic scanning method uses an array type ultrasonic probe having a plurality of ultrasonic transducers and sets a predetermined number of the plurality of ultrasonic transducers as one unit.
The ultrasonic transducer of the unit is excited and the ultrasonic beam is transmitted. For example, the position of the ultrasonic transducer of one unit is electronically shifted by exciting the ultrasonic transducer so that the position of the ultrasonic transducer of one unit changes in sequence while sequentially shifting the pitch by one ultrasonic transducer. Go on. Then, the ultrasonic transducers to be excited shift their excitation timings depending on whether they are located at the central part of the beam or those located laterally so that the ultrasonic beam converges as a beam. The reflected ultrasonic waves are focused (electronically focused) by utilizing the phase difference between the generated acoustic waves of the ultrasonic transducer. Then, ultrasonic waves reflected from the subject are received by the same ultrasonic transducer as the excited ultrasonic transducer and converted into electric signals, and echo information by each transmission / reception is formed as, for example, a tomographic image. Display an image on a tube, etc.

In the sector electronic scanning method, ultrasonic waves are oscillated so that the transmission direction of the ultrasonic beam is sequentially changed into a fan shape for each pulse of the ultrasonic beam with respect to one unit of the ultrasonic transducer group to be excited. The excitation timing of the child is changed according to the desired direction. The electron focusing of the sector electronic scanning method is basically the same as that of the linear electronic scanning method described above.

Next, the variable focus and the variable aperture will be described.

The variable focus is a technique for improving the azimuth resolution by moving the focusing of the ultrasonic beam at the time of reception in a long range from the shallow portion to the deep portion when the above-mentioned electronic focusing is performed.

The variable aperture is a technique for improving the lateral resolution near the ultrasonic probe. When receiving an ultrasonic wave reflected by a reflection pair in the vicinity, the aperture is made smaller toward the vicinity to prevent lateral spread and improve resolution.

As described above, techniques for improving resolution such as variable focus and variable aperture have been devised, but in order to make full use of the above technique, each element must have an independent channel. Is. In the case of a two-dimensional array of ultrasonic transducers, N × L channels are required, where N is the number of elements in the scanning direction and L is the number of elements in the slice direction. In that case, L times as many channels are required. However, there are limits to having many channels due to various constraints, including cost.

A large aperture is required to improve the lateral resolution in the internal area of the subject. When the number of channels is small, the width of one element is inevitably widened. Along with that, side lobes are generated in the vicinity of the main lobe, which causes an artifact.

Further, in the conventional variable aperture and variable focus method, there is a technique of electrically common-joining the centers of the element rows symmetrically. However, in this method, the commonly-joined elements are fixed, so that it is not always optimal. Not necessarily.

[0012]

As described above, the number of channels of the independent delay line of the ultrasonic diagnostic apparatus cannot be too large due to various restrictions. Therefore, when a large aperture is required in the deep part, the element width becomes large, and a grating lobe occurs near the main lobe at a short distance. Causes artifacts.

The present invention has been made based on the above circumstances, and even an ultrasonic diagnostic apparatus having a limited number of channels can obtain a resolution equivalent to that of an ultrasonic diagnostic apparatus having many channels. It is an object of the present invention to provide an ultrasonic diagnostic apparatus capable of performing the above-mentioned operation and changing the aperture according to the focal length.

[0014]

The present invention has taken the following means in order to solve the above problems.

The ultrasonic diagnostic apparatus of the present invention comprises an ultrasonic probe composed of a plurality of ultrasonic transducers, and each ultrasonic transducer of the ultrasonic probe is electrically delayed to focus on the inside of the subject. An ultrasonic diagnostic apparatus configured to obtain ultrasonic echo information of the subject, wherein the plurality of ultrasonic transducers are a predetermined number of ultrasonic transducers corresponding to the focal length in the subject. And a means for driving at least one of the ultrasonic transducers by applying an independent electrical delay to the group.

[0016]

As a result of taking the above-mentioned means, the following effects occur.

The ultrasonic diagnostic apparatus of the present invention has means for classifying a plurality of ultrasonic transducers into a predetermined ultrasonic transducer group according to the focal length in the subject, and at least one of the ultrasonic transducers. Since the ultrasonic transducer group is driven by giving an independent electrical delay, even if the ultrasonic diagnostic apparatus has a limited number of channels, the same resolution as that having many channels can be obtained. It is possible to change the aperture according to the focal length.

Further, since the ultrasonic transducers are classified into predetermined groups and driven independently, the grating lobe is narrowed by narrowing the element spacing of the ultrasonic transducers in short-distance scanning. The effect of is reduced and the resolution is improved. In long-distance scanning, the diameter of the ultrasonic probe can be increased, and it can be equivalent to the case where the elements of the ultrasonic transducer are divided into unequal intervals, so that phase interference is dispersed and the grating lobe is reduced.

[0019]

1 is a schematic block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention.

The ultrasonic diagnostic apparatus of the present invention comprises an ultrasonic probe 1 which is composed of a plurality of ultrasonic transducers and which transmits and receives ultrasonic pulses to and from an object (not shown), and the ultrasonic transducer which operates at the same timing. The details of setting the connection according to the depth of the subject will be described later, a channel switching unit 2, a preamplifier 3 that amplifies an ultrasonic signal received by the ultrasonic probe 1, and an ultrasonic pulse is generated from the ultrasonic probe 1. Pulser 4 for generating an electrical signal for the purpose, a delay line 5 for adjusting the phase of the received ultrasonic signal, an oscillator 6 for generating a reference vibration signal, and a signal for each ultrasonic transducer in the ultrasonic probe 1. , An adder 7 for adding the signal, a detection circuit 8 for detecting the envelope of the added signal, and a digital scan converter 9 (hereinafter, DS) for converting the output of the detection circuit 8 into a TV signal. 9 and called), a D / A converter 10 for converting the output of DSC9 into an analog signal, and a monitor 11 for displaying an ultrasonic diagnostic image.

The operation of the ultrasonic diagnostic apparatus constructed as shown in FIG. 1 will be described below.

First, the pulser 4 generates an electric signal having a pulse width of a predetermined frequency and supplies the electric signal to the channel switching section 2. As will be described later in detail, the assignment of ultrasonic transducers to each channel is changed so that the aperture of the ultrasonic probe changes to a desired size according to the focal length of the ultrasonic wave (hereinafter, referred to as “channel switching”). Is performed by the channel switching unit 2, and each ultrasonic transducer in the ultrasonic probe grouped and classified by the channel switching by the channel switching unit 2 is excited through the channel switching unit 2. By this excitation, an ultrasonic pulse is transmitted to a subject (not shown). The ultrasonic pulse transmitted to the subject is reflected by a reflector in the subject and then received by the ultrasonic probe 1. The received reflected signal is output to the preamplifier 3 as a received signal via the channel switching unit 2 similarly to the transmitted wave.

After the received signal is amplified by the preamplifier 3, the phase of the received signal wave is adjusted by the delay line 5 based on the signal of the oscillator 5, and the adder 7 performs ultrasonic wave adjustment on each ultrasonic wave in the ultrasonic probe 1. The signals for each oscillator are added. Then, the signal output from the adder 7 is envelope-detected by the detection circuit 8 and then output to the DSC 9 as information for obtaining a tomographic image of the subject. The received signal converted into a TV signal by the DSC 9 is converted into an analog signal by the D / A converter 10 and displayed on the monitor 11.

As described above, according to the present invention, the ultrasonic wave vibrators can be freely combined in the channel switching unit 2. Therefore, even if the number of channels is limited, the connection relationship between the ultrasonic transducers and the channels can be changed only by switching the channels, that is, changing the assignment of the ultrasonic transducers to each channel. It becomes possible to control the ultrasonic transducer as in the case of having channels. Further, since the ultrasonic transducers can be classified and excited for each predetermined group according to the focal length, the aperture can be changed according to the focal length. In addition, according to this configuration, it is possible to independently give a delay to each group of ultrasonic transducers classified into each group.

FIG. 2 is a block diagram showing a modification of FIG. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

FIG. 2 shows a configuration example in which the channel switching unit 2 is connected between the preamplifier 3 and the delay line 5. In this case, after the reception signals amplified by the preamplifier 3 are classified into groups by the channel switching unit 2,
It is output to the delay line 5. Also in the configuration in FIG. 2 as described above, like the ultrasonic diagnostic apparatus in FIG.
Even an ultrasonic diagnostic apparatus having a limited number of channels can be handled in the same manner as an ultrasonic diagnostic apparatus having a large number of channels simply by switching channels, and the ultrasonic probe 1 can be set to a desired size. Can be changed to.

A specific example of grouping by the channel switching unit 2 will be described below with reference to FIGS. 3 to 7.

FIG. 3 is a diagram showing a first embodiment in which the grouping of the present invention is applied to a one-dimensional array ultrasonic probe. 3A is a method of exciting an ultrasonic transducer at a short distance, FIG. 3B is a method of exciting an ultrasonic transducer at a medium distance, and FIG. 3C is a method of exciting an ultrasonic transducer at a long distance. Are shown respectively. Further, in FIG. 3, for the sake of convenience, the number of ultrasonic transducers will be _{16 from} 1 ₁ to 1 ₁₆ and the number of input / output channels of the pulser and preamplifier will be 4 from A to D. In fact, if the number of input / output channels of the pulser and preamplifier is N and the total number of ultrasonic transducer elements is n, then n >> N. It is as small as the wavelength of a sound wave. Figure 3
1 is similar to that of FIG. 1, and in FIG. 3, the ultrasonic transducers 1 ₁ to 1 ₁₆ and the channel switching unit 2 in the configuration of FIG.
Only the preamplifier 3 and the pulser 4 are shown.

FIG. 3A shows an excitation method when the focal length is short. In this case, since the focal lengths are close, in order to reduce the aperture, the ultrasonic transducer 1 ₁₀ is used for channel A, the ultrasonic transducer 1 ₉ is used for channel B, and the ultrasonic transducer 1 ₈ is used for channel C. , The ultrasonic transducer ₁₇ is assigned to the channel D, that is, one ultrasonic transducer is assigned to one channel. The ultrasonic transducer ₁ 1 to 1 ₆ and 1 _{11-1 16} are removed from the grouping target. As described above, at a short distance, a small number of ultrasonic transducers for one channel (in this case, one ultrasonic transducer for one channel) is assigned by the channel switching unit 2 so that the diameter can be reduced. So
It is possible to improve the lateral resolution at a short distance.

FIG. 3B shows the excitation method when the focal length is medium. In this case, two ultrasonic transducers 1 ₈ and 1 ₉ are provided for channel A, four ultrasonic transducers 1 ₆ , 1 ₇ , 1 ₁₀ and ₁₁ 1 are provided for channel B, and 2 ultrasonic transducers are provided for channel C.
One ultrasonic transducer 1 ₅ and 1 ₁₂ and two ultrasonic transducers 1 ₄ and 1 ₁₃ are assigned to the channel C. Further, in FIG. 3 (b), the ultrasonic transducer ₁ 1 to 1 ₃ and 1 ₁₄ -
1 ₁₆ is excluded from the grouping target. Figure 3
(C) shows an excitation method when the focal length is a long distance. In this case, channel A has four ultrasonic transducers 1 ₇
To 1 _10, the channel B is six ultrasonic vibrator 1 ₄ to 1
_6, 1 _{11-1 13,} the channel C is four ultrasonic vibrator 1 _2, 1 _3, 1 _14, 1 _15, two ultrasonic transducers ₁ 1, 1 ₁₆ are assigned to the channel C .

As described above, FIG. 3 (a) to FIG. 3 (c)
In the ultrasonic transducers assigned to each channel, channel A is 1 → 2 → 4, channel B is 1 → 4 → 6, channel C is 1 →
It can be seen that the number becomes 2 → 4 and the number of channel D becomes 1 → 2 → 2, and the aperture becomes larger as the focal length becomes longer. In addition, since a desired number of ultrasonic transducers can be assigned to any one channel, the aperture can be freely changed and the element pitches of the ultrasonic transducers are made unequal intervals as described above. It is possible to arrange, for example, Fresnel division. Therefore, according to the present invention, it is possible to obtain an ultrasonic diagnostic apparatus having a desired variable aperture with a small number of channels and having unequal intervals, so that the resolution is improved and
Grating lobes are reduced.

The reason why the grating lobes are reduced by the grouping shown in FIG. 3 will be described below.

The cause of the grating lobe generated by using the ultrasonic transducers arranged at equal intervals is as follows. Grating lobes are generated because when the phase difference between the waves transmitted or received from the adjacent elements of the array-shaped ultrasonic transducer is an integral multiple of the wavelength, the waves strengthen each other and produce a maximum. The conditional expression in this case is shown as d · si
nθ = mλ (d is an element interval, θ is a direction in which a grating lobe is generated, λ is a wavelength, and m is an integer multiple). Here, since sin θ ≦ 1, since θ does not exist when λ / d> 1, the condition for not producing a grating lobe is when the condition of d <λ is satisfied.

Therefore, in the grouping shown in FIG. 3, since the element intervals of the ultrasonic transducers are small at a short distance as shown in FIG. 3A, the influence of the grating lobe is small and the resolution is good. Further, as shown in FIGS. 3 (b) and 3 (c), at the medium distance and the long distance, the aperture can be increased, and the array of the elements of the ultrasonic transducer is equivalent to the case where the elements are divided into unequal intervals. As such, the phase interference is distributed and the grating lobe level is reduced. In the above description, when the array of the elements of the ultrasonic transducer is equidistant, the array of the elements of the ultrasonic transducer is made to appear to be unequal by the grouping. It goes without saying that the present invention is effective for reducing side lobes even when divided into unequal intervals.

FIG. 3 shows an example in which the ultrasonic wave oscillators assigned to the channels are provided one by one by the channel switching unit 2, but an ultrasonic probe in which ultrasonic wave oscillators are connected to each other is used. The present invention can also be applied. FIG. 4 is a diagram showing a second embodiment in which the present invention is applied to an ultrasonic probe in which ultrasonic transducers are connected to each other. Here, FIG. 4 shows a case where the number of channels is 2, and eight ultrasonic transducers are connected as described below to form a group.

[0036] In this case, transducer group 1A is composed of a ultrasonic vibrator 1 ₄ and 1 _5, transducer group 1B
Is composed of ultrasonic transducers 1 ₃ and 1 ₆ , the transducer group 1C is composed of ultrasonic transducers 1 ₂ and 1 ₇ , and the transducer group 1D is composed of ultrasonic transducers 1 ₁ And 1 ₈ .

An example in which the present invention is applied to the ultrasonic transducer configured as described above will be shown with reference to FIG. FIG. 4 shows excitation methods by four types of grouping according to the depth of field. According to FIG. 4, in the case of the first distance (short distance), only the transducer group 1A is assigned to the channel A by the channel switching unit 2 and used. At the second distance, the channel switching unit 2 allocates the transducer group 1A to the channel A and the transducer group 1B to the channel B for use. At the third distance, the channel switching unit 2 allocates the transducer group 1A to the channel A, and the transducer group 1B and the transducer group 1C to the channel B for use. At the fourth distance, the channel switching unit 2 causes the transducer group 1A and the transducer group 1B to move to the channel A.
Then, the transducer group 1C and the transducer group 1D are assigned to the channel B and used.

Therefore, even when the ultrasonic transducers are connected to each other to form a transducer group as shown in FIG. 4, the channel switching section 2 performs grouping on the transducer group. As in FIG. 3, the aperture can be reduced at a short focal length, and can be increased as the focal length becomes longer. Therefore, the resolution is improved and the grating lobe is reduced. In addition, in the example of FIG. 4, only the third distance is shown, but since the element widths of the ultrasonic transducer can be arranged at unequal intervals, it is further effective in reducing the grating lobe and the side lobe.

FIG. 5 shows a case where the number of channels is two and seven ultrasonic transducers are connected to each other so as to form four transducer groups. FIG. 5 shows a case where the ultrasonic transducer is Fresnel-divided in FIG. 4 and one ultrasonic transducer element is coupled to the group A. Further, in FIG. 5, the same parts as those in FIG.

[0040] In FIG. 5, transducer group 1A is composed of a ultrasonic vibrator 1 _4, transducer group 1B is composed of a ultrasonic vibrator 1 ₃ and 1 _5, transducer group 1C Is
The ultrasonic transducers 1 ₂ and 1 ₆ are included, and the transducer group 1D is formed of the ultrasonic transducers 1 ₁ and 1 ₇ .

An example in which the present invention is applied to the ultrasonic transducer configured as described above will be described with reference to FIG. FIG. 5 shows excitation methods by four types of grouping according to the depth of field. According to FIG. 5, in the case of the first distance (short distance), only the transducer group 1A is assigned to the channel A by the channel switching unit 2 and used. At the second distance, the channel switching unit 2 allocates the transducer group 1A to the channel A and the transducer group 1B to the channel B for use. At the third distance, the channel switching unit 2 allocates the transducer group 1A to the channel A, and the transducer group 1B and the transducer group 1C to the channel B for use. At the fourth distance, the channel switching unit 2 causes the transducer group 1A and the transducer group 1B to move to the channel A.
Then, the transducer group 1C and the transducer group 1D are assigned to the channel B and used.

As described above, in the case of the example shown in FIG.
By performing the same grouping as in (1), the aperture is small at a short focal length, and becomes larger as the focal length becomes longer as in the case of FIG. Therefore, as in the case of FIG. 4, the resolution is improved and the grating lobe is reduced. In addition, since the element itself of the ultrasonic transducer is Fresnel-divided, that is, all the ultrasonic transducers except the first distance are Fresnel-divided, the grating lobe is further reduced as compared with FIG. .

FIG. 6 is a diagram showing a third embodiment in which the present invention is applied to an ultrasonic diagnostic apparatus in which elliptical ultrasonic transducers are arranged on concentric circles. The basic configuration of FIG. 6 is the same as that of FIG. 3, and the same parts are denoted by the same reference numerals and the description thereof is omitted. In the case of this embodiment, the ultrasonic transducer is 1 ₁
It is composed of eight elements of the ultrasonic vibrator to 1 _8.

FIG. 6A shows an ultrasonic transducer excitation method at a short distance, FIG. 6B shows an ultrasonic transducer excitation method at a medium distance, and FIG. 6C shows an ultrasonic transducer at a long distance. The excitation methods are shown below.

FIG. 6A shows the excitation method when the focal length is short. In this case, since the near focal length, in order to reduce the diameter, the channel A is the ultrasonic transducer 1 _1, the channel B is ultrasonic vibrator 1 _2, the channel C is the ultrasonic transducer 1 ₃ , the channel D ultrasonic vibrator 1 _4, i.e., one ultrasound transducer for a single channel are allocated. As described above, at a short distance, a small number of ultrasonic transducers for one channel (in this case, one ultrasonic transducer for one channel) is assigned by the channel switching unit 2 so that the diameter can be reduced. Therefore, the lateral resolution at a short distance can be improved.

FIG. 6B shows the excitation method when the focal length is medium. In this case, two ultrasonic transducers 1 ₁ and 1 ₂ are provided for channel A, two ultrasonic transducers 1 ₃ and 1 ₄ are provided for channel B, and one ultrasonic transducer 1 ₅ is provided for channel C. One ultrasonic transducer 1 ₆ is assigned to the channel D. Further, FIG. 3C shows an excitation method when the focal length is a long distance. In this case, channel A has three ultrasonic transducers 1 ₁ to 1 ₃ , channel B has two ultrasonic transducers 1 ₄ and ₁₅ and channel C has 4 ultrasonic transducers.
One ultrasonic transducer 1 ₆ and one ultrasonic transducer 1 ₇ and one ultrasonic transducer 1 ₈ are assigned to the channel C.

As described above, FIG. 6 (a) to FIG. 6 (c)
In the ultrasonic transducers assigned to each channel, channel A is 1 → 2 → 3, channel B is 1 → 2 → 2, channel C is 1 →
2 → 2 and channel D 1 → 1 → 1 and the aperture becomes 4 → 6 as the focal length becomes longer.
→ You can see that it is getting bigger, such as 8. Further, since it is possible to assign the desired number and arrangement of ultrasonic transducers to be assigned to one arbitrary channel, the aperture can be freely changed and the element pitch of the ultrasonic transducers can be changed as described above. It is possible to arrange them at unequal intervals, for example, Fresnel division. Therefore, also in the present embodiment, as in the case of FIG. 3, it is possible to obtain an ultrasonic diagnostic apparatus having a desired variable aperture and unequal intervals with a small number of channels, so that the resolution is improved and , The grating lobe is reduced.

FIG. 7 shows a fourth embodiment in which the present invention is applied to a two-dimensional array ultrasonic probe. The basic configuration of this embodiment is similar to that of FIG. 3, and the ultrasonic transducer of FIG.
Since it is a dimensional array, the same parts are designated by the same reference numerals and the description thereof is omitted. Specifically, the ultrasonic transducer element is divided into n × L (n: scan direction, L: slice direction), a channel switching unit 2, a preamplifier 3, and a pulser 4. Although FIG. 3 shows the grouping excitation method only in the scan direction (n direction) because it is a one-dimensional array, in FIG. 7, this is also applied to the slice direction of the two-dimensional array ultrasonic probe. Therefore, even when the present invention is applied to a two-dimensional array ultrasonic probe, the aperture is reduced at a short focal length, and the aperture is increased as the focal length becomes longer, as in the case of FIG. can do. Therefore, the resolution is improved and the grating lobe is reduced.

FIG. 8 is a diagram for explaining the reason why the side lobes are reduced by grouping the elements of the ultrasonic transducer by applying the present invention.

FIG. 8 shows an error between a stepwise quantization pattern and an ideal delay pattern caused by the existence of the width of the ultrasonic transducer when the element is delayed and focused to be focused. FIG. 8 (a) shows the case of focusing on a long distance, and FIGS. 8 (b) and 8 (c) show the case of focusing on a short distance. 8 (a) and 8 (b) have the same diameter, and the diameter of FIG. 8 (c) is the same as those of FIGS. 8 (a) and 8 (b).
It is smaller than that.

In this case, the error due to quantization in the case of focusing on a long distance as shown in FIG. 8A becomes large as shown in FIG. 8B by focusing on a short distance. For this reason, when the aperture is large, the error due to the quantization increases as the focal point becomes closer. Therefore,
When the focal points are connected at a short distance, the error due to the quantization is reduced by reducing the aperture as shown in FIG. 8 (c). That is, by grouping the elements of the ultrasonic transducer according to the present invention, the diameter is increased as shown in FIG. 8A when focusing at a long distance, and the focusing is performed at a short distance when focusing at a long distance. By reducing the aperture as shown in FIG. 8C, the error due to quantization, that is, the delay error can be reduced, so that the side lobe can be reduced even at a short distance.

The present invention is not limited to the above embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0053]

According to the present invention, the following effects can be obtained.

The ultrasonic diagnostic apparatus of the present invention has a means for classifying a plurality of ultrasonic transducers into a predetermined ultrasonic transducer group according to the focal length in the subject, and at least one of the ultrasonic transducers. Since the ultrasonic transducer group is driven by giving an independent electrical delay, even if the ultrasonic diagnostic apparatus has a limited number of channels, the same resolution as that having many channels can be obtained. It is possible to change the aperture according to the focal length.

Further, since the ultrasonic transducers are classified into predetermined groups and driven independently, the grating lobes can be reduced by narrowing the element spacing of the ultrasonic transducers in the short-distance scanning. The effect of is reduced and the resolution is improved. In long-distance scanning, the diameter of the ultrasonic probe can be increased, and it can be equivalent to the case where the elements of the ultrasonic transducer are divided into unequal intervals, so that phase interference is dispersed and the grating lobe is reduced.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 2 is a schematic block diagram showing a modified example of the ultrasonic diagnostic apparatus of FIG.

FIG. 3 is a diagram showing a first embodiment in which the present invention is applied to a conventional one-dimensional array ultrasonic probe.

FIG. 4 is a diagram showing a second embodiment in which the present invention is applied to an ultrasonic probe in which ultrasonic transducers are connected to each other.

FIG. 5 shows an example in which the ultrasonic transducer is Fresnel-divided in FIG.

FIG. 6 is a diagram showing a third embodiment in which the present invention is applied to a circular ultrasonic transducer arranged concentrically.

FIG. 7 is a diagram showing a fourth embodiment in which the present invention is applied to a two-dimensional array probe.

FIG. 8 is a diagram showing an example in which a delay error is reduced by the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic probe (ultrasonic transducer), 2 ... Channel switching part, 3 ... Preamplifier, 4 ... Pulser, 5 ... Delay line, 6 ... Oscillator, 7 ... Adder, 8 ... Detection circuit, 9 ... Digital scan -Converter (DSC), 10 ... Digital / analog (D / A) converter, 11 ... Monitor.

Claims (1)

[Claims] 1. An ultrasonic probe comprising a plurality of ultrasonic transducers, wherein each ultrasonic transducer of the ultrasonic probe is electrically delayed to focus on the inside of the subject, and the ultrasonic wave of the subject is measured. In an ultrasonic diagnostic apparatus configured to obtain echo information, the plurality of ultrasonic transducers are classified into a plurality of groups including a predetermined number of ultrasonic transducers corresponding to the focal length in the subject. In addition, the ultrasonic diagnostic apparatus is provided with means for applying an independent electrical delay to the group of at least one ultrasonic transducer to drive the ultrasonic transducer.