JPH03974Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is an ultrasonic imaging device that transmits or receives ultrasonic signals using an array type transducer consisting of a large number of elements arranged at equal intervals. The present invention relates to a device for forming a transmitting or receiving beam by giving a common delay time to the signals of one or more elements adjacent to each other.

The delay time τ ₁ that should be given to the signal of each element for the purpose of forming a transmit beam or a receive beam is
The foot of the perpendicular line drawn from the focal point F to the array is 0, the center of the element is E ₁ , 0=f, E ₁ 0=e ₁ , e ₁ /f
= x ₁ and the speed of sound is c, then τ ₁ (x ₁ ) = (T-√1+ ₁ ² ) f/c... (T is a certain constant), and when illustrated for x ₁ , it becomes as shown in Figure 1. . In the conventional method, the delay time according to the formula is given to each element independently as shown in Fig. 2, but in this case, it is necessary to have as many delay mechanisms as the number of elements in the used aperture, and when the used aperture is large, the delay time of the delay mechanism is The disadvantage is that the cost is high.

In order to eliminate this drawback, the present invention aims to save the number of delay mechanisms and reduce the cost of this part while maintaining a good receiving or transmitting beam.

The present invention focuses on the fact that in Fig. 1, the rate of change of τ ₁ with respect to x ₁ is small where |x ₁ | is small, and for elements with small |x ₁ | By providing a delay time as shown in FIG. 3, for example, the number of required delay mechanisms can be saved, and the cost of the entire delay mechanism can be reduced while minimizing deterioration of the transmitting beam or receiving beam. It is something to be measured.

FIG. 4 is a block diagram of a receiving beam forming section in an embodiment of the present invention, which corresponds to the delay time shown in FIG. 3. The received signal from the element near the center of the aperture used is added to the received signals from adjacent elements and then input to one delay mechanism. The outputs of the delay mechanisms D1 to DN are input to an adder A, and a reception beam is formed at the output of the adder.

Figure 5 shows all elements E1~ in the diameter used.
Divide EM into segments consisting of n elements adjacent to each other, and select m elements (1≦
Select mutually adjacent elements with m≦n),
This is an example of inputting to one delay mechanism, and in particular, an example of the element configuration when n=4. The shaded areas in the figure are elements that do not use received signals. By dividing all the elements into segments and controlling them, there is an advantage that the control mechanism when electronically scanning a raster is simplified.

Incidentally, in the present invention, the sensitivity and directivity characteristics of the element group that provides a common delay time vary depending on the number m of elements constituting the element group. That is, when m is large, the sensitivity to the front direction becomes large but the width of the main lobe becomes small, and when m is small, the opposite is true. When the element width is w and the wavelength of the ultrasonic wave used is λ, as an example, in the case of w=λ, m=1, 2, 3,
FIG. 6 shows the main lobe of the sensitivity and directivity of the element group when the number of elements is 4. Since the element groups have such sensitivity and directivity characteristics, the method of the present invention in which the value of m is changed non-monotonically and non-increasing from the center of the array to the periphery is based on the angle at which the focal point F is viewed from each element group. Therefore,
This also has the effect of maximizing the sensitivity of the element group to the focal point F.

Since the optimal value of m depends on the angle at which the focal point F is viewed from the element group, it is desirable to optimally change the value of m for the same element group in the vicinity of the aperture used, depending on the focal length f. Therefore, when implementing the method of the present invention and the dynamic focus reception method at the same time, it is desirable to dynamically change the value of m according to the focal length f. FIG. 7 shows an example of a mechanism for dynamically changing the value of m. The received signals from each element E1-EM are once amplified by variable gain amplifiers A1-AM, electrically coupled within the segment, and input to delay mechanisms D1-DN.

Further, in order to minimize the level of grating caused by dividing the aperture used into segments, the above-mentioned m may be set as follows. In Fig. 8, when the distance between the main lobe and the grating globe is d, and the foot of the perpendicular line drawn from the focal point F to the array is 0, then m= n, that is, all the elements in each segment are set to be electrically coupled, and for the other segments, m is set to 1, that is, they are set to operate as a single element. In this method, for segments where the main rope is viewed at an angle closer to the front than the grating globe, the segment is set in a state with strong directivity, that is, a state where m is large; Based on the idea that a segment viewed at an angle close to the front is set in a state where the directivity of the segment is weak, that is, a state where m is small, FIG. 9 shows the effect of the above method using one embodiment as an example. It is something that When the ultrasonic wavelength used is λ, the element width is w, and the focal length is f, f=333λ, w=
1.07λ, segment width 3w, and working aperture 192w, the reception beam pattern obtained by the above method is curve B0, and the one where m = n = 3 for all segments is curve B3, m for all segments.
The curve B1 is set to =1. Comparing the grating levels, B0 is suppressed to a value 2 dB lower than B1 and 6 dB lower than B3, demonstrating the effectiveness of the above method.

As described above, the present invention saves the number of delay mechanisms while preventing deterioration of the receiving or transmitting beam, compared to the case where independent delay mechanisms are provided for all elements in the aperture used. This is highly effective in that it can significantly reduce costs.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the delay time to be given to the signal of each element, Fig. 2 is a diagram of the delay time given to each element independently, and Fig. 3 is a diagram of the delay time given to each element in the embodiment of the present invention. , FIG. 4 is a configuration diagram of a receiving beam forming section in an embodiment of the present invention, FIG. 5 is an element configuration diagram in the present invention, and FIG. 6 is a diagram showing the main lobe in sensitivity and directivity of the element group. 7 is a diagram of a configuration for dynamically changing the number of elements belonging to one element group, FIG. 8 is an explanatory diagram for explaining the present invention, and FIG. 9 is a diagram showing its effect. It is.

Claims (1)

[Claims for Utility Model Registration] 1. An ultrasonic imaging device that transmits or receives ultrasonic signals using an array type transducer consisting of a large number of elements arranged at equal intervals, which In a device that forms a transmission or reception beam by giving a common delay time to the signals of one or more elements adjacent to each other, a group of elements at the center of the aperture located at the foot of a perpendicular line drawn from the beam focus to the above array is used. A connecting means for commonly connecting the signals of each element group by changing the number of elements such that the element group around the diameter has the maximum number of elements, and the element group at the center of the diameter that is commonly connected. 1. An ultrasonic imaging device comprising: delay means that gives a maximum delay to a signal, and gives a smaller delay to signals from peripheral element groups. 2 Utility Model Registration In the device according to claim 1, all the elements in the aperture used are divided into segments consisting of n elements adjacent to each other, and m elements from each segment are used as the group of elements giving the common delay time. (1≦m≦n)
An ultrasonic imaging device characterized in that elements adjacent to each other are selected to form one element group. 3. Utility model registration In the device according to claim 2, for the k (≧1) element groups centered on the central element group, m is set as m=n, and the other element groups An ultrasonic imaging device characterized in that m=1.