JPH04193268A - Retardation time generating apparatus for ultrasonic diagnosis apparatus - Google Patents

Abstract

PURPOSE:To make it possible to perform generation of retardation time by performing a specified unit recovery operation on a normalized retardation time T obtd. by a normalized retardation time table. CONSTITUTION:A unit recovery operation part 28 performs multiplication of a normalized retardation time T by f/C and addition of a specified const. K to the result of multiplication. The unit recovery operation part 28 is constituted of an f/C generator 40, a K generator 42, a multiplicator 44 multiplicating a retardation time T output from an interpolation treating part 26 by a value output from the f/C generator 40 and an adder 45 adding a const. K output from the K generator 42 and being different depending on the kind of a probe to the output of the multiplicator 44. Therefore, by performing this operation, a retardation time is successively output.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a delay time generator for an ultrasonic diagnostic apparatus that provides a delay time to the transmitted and received signals of each vibrating element constituting an array transducer.

[Background Art] In the medical field, ultrasonic diagnostic apparatuses that use ultrasonic waves to obtain tomographic images of in-vivo images are utilized.

In this ultrasonic diagnostic apparatus, ultrasonic waves are transmitted and received using an array transducer within the membrane. By giving different delay times to the transmitted and received signals of each of the plurality of transducer elements constituting the array transducer,
Electronic deflection and electronic focusing of the ultrasound beam are performed. For example, electronic sector scanning is known as an electronic scanning method, and a dynamic focus method is known as an electronic focusing method.

FIG. 6 shows the concept of electronic deflection and electronic focusing of an ultrasound beam.

In FIG. 6, ultrasonic waves are transmitted and received by N array transducers 10 arranged in a straight line. Each vibrating element 10a constituting the array vibrator is provided with a delay device 12a that delays transmitted and received signals.

The delay time given to the delay device 12a connected to the i-th vibration element 10a can be expressed, for example, by the following first equation.

τi = (f − (f2+ (i−Δp (m+1) /2
) 2-2Δpf (m+1)s inθ/2)l/2
)/C+K...(1st formula)
Here, f is the focal length, m is the total number of vibrating elements, Δp is the interval between micro-vibrating elements, θ is the deflection angle of the ultrasonic wave, and C is the propagation speed of the ultrasonic wave in the medium (e.g., living body). . Further, K is a positive constant to avoid a negative delay time that cannot be realized physically.

Therefore, by giving the delay time obtained by the first equation to the delay device connected to each vibrating element, the ultrasonic beam can be deflected in the θ direction, and the ultrasonic beam can be deflected at the focal length f. can be focused.

By the way, in conventional ultrasonic diagnostic apparatuses, the first equation above is calculated in advance to obtain the delay time, and the obtained delay time is stored in a storage device such as a ROM. The delay time is read out from the ROM each time an ultrasonic wave is transmitted or received, and is applied to the delay device 12'a.

Here, under ideal conditions, the amount of information about the delay time stored in the storage device is roughly estimated as follows.

First, if there are 128 vibrating elements, it is necessary to hold delay times for each vibrating element, so it is necessary to hold 128 types of delay times.

Next, considering the focal length f, dynamic focusing is generally performed during transmission and reception in an ultrasonic diagnostic apparatus, so for example, 32 types of delay times are required for f.

Furthermore, if the deflection angle θ of the ultrasonic beam is set in 256 directions, 256 types of delay times are required.

Regarding the spacing Δp between the vibrating elements, this is a value unique to the probe and varies depending on the type of probe. For example, in order to use 32 types of probes, Δp must be
It is necessary to maintain two types of delay times.

Considering these combinations of each parameter,
If one delay time is represented by 10 bits, the amount of delay time information to be held is 40 Mbytes, which is a very large amount of information.

In this way, if we ideally calculate the amount of information in the delay time,
A large-capacity storage device is required, and problems arise such as the time it takes to access the storage device.

Therefore, in the past, the types of probes that could be connected were reduced, and the types of other parameters were reduced by half or less, reducing the amount of information and storing it in large-capacity ROM. This was an obstacle to improving diagnostic accuracy.

In order to solve the above-mentioned problem, a delay time generation device that reduces the amount of delay time information to be held is proposed in Japanese Patent Laid-Open No. 193679.

Before explaining this conventional device, the delay time calculation formula shown in the first formula will be rewritten into another mathematical expression.

FIG. 7 geometrically shows the positional relationship between the array vibrator and the focal point F along the X-axis direction.

Here, 0 is the center point related to ultrasonic beam formation, and P indicates the position of the vibrating element separated by X from the center point O.

In the figure, if we draw a circular arc with radius f centered on focal point F, with the distance (focal length) f between focal point F and center point 0 as the radius, this circular arc is considered to be the wavefront of the ultrasound focused on focal point F. be able to. Therefore, it is understood that in order to synthesize such wavefronts in each vibrating element, a time difference corresponding to the distance between the circular arc shown in the figure and the X-axis may be added to the transmitted and received signals.

Now, consider the vibrating element at position P. In addition, in the figure, the point where the straight line including the focal point F and the position P of the vibrating element intersects with the circular arc is indicated by Q.

In the figure, the distance ■ is expressed by the following second equation.

PQ-f-(f+x-2xfsinθ)l/2
...(Second Equation) Then, the time for the ultrasonic wave to propagate over the distance -PQ-, that is, the delay time τ given to the vibrating element at the position P, is expressed by the following third equation.

τ-P Q/C -(f (f2+x2-2x fs inθ door/2)/c...(3rd formula) Therefore, by finding this τ for each vibrating element, the ultrasonic wavefront can be synthesized. can be realized, and the ultrasonic beam can be deflected and focused.

Now, in the delay time generation device proposed in the above-mentioned Japanese Patent Application Laid-Open No. 1-193679, generation of the delay time is realized by a method of expanding the above-mentioned formula 3 into a Macrolin series up to the cubic term with respect to X.

The calculation formula is shown below for reference. (Refer to Japanese Patent Application Laid-Open No. 1-193679 for details of this formula.) 1M(X, θ) - τM(0, θ) + x τ '(0, θ) + X2r 0. θ)/2! M(0,θ)/3! = (a x + a x + a, x)/C...
(Equation 4) However, am-cos2θ/(2f) al m5inθ And, this conventional device has three adders each having a feedback loop, and addition coefficients (a 1 to a The calculation of the fourth equation is electrically realized by connecting the three adders in three stages in series.

Therefore, in this conventional delay time generator, basically,
R
Since it is sufficient to hold the information in the OM, the amount of information related to the occurrence of delay time can be reduced.

[Problems to be Solved by the Invention] However, the conventional delay time generating device described above has a problem in that the accuracy of the obtained delay time is not sufficient. That is, in the fourth equation after expansion into the Macrolin series, there is a problem that as the absolute value of X becomes larger, the accuracy of the delay time determined becomes worse.

Here, in order to obtain the delay time error using the Macrolin series expansion method, f=1c
Substitute lomm, lxl-25mm, θ-〇@,
Furthermore, the propagation speed C of the ultrasonic wave is 1.53 x 10'mm/
Comparing the two as ns, the error related to the occurrence of the delay time is found to be 31 ns.

Furthermore, in the delay time generator disclosed in Japanese Patent Application Laid-open No. 1-193679, a method using a Legendre polynomial is also proposed as a method for series expansion of the third equation. However, the conclusion obtained by substituting each of the above values is that even with this method, the error is 38 ns.

Incidentally, as described above, a delay element such as a delay device is generally used to delay transmitted and received signals.

The quantized delay unit, which is the minimum delay time in the delay element, generally needs to be shortened to about one-tenth of the period of the transmitted and received ultrasonic waves.

Therefore, if the error in the delay time generated by the delay time generator falls within the quantized minimum unit time, no problem will actually occur.

Under such a premise, when using 5 MHz ultrasonic waves in an ultrasonic diagnostic apparatus, for example, the quantization unit time of the delay element needs to be about 20 ns.

However, as can be understood from the above-mentioned values, the delay time error generated in the conventional device is not within the required 2 On s, and there may be a problem in terms of accuracy in some cases.

From the above, the method of approximating a calculation formula using Macrolin series expansion or Legendre polynomials may not provide sufficient accuracy.

On the other hand, in order to increase this accuracy, it is also possible to perform series expansion up to the fourth order term for X, but in this case,
There are problems in that the device becomes very complex and it becomes difficult to quickly generate a delay time.

The present invention has been made in view of the above-mentioned conventional problems,
The purpose is to provide a delay time generation device for an ultrasonic diagnostic apparatus that can reduce the amount of delay time information stored in a storage device while maintaining accuracy regarding delay time generation within a certain range.

[Means for Solving the Problems] In order to achieve the above object, the present invention uses the following principle.

Principle of the Invention The present invention is realized by transforming the above i3 equation as follows. Below, we will refer to the third equation again and explain its transformation.

τ-PQ/C = (f-(f2+x2-2xfsinθ) 112) /C (3rd formula) First, from the ultrasonic beam forming center point O of the array transducer shown in Fig. 7, the delay time is generated. The normalized position X is defined as the distance X to the position P of the vibrating element divided by the focal length f.

Xmx/f ゛...(5th formula)
Therefore, when this equation is transformed, it becomes x-Xf, and this X is substituted into the third equation above. Then, the following formula 6 is obtained.

r-(1(1+X2-2Xsinθdoor/2)/(C/
f) ...(Equation 6) and,
Both sides of this sixth equation are ultrasonic propagation time f/C (ultrasonic propagation time from the ultrasonic beam forming center point to focal point F)
Divided by the following formula 7% formula % (12 ... (7th formula) Here, the left side is the delay time τ as the ultrasonic propagation time (f /
C), and this is defined as the normalized delay time T.

T-τ/ (f/C) ...(8th
(Equation) Therefore, this normalized delay time T is a function of the normalized position It is understood that it does not depend on f and the spacing Δp between each vibrator.

T (X, θ) = 1- (1+X"-2XS i n θ) 1/2...
・(Equation 9) In this way, by introducing the concepts of normalized delay time T and normalized position This makes it possible to reduce the amount of information stored in the storage device related to the occurrence of delay time. Note that in order to restore the ζ normalized delay time T to the delay time τ, the normalized delay time T may be multiplied by f/C, as understood from the above equation 8.

FIG. 1 is a block diagram showing the principle explained above. Here, deflection angle information θ, focal length information f, probe type information P(
(Including information on the interval Δp between vibrating elements and the number m of vibrating elements)
is supplied.

In the figure, a normalized position generating section 10 receives f and P from the main body of the ultrasonic diagnostic apparatus, performs the calculation of equation 5 above, and generates a normalized position X. Here, X is
It corresponds to the product of the interval Δp between the vibrating elements and the address i of the vibrating elements.

Then, the normalized position
2 is entered.

As mentioned above, this standardized delay time table 12 is
This table shows the normalized delay time T as a function of the normalized position X and the deflection angle θ.

Therefore, the normalized delay time T corresponding to the above-mentioned X and θ is output.

The output normalized delay time T is then input to the unit restoration calculation section 14.

The unit restoration calculation unit 14 calculates the delay time τ from the normalized delay time T by calculating the 10th equation shown below.

τ-T・(f/C)10K...(Equation 10)
However, K is a constant to avoid negative delay time.

As described above, the normalized delay time table has only two parameters, X and θ, and has the advantage that at least one parameter can be eliminated compared to the conventional method.

Next, with reference to FIG. 2, sampling using the normalized delay table described above based on linear interpolation will be described.

By sampling both or one of the two parameters, X and θ, that determine the standardized delay time T in the standardized delay time table,
It is possible to significantly reduce the amount of information held in the standardized delay time table.

As an example, FIG. 2A shows a normalized delay time table 16 in which only X is sampled at predetermined sampling intervals. Note that (B) shows the concept of a table.

Further, FIG. 2(A) shows an interpolation processing section 18 for compensating for the deterioration in precision caused by the sampling.

Therefore, when certain θ and X are specified, two adjacent delay times Tl and T2 (or T1.ΔT) can be found from the normalized delay time table 16. The interpolation processing unit 18 then uses the obtained T1.
By performing linear interpolation processing on T2 (or Tt, ΔT) with X weighting, it is possible to generate the delay time τ while compensating for the deterioration in precision caused by the sampling.

Note that the number of sampling points may be determined as appropriate depending on the required accuracy.

Means for solving problems by applying the above principle A delay time generating device according to the present invention to which the above principle is applied has the following configuration.

First, the invention described in claim (1) provides a normalized position generating means for generating a normalized position and a normalized delay time table that holds the normalized delay time T determined by the normalized position Delay time τ after performing restoration calculation
It is characterized by the occurrence of

Further, the invention according to claim (3) provides the normalized position generating means, and the focal length f and the propagation velocity C of the ultrasonic wave at the normalized delay time T defined by the normalized position X and the deflection angle θ. It is characterized by including a delay time table that holds delay times multiplied by a determined unit restoration coefficient (f/C).

Furthermore, the inventions described in claims (2) and (4) provide that at least one of the normalized delay time T or the parameter defining the delay time is sampled, and T or D is held for the sampled sample point. The present invention is characterized in that it is further provided with an interpolation processing means for compensating for deterioration in accuracy due to sampling.

[Function] According to the structure of the present invention as set forth in claim (1) above, the normalized position generating means generates the normalized position X for the vibration element related to the generation of the delay time τ.

Then, the generated normalized position X is manually entered into a normalized delay time table together with the deflection angle θ, and the normalized delay time T defined by both is output.

Therefore, by performing a predetermined unit restoring operation on the output normalized delay time T, it is possible to generate the delay time τ.

Further, according to the configuration of the present invention as set forth in claim (3), by providing a delay time table in place of the normalized delay time table, it is possible to directly obtain the delay time without performing the above-described unit restoration operation. It is possible.

Here, the delay time stored in the delay time table is
It is obtained by multiplying the normalized delay time T determined by the normalized position Although the delay time is increased by one compared to the configuration of the invention, it has the advantage that the delay time can be directly determined from the delay time table.

Therefore, the configuration of the circuit after the delay time table is simplified. In addition, since the unit restoration coefficient (f/C) does not depend on the normalized position be.

Further, according to the configurations of the present invention described in claims (2) and (4), input parameters can be sampled in the table on the premise of linear interpolation by the interpolation processing means, so that the input parameters held in the table can be sampled in the table. It has the advantage of being able to significantly reduce the amount of information.

[Examples] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 3 shows a preferred embodiment of the delay time generating device according to the present invention. The delay time generating device shown in FIG. 3 is a further embodiment of the configuration shown in FIG. Note that this device is incorporated into, for example, an ultrasonic diagnostic device.

In the figure, this device includes a normalized position generator 22 that generates a normalized position X, and a normalized delay time that receives the generated normalized position X and deflection angle θ and outputs a normalized delay time T. A table (hereinafter referred to as table) 24, an interpolation processing unit 26 that performs linear interpolation on the standardized delay time T output from the table 24, and a standardized delay time T output from the interpolation processing unit 26. It is composed of a unit restoration calculation section 28 that performs a predetermined unit restoration calculation.

Here, the integer part XR of the normalized position X output from the normalized position generator 22 is input into the table 24 together with the deflection angle θ given as an integer value from the ultrasound diagnostic apparatus main body.

On the other hand, the decimal part r of the normalized position X output from the normalized position generating section 22 is supplied to the interpolation processing section 26, and is used for weighting related to the linear interpolation process.

In addition, in this example, since the number of types of θ is not so large as 256 types, θ is not sampled.
Sampling is performed only for X. Of course, sampling may be performed for θ. This sampling, especially the calculation of the number of sample points, will be detailed later.

First, the normalized position generating section 22 that generates the normalized position X for the table 24 of this embodiment will be explained.

This normalized position generating section 22 inputs probe information P (including information on the interval Δp between transducer elements and the number m of transducer elements) and focal length information f from the ultrasound diagnostic apparatus main body, and generates an accumulation coefficient α and An addition coefficient generator 30 that outputs an initial addition value β, an adder 32 to which the cumulative coefficient α is input to one input terminal and the normalized position X fed back to the other input terminal, and an ultrasonic diagnostic apparatus. The register 34 temporarily stores the output value of the adder 32 according to the clock 1 supplied from the main body. Note that the register 34 is supplied with the addition initial value β from the addition coefficient generator 30 at the time of the first addition operation.

The operating principle of the normalized position generating section 22 configured in this way will be explained below.

First, from Equation 5, the normalized position X for the first vibrator can be expressed as follows.

X-Δp(i-(m+1)/2)/f...(12th
(Formula) Where, m is the total number of vibration elements.

In order to give the address of X in the table 24 as an integer, let the sample interval of sampling regarding the normalized position
Rewrite the equation as the 13th equation below.

X-Δ1)(i-(m+1)/2)/(f-ΔX)+Xo -= (Equation 13) Therefore, by dividing Equation 13 into coefficients related to i and others, the following Equation 14 can be obtained. get.

X - αl + β ... (Equation 14) However, α Δp / (f - ΔX) β only Δp (m + 1) / (2φf - ΔX) + X.

Therefore, depending on the probe type information P and the focal length information f supplied from the ultrasound diagnostic equipment main body, the cumulative coefficient
and the addition initial value β, and the generated α and β
It is possible to sequentially generate the normalized position X for each order of the vibrating elements by cumulatively adding them based on Equation 14.

That is, during the first addition, the adder 32 is supplied with α, while the register 34 is supplied with β. and,
At the time of the next addition, the adder 32
α and β are added at , and the value after the addition is stored in the register 34 (
α + β) will be stored. Such a process is sequentially repeated, and normalized positions X are sequentially generated.

Next, the table 24 will be explained.

The table 24 is supplied with the integer part XR of the normalized position X generated by the normalized position generator 22. In addition,
One fractional part r is supplied to an interpolation processing unit 26, which will be described later, and branching between the two is performed, for example, by extracting the upper bit or the lower bit. Specifically, the normalized position
If a parallel bus is used for the transmission of , some of the buses are used for the integer part, and the remaining buses are used for the decimal part r.

Here, the table 24 outputs the normalized delay time T determined by the supplied integer part XR and the deflection angle θ information supplied from the ultrasound diagnostic apparatus main body.

In this embodiment, the output is the normalized delay time T determined by XR and θ and the difference ΔT between the samples of X, as shown in FIG. 2(B). There is.

That is, since ΔT is always required for subsequent linear interpolation, ΔT is also output at the same time as the normalized delay time T1. Of course, the same result can be obtained by simultaneously outputting T1 and T2, which is the next value for X of T1, and performing interpolation processing.

Next, the interpolation processing section 26 includes a multiplier 36 and an adder 38.゛Then, ΔT is supplied from the table 24 to the multiplier 36, and together with this, the decimal part r of the normalized position It is being said.

Then, the result of the multiplication is added to T1 outputted from the table 24 in an adder 38.

In other words, ΔT is weighted by r, and the result is T
By adding to 1, linear interpolation is realized.

Next, the unit restoration calculation unit 28 will be explained.

This unit restoration calculation unit 28 multiplies the normalized delay time T expressed by the above equation 10 by f/C, and adds the multiplication result to a predetermined constant.

This unit restoring calculation unit 28 includes an f/C generator 40
, a K generator 42 , a multiplier 44 for multiplying the delay time T output from the interpolation processing section 26 by the value output from the f/C generator 40 , and a multiplier 44 for multiplying the delay time T output from the interpolation processing section 26 , and an adder 45 that adds a constant K that varies depending on the type of probe output from the generator 42. Therefore, according to this configuration, the above-mentioned equation 10 is calculated, and as a result, the delay times τ are sequentially output.

As described above, according to the delay time generating device of this embodiment,
Since the amount of information in the table 24 can be extremely reduced by using sampling on the premise of linear interpolation, it is possible to easily and quickly generate a delay time in an ultrasonic diagnostic apparatus. In particular, it is possible to realize the demands for increasing the variety of deflection angles and increasing the number of focus points, which were previously limited by the capacity of the table. This has the effect of allowing ultrasound diagnosis to be performed.

Consideration of the number of sample points regarding sampling Below, the normalized position X in the normalized delay time table
and the number of sample points for sampling the deflection angle θ.

First, consider the number of sample points regarding the normalized position X.

Letting the normalized delay time T in the above equation 9 as Y, the following equation 15 for Y is obtained.

Y-T (X, θ) Y-1-(1+X -2Xs inθ)1/2...
(Equation 15) Here, by transforming Equation 15, the following Equation 16 is obtained.

(Y-1) 2(X-s inθ) -CO82θ
(Equation 16) FIG. 5 shows the relationship between X and Y shown in Equation 16. As shown here, lX-5inθ
When it becomes larger than 1, the change in Y approaches an asymptote (straight line),
It is understood that linear interpolation also provides a sufficiently good approximation.

In this case, the maximum error in linear interpolation is at the intersection of the straight line of Xm5inθ and the hyperbola shown in FIG.
If the sample interval for X is ΔX, the error e due to linear interpolation is expressed by the following equation 17.

e””cosθ−(CO52θ+(ΔX/2)2)112...(Equation 17) Here, lel increases as θ increases, so if the upper limit of θ is set to 45°, then , lel is maximum at θ-45°. Then, by multiplying e in this case by f/C and converting it into a unit of time, the maximum delay error can be obtained.

Under these assumptions, ΔX is such that the maximum delay error when f = 100 mm is smaller than, for example, 5 ns.
When calculating, ΔX<Q, 02...(18th
(Formula) Here, regarding X, when the focal path Mf is small, the possible range of X is , -0,25≦X≦0.25
... Assuming (Equation 19), the range of X (0
, 5) is sampled by ΔX (0°02), it is understood that an accuracy of 5 ns is guaranteed. In other words, it is understood that the number of sample points for X is 25 points (0,510,02).

Next, consider the number of sample points regarding θ.

Here, in Equation 9, 1θ1≦45°.

In the range of lxl≦0.25, the right side of Equation 9, X2-2X
Since sin θ is smaller than 1, if this is a, then the tailor up to the second order term for a is as follows (1+a) 1/2-1+a/2-a2/8...(Equation 20) - You can apply the expansion to Equation 9. When this approximation formula is applied, the ninth formula becomes the following formula 21.

T (X, θ) ≠-(X2-2Xs inθ)/2 + (X2-2Xs inθ) 2/8- (Equation 21)
In this case, when the linear interpolation error e is calculated when the sampling interval for θ· is Δθ, it becomes the following Equation 22.

e − (T (X, θ+Δθ/2)+T (X,
θ−Δθ/2) l /2−T (X, θ) Both XΔθ2 (Xcos2θ−5inθ)/8...(
(22nd formula) Here, the 22nd formula is X--0, 25 (minimum value of X),
It is understood that θ-45' (the maximum value of θ) is the maximum value of e.

Therefore, in this 22nd equation, X--0, 25, θ-45°
f/ in the case of f=100mm to e obtained by substituting
By multiplying by C and converting to units of time, the maximum delay error is obtained. Then, when calculating Δθ when the maximum delay error is smaller than 5 ns, Δθ≦3.37° (Equation 23) Therefore, the accuracy of 50S is guaranteed in the range of -45°≦θ≦45°. In this case, the number of sample points for θ is 27 points (9
0°/3.37°).

From the above, the number of sample points for sampling X and θ should be approximately 25 each, and by using a normalized delay time table configured with such a number of sample points, it is possible to calculate the delay time with an error of 5 ns or less. Occurrence is realized.

It is understood that increasing the number of samples helps to further reduce the error associated with delay time generation, and it is possible to generate a delay time with sufficient accuracy compared to the conventional example described above.

Modified Example of Delay Time Generating Device Next, a modified example of the delay time generating device according to the present invention shown in FIG. 3 will be described below.

FIG. 4 shows a modification of the device shown in FIG. Note that since the normalized position generating section 22 shown in FIG. 3 has the same configuration, a description thereof will be omitted.

A characteristic feature of this modification is that the normalized delay time T mentioned above is added to the unit restoration coefficient f/C in the delay time table 46.
This is because the delay time multiplied by .

That is, by holding the delay time multiplied by f/C in the delay time table 46, it is possible to omit the main part of the unit restoration calculation.

However, in this modification, the delay time table 46
, focal length information f is required, and for the second reason, the focal length f from the ultrasound diagnostic equipment body is
6 is man-powered.

Therefore, with such a configuration, compared to the embodiment shown in FIG. 3, an increase in the amount of information regarding the delay time τ stored in the table may be unavoidable, or the unit restoration calculation performed later may be extremely simplified. It has the advantage of being able to

Here, also in this modification, sampling is performed for the normalized position The same is true.

That is, f/C does not affect X and θ, and its accuracy remains unchanged. Therefore, also in this modification,
For example, if there are about 25 sample points for X and θ, it is possible to generate the delay time with sufficient accuracy.

In FIG. 4, the delay time table 46 outputs the delay time D1, and also outputs the difference ΔD between samples related to sampling, as in the above embodiment.

Both of these are input to the interpolation processing section 48. This interpolation processing section 48, like the above-mentioned interpolation processing section 26,
It consists of a multiplier 50 and an adder 52, and the decimal part r of the normalized position WX output from the normalized position generator 22.
Linear interpolation of the delay time is performed by weighting.

The delay time output from the interpolation processing unit 48 is
It is input to the coefficient adding section 54.

Here, the coefficient adding section 54 manually generates a constant K by 8 by using the probe information P supplied from the main body of the ultrasonic diagnostic apparatus, and a generator 56 outputs this constant K from the interpolation processing section 48. and an adder 58 that performs addition according to the delay time.

Therefore, in this modification as well, as in the above embodiment,
Delay times τ are generated sequentially.

As described above, in this modification, the delay time table 46
On the other hand, the circuit structure subsequent to the table 46 can be omitted, and as a result, the delay time τ can be generated quickly.

Consideration of the amount of information held In the configuration of the embodiment of the delay time generating device according to the present invention shown in FIG. 3, the total amount of information held is estimated as follows.

First, in the normalized delay time table 24, T1 is given as 13 bits, ΔT is given as 8 bits, the number of samples for the normalized position X is 64, and the number of samples for the deflection angle θ, that is, the number of beams is 256. Then, the amount becomes the following.

(13+8) ・64・256 Byte 42 On the other hand, considering the total information stored in the addition coefficient generator 30, the f/C calculator 40, and the calculator 42, α can be set to 1.
2 bits, β is 16 bits, f/C is 6 bits, and K is 11 bits.Furthermore, the number of focal points f is 32 types, and the number of connectable probes is N, then the following quantities are obtained. Become.

(32・(12+16+6)+11) ・N-140
ΦN bytes Therefore, even if N is 32, the total amount of information is approximately 46 bytes, which is approximately 1/870 of the aforementioned approximately 40M hide.

On the other hand, when considering the total amount of information to be held in the modified example of the delay time generating device according to the present invention shown in FIG. The amount of information is about 1/30 of about 40 Mbytes according to the conventional method.

In this way, it is understood that especially in the embodiment of the apparatus of the present invention shown in FIG. 3, it is possible to reduce the amount of information to be held to a greater extent than in the conventional example.

On the other hand, in the modification of the device of the present invention shown in FIG.
Although an increase in the amount of information to be retained cannot be avoided compared to the embodiment shown in FIG. 3, it still has the effect of significantly reducing the amount of information than the conventional method.

Other Modifications As a modification of the configuration of the delay time generating device according to the present invention shown in FIGS. 3 and 4, T (X, θ)−X
The configuration of the circuit can be modified using the symmetry of (-X, -〇).

For example, as a first example, it is also possible to hold the normalized delay time T or delay time RI in a table for the partial length of θ≧0. In addition, as a second example, since the normalized position
It is also preferable to generate normalized delay times T (or delay times D) in parallel with ≦O.

Further, by using the first example and the second example together, it is possible to easily and quickly generate a delay time.

[Effects of the Invention] As explained above, according to the invention recited in claim 1, it is possible to configure a table related to the generation of delay time τ using two input parameters: the normalized position X and the deflection angle θ. .

Further, according to the invention described in claim (3), the delay time obtained by multiplying the normalized delay time T by a predetermined unit restoration coefficient f/C is maintained in a table, and the delay time is directly obtained from the table. This has the effect of simplifying the configuration required for unit restoration calculations.

Furthermore, according to the inventions described in claims (2) and (4), the amount of information stored in the normalized delay time table and the delay time table can be significantly reduced on the premise of linear interpolation. In particular, By appropriately setting the number of sampling points, it is possible to generate a delay time with desired accuracy, and as a result, it is possible to construct a highly reliable delay time generation device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the principle of the present invention, and FIG. 2 is a block diagram showing the principle of the present invention.
An explanatory diagram showing the flow of sampling and interpolation processing, FIG. 3 is a block diagram showing an embodiment of the delay time generating device according to the present invention, and FIG. 4 is a block diagram showing an embodiment of the delay time generating device according to the present invention. A block diagram showing a modified example; FIG. 5 is a diagram showing the relationship between normalized position X and normalized delay time Y(T); FIG. 6 is an explanatory diagram showing electronic deflection and electronic focus of the ultrasound beam. , FIG. 7 is an explanatory diagram geometrically showing the positional relationship with the array vibration extraction focus F along the X-axis direction and explaining the calculation of the delay time. 10.22... Normalized position generating section 12, 16
．． 24... Standardized delay time table 14.2
8... i-place restoration calculation unit 18, 26...
Interpolation processing section

Claims (4)

[Claims] (1) In an ultrasound diagnostic apparatus that performs electronic deflection and electronic focusing of an ultrasound beam by giving different delay times to the transmission and reception signals of each transducer element constituting an array transducer that forms an ultrasound beam, the array vibration normalized position generating means for generating a normalized position a normalized delay time table holding a normalized delay time T determined by X and the deflection angle θ of the ultrasound beam; A delay time generation device for an ultrasonic diagnostic apparatus, characterized in that the delay time τ is generated by performing a restoration calculation. (2) In the delay time generation device for an ultrasound diagnostic apparatus according to claim (1), in the normalized delay time table, at least one of the normalized position X and the deflection angle θ, which are parameters of the table, is set to a predetermined value. Delay time generation for an ultrasonic diagnostic apparatus, characterized in that the table is configured by sampling at sample intervals of , and an interpolation means for interpolating the normalized delay time T obtained from the normalized delay time table is provided. Device. (3) In an ultrasonic diagnostic apparatus that performs electronic deflection or electronic focusing of an ultrasound beam by giving different delay times to the transmission and reception signals of each transducer element constituting an array transducer that forms an ultrasound beam, the array vibration normalized position generating means for generating a normalized position x, which is obtained by dividing the distance x from the center point of ultrasound beam formation in the ultrasound beam to the vibrating element related to the generation of delay time τ by the focal length f of the ultrasound beam; A delay time table that holds a delay time D obtained by multiplying the normalized delay time T determined by A delay time generator for an ultrasonic diagnostic apparatus, comprising: and. (4) In the delay time generation device for an ultrasound diagnostic apparatus according to claim (3), the delay time table includes table parameters such as the normalized position X, the deflection angle θ, and the focal length f.
At least one of them is sampled at predetermined sample intervals to form a table, and an interpolation means for interpolating the delay time D determined from the delay time table is provided. Time generator.