JPH0560B2 - - Google Patents

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 inside a living body are utilized.

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

FIG. 6 shows the concept of electron deflection and focus 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 - (f ² + (i - Δp (m + 1) / 2) ^{2 - 2} Δpf (m + 1) sin θ / 2) ^1/2 ) /C + K ... (1st equation) However, f is the focal length, m is the total number of vibrating elements,
Δp is the interval between micro-vibration elements, θ is the deflection angle of the ultrasonic wave, and C is the propagation speed of the ultrasonic wave in a medium (for example, a 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 determined 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. Focusing can be performed.

By the way, in the conventional ultrasonic diagnostic apparatus, the delay time is obtained by calculating the first equation above in advance, and the obtained delay time is stored in a storage device such as a ROM. And for each ultrasonic wave transmission and reception
The delay time is read from the ROM and the delay device 12 is
It was given to 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, since dynamic focusing is generally performed in an ultrasonic diagnostic apparatus during transmission and reception, 32 types of delay times are required for f, for example.

Further, when the deflection angle θ of the ultrasound 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, 32 types of delay for Δp are required. Need to keep time.

Considering such 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 the amount of information of the delay time is calculated ideally, a large capacity storage device will be required, and there will be problems such as the time required 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 halved or less, reducing the amount of information and storing it in large-capacity ROM. This has become an obstacle to improving diagnostic accuracy.

In order to solve the above problem, JP-A-1-193679
proposed a delay time generation device that reduces the amount of delay time information to be retained.

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, O 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 O 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, it is sufficient to give the transmitted and received signals a time difference corresponding to the distance between the circular arc shown in the figure and the X-axis.

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 second equation below.

= f - (f ² + x ² - 2xfsinθ) ^1/2 ... (2nd formula) Then, the time it takes for the ultrasonic wave to propagate over a distance, that is, the delay time τ given to the vibrating element at position P, is as follows: It is shown by the third equation.

τ=/C={f−(f ² +x ² −
2xfsinθ) ^1/2 }/C... (Third Formula) Therefore, by determining this τ for each vibrating element, synthesis of the ultrasonic wave front 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 Maclaurin 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) τ _M (x, θ) = τ _M (0, θ) + xτ _M ′ (0, θ) + x ² τ _M ″ (0, θ)/2 !+x ³ τ _M (0, θ) / 3! = (a ₃ x ³ + a ₂ x ² + a ₁ x) / C ... (4th formula) However, a ₃ = -sinθ cos ² θ / (2f ² ) a ₂ = -cos ² θ/(2f) a ₁ = sin θ This conventional device has three adders, each with a feedback loop, and an addition coefficient (a ₁ to a ₃ ) occurs
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 generating device, basically, the coefficients a ₁ to .
Since only _a3 needs to be held in the ROM, 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 the Maclaurin series expansion, 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 Maclaurin series expansion method, the third equation above and the fourth equation above are used.
Substitute f = 100 mm ^, |
Comparing the two, the error related to the occurrence of delay time is found to be 31 ns.

In addition, in the delay time generator of JP-A-1-193679, as a method for series expansion of the third equation,
A method using Lujendre polynomials has also been proposed. However, the conclusion obtained by substituting 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 generating device falls within the above-mentioned quantized minimum unit time, no problem will actually occur.

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

However, as can be understood from the above values, the delay time error generated in the conventional device is not within the required 20 ns.
In some cases, there may be problems with accuracy.

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

On the other hand, in order to improve this accuracy, it is 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 complicated and it becomes difficult to quickly generate a delay time.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to reduce the amount of delay time information stored in a storage device while maintaining accuracy regarding delay time generation within a certain level. An object of the present invention is to provide a delay time generating device for a sonic diagnostic device.

[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 third equation above as follows. Below, we will refer to the third equation again and explain its transformation.

τ=/C = {f-(f ² +x ² -2xfsinθ) ^1/2 }/C ...(3rd formula) First, the delay from the ultrasonic beam forming center point O of the array transducer shown in Figure 7 The normalized position X is defined as the distance x to the position P of the vibration element related to time generation divided by the focal length f.

X=x/f...(5th equation) Therefore, if you transform this equation, x=Xf,
Substitute this x into the third equation above. Then, the following formula 6 is obtained.

τ = {1 - ( ^{1 +} From center point to focal point F
The propagation time of ultrasonic waves up to
It is a formula.

τ/(f/C)={1-(1+X ² -2Xsinθ) ^1/2 } /{(C/f)・(f/C)} ...(Equation 7) Here, the left side is the delay time It is obtained by dividing τ by the ultrasound propagation time (f/C), and this is defined as the normalized delay time T.

T=τ/(f/C)...(Equation 8) Therefore, this normalized delay time T is expressed by the following 9th equation.
As shown in the formula, it is a function of the normalized position X and the deflection angle θ of the ultrasonic wave, and it is understood from the ninth formula that it does not depend on the focal length f and the interval Δp between each vibrator.

T (X, θ) = 1 - (1 + X ^{2 -} 2 In other words, by storing T represented by X and θ in a table, it is possible to reduce the amount of information stored in the storage device related to the occurrence of delay time. Note that the normalized delay time T can be restored to the delay time τ by multiplying the normalized delay time T 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, and probe type information P (including information on the interval Δp between transducer elements and the number m of transducer elements) are supplied from the ultrasound diagnostic apparatus main body.

In the figure, the normalized position generating section 10 inputs f and P from the main body of the ultrasound diagnostic apparatus, and
It calculates the equation and generates the normalized position X. Here, x corresponds to the product of the interval Δp between the vibrating elements and the address i of the vibrating elements.

The normalized position X generated by the normalized position generator 10 is input into the normalized delay time table 12 together with the θ information.

As described above, this normalized delay time table 12 is a table of 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)+K (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 that determine the normalized delay time T in the normalized delay time table, namely X and θ, the amount of information retained in the normalized delay time table can be greatly increased. It is possible to achieve significant reductions.

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. 2A shows an interpolation processing section 18 for compensating for the deterioration in accuracy caused by the sampling.

Therefore, when certain θ and X are specified, two adjacent delay times T ₁ and T ₂ (or T ₁ and ΔT) are determined from the normalized delay time table 16. Then, the interpolation processing unit 18 linearly interpolates the obtained T ₁ and T ₂ (or T ₁ and ΔT) with weighting of It is possible to generate

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 according to claim 1 provides a normalized position generating means for generating a normalized position X obtained by dividing the distance x from the ultrasound beam forming center point to the vibrating element related to the generation of the delay time τ by the focal length f; A normalized delay time table that holds the normalized delay time T determined by the normalized position It is characterized in that the delay time τ is generated by performing the following steps.

Further, the invention according to claim 3 provides the normalized position generating means, and a unit defined by the focal length f and the propagation velocity C of the ultrasonic wave in the normalized delay time T defined by the normalized position X and the deflection angle θ. Restoration factor (f/
C); and a delay time table holding a delay time D multiplied by C).

Furthermore, the invention according to claims 2 and 4 provides that at least one of the parameters defining the normalized delay time T or the delay time D is sampled, and T or D is held for the sampled sample point; The present invention is characterized in that an interpolation processing means is provided to compensate for the deterioration in accuracy caused by the change in accuracy.

[Operation] According to the configuration 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 input into the normalized delay time table together with the deflection angle θ,
A standardized 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.

Furthermore, according to the configuration of the present invention as set forth in claim 3,
By providing a delay time table instead of the normalized delay time table, it is possible to directly obtain the delay time D without performing the above-described unit restoration operation.

Here, the delay time D stored in the delay time table is obtained by multiplying the normalized delay time T determined by the normalized position X and the deflection angle θ by the unit restoration coefficient (f/C) determined by the focal length f. Although the number of input parameters in the table is increased by one compared to the structure of the present invention recited in claim 1, it has the advantage that the delay time D can be directly determined from the delay time table.

Therefore, the configuration of the circuit after the delay time table is simplified. It should be noted that the delay time D has the same accuracy in delay time generation as the configuration of the present invention according to claim 1, since the unit restoration coefficient (f/C) does not depend on the normalized position X and the deflection angle θ.

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 amount of information held in the table can be greatly increased. It has the advantage of being able to reduce costs.

[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. In addition, this device
For example, it is incorporated into ultrasonic diagnostic equipment.

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 X _R 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.

Note that in this embodiment, since the number of types of θ is not so large as 256 types, θ is not sampled, and only X is sampled. Of course, sampling may be performed for θ. This sampling, especially the calculation of the number of sample points, will be described in detail later.

First, the normalized position generating section 2 generates the normalized position X for the table 24 of this embodiment.
2 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 main body of the ultrasonic diagnostic apparatus, and generates a cumulative 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 in accordance with the clock i 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 i-th vibrator can be expressed as follows.

X=Δp(i-(m+1)/2)/f
...(Formula 12) where m is the total number of vibrating elements.

The sample interval of sampling regarding the normalized position X in table 24 is ΔX, and further table 2
In order to give the address of X in table 24 as an integer, assuming that the center address of X in Table 24 is X _O , the above equation 12 is rewritten as the following equation 13.

X=Δp(i-(m+1)/2)/(f・ΔX)+X _O ...(Equation 13) Therefore, by dividing Equation 13 into coefficients related to i and other factors, the following 14th Get the formula.

X=αi+β...(Equation 14) However, α=Δp/(f・ΔX) β=−Δp(m+1)/(2・f・ΔX)+X _OTherefore , it is supplied from the ultrasound diagnostic equipment main body. By generating a cumulative coefficient α and an initial addition value β according to probe type information P and focal length information f, and cumulatively adding the generated α and β based on Equation 14, the vibration element It is possible to generate the normalized position X sequentially for each order.

That is, during the first addition, the adder 32 has α
is supplied to the register 34, while β is supplied to the register 34. Then, at the time of the next addition, α and β are added by the adder 32 in response to the input of the clock i, and the value after the addition (α+β) is stored in the register 34. 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 X _R of the normalized position X generated by the normalized position generator 22 . Note that one fractional part r is supplied to an interpolation processing section 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, if a parallel bus is used to transmit the normalized position used.

Here, in table 24, the supplied integer part
A normalized delay time T determined by X _R and the deflection angle θ information supplied from the ultrasound diagnostic apparatus main body is output.

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

That is, since ΔT is always required in the subsequent linear interpolation, ΔT is also output at the same time as the output of this normalized delay time _T1 . Of course, the same result can be obtained by simultaneously outputting T ₁ and T ₂ , which is the next value for X of T ₁ , 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 ing. Then, the result of the multiplication is added to T ₁ outputted from the table 24 in an adder 38.

That is, linear interpolation is realized by weighting ΔT with r and adding the result to _T1 .

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

This unit restoration calculation unit 28 multiplies the normalized delay time T shown in the above equation 10 by f/C,
A predetermined constant K is added to the multiplication result.

The unit restoration calculation unit 28 includes an f/C generator 40, a K generator 42, and an f/C generator 40.
The multiplier 44 multiplies the delay time T output from the interpolation processing section 26 by the value output from the interpolation processing section 26, and the output of the multiplier 44 corresponds to the type of probe output from the K generator 42. ing. 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, the amount of information in the table 24 can be extremely reduced by using sampling on the premise of linear interpolation. It becomes possible to easily and quickly perform the occurrence. In particular, it is possible to realize the requests 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 improving the resolution of the ultrasonic diagnostic device and making it possible to perform highly accurate ultrasonic diagnosis.

Consideration of the number of sample points related to sampling The number of sample points related to sampling of the normalized position X and deflection angle θ in the normalized delay time table will be considered below.

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

If the normalized delay time T in the above formula 9 is set as Y, then
We obtain the following equation 15 for Y.

Y=T(X, θ) Y=1−(1+X ² −2Xsinθ) ^1/2
...(Equation 15) Now, by transforming this Equation 15, we obtain the following Equation 16.

(Y-1) ² - (X-sinθ) ² = cos ² θ
...(Equation 16) FIG. 5 shows the relationship between X and Y shown in Equation 16. As shown here, |
It is understood that as X-sin θ| increases, the change in Y approaches an asymptote (straight line), and a sufficiently good approximation can be obtained even by linear interpolation.

In this case, the maximum error in linear interpolation is
This is the intersection of the straight line of X=sin θ shown in FIG. 5 and the hyperbola, and if the sample interval for X is ΔX, then the error e due to linear interpolation is expressed by the following equation 17.

e=cosθ−{cos ² θ + (ΔX/2) ² } ^1/2 ... (Equation 17) Here, |e| increases as θ increases, so the upper limit of θ is set to 45°. Then, θ=45° and |e
| becomes maximum. And in this case e is f/C
The maximum delay error can be obtained by multiplying by and converting to units of time.

Under such a premise, when determining ΔX such that the maximum delay error is smaller than, for example, 5 ns when f=100 mm, ΔX<0.02 (Equation 18) is obtained.

Here, regarding X, when the focal length f is small, the possible range of −0.25≦X≦0.25 (Equation 19) It is understood that if the range of X (0.5) is sampled by ΔX (0.02), an accuracy of 5 ns is guaranteed. In other words, it is understood that the number of sample points for X is 25 points (0.5/0.02).

Next, consider the number of sample points regarding θ. Here, in Equation 9, |θ|≦45°, |x|≦
In the range of 0.25, the right side of equation 9, X ² −2Xsinθ, is 1
Since it is smaller, if this is a, (1+a) ^1/2 = 1+a/2-a ² /8
...(Equation 20) The Taylor expansion up to the second-order term for a can be applied to Equation 9. and,
When this approximate expression is applied, Equation 9 becomes Equation 21.

T (X, θ) ≒ - (X ^{2 -} 2Xsin θ) / 2 + (X ² - 2Xsin θ) ² / 8 ... (Equation 21) In this case, the sample interval for θ is Δθ
When calculating the linear interpolation error e when

e={T(X, θ+Δθ/2) +T(X, θ−Δθ/2)}/2 −T(X, θ) ≒XΔθ ² (Xcos2θ−sinθ)/8
...(22nd formula) Here, the 22nd formula is X = -0.25 (minimum value of X),
It is understood that e becomes maximum at (maximum value of θ).

Therefore, in this 22nd equation, X=-0.25, θ=45°
The maximum delay error can be obtained by multiplying e, which is obtained by substituting , by f/C when f=100 mm and converting it into a unit of time. Then, when determining Δθ when the maximum delay error is smaller than 5 ns, Δθ≦3.37° (Equation 23).

Therefore, it is understood that when an accuracy of 5 ns is guaranteed in the range of -45°≦θ≦45°, the number of sample points for θ is 27 points (90°/3.37°).

From the above, the number of sample points for sampling X and θ should be approximately 2 ^{to 5} , respectively, and by using a normalized delay time table configured with such a number of sample points, the delay time can be calculated with an error of 5 ns or less. generation is realized.

It is understood that by increasing the number of samples, it is possible 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 delay time table 46 holds the delay time D obtained by multiplying the above-mentioned normalized delay time T by the unit restoration coefficient f/C.

That is, by holding the delay time D 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, focal length information f is required in the delay time table 46,
For this reason, the focal distance f from the ultrasound diagnostic equipment main body is
is input into the delay time table 46.

Therefore, with such a configuration, although it is unavoidable that the amount of information regarding the delay time τ stored in the table increases compared to the embodiment shown in FIG. It has the advantage of being able to be digitized.

Here, also in this modification, the table 46
Of the parameters that determine the delay time D in , the normalized position X is sampled, and the number of sample points is the same as the number obtained by calculating the number of sample points.

That is, f/C does not affect X and θ,
This is because its accuracy remains unchanged. Therefore, even in this modification, if there are, for example, 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. Like the interpolation processing section 26, this interpolation processing section 48 is composed of a multiplier 50 and an adder 52, and is configured to weight the decimal part r of the normalized position X output from the normalized position generation section 22. Therefore, the delay time D is linearly interpolated.

The delay time D output from the interpolation processing section 48 is input to the coefficient adder 54.

Here, the coefficient adder 54 includes a K generator 56 which inputs the probe information P supplied from the ultrasound diagnostic apparatus main body and outputs a constant K, and a K generator 56 which outputs a constant K by inputting the probe information P supplied from the ultrasound diagnostic apparatus main body, and a K generator 56 which outputs a constant K by inputting the probe information P supplied from the main body of the ultrasound diagnostic apparatus, The adder 58 adds to the delay time D.

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

As described above, in this modified example, the input parameter of the delay time table 46 is increased by one, but on the other hand, the circuit configuration at the stage subsequent to the table 46 can be omitted, and as a result, the delay time τ can be generated quickly. It has the advantage of

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, T ₁
is given as 13 bits, ΔT as 8 bits, the number of sample points for the normalized position X is 64, and the number of sample points for the deflection angle θ, that is, the number of beams.
If it is 256, it will be the following amount.

(13+8)・64・256=42K bytes On the other hand, addition coefficient generator 30 and f/C calculator 4
Considering the total information stored in the 0 and K arithmetic unit 42, we give 12 bits for α, 16 bits for β, 6 bits for f/C, 11 bits for K, and 32 types of focal points f. If the number of probes that can be connected is N, then the following quantity is obtained.

{32・(12+16+6)+11}・N = 140・N bytes Therefore, even if N is 32, the total amount of information is approximately
It is 46K bytes, which is about 1/1/2 of the 40M bytes mentioned above.
It becomes 870.

On the other hand, when considering all the amount of information to be held in the modified example of the delay time generation device according to the present invention shown in FIG.
The total amount of information is approximately 1/1 of the approximately 40MB by the conventional method.
It will be 30.

In this way, it is understood that the embodiment of the apparatus of the present invention shown in FIG. 3 in particular can significantly reduce the amount of information to be held compared to the conventional example.

On the other hand, in the modified example of the device of the present invention shown in FIG. 4, an increase in the amount of information to be retained cannot be avoided compared to the embodiment shown in FIG. This has the effect that it can be reduced.

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)
The configuration of the circuit can be modified by utilizing the symmetry of =X(-X,-θ).

For example, as a first example, for only the part where θ≧0, the normalized delay time T or the delay time D
It is also possible to hold it in a table. Also,
As a second example, since the normalized position It is also suitable to generate D) in parallel.

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 described above, according to the first aspect of the invention, a table related to the generation of delay time τ can be constructed using two input parameters: the normalized position X and the deflection angle θ.

According to the third aspect of the invention, the delay time D obtained by multiplying the normalized delay time T by a predetermined unit restoration factor f/C can be stored in a table, and the delay time D can be directly obtained from the table. This has the effect of simplifying the configuration required for unit restoration calculations.

Furthermore, according to the inventions recited 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 drawings]

FIG. 1 is a block diagram showing the principle of the present invention, FIG. 2 is 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, FIG. 4 is a block diagram showing a modification of the embodiment of the delay time generating device according to the present invention, and FIG. A diagram showing the relationship between the normalized position X and the normalized delay times Y and T, FIG. 6 is an explanatory diagram showing the electron deflection and electron focus of the ultrasound beam,
Figure 7 shows the array transducer and focal point F along the X-axis direction.
FIG. 3 is an explanatory diagram geometrically showing the positional relationship between the two and explaining the calculation of the delay time. 10, 22... Normalized position generator, 12, 1
6, 24... Normalized delay time table, 14, 2
8... Unit restoration calculation section, 18, 26... Interpolation processing section.

Claims (1)

[Scope of Claims] 1. In an ultrasonic 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. , normalized position generating means for generating a normalized position X obtained by dividing the distance x from the ultrasonic beam forming center point of the array transducer to the vibrating element related to the generation of delay time τ by the focal length f of the ultrasonic beam; a normalized delay time table holding a normalized delay time T determined by the normalized position X and the deflection angle θ of the ultrasound beam; and a normalized delay time T determined by the normalized delay time table. 1. A delay time generating device for an ultrasonic diagnostic apparatus, characterized in that a delay time τ is generated by performing a predetermined unit restoring operation. 2. The delay time generation device for an ultrasound diagnostic apparatus according to claim 1, wherein the normalized delay time table has at least one of the normalized position X and the deflection angle θ, which are table parameters, at a predetermined sample interval. A delay time generation device for an ultrasonic diagnostic apparatus, characterized in that the delay time generating device for an ultrasonic diagnostic apparatus is provided with an interpolation means for interpolating the standardized delay time T obtained from the standardized delay time table, which is sampled and configured as a table. 3. In an ultrasonic diagnostic apparatus that performs electronic deflection and electronic focusing of an ultrasound beam by giving different delay times to the transmitting and receiving signals of each vibrating element constituting an array transducer that forms an ultrasound beam, in the array transducer. normalized position generating means for generating a normalized position X obtained by dividing the distance x from the center point of the ultrasonic beam formation to the vibrating element related to the generation of the delay time τ by the focal length f of the ultrasonic beam; and the normalized position X and a delay time table holding a delay time D obtained by multiplying a normalized delay time T determined by the deflection angle θ of the ultrasound beam by a unit restoration coefficient f/C determined by the focal length f and the propagation speed C of the ultrasound; A delay time generator for an ultrasonic diagnostic apparatus, comprising: 4. The delay time generating device for an ultrasound diagnostic apparatus according to claim 3, wherein the delay time table is such that at least one of the normalized position X, the deflection angle θ, and the focal length f, which are parameters of the table, A delay time generation device for an ultrasonic diagnostic apparatus, characterized in that the delay time generating device for an ultrasonic diagnostic apparatus is provided with an interpolation means for interpolating the delay time D obtained from the delay time table, the delay time being sampled at sample intervals and configured as a table.