JPH0592005A - Ultrasonic imaging device - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to an ultrasonic imaging apparatus for obtaining a tomographic image of an object to be inspected by ultrasonic irradiation, and due to the non-uniformity of the sound velocity in the object to be inspected while following a small amount of hardware. It is an object of the present invention to prevent image deterioration due to the above-mentioned deterioration and obtain a highly accurate image. According to the phase of a received signal, a phase detecting means 45 for detecting non-uniformity of sound velocity in an object to be inspected calculates a cross-correlation value of two received signals to be detected which are sampled at a prescribed sampling frequency. Calculating means 450
And an interpolating unit 451 for interpolating the cross-correlation value calculated by the calculating unit 450, and a cross-correlation value interpolated by the interpolating unit 451 to detect the phase disturbance value of the two reception signals for which the cross-correlation value has been calculated. The detecting means 452 is provided to detect nonuniformity of sound velocity in the object to be inspected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic imaging apparatus for obtaining a tomographic image of an object to be inspected in accordance with ultrasonic irradiation.
The present invention relates to an ultrasonic imaging apparatus capable of obtaining a highly accurate image by preventing image deterioration due to non-uniformity of sound velocity in an object to be inspected while complying with a small amount of hardware.

Ultrasound imagers for visualizing the inside of an object are widely used mainly in the medical field and the like. This ultrasonic imaging apparatus includes an electroacoustic transducer that emits ultrasonic waves.
By arranging in rows and detecting ultrasonic waves reflected from points inside the object with this electroacoustic conversion element, phasing these detected values according to delay processing and then adding In addition to obtaining the image signal focused on a specific point, the electroacoustic transducer that radiates ultrasonic waves scans the focus point on a straight line, or controls the delay process to change the focus point. The configuration is such that a tomographic image inside the object is obtained by scanning in a fan shape. Since such a configuration is adopted, a clear image cannot be obtained unless the sound velocity inside the object is uniform. From this, it is necessary for the ultrasonic imaging apparatus to be provided with means for preventing image deterioration due to non-uniformity of sound velocity in the object to be inspected.

[0003]

2. Description of the Related Art First, the basic operation of an ultrasonic image device will be described in accordance with the circuit configuration of the ultrasonic image device disclosed in JP-A-53-28989 and JP-A-54-96286. ..

FIG. 9 shows a circuit configuration of the ultrasonic image device. In the figure, 1-i (i = 1 to n) are arranged in one row, and a plurality of electroacoustic conversion elements for radiating ultrasonic waves and detecting reflected ultrasonic waves, 2 are electroacoustic conversion elements A transmission circuit that controls ultrasonic radiation by applying an electric pulse to 1-i, 3-i (i = 1 to n) is a preamplifier that amplifies the reflected ultrasonic signal detected by the electroacoustic conversion element 1-i, 4-i (i = 1 to n) is composed of an LC circuit,
The small delay line 5-i (i = 1 to n) that delays the electric signal output from the preamplifier 3-i with a delay amount that can be changed is configured by an LC circuit, and the output of the small delay line 4-i is output. A fixed delay line that delays the electric signal to be set by a delay amount that can be changed, 6 is an adder circuit for phasing addition of the electric signal output from the fixed delay line 5-i, and 7 is a small delay line 4-i and a fixed delay Line 5-i
The ROM 8 for managing the delay amount of 1 is a control circuit for setting the delay amount to the small delay line 4-i and the fixed delay line 5-i according to the delay amount managed by the ROM 7.

The small delay line 4-i and the fixed delay line 5-i are provided with two types of delay means.
The reason is that by enabling the setting of a minute delay amount, the quantization of the delay amount of the fixed delay line 5-i is increased and the cost is reduced. In addition, the fixed delay line 5
-i is, as disclosed in Japanese Patent Laid-Open No. 53-28989, actually prepared with a structure for simultaneously performing delay and addition with taps as shown in FIG. The output of 4-i is input to this tap via a switch so that only one is sufficient and the addition circuit 6 can be omitted. A phase conversion circuit using a mixer or the like may be used instead of the small delay line 4-i.

[0006] In such a configuration, FIG.
As shown in FIG. 1, n electroacoustic transducers 1-i are provided.
When focusing on a point P located at a distance L just below the center point O of the group, i is counted from the center point O and the center point O.
If the distance between the i-th electroacoustic transducer 1-i is X _i , the delay amount τ of this i-th electroacoustic transducer 1-i is τ.
_i ,

[Equation 1] However, c: the speed of sound of ultrasonic waves τ ₀ : Set to a constant for making τ _i positive, and add the reception signals of n electroacoustic conversion elements 1-i phased by this delay amount τ _i It will be realized by doing.
That is, the i-th electroacoustic conversion element 1-i counted from the center point O has a delay in arrival of the reflected wave of the ultrasonic wave as the distance from the point P becomes longer, so that the delay is delayed more than the center point O. Focusing on the point P is realized by setting the amount τ _i to be short and performing phase adjustment, and adding the phased reception signals. Here, this X _i is

[Equation 2] However, p is represented by the pitch interval of the electroacoustic conversion element 1-i.

In the ultrasonic imaging apparatus, the focus point is scanned on a straight line by scanning the electroacoustic conversion element 1-i group for detecting and radiating ultrasonic waves, or the delay processing is controlled to focus. By scanning the points in a fan shape, the focused image signals thus obtained are combined to obtain a tomographic image of the inside of the object.

The delay amount τ _i is set concretely if the quantization error of the fixed delay line 5-i is Δτ.
The delay amount T _i of each fixed delay line 5-i is T _i = int (τ _i / Δτ) × Δτ, where int is an integer value rounded down to the nearest whole number, while the small delay line 4-i The delay amount t _i is set according to t _i = τ _i −T _i , the ROM 7 manages these delay amounts calculated in advance, and the control circuit 8 manages the delay amount managed by the ROM 7. Read out the small delay line 4-i
And the delay amount of the fixed delay line 5-i is set to this value. When a phase conversion circuit is used instead of the small delay line 4-i, this phase conversion circuit has a phase shift amount Δφ _i Δφ _i = 2πf ₀ × t _i defined by the following equation, where f ₀ : Phase shift processing for the central frequency of ultrasonic waves is executed.

In the ultrasonic image device constructed as described above, as is clear from the above, the condition is that the sound velocity c inside the object is constant. However, in the tissues of the human body, the speed of sound of tissues such as muscle and liver is 1570 m /
s is fast, whereas the speed of sound of fat tissue near the body surface is slow at 1480 m / s. The thickness of this fat tissue varies depending on the position of the body, as shown in FIG. From this, when a human body is an object to be inspected, there is a problem that a wavefront of a received wave is distorted, focus is deteriorated, and a clear image cannot be obtained.

Next, a conventional technique used to solve this problem will be described. FIG. 13 shows the basic circuit configuration of these conventional techniques. In the figure, the same components as those described in FIG. 9 are denoted by the same symbols. As can be seen from this circuit configuration, in the conventional technology,
In order to prevent the deterioration of the image due to the non-uniformity of the sound velocity, the phase detection circuit 9 is newly provided.

This phase detection circuit 9 is described in "USP4817".
As disclosed in US Pat. No. 4,614,178, the received signal of the adjacent electroacoustic conversion element 1-i is input as a processing target signal.
As disclosed in "5", by calculating the cross-correlation value of the two input signals to be processed, the time shift between the two received signals is specified, and the disturbance of the wavefront of the received wave is detected. U
As disclosed in "SP4484477", the disturbance of the wavefront of the received wave is corrected by rewriting the setting delay amount held in the control circuit 8 according to the specified delay amount of the temporal displacement. It is a process for performing Here, the calculation processing of the cross-correlation may be executed according to analog signal processing.
5 "and" USP 4844477 ",
It may be performed according to digital signal processing.

FIG. 14 shows a detailed circuit configuration of the phase detection circuit 9. As shown in this figure, the phase detection circuit 9 stores the waveform memory 10 for temporarily storing the reception signal output from the preamplifier 3-i and the reception signal of the adjacent electroacoustic conversion element 1-i from the waveform memory 10. A cross-correlator 11 for selecting and calculating a cross-correlation value, a displacement detector 12 for detecting a time displacement indicating the maximum cross-correlation value calculated by the cross-correlator 11, and a time displacement detected by the displacement detector 12. And an integrator 13 that determines the delay amount of all the received signals and notifies the control circuit 8 of the delay amount.
If the waveform memory 10 is a digital memory, an A / D converter is required, and if it is an analog memory, a sample and hold circuit is required. It is omitted to be shown as being included in 10.

That is, the phase detection circuit 9 is shown in FIG.
For received signals u ₁ (t) and u ₂ (t) of two adjacent electroacoustic transducers 1-i sampled at a specified sampling time interval Δt as shown in (a),

[Equation 3] However, by performing the cross-correlation calculation represented by t _{1 to} t ₂ : calculation time range, as shown in FIG. 15B, the cross-correlation value Q at each time displacement τ _i (≡Δt × i) (tau _i) is calculated, and that will identify the time displacement tau _M taking the maximum value of the cross-correlation value Q (τ _i), the delay amount tau _M of the two received signals operand As it is determined, the delay amount τ _M is integrated to determine the delay amounts of all the received signals, and the control circuit 8 is notified.

It should be noted that the number of the phase detection circuits 9 is only one, and the one phase detection circuit 9 is used.
However, there is a case where the configuration is such that the delay amount of all the received signals is determined, or a configuration in which the number of electroacoustic conversion elements 1-i is subtracted by “1” is provided, and each phase detection circuit is provided. In the case where the configuration is such that 9 determines the delay amount of the corresponding received signal and the delay amount of all the received signals is determined by executing the delay amount integration process on the control circuit 8 side. There is also.

Further, in the prior art of FIG. 13, the phase detection circuit 9 is shown as an object of detection of the output signal of the preamplifier 3-i, which is the fixed delay line 5-i shown in FIG. The reason is that the individual delay outputs cannot be taken out from the fixed delay line 5-i because the delay and addition are configured at the same time. In the case of adopting the configuration provided, it is preferable to set the output signal of the fixed delay line 5-i, which will be phased when the sound velocity is uniform, as the detection target.

As another conventional technique, there is "USP483".
No. 5689 ”, there is disclosed a technique in which quadrature detection is used to correct deterioration of an image due to nonuniformity of sound velocity.

In the configuration of the prior art described above, the turbulence of the wavefront that occurs during transmission is not taken into consideration, but the fact that the turbulence of the wavefront that occurs during transmission has a small effect means that "SW FLAX and M.O'DONNEL," Phase-Abe
rration Correction Using Signals From Point Reflec
tors and Diffuse Scatterres: Basic Principles ", IEEE
TRANSACTION ON ULTRASONICS, FERROELECTRICS, AND FRE
QUENCY CONTROL, VOL 35, NO.6, NOVEMBER 1988, p758-767
] Is suggested.

[0018]

As described above, since the phase detection circuit 9 determines the delay amount of the received signal required to prevent the image deterioration due to the non-uniformity of the sound velocity. Then, the cross-correlation calculation processing of the reception signal of the electroacoustic conversion element 1-i is executed. This cross-correlation value is, as shown in FIG. 15B, the sampling time of the reception signal. Since it is obtained by the interval Δt, the delay amount determined by the phase detection circuit 9 includes the error of Δt. From this, when the delay amounts are integrated, this error accumulates, so that the delay amount of the reception signal of the electroacoustic conversion element 1-i cannot be accurately obtained.

In order to solve this problem, the above-mentioned "S.
In the W.FLAX and M.O'DONNEL "literature, when 3.5 MHz is used as the ultrasonic frequency,
Although a delay amount accuracy defined by a sampling frequency of about 20 MHz is sufficient, a method is disclosed in which a received signal is sampled at 100 MHz in order to prevent a cumulative error. However, increasing the sampling frequency in this way requires collecting a large amount of sampling data, which causes a problem that the circuit scale of the phase detection circuit 9 becomes enormous. That is, the conventional technology has a problem that a circuit having a huge amount of hardware is required in order to prevent image deterioration due to non-uniformity of sound velocity and obtain a highly accurate image. There was.

The present invention has been made in view of the above circumstances, and in an ultrasonic imaging apparatus for obtaining a tomographic image of an object to be inspected by irradiating ultrasonic waves, the sound velocity in the object to be inspected can be reduced while following a small amount of hardware. It is an object of the present invention to provide a new ultrasonic imaging apparatus that can obtain a highly accurate image while preventing image deterioration due to nonuniformity.

[0021]

FIG. 1 illustrates the principle configuration of the present invention. In the figure, 30 is an ultrasonic wave detecting end, and 40 is an ultrasonic imager main body. The ultrasonic detecting ends 30 are arranged in one row or in a grid pattern to emit ultrasonic waves to the object to be inspected and to convert the ultrasonic waves reflected from the object to be inspected into electric signals. Element 31-i (i = 1 to 1
n).

The ultrasonic image device main body 40 includes a transmitting means 41.
A phase adjusting means 42-i (i = 1 to n) provided for the electroacoustic transducer 31-i, a storage means 43, a reference signal generating means 44, and one or more detection unit means. The phase detection means 45, the addition means 46, the display signal generation means 47, the display means 48, and the control means 49 are provided.

The transmitting means 41 is composed of the electroacoustic conversion element 3
The ultrasonic wave is controlled by applying an electric pulse to 1-i, and the phasing means 42-i converts the received signal output from the electroacoustic conversion element 31-i to the electroacoustic conversion element 31-i to be inspected. Phased by delaying according to the distance to the object, and the storage means 4
3 manages the delay amount according to the distance between the electroacoustic transducer 31-i to be set in the phasing means 42-i and the object to be inspected, and the reference signal generating means 44 is the same as the received signal. Of the electroacoustic conversion element 31-i or the phasing means 42 for generating a reference signal having a frequency of
calculating means 450 for calculating a cross-correlation value of two adjacent received signals output by -i (the reference signal generated by the reference signal generating means 44 may be used in place of one of the received signals). The provision of the interpolating means 451 for interpolating the cross-correlation value calculated by the calculating means 450 and the detecting means 452 for detecting the disturbance value of the phase of the received signal from the cross-correlation value interpolated by the interpolating means 451 makes it possible to determine the sound velocity The phase disturbance value of the received signal caused by the uniformity is detected, and the adding means 46 is added.
Is for adding the phased reception signals output by the phasing means 42-i, and the display signal generating means 47 is for generating a display signal by converting the luminance of the addition signal output by the adding means 46, and for displaying means. 48 visualizes the display signals generated by the display signal generating means 47, and the control means 49 executes control processing of these means.

The interpolating means 451 calculates the coefficient of a high-order interpolating function whose coefficient has not been determined, according to the cross-correlation value calculated by the calculating means 450, and determines the function form of the interpolating function. , The cross-correlation value calculated by the calculation means 450 may be interpolated, and at this time, the maximum cross-correlation value is calculated from the value relationship of the cross-correlation values calculated by the calculation means 450. In some cases, the area to be taken is specified and the functional form of the interpolation function is determined according to the cross-correlation value included in the area.

[0025]

In the present invention, the calculation means 45 of the phase detection means 45
0 calculates the cross-correlation value of the two received signals sampled according to the specified sampling frequency, and the interpolator 451 calculates the cross-correlation value of the cross-correlation value calculated according to this sampling time interval unit at a finer time interval. By interpolating so that the value can be specified, the detecting means 452 specifies the time displacement τ _M indicating the maximum value of the interpolated cross-correlation value, thereby determining the delay amount of the two adjacent reception signals. By specifying the difference and accumulating the delay amounts obtained by the self-detection unit means or another detection unit means, the delay amounts for all the received signals are determined.

Then, the detection means 452, when the reception signal output from the electroacoustic conversion element 31-i is to be detected, the determined delay amount and the storage set in the phasing means 42-i. By calculating the difference value with the corresponding delay amount managed by the means 43, the delay amount of the phase disturbance due to the non-uniformity of the sound velocity is detected, while the received signal output from the phasing means 42-i is detected. Is detected, the determined delay amount is detected as the delay amount of the phase disturbance caused by the non-uniformity of the sound velocity, and the control means 49 detects the delay of the phase disturbance thus detected. The delay amount set in the phasing unit 42-i is corrected according to the amount.

Here, in this processing, the calculation means 45
When 0 is used to calculate the cross-correlation value between the reference signal generated by the reference signal generating means 44 and the received signal, the delay amount with the reference signal as a common reference is detected, so the detecting means 451.
Will determine the delay amount for all received signals without performing the delay amount accumulation process.

In this way, according to the present invention, the delay amount of the received signal is determined with a resolution higher than the sampling frequency without increasing the sampling frequency of the received signal. Therefore, the delay amount is determined by the accumulation process. Even in the case of doing so, it becomes possible to determine the delay amount set in the phasing means 42-i without a cumulative error due to sampling. From this, it becomes possible to prevent the image deterioration due to the non-uniformity of the sound velocity in the object to be inspected and obtain a highly accurate image.

[0029]

The present invention will be described in detail below with reference to examples. FIG. 2 illustrates one embodiment of the present invention. In the figure,
3 and those which are the same as those described in FIG. 14 are denoted by the same symbols. Here, in this embodiment, one phase detection circuit 9 is prepared, and the received signals output from all the purine amplifiers 3-i are stored in the waveform memory 10 of this phase detection circuit 9 to determine the speed of sound in the object to be inspected. It is assumed that the image deterioration due to the non-uniformity of the sound velocity is corrected by detecting the disturbance of the delay amount due to the non-uniformity of.

As can be seen by comparing this embodiment with the prior art described in FIGS. 13 and 14, in the present invention,
In order to determine the delay amount for correcting the non-uniformity of the sound velocity in the object to be inspected, the phase detector 9 is newly provided with an interpolator 20.

The newly provided interpolator 20 interpolates the cross-correlation value calculated by the cross-correlator 11 obtained at the same time interval as the sampling frequency of the received signal, and cross-correlate at finer time intervals. The value is processed so that it can be specified. Then, the displacement detector 12 of the present invention detects the time displacement indicating the maximum value of the cross-correlation value interpolated by the interpolator 20, and the integrator 13 accumulates the time displacement detected by the displacement detector 12. By doing so, the delay amount of all the received signals is determined, and the control circuit 8 is notified of the delay amount.

Next, an example of this interpolation processing will be described. When the interpolator 20 receives the discrete cross-correlation value Q (τ _i ) represented by the expression (3) from the cross-correlator 11, first, the interpolator 20 determines the maximum value among the received Q (τ _i ). Showing Q
Detect (τ _i ). That is, in the case of the example shown in FIG. 3, Q (τ _j ) is detected. Then, Q (τ _i ) located on both sides of Q (τ _j ) showing the maximum value
The Q (τ _i ) that has the larger value of is specified. That is, to explain with the example shown in FIG. 3, the one Q (τ _i ) which shows a larger value out of Q (τ _{j + 1} ) and Q (τ _j-1 ) is specified. In this way, the interpolator 20, the maximum value Q ₁ from the received cross-correlation value Q (τ _i), the larger of the cross-correlation value Q (τ _i) adjacent to the maximum value Q _{1 Two} values of Q ₂ are specified. As can be seen from FIG. 3, there is an accurate maximum value Q _M of the cross-correlation value Q (τ _i ) between these two Q ₁ and Q ₂ values.

The interpolator 20 uses the property that the cross-correlation value Q (τ _i ) changes periodically, and moves the time origin to the time point showing the small τ of the Q ₁ value and the Q ₂ value. Q (τ _i ) = A cos (τ−Δτ _M ) * Δτ _M is assumed to be a function of the time difference between the time showing the maximum value Q _M and the time origin. This function is added to the above Q ₁ and Q ₂
Substituting, as shown in FIG. 3, when the time origin is at the Q ₁ value, Q ₁ = Acos (−Δτ _M ) Q ₂ = Acos (Δt−Δτ _M ) is obtained. .. From these two formulas,

[Equation 4] Is derived, the time difference Δτ _M between the time showing the maximum value Q _M and the time origin is

[Equation 5] Will be decided according to.

From this, when the interpolator 20 specifies _two Q ₁ and Q ₂ values,

[Equation 6] By calculating the calculated value α in accordance with the above, the cross-correlation value calculated by the cross-correlator 11 is interpolated
The displacement detector 12 detects the time difference Δτ _M by searching the table of the inverse function of tan prepared using the calculated value α as a search key, and detects the time origin movement value τ _i and this time difference Δτ _M. By adding and
An accurate delay amount τ _M of the one received signal is determined, and in response to this determination processing, the integrator 13 determines the determined delay amount τ _M.
Determine the delay amount of all received signals by accumulating
The processing is performed so as to notify the control circuit 8.

Upon receiving this delay amount, the control circuit 8
Small delay line 4-i
Set the delay amount to correct the non-uniformity of sound velocity. In other words, the delay amount notified from the integrator 13 and the ROM associated with the received signal of the notified delay amount
By calculating the difference value with the corresponding delay amount managed by the No. 7 (the delay amount described in [Equation 1]), the delay amount of the phase disturbance due to the non-uniformity of the sound velocity is detected, and the small delay The delay amount set on the line 4-i is corrected by the detected delay amount.

In this way, according to the present invention, the phase detection circuit 9 detects the delay amount of the received signal with a resolution higher than the sampling frequency. Therefore, the sampling frequency of the received signal is not increased. However, the cumulative error can be prevented and the delay amount set in the small delay line 4-i can be accurately determined. As a result, it is possible to prevent image deterioration due to non-uniformity of sound velocity in the object to be inspected and obtain a highly accurate image.

4 and 5 show another embodiment of the present invention. The embodiment of FIG. 4 includes a reference signal generator 21 that generates a reference signal having the same frequency as the received wave of the ultrasonic wave received by the electroacoustic transducer 1-i, and the cross-correlator 1
1 calculates the cross-correlation value between the received signal read from the waveform memory 10 and the reference signal generated by the reference signal generator 21, and the interpolator 20 interpolates the cross-correlation value using this reference signal. This is an example configured by the above. With this configuration, the displacement detector 12 detects the delay amount of each received signal using the reference signal as a common reference, so that the integrator 13 required in the embodiment of FIG. It can be omitted.

At this time, the reference signal generator 21
When the phase of the reference signal is changed so as to correspond to the received signal so as to have a corresponding delay amount managed by the ROM 7 associated with the received signal, the displacement detector 12
Since it becomes possible to directly detect the delay amount to be corrected, the control circuit 8 does not have to execute the above-mentioned difference processing. Further, without the reference signal generator 21,
It is also possible to use the phasing-added received signal output from the adder circuit 6 as the reference signal. Also at this time, the control circuit 8 does not have to execute the above-mentioned difference processing.

In the embodiment shown in FIG. 5, the received signal output from the preamplifier 3-i is converted into a digital value by the A / D converter 22 and stored in the memory 23 in a stacked manner. For the configuration that executes the delay processing by controlling the read position of
It is an example to which the present invention is applied. As described with reference to FIG. 10, when the delay configuration of the small delay line 4-i and the fixed delay line 5-i is adopted, as a practical problem, the delay is delayed by the small delay line 4-i and the fixed delay line 5-i. The received signals cannot be extracted individually. On the other hand, if the delay configuration of FIG. 5 is adopted, the received signal can be taken out at the input stage of the adder circuit 6,
The phase detection circuit 9 can directly detect the delay amount to be corrected. As a result, the control circuit 8 does not have to execute the above-mentioned difference processing.

In the interpolation processing described with reference to FIG. 3, when the sampling time interval Δt becomes coarse, the maximum value Q is obtained as shown in FIG.
_It will not hold because there may be an error in detecting ₁ . In order to eliminate such inconvenience, the interval [τ _i,
For each τ _{i + 1} ], it is approximated by a cubic function of Q (τ) = Q (τ _i ) + b _i (τ−τ _i ) + c _i (τ−τ _i ) ² + d _i (τ−τ _i ) ³ It is possible to adopt a method of performing interpolation by using the spline interpolation method. In particular, as such an interpolation method, it is preferable to use spline interpolation that adds a condition that the boundary is smoothly continuous up to the second derivative.

FIG. 7 and FIG. 8 show examples of the configuration of the interpolator 20 of the phase detection circuit 9 when this spline interpolation is used. The interpolator 20 shown in FIG. 7 has a first memory that stores all the cross-correlation values calculated by the cross-correlation value 11 in order to add a condition that smoothly continues up to the second derivative.
A coefficient calculator for obtaining a spline coefficient using the data stored in the first memory, a correlation value calculator for calculating an interpolated value of a cross-correlation value using the spline coefficient obtained by the coefficient calculator, and a correlation value calculator And a second memory for storing the cross-correlation value with the increased data amount calculated by the value calculator. Then, the displacement detector 12 detects the delay amount of each received signal using the data stored in the second memory. On the other hand, the interpolator 20 shown in FIG. 8 uses the property that the time position showing the maximum value is directly obtained if the spline coefficient is obtained, and the interpolator 20 stores it in the first memory. The displacement detector 1 has a configuration including only a corresponding memory and a coefficient calculator.
2 is a configuration example in which the delay amount of each received signal is detected by using the spline coefficient calculated by the coefficient calculator.

[0042]

As described above, according to the present invention,
Since it becomes possible to accurately determine the delay amount of the reception signal of the electroacoustic conversion element of the ultrasonic image device without increasing the sampling frequency, while following the small hardware amount,
It is possible to prevent the image deterioration due to the non-uniformity of the sound velocity in the object to be inspected and obtain a highly accurate image.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is an example of the present invention.

FIG. 3 is an explanatory diagram of processing of the present invention.

FIG. 4 is another embodiment of the present invention.

FIG. 5 is another embodiment of the present invention.

FIG. 6 is an explanatory diagram illustrating a problem of processing of the present invention.

FIG. 7 is another embodiment of the phase detection circuit.

FIG. 8 is another embodiment of the phase detection circuit.

FIG. 9 is a circuit configuration diagram of an ultrasonic imaging apparatus.

FIG. 10 is an explanatory diagram of a fixed delay line.

FIG. 11 is an explanatory diagram of a delay amount.

FIG. 12 is an explanatory diagram of human body tissue.

FIG. 13 is a circuit configuration diagram of an ultrasonic image device.

FIG. 14 is a circuit configuration diagram of a phase detection circuit.

FIG. 15 is an explanatory diagram of cross-correlation calculation.

[Explanation of symbols]

 30 ultrasonic detection end 31 electroacoustic conversion element 40 ultrasonic image device main body 41 transmission means 42 phasing means 43 storage means 44 reference signal generation means 45 phase detection means 46 addition means 47 display signal generation means 48 display means 49 control means 450 Calculation means 451 Interpolation means 452 Detection means

Claims (4)

[Claims] 1. An ultrasonic wave, which is arranged in one row or in a grid pattern, emits ultrasonic waves to an object to be inspected in response to an electric pulse applied by a transmitting means, and is reflected by the object to be inspected. A plurality of electroacoustic conversion elements (31) for converting the received wave of the electroacoustic conversion element (31), the reception signal output by the electroacoustic conversion element (31) is the distance between the electroacoustic conversion element (31) and the object to be inspected. Phasing means (42) for phasing the received signal by delaying it according to, and the electroacoustic conversion element (31) or the phasing means
(42) is provided with a phase detecting means (45) for detecting the phase disturbance value of the received signal, and the delay amount of the phasing means (42) is corrected according to the detection value of the phase detecting means (45). At the same time, in the ultrasonic image device for visualizing the inspected object by converting the luminance of the added signal of the phased reception signals output from the phasing means (42), the phase detection means (45) Is composed of one or a plurality of detection unit means, and the detection unit means are to be detected at a sampling rate of 2 according to a specified sampling frequency.
Calculation means (450) for calculating the cross-correlation value of two received signals
And an interpolating means (451) for interpolating the cross-correlation value calculated by the calculation means (450), and two cross-correlation value calculated from the inter-correlation value interpolated by the interpolating means (451). A detection means (452) for detecting the phase disturbance value of the signal, and the phase disturbance value of all the received signals is detected according to the cumulative value of the phase disturbance value detected by the detection means (452). An ultrasonic imaging device characterized by being performed. 2. The ultrasonic imaging apparatus according to claim 1, wherein the interpolating means (451) comprises a high-order interpolation function of which coefficient is not determined, which is prepared according to the cross-correlation value calculated by the calculating means (450). An ultrasonic imaging apparatus characterized by performing processing to interpolate a cross-correlation value calculated by the calculating means (450) by calculating a coefficient and determining a functional form of the interpolation function. .. 3. The ultrasonic imaging apparatus according to claim 2, wherein the interpolating means (451) specifies a region having the maximum cross-correlation value from the value relation of the cross-correlation values calculated by the calculating means (450). Then, the ultrasonic imaging apparatus is characterized in that processing is performed so as to determine the functional form of the interpolation function according to the cross-correlation value included in the region. 4. The ultrasonic imaging apparatus according to claim 1, 2 or 3, wherein the calculating means (450) replaces one of the received signals to be detected with a reference signal having the same frequency as the received signal. An ultrasonic imaging apparatus characterized in that a detection means (452) performs processing so that a phase disturbance value for which accumulation processing is not required is detected by making a cross-correlation value calculation target.