CN100588471C - Phase control annular ultrasound focusing method - Google Patents

Abstract

The invention relates to an ultrasonic focusing or orientation method, in particular to a phase control circular ring shaped ultrasonic focusing method for controlling the local ultrasonic energy density, and solves the problem that the prior ultrasonic energy focusing is poor. The method comprises the following steps: S1: the step of deciding the target location and the size according to the measurement; S2, the step of setting the position of a circular ring Rh according to the distance from the edge of the target to the array of a ultrasonic transducer; S3: the step of determining the actual focal position Rf according to the size of the target and the definite operating position, and accurately calculating the diameter d of the circular ring according to the formula (3); S4: the step of accurately adjusting and controlling the operating position; S5: the step of accurately calculating the advanced emission time for the array elements on each distribution position according to the formulas (1) and (2), and exciting each array element to realize the circular ring shaped focusing. The method can improve the focusing effect of the ultrasonic energy to the focus area (operating target area), improve the ultrasonic energy density in the operating target area, and simultaneously reduce the ultrasonic energy density in the non-operating target area.

Description

Phase control annular ultrasound focusing method

Technical field

The present invention relates to a kind of focus ultrasonic or directed method and promptly control the method for focusing of local ultrasonic energy density.This method is the pumping signal by each array element in the regulation and control phased array focusing ultrasonic transducer, ultrasonic wave is focused on to the annulus of setting, and according to size, the position of target, set and adjust the position of annulus and the size of diameter, reach the accurate adjusting control of work focal length (target area), the phase control annular ultrasound focusing method of the required ultrasonic energy in target area is provided.

Background technology

At present, focus supersonic has been widely used in every field such as industry, agricultural, medical science, as industrial processes, flaw detection, and medical diagnosis, treatment or the like, the high intensity focused ultrasound technology has that penetration depth is big, directive property is strong, the advantage of good condensing performance, is subjected to common concern.Part crucial in the high intensity focused ultrasound system is the focusing technology of ultrasonic transducer.This technology comprises contents such as the various types of focusing contrast, the sound field characteristic of the various types of focusing, transducer architecture design.At present, the ultrasonic type of focusing has: sphere self-focusing, ultrasonic lens focus on and phase array focusing, respectively as shown in Figure 1, 2, 3, and their principle, formation, excellent, shortcoming and remain in the problem brief introduction in down:

Fig. 1. the sphere self-focusing is to utilize the spherical surface focusing transducer directly to focus on, sphere self-focusing transducer is that piezoelectric ceramic piece is ground to form the spherical crown shape, or form a spherical crown shape by tens an even hundreds of plane pottery sheet gummed, the performance requirement of its manufacture craft and power amplifier generally adopts the mechanical scanning mode than higher and this transducer, volume is big, electroacoustic efficiency is on the low side, and focal length is unadjustable;

Fig. 2. ultrasonic lens focuses on, form focusing by ultrasonic scioptics material, though the lens handling ease, the lens material that is difficult to find performances such as high temperature resistant, impedance matching, decay be little to be taken into account is in addition because during high-strength focus ultrasonic, lens itself sound absorption and produce high temperature and can make lens distortion, the focusing effect of ultrasonic lens is not only relevant with medium, and is also relevant with lens material, and boundary reflection and acoustic lens decay also can cause the acoustic energy loss, its electroacoustic efficiency is low, and focal length is unadjustable;

Fig. 3. phase array focusing is different with last two kinds of types of focusing, supersonic source is to be combined into by the cell array transducer, as shown in the figure, it is by controlling the phase place of array element pumping signal that phased array focuses on, acoustic wave front curvature and center are changed, realize one or more focusing, can realize focus adjustment and scanning simultaneously.

Currently used above-mentioned ultrasound focusing method, no matter be by machinery or electronics phase-control focusing, all be to a certain point focusing, and the shortcoming that exists in real work is the poor effect that ultrasonic energy focuses on, and in order to reach institute's energy requirement of focus area, inoperative zone in the focus front inevitably also forms certain high-energy zone, these high-energy can make the focus forefoot area be damaged and focus place acoustic energy be incurred loss and efficiency decline, as Fig. 7, shown in 8, obtain under the identical condition of maximum energy-density at the focus place, point focusing before focus on the matrix row 70mm section maximum energy-density higher by 10% than annular ultrasound focusing method, this acoustic energy is wasted in the inoperative of focus front zone and can be caused damage to the inoperative zone.

Summary of the invention

The present invention proposes and discloses a kind of phase control annular ultrasound focusing method for the problem that solves above-mentioned prior art existence, the focusing principle of its exciting unit array transducer as shown in Figure 4, this focus method is to utilize the method for phase controlling to control the time that each array element is sent pumping signal, pumping signal is set to desired location on the annulus edge of diameter evenly focused on, utilize the self-focusing of high-strength ultrasonic nonlinear propagation characteristic to form the novel focus method of focus area at the annulus rear.Utilize this focus method in real work, according to size, shape and the position of target, the position R of initial setting annulus _hSize, the accurate setting of the diameter d by annulus and adjustment make the position consistency of position with the work target area of the actual focusing focal point F that high-strength ultrasonic forms again, make location, work target area more accurate, minimizing improves the reliable and secure property of this method of work near the infringement of the non-target area material target.The phase controlling of concrete phase control annular ultrasound focusing method as shown in Figure 4 is with O _hPoint calculates O for datum mark respectively according to following formula (1), (2) _hThe time of the leading emission of each array element ultrasonic action signal of the inside and outside interval array of point is:

$t_1({\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M}_{}{}_1,R_h)=\frac{M_1{M}_2}{c}=\frac{\sqrt{{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M_{}}^{}{{}_1}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M_{}}^{}{{}_1}^2+{R_h}^2}-R_h}{c}$ $(0\&le;{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M}_{}{}_1\&le;\frac{D-d}{2})---\left(1\right)$

$t_2(O_h{M}_3,R_h)=\frac{M_3{M}_4}{c}=\frac{\sqrt{O_h{M_3}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{O_h{M_3}^2+{R_h}^2}-R_h}{c}$ $(0\&le;O_h{M}_3\&le;\frac{d}{2})---\left(2\right)$

Wherein: t ₁(O _hM ₁, R _h)--O _hThe time of the leading emission of M section array element; t ₂(O _hM ₃, R _h)-O _hThe time of the leading emission of O section array element; R _h-setting annulus position (distances of annulus matrix row); The C-velocity of sound; D-array element distribution disc diameter; The d-circle diameter; F _hFocus on the-annulus; M ₁M ₂, M ₃M ₄-be respectively O _hM section and O _hEach array element of O section array focal point F to the annulus _hDistance and R _hPoor.

The approximate formula (3) that experimental data is released phase control annular ultrasound focusing method formation real focal length of the present invention is:

R _f=R _h+ 2d+6.0 (unit: mm) (3)

Wherein: R _f-actual formation focal length is a factual focus location; The d-circle diameter; R _h-setting annulus position (distances of annulus matrix row).

Below be that high-strength ultrasonic is at different setting annulus position R _h, the actual focal length R that forms of following of circle diameter d _f, approximate formula (3) focal position and the two error of calculating be as shown in the table:

Annulus desired location R h (mm)	Circle diameter d (mm)	The actual focal length R that forms f(mm)	Focal position (mm) R that approximate formula (3) calculates The f meter＝R h+2d+6.0	Approximate calculation error R f-R The f meter (mm)
					100	0	106.31	106.00	0.31
100	5	115.06	116.00	-0.94
					100	10	124.63	126.00	-1.37
110	0	117.06	116.00	1.06
					110	5	125.75	126.00	-0.25
110	10	135.88	136.00	-0.12
					120	0	126.69	126.00	0.69
120	5	136.13	136.00	0.13
					120	10	146.69	146.00	0.69

As seen from the above table, the focal position that utilizes approximate formula to calculate very forms focal length near reality, and maximum difference is ± 1.37mm.

According to above-mentioned phase control annular ultrasound focusing principle, phase control annular ultrasound focusing method of the present invention included with the next stage:

S1: according to measuring the stage of determining target location and size; S2: set annulus position R apart from the distance of ultrasound transducer array according to object edge _hStage; S3: factual focus location (operating position) R is determined in size and planning work position according to target _fAnd be R by formula (3) _f=R _h+ 2d+6.0 (mm) calculates the stage of circle diameter d; S4: the stage of accurately regulating control operating position (work focal length); S5: promptly according to formula (1), (2)

$t_1({\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M}_{}{}_1,R_h)=\frac{M_1{M}_2}{c}=\frac{\sqrt{{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M_{}}^{}{{}_1}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M_{}}^{}{{}_1}^2+{R_h}^2}-R_h}{c}$ $(0\&le;{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M}_{}{}_1\&le;\frac{D-d}{2})---\left(1\right)$

$t_2(O_h{M}_3,R_h)=\frac{M_3{M}_4}{c}=\frac{\sqrt{O_h{M_3}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{O_h{M_3}^2+{R_h}^2}-R_h}{c}$ $(0\&le;O_h{M}_3\&le;\frac{d}{2})---\left(2\right)$

The leading launch time of array element on each distributing position of accurate Calculation ultrasonic transducer, the stage of realizing annular ultrasound focusing.

Its stage of accurately regulating control operating position (work focal length) is to be R to formula (3) _f=R _hSetting annulus position R among the+2d+6.0 (mm) _hCarry out coarse adjustment, wherein circle diameter d is carried out thin tuning with accuracy controlling operating position R _fStage.

It is according to the leading launch time of array element on formula (1), each distributing position of (2) accurate Calculation ultrasonic transducer, and the stage of realizing annular ultrasound focusing is to set annulus position R _h, under ultrasonic transducer array element distribution disc diameter D, the circle diameter d situation about determining with

$t_1({\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M}_{}{}_1,R_h)=\frac{M_1{M}_2}{c}=\frac{\sqrt{{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M_{}}^{}{{}_1}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M_{}}^{}{{}_1}^2+{R_h}^2}-R_h}{c}$ $(0\&le;{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M}_{}{}_1\&le;\frac{D-d}{2})---\left(1\right)$

$t_2(O_h{M}_3,R_h)=\frac{M_3{M}_4}{c}=\frac{\sqrt{O_h{M_3}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{O_h{M_3}^2+{R_h}^2}-R_h}{c}$ $(0\&le;O_h{M}_3\&le;\frac{d}{2})---\left(2\right)$

Two formulas are divided into the stage of the leading launch time of array element on inside and outside interval each distributing position of accurate Calculation ultrasonic transducer.

Advantage and good effect: the present invention compares its advantage with existing other focus method and is:

1. the present invention is except that one or more that have that phased point focusing has focus on, the advantage of focus adjustment, also have and assemble the advantage that improves focusing efficiency, disperses non-target area ultrasonic energy than phased point.Shown in Fig. 5,6, under ultrasound transducer array array element the same terms, the maximum energy-density that the annular ultrasound method for congregating obtains at the focus place is high more about 30% than phased point focusing method, but the maximum energy-density of the non-target region before the focus is identical; If under the identical condition of the maximum energy-density that obtains at the focus place, the maximum energy-density on the section of annular ultrasound method for congregating before focus is than point focusing about 10% (finding out as Fig. 7,8 contrasts) that descend

2. can avoid focal shift to the target selection location.

3. it is not a bit poly-to certain focusing on, but form the focus territory by focusing on to an annulus, under same excitation, the energy that is obtained when forming focus territory energy greater than point focusing, and ultrasonic energy evenly distributes in the focusing process, object suffered ultrasonic energy in non-target area is reduced, thereby avoided the damage of inoperative target area target and the loss of ultrasonic energy in the course of work.

4. phase control annular ultrasound focusing method of the present invention can carry out coarse adjustment to focusing by the position of control annulus, carries out fine adjustment by circle diameter control, therefore makes focal length, burnt territory control more accurate.

5. circular focusing is identical with size, the shape of the focus area that point focusing forms, and the formation of the dispersion distribution focusing of ultrasonic energy does not have harmful effect (finding out as Fig. 9,10 contrasts) before the target area.

Description of drawings

Fig. 1 is a sphere self-focusing schematic diagram;

Fig. 2 is the sound lens focusing schematic diagram;

Fig. 3 is phased array element point focusing schematic diagram;

Fig. 4 is the phase control annular ultrasound focusing schematic diagram;

Fig. 5,6 be annular ultrasound focusing, point focusing before focus under matrix row 70mm place section maximum energy-density the same terms (shown in Figure 5) the two at focus section maximum energy-density comparison diagram (shown in Figure 6);

Fig. 7,8 is annular ultrasound focusing, point focusing matrix row 70mm place's section maximum energy-density comparison diagram (showing as Fig. 7) before (as shown in Figure 8) its focus under focus maximum energy-density the same terms;

Fig. 9,10 is point focusing, annular ultrasound focusing Jiao Qu and near acoustic pressure distribution map thereof;

Figure 11 is the phase control annular ultrasound focusing method flow chart;

Main label detail among each figure

R _f-actual focal length, factual focus location, the operating position .d-circle diameter of forming

R _hThe distance of-annulus matrix row, the setting annulus position C-velocity of sound

D-array element distribution disc diameter S1-S5-program label

The specific embodiment

In order to further specify content of the present invention, technical characterictic and effect, lift following example and accompanying drawings again in following: phase control annular ultrasound focusing method of the present invention as shown in figure 11 included with the next stage

S1: according to measuring the stage of determining target location and size; S2: set annulus position R apart from the distance of ultrasound transducer array according to object edge _hStage; S3: factual focus location (operating position) R is determined in size and planning work position according to target _fAnd be R by formula (3) _f=R _h+ 2d+6.0 (mm) calculates the stage of circle diameter d; S4: the stage of accurately regulating the control operating position; S5: promptly according to formula (1), (2)

$t_1({\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M}_{}{}_1,R_h)=\frac{M_1{M}_2}{c}=\frac{\sqrt{{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M_{}}^{}{{}_1}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M_{}}^{}{{}_1}^2+{R_h}^2}-R_h}{c}$ $(0\&le;{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M}_{}{}_1\&le;\frac{D-d}{2})---\left(1\right)$

$t_2(O_h{M}_3,R_h)=\frac{M_3{M}_4}{c}=\frac{\sqrt{O_h{M_3}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{O_h{M_3}^2+{R_h}^2}-R_h}{c}$ $(0\&le;O_h{M}_3\&le;\frac{d}{2})---\left(2\right)$

The leading launch time of array element on each distributing position of accurate Calculation ultrasonic transducer, the stage of realizing circular focusing.

Its stage of accurately regulating the control operating position is to be R to formula (3) _f=R _hSetting annulus position R among the+2d+6.0 (mm) _hCarry out coarse adjustment, wherein circle diameter d is realized that thin tuning is with regulation and control operating position R _fStage.It realizes that according to the leading launch time of array element on formula (1), each distributing position of (2) accurate Calculation transducer the stage that annulus focuses on is to set annulus position R _h, under array element distribution disc diameter D, the circle diameter d situation about determining with

$t_1({\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M}_{}{}_1,R_h)=\frac{M_1{M}_2}{c}=\frac{\sqrt{{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M_{}}^{}{{}_1}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M_{}}^{}{{}_1}^2+{R_h}^2}-R_h}{c}$ $(0\&le;{\mathrm{<figure-callout\; id="1"\; label="O\; h\; M"\; filenames="C2007100573610009H3.png,C2007100573610010H2.png"\; state="\{\{state\}\}">O</figure-callout>}}_h{M}_{}{}_1\&le;\frac{D-d}{2})---\left(1\right)$

$t_2(O_h{M}_3,R_h)=\frac{M_3{M}_4}{c}=\frac{\sqrt{O_h{M_3}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{O_h{M_3}^2+{R_h}^2}-R_h}{c}$ $(0\&le;O_h{M}_3\&le;\frac{d}{2})---\left(2\right)$

Two formulas are divided into the stage of the leading launch time of array element on inside and outside interval each distributing position of accurate Calculation ultrasonic transducer.

Claims (2)

1. a phase control annular ultrasound focusing method includes with the next stage: S1: according to measuring the stage of determining target location and size; S2: set annulus position R apart from the distance of ultrasound transducer array according to object edge _hStage; S3: factual focus location R is determined in size and planning work position according to target _fAnd be R by formula (3) _f=R _h+ 2d+6.0mn calculates the stage of circle diameter d; S4: the stage of accurately regulating the control operating position; S5: promptly according to formula (1), (2)

$t_1(O_h{M}_1,R_h)=\frac{M_1{M}_2}{c}=\frac{\sqrt{O_h{M_1}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{O_h{M_1}^2+{R_h}^2}-R_h}{c}$ $(0\&le;O_h{M}_1\&le;\frac{D-d}{2})---\left(1\right)$

$t_2(O_h{M}_3,R_h)=\frac{M_3{M}_4}{c}=\frac{\sqrt{O_h{M_3}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{O_h{M_3}^2+{R_h}^2}-R_h}{c}$ $(0\&le;O_h{M}_3\&le;\frac{d}{2})---\left(2\right)$

The leading launch time of array element on each distributing position of accurate Calculation ultrasonic transducer, in the stage of realizing annular ultrasound focusing, the stage of above-mentioned accurate adjusting control operating position is to be R to formula (3) _f=R _hSetting annulus position R among the+2d+6.0mm _hCarry out coarse adjustment, wherein circle diameter d is carried out thin tuning with accurate control operating position R _fStage, wherein, O _hPoint is datum mark; t ₁(O _hM ₁, R _h) be O _hThe time of the leading emission of M section array element; t ₂(O _hM ₃, R _h) be O _hThe time of the leading emission of O section array element; C is the velocity of sound; D is an array element distribution disc diameter; D is a circle diameter; F _hBe the focus on the annulus; M ₁M ₂, M ₃M ₄Be respectively O _hM section and O _hEach array element of O section array focal point F to the annulus _hDistance and R _hPoor.

2. phase control annular ultrasound focusing method according to claim 1, it is characterized in that: it realizes that according to the leading launch time of array element on formula (1), each distributing position of (2) accurate Calculation ultrasonic transducer the stage of annular ultrasound focusing is at annulus position R _h, under array element distribution disc diameter D, the circle diameter d situation about determining with

$t_1(O_h{M}_1,R_h)=\frac{M_1{M}_2}{c}=\frac{\sqrt{O_h{M_1}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{O_h{M_1}^2+{R_h}^2}-R_h}{c}$ $(0\&le;O_h{M}_1\&le;\frac{D-d}{2})---\left(1\right)$

$t_2(O_h{M}_3,R_h)=\frac{M_3{M}_4}{c}=\frac{\sqrt{O_h{M_3}^2+O_h{F_h}^2}-R_h}{c}=\frac{\sqrt{O_h{M_3}^2+{R_h}^2}-R_h}{c}$ $(0\&le;O_h{M}_3\&le;\frac{d}{2})---\left(2\right)$

Two formulas are divided into the stage of the leading launch time of array element on inside and outside interval each distributing position of accurate Calculation ultrasonic transducer.

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