EP0314487B1 - Delay coefficient calculator - Google Patents

Delay coefficient calculator Download PDF

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Publication number
EP0314487B1
EP0314487B1 EP19880310140 EP88310140A EP0314487B1 EP 0314487 B1 EP0314487 B1 EP 0314487B1 EP 19880310140 EP19880310140 EP 19880310140 EP 88310140 A EP88310140 A EP 88310140A EP 0314487 B1 EP0314487 B1 EP 0314487B1
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EP
European Patent Office
Prior art keywords
series
array
center
focal point
value
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19880310140
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German (de)
English (en)
French (fr)
Other versions
EP0314487A2 (en
EP0314487A3 (en
Inventor
Thomas J. Hunt
David Lipschutz
Bernard J. Savord
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
HP Inc
Original Assignee
Hewlett Packard Co
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Publication date
Application filed by Hewlett Packard Co filed Critical Hewlett Packard Co
Publication of EP0314487A2 publication Critical patent/EP0314487A2/en
Publication of EP0314487A3 publication Critical patent/EP0314487A3/en
Application granted granted Critical
Publication of EP0314487B1 publication Critical patent/EP0314487B1/en
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/18—Methods or devices for transmitting, conducting or directing sound
    • G10K11/26—Sound-focusing or directing, e.g. scanning
    • G10K11/34—Sound-focusing or directing, e.g. scanning using electrical steering of transducer arrays, e.g. beam steering
    • G10K11/341—Circuits therefor
    • G10K11/346—Circuits therefor using phase variation

Definitions

  • pulses of ultrasonic waves are successively transmitted along different radial lines having their origin in the center of the array.
  • a pulse traveling along a radial line meets body tissue, a portion of its energy is reflected back to the array, but because the distances between the point of reflection and each of the transducers is different, the electrical waves produced by the transducers in response to the reflection have different phases. Summing these electrical waves would produce a weak signal for the purpose of controlling the intensity of an image. In order to obtain a strong signal, the electrical waves must be brought reasonably close to a cophasal relationship.
  • a hard wired circuit calculates the differences D between the radius R of a focal point and the distances between the focal point and the transducer elements of the array just prior to the time when reflections from the focal point reach the transducers.
  • the differences D are provided to means for inserting the directly related compensating delays into the circuits for the individual transducer elements. The process is then repeated for each successive focal point in turn. Because of its speed, the circuit can make these calculations in real time for a system having more transducer elements and focal zones than could be practicably handled by a microprocessor.
  • the basic circuit includes a plurality of accumulators connected in series that are respectively preloaded with different values for each focal point before the calculation of D for the transducer elements are made.
  • the values that are preloaded change with the radius R of the focal point, the angle ⁇ that the radial line on which the focal point is located makes with a line perpendicular to the array and the space ⁇ X between the centers of adjacent transducer elements. All accumulators are clocked at the same time.
  • the preloaded value of the last accumulator in the series corresponds to the difference, D, between the radius of the focal point and the distance between that focal point and a transducer element that is on one side of the array.
  • the preloaded values work their way through the accumulators so as to produce a value at the output of the last accumulator that is the difference, D, for the next transducer element. If only one series of accumulators is used, the process would then be performed for the transducer elements on the other side of the array.
  • the respective values with which the accumulators are preloaded are different combinations of the coefficients, or portions thereof, of terms of a series expressing the difference, D, between the radius of a focal point and its distance from a transducer element as a function of the distance X of that element from the center of the array.
  • Each term of the series includes a different power of the independent variable X. The highest power used depends on the required resolution, and the number of accumulators equals the highest power.
  • the calculated distance, D will be correct for a transducer element at the center of the array but will have an error that increases with the distance of a transducer element from the center. A more evenly distributed and smaller error results if the coefficients for the powers of X are derived from Legendre polynomials.
  • One of the advantages of the invention is the fact that simultaneous calculations for the distance D can be made for different groups of transducer elements of the array so as to save time.
  • One way of doing this is to provide a separate series of accumulators for each group and respectively preload them with the values that the accumulators of a single series would have when it reaches the transducer element at the end of the group closer to the center of the array.
  • a focal point F located on a radial line r that makes an angle of ⁇ with a line V that is perpendicular to the array A.
  • FIGURE 2 is a block diagram of an embodiment of the invention designed to calculate the values of D in accordance with equation (12) in which X3 is the highest power of X. Although it is not the usual practice, it will be assumed that there is a transducer element at the center of the array so that, as will appear, the operation will be more apparent.
  • a scanner 2 for the ultrasonic imaging system may operate in ways described in U.S. Pat No. 4,140,022 to transmit pulses of a few cycles of pressure waves along successive radial lines and to provide the delays required for each transducer element that are necessary to focus the array at each focal point.
  • the value of the radius R and the angle ⁇ of the radial line as well as the spacing ⁇ X between adjacent transducer elements of the particular array being used are readily derived from the scanner. These values are applied to ROMs 1, 2, 3 and 4 which respectively output the values of ⁇ , A+B+C, 6A+2B and 6A for each focal point. From equation (12) it can be seen that the values of A, B and C are different for each focal point.
  • accumulator AC1 Because the highest power of X is X3, three accumulators AC1, AC2 and AC3 are provided each having an adder coupled to a register via a multiplexer. Only accumulator AC1 will now be described, but AC2 and AC3 are identical.
  • the output of an adder A1 is connected to one input of a multiplexer MX1, and its output is connected to the input of a register REG1.
  • the other input of MX1 is connected to the output of the ROM1.
  • One input of A1 is connected to the output of REG1 so as to perform the accumulating function, and the other input of A1 is connected to the output of a register REG2 for the accumulator AC2.
  • ROM4 is connected to a register REG4, and its output is connected to one of the inputs of the adder A3 for the accumulator AC3.
  • Clock pulses for the system are derived from the scanner 2 are applied to a multiplexer MX4.
  • MX4 When reflections from a point half way between adjacent focal points are due to arrive at the array, the value of R is updated to the radius of the next farther focal point. This fact is detected by an update detector 3. Its output is applied to MX4 so as to cause it to output a clock pulse that is applied to the clear terminals of the registers REG1, REG2, REG3 and REG4. Subsequent clock pulses are applied to the clock terminals of the registers.
  • the output of the detector 3 is also applied to load terminals of the multiplexers MX1, MX2, and MX3 so as to cause them to preload the values of ⁇ , A+B+C and 6A + 2B for the next focal point into the registers REG1, REG2 and REG3, respectively.
  • the multiplexers MX1, MX2 and MX3 connect the outputs of their adder to the input of this register.
  • the value of 6A from the ROM4 is always applied to one input of the adder A3 for the accumulator AC3.
  • the ROM1 supplies the value of D for the transducer element closest to the center of the array.
  • the preloaded values step through the accumulators AC3, AC2, and AC1 so as to provide a value D for the next outer transducer element at the output of the register REG1 for the accumulator AC1. Its output is supplied to the scanner 2 so as to give it information as to the delay to be used for each transducer element in turn.
  • columns C1, C2, C3 and C4 respectively show the outputs of the registers REG1, REG2, REG3 and REG4 at every clock pulse
  • a column C5 shows the clock pulse number and the number of the transducer element corresponding to the value of D at the output of REG1.
  • the load pulse from the detector 3 causes the multiplexers MX1, MX2 and MX3 to preload the registers REG1, REG2 and REG3 with the values ⁇ , A+B+C and 6A + 2B respectively.
  • the value of D at the output of REG1 is ⁇ , as is required for the transducer element at the center of the array.
  • the delay D is for the transducer #2, which, by substitution of 2 for X in equation (12) is seen to be 8A+ 4B + C.
  • This is derived at clock #4 in the following manner.
  • the values of D for the other transducer elements are derived in a similar manner.
  • the values of X and ⁇ are positive so that the values of D are for transducer elements in FIGURE 1 that are at the right of the center ⁇ of the array and for focal points in the quadrant where the focal point F is located.
  • the values with which the registers are preloaded for other situations will not be fully derived, but it can be seen from FIGURE 1 that D would have a negative value for transducer elements to the left of the center ⁇ of the array and that this would result from making X negative
  • the value of D determined from equation (12) would be -A+B-C, so as to be negative, and this value would be preloaded into REG2 from ROM2, at the second clock pulse.
  • the value preloaded into REG3 by ROM3 would have to be -6A+2B.
  • the value preloaded into REG4 by ROM4 would be found to be -6A.
  • ROMs 8, 10, 12 and 14 respectively provide preloading values to ROMs in each series of accumulators SA8, SA10, SA12. They in turn provide the values of D for the transducer elements in groups G1, G2, G3 and G4. Assume that G1 is immediately to the right of center, G2 is to the right of G2, G3 is to the left of center and G4 is to the left of G3 as shown in FIGURE 5A.
  • the transducer elements of G1 and G3 that are closest to the center ⁇ ' are ⁇ X/2 away from it.
  • Another way of describing the second method is as follows. Express the equation (8) for the distance D in the form of a Taylor series where the offset, a, in the series is the distance between the center of a group and the center of the array. New values of A, B, and C, as well as a value D equal to D(a) will be derived and used to preload the registers of FIGURE 2. Once again, however, it will be necessary to derive these preload values by working backward and to realize that they will be different for the calculations for one half of a group of elements than for the other.
  • FIGURES 6 and 6A Reference is made to FIGURES 6 and 6A for a comparison of the errors resulting from using for the coefficients A, B, and C of the powers of X in a series the values determined by the Legendre method and values ordinarily used.
  • the value of ⁇ and ⁇ are chosen in Step 1 to be the numbers of the transducer elements of a group that are respectively the closest and farthest from the center 0 of the array. By doing this the error within a group is generally reduced and more equally distributed throughout the group.
  • the difference D between the distance of a focal point from a reference point on the array, usually the center, and the distance between a focal point and a transducer element is expressed as a function of the distance X of a transducer element from the reference point.
  • the expression for D is expanded into a series having terms respectively containing different powers of X.
  • the coefficients of these terms will include trigonometric functions of an angle between a perpendicular to the array and a line drawn between the focal point and the reference point, or, in another method, a line drawn between the focal point and the center of a group of transducer elements.
  • the A, B, and C referred to also include the distance of the focal point from the reference point or, in another method, the distance between the focal point and the center of a group of transducer elements.
  • the unit of X is the distance ⁇ X between the center of adjacent transducer elements of the array in use.
  • the number of terms of the series that are required for the desired resolution is determined, and a number of accumulators equal to the highest power of X are coupled in series.
  • the last accumulator in the series was preloaded with the combination of A, B, and C or parts thereof for the transducer elements of a group of elements that was closest to the center of the array, and the preloading for the previous accumulators in the series was determined by working backwards to see what the respective preloading had to be in order to give the correct values of D.
  • the first accumulator in the series was preloaded in two ways, i.e. by preloading the register and by supplying the value 6A to its adder. After the accumulators have been clocked a sufficient number of times for the value 6A to contribute to the value provided by the register of the last accumulator of the series all preloaded values except 6A have no further effect.
  • the preloaded values would be determined by preloading the register of the last accumulator with the values of A, B, C, etc. determined from equation (12) by substitution therein of the value of X for the outermost transducer element and working backward as before.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Ultra Sonic Daignosis Equipment (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
EP19880310140 1987-10-29 1988-10-28 Delay coefficient calculator Expired - Lifetime EP0314487B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US11481587A 1987-10-29 1987-10-29
US114815 1998-07-13

Publications (3)

Publication Number Publication Date
EP0314487A2 EP0314487A2 (en) 1989-05-03
EP0314487A3 EP0314487A3 (en) 1989-10-11
EP0314487B1 true EP0314487B1 (en) 1993-10-13

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EP19880310140 Expired - Lifetime EP0314487B1 (en) 1987-10-29 1988-10-28 Delay coefficient calculator

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EP (1) EP0314487B1 (ja)
JP (1) JP2654130B2 (ja)
DE (1) DE3884905T2 (ja)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR0143247B1 (ko) * 1995-02-06 1998-08-17 이민화 실시간 디지탈 수신집속 방법 및 장치
US5653236A (en) * 1995-12-29 1997-08-05 General Electric Company Apparatus for real-time distributed computation of beamforming delays in ultrasound imaging system
ES2277473B1 (es) * 2004-01-30 2008-07-16 Consejo Sup. Investig. Cientificas Composicion coherente de señales por correccion focal progresiva.
JP5016326B2 (ja) * 2007-03-06 2012-09-05 株式会社日立メディコ 超音波診断装置
JP4974781B2 (ja) * 2007-06-26 2012-07-11 株式会社日立メディコ 超音波診断装置
JP6545089B2 (ja) * 2015-11-27 2019-07-17 エイブリック株式会社 超音波診断用送信回路および超音波送信方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1604159A (en) * 1977-06-15 1981-12-02 Svejsecentralen Apparatus for providing an ultrasonic sectional view
US4140022B1 (en) * 1977-12-20 1995-05-16 Hewlett Packard Co Acoustic imaging apparatus
US4180790A (en) * 1977-12-27 1979-12-25 General Electric Company Dynamic array aperture and focus control for ultrasonic imaging systems

Also Published As

Publication number Publication date
EP0314487A2 (en) 1989-05-03
JP2654130B2 (ja) 1997-09-17
DE3884905T2 (de) 1994-05-05
EP0314487A3 (en) 1989-10-11
DE3884905D1 (de) 1993-11-18
JPH01193679A (ja) 1989-08-03

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