JP6771279B2 - Ultrasonic probe and ultrasonic image display device - Google Patents

Description

The present invention relates to an ultrasonic probe and an ultrasonic image display device that take measures against heat generated when transmitting and receiving ultrasonic waves.

The ultrasonic image display device is a device that displays an ultrasonic image based on an echo signal obtained by performing an ultrasonic scan (scan) on a subject. In such an ultrasonic image display device, the ultrasonic scan is performed by an ultrasonic probe connected to the device main body via a probe cable.

The ultrasonic probe has an ultrasonic oscillator, an acoustic matching layer, and a backing layer. More specifically, the acoustic matching layer is provided on the subject side of the ultrasonic vibrator, and the backing layer is provided on the side opposite to the subject (see, for example, Patent Document 1). Further, an acoustic lens that comes into contact with the subject is provided on the subject side with respect to the acoustic matching layer. The ultrasonic vibrator is composed of a piezoelectric element such as PZT (lead zirconate titanate), and a voltage is applied to the ultrasonic vibrator to transmit ultrasonic waves.

JP-A-2009-611112

By the way, the backing layer has a role of absorbing ultrasonic waves propagated from the ultrasonic vibrator to the side opposite to the subject. If the backing layer having such a role is formed of a material having an acoustic impedance close to the acoustic impedance of the ultrasonic vibrator, the acoustic output to the backing layer side increases and the ultrasonic transmission efficiency deteriorates. Therefore, the backing layer is formed of a material having an acoustic impedance different from the acoustic impedance of the ultrasonic vibrator.

Such a material forming the backing layer is a material having a relatively low thermal conductivity. Here, heat is generated when transmitting and receiving ultrasonic waves. Since the backing layer has a relatively low thermal conductivity, the heat generated during the transmission and reception of ultrasonic waves is transferred not to the backing layer side but to the acoustic matching layer side, that is, the subject side. Therefore, if the ultrasonic probe is continuously used, the temperature of the surface of the acoustic lens rises. Therefore, when transmitting and receiving ultrasonic waves, it is necessary to limit the output of ultrasonic waves from the ultrasonic vibrator so that the temperature of the surface of the acoustic lens does not rise too much. From the above, an ultrasonic probe capable of releasing heat generated during transmission / reception of ultrasonic waves to the opposite side of the subject to the ultrasonic vibrator is desired.

The invention made to solve the above-mentioned problems is provided on an ultrasonic vibrator that transmits ultrasonic waves and a surface of the ultrasonic vibrator on the side opposite to the subject side, and is provided from the ultrasonic vibrator. A backing layer made of a material that reflects the transmitted ultrasonic waves and is provided on the opposite side of the reflective layer from the ultrasonic vibrator side and has a thermal conductivity of 100 W / (m · K) or more. It is an ultrasonic probe characterized by comprising.

Another aspect of the invention is the ultrasonic probe according to the above aspect, which comprises a heat conductive member provided on a part of the surface of the backing layer opposite to the reflective layer side. ..

According to the invention from the above viewpoint, since the reflective layer is provided between the ultrasonic vibrator and the backing layer, the acoustic output from the ultrasonic vibrator to the backing layer is suppressed. Therefore, even if the backing layer is formed of a material having a higher acoustic impedance than the conventional one, high transmission efficiency can be maintained. As a result, the backing layer can be formed by using a material having a thermal conductivity of 100 W / (m · K) or more and a higher thermal conductivity than the conventional material, so that the heat generated when transmitting and receiving ultrasonic waves can be efficiently reduced. It can often escape to the opposite side of the subject.

Further, according to the invention from another viewpoint, the thermal conductivity of the backing layer is 100 W / (m) even when the heat conductive member is in contact with only a part of the surface of the backing layer opposite to the reflective layer. -K) or more, the heat generated during the transmission and reception of ultrasonic waves can be efficiently dissipated to the side opposite to the subject via the heat conductive member. In this way, since the heat conductive member has a structure in which the heat conductive member is in contact with only a part of the backing layer, not the entire surface opposite to the reflective layer, the number of parts can be reduced, and the size and weight of the ultrasonic probe can be reduced. Can be planned.

It is a block diagram which shows an example of embodiment of the ultrasonic diagnostic apparatus which concerns on this invention. It is sectional drawing in the elevation direction of the main part of an ultrasonic probe. It is sectional drawing in the azimuth direction of the main part of an ultrasonic probe. FIG. 3 is a plan view of the ultrasonic probe shown in FIG. 3 as viewed from the heat conductive member side. It is an exploded perspective view of a heat conduction member, a shield member, and a housing member.

Hereinafter, embodiments of the present invention will be described. The ultrasonic diagnostic apparatus 100 shown in FIG. 1 is an example of an ultrasonic image display apparatus according to the present invention, and has an ultrasonic probe 1 and an apparatus main body 101 to which the ultrasonic probe 1 is connected.

The apparatus main body 101 includes a transmission / reception beam former 102, an echo data processing unit 103, a display processing unit 104, a display device 105, an operation device 106, a control unit 107, and a storage device 108.

The transmission / reception beam former 102 supplies an electric signal for transmitting ultrasonic waves from the ultrasonic probe 1 under predetermined scan conditions to the ultrasonic probe 1 based on a control signal from the control unit 107. Further, the transmission / reception beam former 102 performs signal processing such as A / D conversion and phase adjustment addition processing on the echo signal received by the ultrasonic probe 1.

The echo data processing unit 103 performs processing for creating an ultrasonic image on the echo data output from the transmission / reception beam former 102. For example, the echo data processing unit 103 creates B-mode data by performing B-mode processing such as logarithmic compression processing and envelope detection processing.

The display processing unit 104 scans and converts the data input from the echo data processing unit 103 by a scan converter (Scan Converter) to create ultrasonic image data, and displays an ultrasonic image based on the ultrasonic image data in the display device 105. To display. The display processing unit 104 creates B-mode image data based on, for example, B-mode data, and displays the B-mode image on the display device 105.

The display device 105 is composed of, for example, an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube). The operation unit 106 includes a switch, a keyboard, a pointing device (not shown), and the like for the operator to input instructions and information.

The control unit 107 is configured to include a CPU (Central Processing Unit), although not particularly shown. The control unit 107 reads out the control program stored in the storage device 108 and executes the functions of each unit in the ultrasonic diagnostic apparatus 100.

The storage device 108 includes an HDD (Hard Disk Drive), a semiconductor memory (Memory) such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and the like.

The ultrasonic probe 1 will be described with reference to FIGS. 2 to 5. 2 to 5 show only the main part of the ultrasonic probe 1. The ultrasonic probe 1 scans the subject with ultrasonic waves. Further, the ultrasonic probe 1 receives an ultrasonic echo signal.

The ultrasonic probe 1 includes an acoustic matching layer 2, an ultrasonic vibrator 3, a reflective layer 4, a flexible substrate 5, a backing layer 6, and a heat conductive member 7. The acoustic matching layer 2, the ultrasonic vibrator 3, and the reflective layer 4 having a rectangular shape long in the Y-axis direction are stacked in the Z-axis direction, which is the direction along the ultrasonic irradiation direction, to form the laminated body 8. .. A plurality of these laminated bodies 8 are arranged in the X-axis direction.

By the way, the X-axis direction is the azimuth direction, and the Y-axis direction is the elevation direction.

The acoustic matching layer 2 is adhered to the plate surface of the ultrasonic vibrator 3 on the ultrasonic irradiation direction side (subject side) (the adhesive layer is not shown). An acoustic lens portion (not shown) is provided on the ultrasonic irradiation direction side of the acoustic matching layer 2. The acoustic matching layer 2 has an acoustic impedance intermediate between the ultrasonic vibrator 3 and the acoustic lens portion. Further, the acoustic matching layer 2 has a thickness of approximately 1/4 wavelength of the center frequency of the transmitted ultrasonic waves, and suppresses reflection at the interface where the acoustic impedances are different. Further, although the example of one layer is shown in this example, the acoustic matching layer 2 may be two layers or multiple layers.

The ultrasonic vibrator 3 is composed of a piezoelectric body 9 and a conductive layer 10. The piezoelectric body 9 is PZT or the like, and transmits ultrasonic waves. A conductive layer 10 is formed on the surface of the piezoelectric body 9 by sputtering or the like. The ultrasonic vibrator 3 is an example of the embodiment of the ultrasonic vibrator in the present invention.

The conductive layer 10 has a signal electrode 11 and a ground electrode 12. The signal electrode 11 is formed in a portion 9a between the drilling holes 13 and 13, which will be described later, in the piezoelectric body 9. Further, the ground electrode 12 has the first portions 12a and 12a formed on the same surface of the signal electrodes 11 and the drilling holes 13 and 13 at the ends 9b and 9b of the piezoelectric body 9 and the first portions 12a and 12a of the piezoelectric body 9. Between the second portion 12b formed on the surface opposite to the surface on which the first portion 12a, 12a is formed and the first portion 12a, 12a and the second portion 12b in the rectangular parallelepiped ultrasonic transducer 3 It is composed of the third portions 12c and 12c formed on the side surface of the above. The signal electrode 11 is formed so as to be sandwiched between the first portions 12a and 12a of the ground electrode 12, and both electrodes 11 and 12 are electrically insulated by the excavation holes 13 and 13.

The ultrasonic vibrator 3 is adhered to the reflective layer 4 via an adhesive layer (not shown). The combined thickness of the ultrasonic vibrator 3 and the adhesive layer is approximately 1/4 of the center frequency of the ultrasonic waves generated by the vibration of the ultrasonic vibrator 3. Specifically, the combined thickness of the ultrasonic vibrator 3 and the adhesive layer is about several hundred μm.

The reflective layer 4 is adhered to the surface of the ultrasonic transducer 3 on the side opposite to the subject (the side opposite to the acoustic matching layer 2) by the adhesive layer made of an epoxy resin adhesive or the like. The reflective layer 4 is adhered to the signal electrode 11 and the first portions 12a and 12a.

Here, the surface of the reflective layer 4 on the ultrasonic vibrator 3 side is mirror-polished. Further, the surfaces of the signal electrode 11 and the first portions 12a and 12a of the ultrasonic vibrator 3 are also mirror-polished. As a result, the surface of the reflective layer 4 on the ultrasonic vibrator 3 side and the surfaces of the signal electrodes 11 and the first portions 12a and 12a of the ultrasonic vibrator 3 are suppressed to about several μm. Therefore, the thickness of the adhesive layer can be set to about several μm, and can be made as thin and uniform as possible.

As described above, the thickness of the adhesive layer is about the same as the unevenness of the surface of the signal electrode 11, the unevenness of the surface of the first portions 12a and 12a, and the unevenness of the surface of the reflective layer 4. Therefore, although the adhesive layer is an insulator containing an epoxy resin adhesive, the signal electrode 11, the first portions 12a, 12a and the reflective layer 4 are partially in contact with each other at the uneven portion of the surface. It is conducting.

The reflective layer 4 functions as a fixed end that reflects the ultrasonic waves transmitted to the reflective layer 4 side by the vibration of the ultrasonic vibrator 3 in the direction of the subject. The ultrasonic waves reflected by the reflective layer 4 increase the ultrasonic power incident on the subject. The reflective layer 4 is an example of the embodiment of the reflective layer in the present invention. The reflective layer 4 is formed of a material having a higher acoustic impedance than the piezoelectric body 14 for the purpose of reflecting ultrasonic waves from the ultrasonic vibrator 3. For example, the reflective layer 4 is tungsten.

Further, since the tungsten constituting the reflective layer 4 has conductivity, the reflective layer 4 includes the first copper foil layer 14 and the second copper foil layer 15 of the flexible substrate 5, which will be described later, and the ultrasonic transducer 3. It has a function of electrically connecting the signal electrode 11 and the ground electrode 12 of the above. As a result, the voltage supplied from the first copper foil layer 14 and the second copper foil layer 15 is applied to the ultrasonic vibrator 3 via the reflection layer 4.

Drilling holes 13 and 13 are formed at both ends of the reflective layer 4 and the ultrasonic vibrator 3 in the length direction. The drill holes 13 and 13 are formed, for example, by bonding the ultrasonic vibrator 3 and the reflective layer 4 with the adhesive layer, and then cutting from the reflective layer 4 side using a diamond grindstone or the like.

A flexible substrate 5 is adhered to the backing layer 6 by using an adhesive on the surface of the reflective layer 4 opposite to the adhesive surface with the ultrasonic vibrator 3 (adhesive layer is not shown). The flexible substrate 5 is pulled out along the side surface in the thickness direction of the backing layer 6 and is connected to a connection cable (not shown) that connects the ultrasonic probe 1 and the apparatus main body 101.

Explaining the configuration of the flexible substrate 5, the flexible substrate 5 is composed of four layers: a first copper foil layer 14, a second copper foil layer 15, a first polyimide film layer 16, and a second polyimide film layer 17. .. The first copper foil layer 14 and the second copper foil layer 15 are insulated from each other by the first polyimide film layer 16. The first copper foil layer 14 is formed so as to be located on both end sides of the reflective layer 4 with respect to the excavation holes 13 and 13 in a state of being adhered to the reflective layer 4. Further, the second copper foil layer 15 is laminated between the first polyimide film layer 16 and the second polyimide film layer 17, and is a through hole on the central portion side of the reflection layer 4 with respect to the excavation holes 13 and 13. It is also present on the same surface as the first copper foil layer 14 via (throgue hole) H. The first copper foil layer 14 and the second copper foil layer 15 existing on the same surface are insulated from each other by the dividing groove 18. The dividing groove 18 is formed so as to be at the positions of the excavation holes 13 and 13 when the flexible substrate 5 is adhered to the reflective layer 4. As a result, the first copper foil layer 14 is electrically connected to the end side of the excavation holes 13 and 13 in the conductive reflective layer 4, while the second copper foil layer 15 is in the reflective layer 4. It is electrically connected to the intermediate portion between the drilling holes 13 and 13. Therefore, the first copper foil layer 14 is electrically connected to the first portions 12a and 12a of the ground electrode 12 in the ultrasonic vibrator 3 via the reflection layer 4, and the second copper foil layer 15 is super. It is electrically connected to the signal electrode 11 of the ultrasonic vibrator 3 via the reflection layer 4.

By the way, the first copper foil layer 14 connected to the ground electrode 12 is formed on the entire surface of the flexible substrate 5 (excluding the portion where the second copper foil layer 15 is formed), and is arranged in the X-axis direction. The conduction of the ground electrode 12 of all the ultrasonic transducers 3 is common. On the other hand, the second copper foil layer 15 is divided into a plurality of pieces in the X-axis direction by a copper foil dividing groove (not shown), and has a plurality of copper foil patterns (not shown) formed in the flexible substrate 5. This copper foil pattern is formed for each of the plurality of laminated bodies 8 arranged in the X-axis direction.

The backing layer 6 is adhered to the surface of the flexible substrate 5 opposite to the reflective layer 4, or is directly formed on the surface of the flexible substrate 5 opposite to the reflective layer 4 to hold the flexible substrate 5. Therefore, the backing layer 6 is provided on the side opposite to the ultrasonic vibrator 3 with respect to the reflective layer 4. The backing layer 6 is an example of the embodiment of the backing layer in the present invention.

The backing layer 6 is made of a material having a thermal conductivity of 100 W / (m · K) or more. For example, the backing layer 6 may be made of a material having a thermal conductivity of 100 W / (m · K) or more and 300 W / (m · K) or less. However, the backing layer 6 may have a thermal conductivity of 100 W / (m · K) or more, and does not have to be 300 W / (m · K) or less.

The backing layer 6 is an inorganic material, and is made of, for example, graphite or aluminum. Further, the backing layer 6 has a non-uniform structure capable of scattering ultrasonic waves from the ultrasonic vibrator 3. More specifically, the backing layer 6 has a non-uniform structure at the wavelength level of the ultrasonic waves transmitted from the ultrasonic vibrator 3, for example, a non-uniform structure having a size of several tens of μm to 1 mm. Have. By having such a non-uniform structure, sound absorption performance can be ensured.

The heat conductive member 7 is provided on the surface 6a of the backing layer 6 opposite to the reflective layer 4. The heat generated during the transmission and reception of ultrasonic waves is transferred to the heat conductive member 7 via the reflective layer 4, the flexible substrate 5, and the backing layer 6.

The heat conductive member 7 will be described in a little more detail. The heat conductive member 7 has a width smaller than the length of the backing layer 6 in the azimuth direction, and is provided in contact with a part P of the surface 6a of the backing layer 6 as shown in FIGS. 3 and 4. .. Part P is a part of the surface 6a in the azimuth direction. The area of the partial P is less than one-third of the total area of the surface 6a.

By the way, in FIG. 4, the second portions 7b and 7b (reference numerals omitted in FIG. 4), which will be described later, are shown in cross section of the heat conductive member 7.

In this example, the heat conductive member 7 is a heat pipe in which a refrigerant is sealed in a closed container. As shown in FIGS. 2 and 5, the heat conductive member 7 is formed in a substantially U shape. More specifically, the heat conductive member 7 has a first portion 7a and second portions 7b, 7b rising from both ends of the first portion 7a. A bent portion 7c is formed between the first portion 7a and the second portion 7b. The first portion 7a is fixed to the backing layer 6. The first portion 7a extends in the elevation direction along a part P of the backing layer 6 in a state of being fixed to the backing layer 6. The second portion 7b extends from the first portion 7a to the side opposite to the backing layer 6 in a state where the heat conductive member 7 is fixed to the backing layer 6.

The second portion 7b is in contact with the pair of shield members 19a and 19b shown in FIG. 5 (the contact portion is not shown). The shield members 19a and 19b are provided along the housing members 20a and 20b in the pair of housing members 20a and 20b. Therefore, the heat generated during the transmission and reception of ultrasonic waves is diffused from the second portion 7b to the shield members 19a and 19b, and further radiated from the housing members 20a and 20b to the outside.

Incidentally, the pair of housing members 20a and 20b are joined to form the probe housing 20. Further, in the probe housing 20, the shield members 19a and 19b are joined to form the shield body 19.

According to this example, since the ultrasonic wave from the ultrasonic vibrator 3 is reflected to the subject side by the reflective layer 4, the acoustic output from the ultrasonic vibrator 3 to the backing layer 6 is suppressed. Therefore, even if the backing layer 6 is made of a material having a higher acoustic impedance than the conventional one, high transmission efficiency can be maintained.

Here, in the ultrasonic probe that does not have the reflection layer 4, in order to secure the transmission efficiency, it is necessary to form the backing layer with a material that can sufficiently absorb the ultrasonic waves from the ultrasonic vibrator. Such a material has a thermal conductivity of, for example, 0.1 W / (m · K) to 1.0 W / (m · K). On the other hand, according to this example, since the reflective layer 4 can maintain high transmission efficiency as described above, it is possible to form the backing layer 6 with a material having higher acoustic impedance and lower sound absorption than the conventional one. Therefore, the backing layer 6 can be formed of a material having a thermal conductivity of 100 W / (m · K) or more, which is higher than the conventional material.

Since the backing layer 6 can be formed of a material having a higher thermal conductivity than the conventional one, the heat conductive member 7 is a part P having an area of one-third or less of the entire surface 6a of the backing layer 6. Even in the state of contact with the chisel, the heat generated during the transmission and reception of ultrasonic waves can be efficiently dissipated to the side opposite to the subject via the heat conductive member 7. As described above, since the heat conductive member 7 has a structure in which the backing layer 6 is in contact with only a part P, not the entire surface opposite to the reflective layer 4, the number of parts is reduced and the ultrasonic probe 1 is made smaller. It is possible to reduce the weight and weight.

Moreover, since the heat conductive member 7 is a heat pipe, heat can be transferred with higher efficiency.

Although the present invention has been described above with reference to the above-described embodiment, it goes without saying that the present invention can be modified in various ways without changing its gist.

1 Ultrasonic probe 3 Ultrasonic vibrator 4 Reflective layer 6 Backing layer 7 Heat conductive member 100 Ultrasonic diagnostic device

Claims (6)

An ultrasonic oscillator that sends ultrasonic waves and
A reflective layer provided on the surface of the ultrasonic vibrator on the side opposite to the subject side and reflecting ultrasonic waves transmitted from the ultrasonic vibrator.
Wherein in said reflecting layer and the ultrasonic vibrator-side a backing layer that is provided on the opposite side, across the backing layer, the thermal conductivity Ri Do from 100W / (m · K) or more der Ru material, A backing layer having a non-uniform structure capable of scattering ultrasonic waves from the ultrasonic vibrator,
A heat conductive member provided on a part of the surface of the backing layer opposite to the reflective layer side,
An ultrasonic probe characterized by being equipped with. The claim is characterized in that the area of the part of the backing layer provided with the heat conductive member is one-third or less of the total area of the surface of the backing layer opposite to the reflective layer side. Item 1. The ultrasonic probe according to item 1. The heat conductive member comprises a first portion extending along the portion of the backing layer and a second portion extending from the first portion to the side opposite to the backing layer, and the first portion. The ultrasonic probe according to claim 1 or 2, wherein a bent portion is provided between the second portion and the second portion. The ultrasonic probe according to any one of claims 1 to 3, wherein the heat conductive member is a heat pipe. The ultrasonic probe according to any one of claims 1 to 4, wherein the backing layer is made of an inorganic material. An ultrasonic image display device comprising the ultrasonic probe according to any one of claims 1 to 5.