Ultrasonic probe and ultrasonic endoscope

Abstract

An ultrasonic probe includes: an ultrasonic transducer array in which a plurality of ultrasonic transducers for transmitting and receiving ultrasonic waves are arranged; a backing layer provided at a base end surface of the ultrasonic transducer array; and a piezoelectric body provided at a base end surface of the backing layer, the piezoelectric body having a polarization direction opposite to a polarization direction of the ultrasonic transducers. Thus, an ultrasonic probe having a small front end is provided.

Description

Technical Field

[0001] This invention relates to ultrasonic probes and ultrasonic endoscopes. Background Technology

[0002] Previously, an ultrasonic probe with multiple ultrasonic transducers for transmitting and receiving ultrasonic waves was known. The ultrasonic probe was positioned at the front end of the insertion section of an endoscope, and ultrasonic waves were used to observe the contents of the patient's body. Ultrasonic waves transmitted in the direction of the acoustic axis (which serves as the direction of observation by the ultrasonic transducers) were reflected within the patient's body, and the ultrasonic transducers received the reflected ultrasonic waves. Furthermore, an attenuation effect on the observation was prevented by using a backing layer provided on the side of the ultrasonic transducer opposite to the acoustic axis direction.

[0003] Furthermore, there is a growing trend in endoscopes to miniaturize the tip of the insertion section in order to reduce the burden on patients. Patent Document 1 discloses an ultrasonic endoscope in which the tip of the insertion section is miniaturized by cutting away a portion of the backing layer.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2006-255246 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] However, in the technology of Patent Document 1, although a portion of the backing layer is cut off, the backing layer itself cannot be thinned.

[0009] The present invention was made in view of the above circumstances, and its purpose is to provide a small-sized ultrasonic probe and an ultrasonic endoscope.

[0010] Solution for solving the problem

[0011] To address the aforementioned problems and achieve the objective, one technical solution of the present invention provides an ultrasonic probe comprising: an ultrasonic transducer array having a plurality of ultrasonic transducers arranged thereon for transmitting and receiving ultrasonic waves; a backing layer disposed on the base end face of the ultrasonic transducer array; and a piezoelectric element disposed on the base end face of the backing layer, wherein the polarization direction of the piezoelectric element is opposite to the polarization direction of the ultrasonic transducers.

[0012] Furthermore, in one embodiment of the present invention, the base end face of the ultrasonic transducer array and the base end face of the backing layer are the sides opposite to the direction in which the ultrasonic transducer uses ultrasonic waves for observation.

[0013] Furthermore, in one embodiment of the present invention, the ultrasonic transducer is arranged along at least a portion of a circular arc, and the backing layer is disposed on the inner circumferential side of the circular arc.

[0014] Furthermore, in one embodiment of the present invention, the ultrasonic transducer is arranged along an arc, and the backing layer is cylindrical and disposed on the inner circumference of the arc.

[0015] Furthermore, in one embodiment of the ultrasonic probe of the present invention, the resonant frequency of the piezoelectric element is 5MHz or higher and 12MHz or lower.

[0016] Furthermore, in an ultrasonic probe of one embodiment of the present invention, the wavelength of the ultrasonic wave, which is the resonant frequency of the piezoelectric element, in the backing layer is set as λ. The thickness T1 of the backing layer along the acoustic axis direction, which serves as the direction in which the ultrasonic transducer is used for observation, satisfies T1 = (1 / 2 × odd number) × λ. The resonant frequency of the piezoelectric element is set as f0, the frequency constant of the piezoelectric element is set as N, and the thickness T2 of the piezoelectric element along the acoustic axis direction satisfies f0 = N / T2.

[0017] Furthermore, in one embodiment of the present invention, an ultrasonic probe includes a dematching layer disposed on the base end face of the piezoelectric element, which has an acoustic impedance higher than that of the piezoelectric element.

[0018] Furthermore, in an ultrasonic probe of one embodiment of the present invention, the wavelength of the ultrasonic wave, which is the resonant frequency of the piezoelectric element, in the backing layer is set as λ. The thickness T1 of the backing layer along the acoustic axis direction, which serves as the direction in which the ultrasonic wave is observed, satisfies T1 = (1 / 2 × odd number) × λ. The resonant frequency of the piezoelectric element is set as f0, the frequency constant of the piezoelectric element is set as N, and the thickness T3 of the piezoelectric element along the acoustic axis direction satisfies f0 = N / (2 × T3).

[0019] Furthermore, one embodiment of the present invention provides an ultrasonic endoscope comprising: an ultrasonic probe; a rigid front end portion on which the ultrasonic probe is disposed; an illumination portion extending through the inner side of the backing layer to irradiate illumination light onto the subject from the front end of the rigid front end portion; an imaging portion extending through the inner side of the backing layer for imaging the subject from the front end of the rigid front end portion; and a treatment instrument channel extending through the inner side of the backing layer to allow a treatment instrument to protrude from the front end of the rigid front end portion.

[0020] The effects of the invention

[0021] According to the present invention, a small-sized ultrasonic probe and ultrasonic endoscope can be realized. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an endoscope system including the ultrasonic probe of Embodiment 1.

[0023] Figure 2 It is a three-dimensional view of the front end of the insertion part.

[0024] Figure 3 It is Figure 2 The sectional view obtained by cutting along line A-A.

[0025] Figure 4 yes Figure 3 The image shows a view of the ultrasonic probe from direction B.

[0026] Figure 5 Is with Figure 4 The sectional view corresponding to the C-C line.

[0027] Figure 6 It is a diagram used to illustrate the polarization direction.

[0028] Figure 7 This is a diagram illustrating the situation where vibrations cancel each other out.

[0029] Figure 8 This is a diagram used to illustrate the polarization direction of the ultrasonic probe in Embodiment 2.

[0030] Figure 9 This is a perspective view of the front end of the insertion section of an endoscope system including the ultrasonic probe of Embodiment 3.

[0031] Figure 10 Is with Figure 9 The sectional view corresponding to the E-E line.

[0032] Figure 11 Is with Figure 10 The sectional view corresponding to the F-F line.

[0033] Figure 12 This is a partial cross-sectional view of the ultrasonic probe of embodiment 4.

[0034] Figure 13 This is a partial cross-sectional view of the ultrasonic probe of embodiment 5.

[0035] Figure 14 This is a partial cross-sectional view of the ultrasonic probe of embodiment 6. Detailed Implementation

[0036] Hereinafter, embodiments of the ultrasonic probe and ultrasonic endoscope of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to these embodiments. The present invention can generally be applied to ultrasonic probes and ultrasonic endoscopes.

[0037] Furthermore, in the following accompanying drawings, the same or corresponding elements will be appropriately labeled with the same reference numerals. However, the drawings are schematic, and it should be noted that the dimensional relationships and scales of the elements may sometimes differ from reality. The drawings may also contain portions with different dimensional relationships and scales.

[0038] (Implementation Method 1)

[0039] Figure 1 This is a schematic diagram illustrating an endoscope system including the ultrasonic probe of Embodiment 1. Endoscope system 1 is a system for performing ultrasonic observation within a human or other body using an ultrasonic endoscope. Figure 1 As shown, the endoscope system 1 includes an ultrasonic endoscope 2, an ultrasonic observation device 3, an endoscope observation device 4, and a display device 5.

[0040] The ultrasonic endoscope 2 can be partially inserted into the body of the patient. It has the functions of sending ultrasonic pulses (acoustic pulses) toward the body wall of the patient and receiving ultrasonic echoes reflected from the patient to output echo signals, as well as taking pictures of the patient and outputting image signals. The detailed structure of the ultrasonic endoscope 2 will be described later.

[0041] The ultrasonic observation device 3 is equipped with an ultrasonic cable 31. Figure 1 It is electrically connected to the ultrasonic endoscope 2, outputs pulse signals to the ultrasonic endoscope 2 via the ultrasonic cable 31, and inputs echo signals from the ultrasonic endoscope 2. Moreover, in the ultrasonic observation device 3, the echo signals are subjected to predetermined processing to generate an ultrasonic image.

[0042] The endoscope connector 9 (described later in the section on ultrasonic endoscope 2) Figure 1 It is connected to the endoscope observation device 4 in a detachable manner. For example... Figure 1 As shown, the endoscopic observation device 4 includes a video processor 41 and a light source device 42.

[0043] The video processor 41 receives image signals from the ultrasonic endoscope 2 via the endoscope connector 9. Furthermore, the video processor 41 performs predetermined processing on the image signals to generate an endoscopic image.

[0044] The light source device 42 supplies illumination light to the ultrasonic endoscope 2 via the endoscope connector 9 to illuminate the body being examined.

[0045] The display device 5 is constructed using liquid crystal or organic EL (Electro Luminescence) and is used to display ultrasonic images generated by the ultrasonic observation device 3, endoscopic images generated by the endoscopic observation device 4, etc.

[0046] [Structure of an ultrasonic endoscope]

[0047] Next, the structure of the ultrasonic endoscope 2 will be described. For example... Figure 1 As shown, the ultrasonic endoscope 2 includes an insertion section 6, an operating section 7, a universal cable 8, and an endoscope connector 9. Furthermore, the term "front end side" as used below refers to the front end side of the insertion section 6 (the front end side in the insertion direction into the patient's body). Additionally, the term "base end side" as used below refers to the side furthest from the front end of the insertion section 6 (the operating section 7 side).

[0048] Insertion part 6 is the part that is inserted into the body being examined. For example... Figure 1 As shown, the insertion part 6 includes an ultrasonic probe 10 that transmits and receives ultrasonic waves at its front end, a bendable portion 61 connected to the base end of the ultrasonic probe 10, and a flexible tube 62 connected to the base end of the bendable portion 61. Furthermore, the detailed structure of the ultrasonic probe 10 assembled in the insertion part 6, which is a key part of the present invention, will be described later.

[0049] The operating part 7 is connected to the base of the insertion part 6, and is the part from which doctors and others receive various operations. For example... Figure 1 As shown, the operating unit 7 includes a bending knob 71 for bending the bending section 61, multiple operating components 72 for performing various operations, and a treatment device insertion port 73 for inserting treatment devices.

[0050] The general-purpose cable 8 extends from the operation unit 7 and is equipped with a light guide for transmitting illumination light supplied from the light source device 42, a vibrator cable for transmitting the aforementioned pulse signal and echo signal, and a signal cable for transmitting the aforementioned image signal.

[0051] The endoscope connector 9 is located at the end of the universal cable 8. Furthermore, the endoscope connector 9 is connected to the ultrasonic cable 31 and is connected to the video processor 41 and the light source device 42 by being inserted into the endoscope observation device 4.

[0052] [Structure of an ultrasonic probe]

[0053] Next, the structure of the ultrasonic probe 10 will be explained. Figure 2 This is a three-dimensional view of the front end of the insertion section. For example... Figure 2As shown, the ultrasonic probe 10 is an ultrasonic probe with an electronic radial scanning method at the front end, which transmits ultrasonic pulses radially. At the front end of the insertion part 6 are provided: a front rigid part 100, which houses the ultrasonic probe 10; an illumination part 101, which illuminates the subject from the front end of the front rigid part 100 with illumination light from the light source device 42; an imaging part 102, which is used to take images of the subject from the front end of the front rigid part 100; and a treatment instrument channel 103, which allows the treatment instrument to protrude from the front end of the front rigid part 100.

[0054] Figure 3 It is Figure 2 The sectional view obtained by cutting along line A-A. For example... Figure 3 As shown, the ultrasonic probe 10 includes an ultrasonic transducer array 104 having multiple ultrasonic transducers 104a, a backing layer 105 disposed on the base end face of the ultrasonic transducer array 104, a piezoelectric element 106 disposed on the base end face of the backing layer 105, a first acoustic impedance matching layer 107 disposed on the front end face of the ultrasonic transducer array 104, a second acoustic impedance matching layer 108 disposed on the front end face of the first acoustic impedance matching layer 107, and an acoustic lens 109 covering the outer periphery of the ultrasonic probe 10. The illumination unit 101, the imaging unit 102, and the processing device channel 103 extend through the inner side of the backing layer 105. Furthermore, hereafter, the direction in which the ultrasonic transducer 104a observes using ultrasonic waves is defined as the acoustic axis direction (the direction that extends radially from the center of the circle formed by the ultrasonic transducer 104a), the front end face in the acoustic axis direction is called the front end face, and the base end face in the acoustic axis direction is called the base end face.

[0055] Figure 4 yes Figure 3 The image shows a view of the ultrasonic probe from direction B. Figure 5 Is with Figure 4 The sectional view corresponding to the C-C line. Figure 4 Is with Figure 5 The sectional view corresponding to the D-D line. For example... Figure 5 As shown, the ultrasonic probe 10 has a side plate 110 provided on the front end side and the base end side in the length direction of the insertion part 6.

[0056] The ultrasonic transducer array 104 has a plurality of ultrasonic transducers 104a arranged along an arc. The ultrasonic transducers 104a are prismatic and arranged in alignment along their length.

[0057] The ultrasonic transducer 104a transmits and receives ultrasonic waves based on control by the ultrasonic observation device 3. For example, the ultrasonic transducer 104a transmits ultrasonic waves in a frequency band of 5 MHz to 12 MHz. A grounding wire GND 104b is formed on the front end face of the ultrasonic transducer 104a.

[0058] The ultrasonic transducer 104a can be formed using lead zirconate titanate (PZT), but it can also be formed using PMN-PT single crystals, PMN-PZT single crystals, PZN-PT single crystals, PIN-PMN-PT single crystals, PIN-PZN-PT single crystals, or relaxor piezoelectric materials. There are no particular limitations on the material as long as it possesses piezoelectric properties. Furthermore, PMN-PT single crystal is an abbreviation for a solid solution of lead magnesium niobate and lead titanate. PMN-PZT single crystal is an abbreviation for a solid solution of lead magnesium niobate and lead zirconate titanate. PZN-PT single crystal is an abbreviation for a solid solution of lead zinc niobate and lead titanate. PIN-PMN-PT single crystal is an abbreviation for a solid solution of lead indium niobate, lead magnesium niobate, and lead titanate. PIN-PZN-PT single crystal is an abbreviation for a solid solution of lead indium niobate, lead zinc niobate, and lead titanate. Relaxorable piezoelectric materials are a general term for three-component piezoelectric materials obtained by adding lead-based composite perovskites as relaxants to lead titanate (PT) to increase the piezoelectric constant and dielectric constant. Lead-based composite perovskites are represented by Pb(B1,B2)O3, where B1 is any of magnesium, zinc, indium, and scandium, and B2 is any of niobium, tantalum, and tungsten. These materials exhibit excellent piezoelectric effects. Therefore, even with miniaturization, the electrical impedance can be reduced.

[0059] The backing layer 105 is cylindrical and disposed on the inner periphery of the arc formed by the ultrasonic transducer array 104. The backing layer 105 attenuates unwanted ultrasonic vibrations generated by the movement of the ultrasonic transducer 104a. The backing layer 105 is formed using a material with a high attenuation rate, such as epoxy resin dispersed with fillers such as alumina and zirconium oxide, or rubber dispersed with the aforementioned fillers. The wavelength of the ultrasonic wave with the resonant frequency of the piezoelectric element 106 in the backing layer 105 is set as λ, and the thickness T1 of the backing layer 105 along the acoustic axis preferably satisfies T1 = (1 / 2 × odd number) × λ.

[0060] A piezoelectric element 106, in a cylindrical shape, is disposed on the inner circumference of the arc formed by the ultrasonic transducer array 104. The piezoelectric element 106 can be formed in a continuous series along the circumference, or it can be divided into elongated rectangular shapes along the circumference, similar to the ultrasonic transducer array 104. The polarization direction of the piezoelectric element 106 is opposite to that of the ultrasonic transducer 104a, thereby attenuating the vibration of the ultrasonic transducer 104a. The piezoelectric element 106, like the ultrasonic transducer 104a, is formed of a piezoelectric material, which can be the same material as the ultrasonic transducer 104a or a different material. The resonant frequency of the piezoelectric element 106 only needs to be within the frequency band of the ultrasonic waves transmitted by the ultrasonic transducer 104a, for example, between 5 MHz and 12 MHz. However, by setting it to the low-frequency side of the ultrasonic waves transmitted by the ultrasonic transducer 104a, the ultrasonic waves attenuated at low frequencies can be attenuated. Therefore, the resonant frequency of the piezoelectric element 106 is more preferably 5 MHz, and an example with a resonant frequency of 5 MHz will be described below. Let the resonant frequency of the piezoelectric element 106 be f0, the frequency constant of the piezoelectric element 106 be N, and the thickness T2 of the piezoelectric element 106 along the acoustic axis satisfy f0 = N / T2. A grounding wire GND106a is formed on the base end face of the piezoelectric element 106.

[0061] The first acoustic impedance matching layer 107 and the second acoustic impedance matching layer 108 match the acoustic impedance between the ultrasonic transducer array 104 and the observed object, so as to allow sound (ultrasound) to pass through efficiently between the ultrasonic transducer array 104 and the observed object. The first acoustic impedance matching layer 107 and the second acoustic impedance matching layer 108 are formed of different materials. In addition, in this embodiment 1, it is described as having two acoustic impedance matching layers (the first acoustic impedance matching layer 107 and the second acoustic impedance matching layer 108), but depending on the characteristics of the ultrasonic transducer array 104 and the observed object, acoustic impedance matching layers may not be provided, or one layer may be provided, or three or more layers may be provided.

[0062] The acoustic lens 109 is formed using materials such as silicon, polymethylpentene, epoxy resin, and polyetherimide. One side of the lens is convex or concave, which enables it to focus ultrasonic waves, either projecting the ultrasonic waves that have passed through the acoustic impedance matching layer to the outside or receiving ultrasonic echoes from the outside. The acoustic lens 109 can be arbitrarily configured, or it can be a structure without the acoustic lens 109.

[0063] The side plate 110 houses the ultrasonic transducer 104a and the backing layer 105. The side plate 110 is preferably separate from the ultrasonic transducer 104a so as not to transmit the vibration of the ultrasonic transducer 104a.

[0064] Figure 6 This is a diagram used to illustrate the polarization direction. The wavelength of the ultrasonic wave at the resonant frequency of the piezoelectric material 106 in the backing layer 105 is defined as λ. Figure 6 The thickness T1 of the backing layer 105 along the acoustic axis satisfies T1 = (1 / 2 × odd number) × λ. For example, when the sound velocity in the backing layer 105 is 1800 m / s and the resonant frequency of the piezoelectric element 106 is 5 MHz, λ / 2 = (1800 / 5000000) / 2 = 180 μm. Therefore, the thickness T1 of the backing layer 105 only needs to be set to 180 μm. Furthermore, since the sound velocity in the backing layer 105 varies depending on the material, type, and amount of filler, the thickness T1 of the backing layer 105 needs to be appropriately selected according to the conditions of the backing layer 105. Let the elastic modulus of the medium be M, and the density of the medium be ρ. The sound velocity c in the medium can be expressed as c = √(M / ρ). Therefore, the thickness T1 should be appropriately selected according to their physical properties.

[0065] According to the above relationship, the thickness T2 of the piezoelectric material 106 in the acoustic axis direction satisfies T2 = N / f0. For example, when the resonant frequency of the piezoelectric material 106 is 5MHz and the frequency constant of the piezoelectric material 106 is 1400, the thickness T2 can be set to 1400 / 5000000 = 280μm. Furthermore, since the frequency constant varies depending on the material of the piezoelectric material 106, the thickness T2 of the piezoelectric material 106 needs to be appropriately selected accordingly.

[0066] The polarization direction PD1 of the ultrasonic transducer 104a is opposite to the polarization direction PD2 of the piezoelectric body 106. As a result, the ultrasonic waves emitted by the ultrasonic transducer 104a and the ultrasonic waves emitted by the piezoelectric body 106 are out of phase.

[0067] Figure 7 This is a diagram illustrating the situation where vibrations cancel each other out. For example... Figure 7 As shown, when the thickness T1 of the backing layer 105 is λ / 2, the 5MHz frequency component of the ultrasonic wave transmitted by the ultrasonic transducer 104a, i.e., ultrasonic wave W1, cancels out the 5MHz resonant frequency ultrasonic wave W2 transmitted by the piezoelectric element 106 due to their opposite phases, resulting in a composite wave W3 (no vibration). Furthermore, in Figure 7 The figure shows the case where the thickness T1 of the backing layer 105 is λ / 2. However, since the thickness T1 of the backing layer 105 is (1 / 2 × odd number) × λ, it also cancels out. Therefore, the thickness T1 of the backing layer 105 can also be set to (1 / 2 × odd number) × λ.

[0068] According to Embodiment 1 described above, since the ultrasonic waves from the piezoelectric element 106 attenuate the ultrasonic waves from the ultrasonic transducer 104a, the backing layer 105 can be made thinner. As a result, a small-diameter (capable of being miniaturized) ultrasonic probe 10 can be realized. Furthermore, if the resonant frequency of the piezoelectric element 106 is within the frequency band of the ultrasonic waves transmitted by the ultrasonic transducer 104a, it achieves the effect of attenuating the ultrasonic waves. By setting the resonant frequency of the piezoelectric element 106 to the low-frequency side of the ultrasonic waves transmitted by the ultrasonic transducer 104a, the ultrasonic waves at low frequencies that are difficult to attenuate can be attenuated.

[0069] Furthermore, according to Embodiment 1, since the backing layer 105 can be made thinner, the inner circumferential portion through which the lighting unit 101, the imaging unit 102, and the processing device channel 103 pass can be enlarged.

[0070] (Implementation Method 2)

[0071] Figure 8 This is a diagram illustrating the polarization direction of the ultrasonic probe in Embodiment 2. (Example) Figure 8 As shown, the polarization direction PD1A of the ultrasonic transducer 104Aa is opposite to the polarization direction PD1 of the ultrasonic transducer 104a in Embodiment 1. Similarly, the polarization direction PD2A of the piezoelectric element 106A is opposite to the polarization direction PD2 of the piezoelectric element 106 in Embodiment 1. In this case, it is also similar to... Figure 7 Similarly, as described above, the ultrasonic waves from the ultrasonic transducer 104Aa cancel each other out with the ultrasonic waves from the piezoelectric element 106A.

[0072] As explained above, the polarization direction is not limited to the direction of Embodiment 1, but can also be the direction of Embodiment 2. Moreover, it is preferable to appropriately select the polarization direction of the ultrasonic probe connected to the ultrasonic observation device 3 in accordance with the waveform of the signal output by the ultrasonic observation device 3.

[0073] (Implementation Method 3)

[0074] Figure 9 This is a perspective view of the front end of the insertion section of an endoscope system including the ultrasonic probe of Embodiment 3. Figure 9 As shown, the ultrasonic probe 10B is an ultrasonic probe with an electronically convex scanning front end, which emits ultrasonic pulses radially. At the front end of the insertion part 6 are provided: a rigid front end part 100B, which houses the ultrasonic probe 10B; an illumination part 101B, which illuminates the subject from the light source device 42 from the front end of the insertion part 6; an imaging part 102B, which takes an image of the subject from the front end of the insertion part 6; and a treatment device channel 103B, which allows the treatment device to protrude from the front end of the insertion part 6.

[0075] Figure 10Is with Figure 9 The sectional view corresponding to the E-E line. Figure 11 Is with Figure 10 The sectional view corresponding to the F-F line. Figure 10 Is with Figure 11 The sectional view corresponding to the G-G line. For example... Figure 10 , Figure 11 As shown, the ultrasonic probe 10B includes an ultrasonic transducer array 104B having multiple ultrasonic transducers 104Ba, a backing layer 105B disposed on the base end face of the ultrasonic transducer array 104B, a piezoelectric element 106B disposed on the base end face of the backing layer 105B, a first acoustic impedance matching layer 107B disposed on the front end face of the ultrasonic transducer array 104B, a second acoustic impedance matching layer 108B disposed on the front end face of the first acoustic impedance matching layer 107B, an acoustic lens 109B covering the outer periphery of the ultrasonic probe 10B, and side plates 110B disposed at both ends.

[0076] The ultrasonic transducer array 104B has multiple ultrasonic transducers 104Ba arranged along a portion of an arc (e.g., with a central angle θ of 50° ≤ θ ≤ 180°). This central angle corresponds to the emission angle of the ultrasonic waves emitted by the ultrasonic probe 10B.

[0077] The backing layer 105B is located on the inner periphery of the arc formed by the ultrasonic transducer array 104B.

[0078] The piezoelectric element 106B is disposed on the inner circumference of the arc formed by the ultrasonic transducer array 104B.

[0079] Since the structure other than this can be the same as that in Embodiment 1, the description is omitted.

[0080] As explained above, according to Embodiment 3, in the convex ultrasonic probe 10B, since the backing layer 105B can also be thinned, a small-front ultrasonic probe 10B can be achieved. Especially in ultrasonic probes 10B used in the lungs and other applications with a radiation angle of 50° to 60°, the thickness of the ultrasonic probe 10B can be reduced ( Figure 11 The effect of thinning (the thickness in the vertical direction) is relatively high.

[0081] (Implementation Method 4)

[0082] Figure 12 This is a partial cross-sectional view of the ultrasonic probe of embodiment 4. Figure 12 This indicates the difference from implementation method 1. Figure 6 A cross-sectional view of the corresponding section. The ultrasonic probe includes a piezoelectric element 106C and a dematching layer 111C. Structures identical to those in Embodiment 1 are labeled with the same reference numerals as in Embodiment 1, and descriptions are omitted.

[0083] The polarization direction of the piezoelectric element 106C is opposite to that of the ultrasonic transducer 104a, thereby attenuating the vibration of the ultrasonic transducer 104a. The resonant frequency of the piezoelectric element 106C only needs to be within the frequency band of the ultrasonic waves transmitted by the ultrasonic transducer 104a, for example, between 5 MHz and 12 MHz. By setting the resonant frequency of the piezoelectric element 106C to the low-frequency side of the ultrasonic waves transmitted by the ultrasonic transducer 104a, the ultrasonic waves attenuated at low frequencies can be attenuated. Therefore, the resonant frequency of the piezoelectric element 106C is more preferably 5 MHz, and an example with a resonant frequency of 5 MHz is described below. The resonant frequency of the piezoelectric element 106C is set to f0, the frequency constant of the piezoelectric element 106C is set to N, and the thickness T3 of the piezoelectric element 106C along the acoustic axis satisfies f0 = N / (2 × T3).

[0084] The matching layer 111C is disposed on the base end face of the piezoelectric body 106C and has a higher acoustic impedance than the piezoelectric body 106C.

[0085] By providing a dematching layer 111C on the base end face of the piezoelectric body 106C, the base end face of the piezoelectric body 106C becomes the fixed end of the ultrasonic wave. As a result, the thickness 3 of the piezoelectric body 106C can be half the thickness of Embodiment 1, satisfying f0 = N / (2 × T3). For example, when the resonant frequency of the piezoelectric body 106C is 5MHz and the frequency constant of the piezoelectric body 106C is 1400, it is sufficient to set the thickness T3 = 1400 / (2 × 5000000) = 140μm.

[0086] According to Embodiment 4 described above, by providing the dematching layer 111C, the thickness of the piezoelectric element 106C can be half that of Embodiment 1, thus resulting in a higher efficiency in miniaturizing (reducing the diameter) the front end of the insertion portion 6. Furthermore, by reflecting the ultrasonic waves from the piezoelectric element 106C through the dematching layer 111C, the attenuation efficiency of the ultrasonic waves from the ultrasonic transducer 104a is increased. Moreover, by providing the dematching layer 111C, the bandwidth of the piezoelectric element 106C is broadened, enabling attenuation of the ultrasonic waves from the ultrasonic transducer 104a over a wider frequency band. Furthermore, by making the dematching layer 111C a rigid material, the strength of the inner circumference of the ultrasonic probe can be improved. Additionally, by providing the dematching layer 111C, the propagation of ultrasonic waves from the piezoelectric element 106C into internal structures (such as the illumination portion 101, the imaging portion 102, and the treatment device channel 103) can be prevented.

[0087] (Implementation Method 5)

[0088] Figure 13 This is a partial cross-sectional view of the ultrasonic probe of embodiment 5. Figure 13 This indicates the implementation method 3. Figure 11A cross-sectional view of the corresponding section. The ultrasonic probe includes a piezoelectric element 106D and a dematching layer 111D. Structures identical to those in Embodiment 3 are labeled with the same reference numerals as in Embodiment 3, and descriptions are omitted.

[0089] The polarization direction of the piezoelectric element 106D is opposite to that of the ultrasonic transducer 104Ba, thereby attenuating the vibration of the ultrasonic transducer 104Ba. The resonant frequency of the piezoelectric element 106D only needs to be within the frequency band of the ultrasonic waves transmitted by the ultrasonic transducer 104Ba, for example, between 5MHz and 12MHz. By setting the resonant frequency of the piezoelectric element 106D to the low-frequency side of the ultrasonic waves transmitted by the ultrasonic transducer 104Ba, the ultrasonic waves attenuated from the low-frequency side, which are difficult to attenuate, can be attenuated. Therefore, the resonant frequency of the piezoelectric element 106D is more preferably 5MHz, for example, as long as the piezoelectric element 106D is formed in the same manner as in Embodiment 4, satisfying f0 = N / (2×T3).

[0090] The matching layer 111D is disposed on the base end face of the piezoelectric body 106D and has a higher acoustic impedance than the piezoelectric body 106D.

[0091] By providing a dematching layer 111D on the base end face of the piezoelectric element 106D, the base end face of the piezoelectric element 106D becomes the fixed end of the ultrasonic wave. As a result, the thickness 3 of the piezoelectric element 106D can be half the thickness of Embodiment 3, satisfying f0 = N / (2 × T3). For example, when the resonant frequency of the piezoelectric element 106D is 5MHz and the frequency constant of the piezoelectric element 106D is 1400, it is sufficient to set the thickness T3 = 1400 / (2 × 5000000) = 140μm.

[0092] According to Embodiment 5 described above, in the convex ultrasonic probe 10B, similar to Embodiment 4, by providing a dematching layer 111D, the thickness of the piezoelectric element 106D can be half that of Embodiment 3, thus resulting in a higher effect of miniaturizing (reducing the diameter) the front end of the insertion portion 6. Furthermore, by reflecting the ultrasonic waves from the piezoelectric element 106D through the dematching layer 111D, the attenuation efficiency of the ultrasonic waves from the ultrasonic transducer 104Ba is increased. Moreover, by providing the dematching layer 111D, the bandwidth of the piezoelectric element 106D is broadened, enabling attenuation of the ultrasonic waves from the ultrasonic transducer 104Ba over a wider frequency band. Furthermore, by using a rigid material for the dematching layer 111D, the strength of the inner circumference of the ultrasonic probe can be improved. Additionally, by providing the dematching layer 111D, the propagation of ultrasonic waves from the piezoelectric element 106D to internal structures (illumination portion 101, imaging portion 102, and treatment device channel 103, etc.) can be prevented.

[0093] (Implementation Method 6)

[0094] Figure 14 This is a partial cross-sectional view of the ultrasonic probe of embodiment 6. Figure 14 This indicates the difference from implementation method 1. Figure 6 A cross-sectional view of the corresponding section. The ultrasonic probe is equipped with a piezoelectric element 106E. Structures identical to those in Embodiment 1 are labeled with the same reference numerals as in Embodiment 1, and descriptions are omitted.

[0095] The piezoelectric element 106E is formed from a polymeric piezoelectric element such as PVDF (Polyvinylidene DiFluoride), and is flexible. As a result, by rolling up the layered structure after stacking the layers constituting the ultrasonic probe on a plane, radial and convex shapes can be easily formed.

[0096] Furthermore, while the above embodiments illustrate radial or convex types, they can also be applied to linear types. In the case of a linear type, the backing layer can be thinned by forming a piezoelectric material, thereby enabling miniaturization (thinning) of the ultrasonic probe.

[0097] Further effects and variations can be readily derived by those skilled in the art. Therefore, the broader form of the invention is not limited to the specific details and representative embodiments shown and described above. Thus, various modifications can be made without departing from the spirit or scope of the overall inventive concept as defined by the appended claims and their equivalents.

[0098] Explanation of reference numerals in the attached figures

[0099] 1. Endoscopic system; 2. Ultrasonic endoscope; 3. Ultrasonic observation device; 4. Endoscopic observation device; 5. Display device; 6. Insertion section; 7. Operating section; 8. Universal cable; 9. Endoscopic connector; 10, 10B. Ultrasonic probe; 31. Ultrasonic cable; 41. Video processor; 42. Light source device; 61. Bending section; 62. Flexible tube; 71. Bending knob; 72. Operating component; 73. Instrument insertion port; 100, 100B. Rigid front section; 101, 101B. Illumination section; 102, 102B. Imaging section; 103, 103B. Instrument channel; 104, 104B. Acoustic transducer array; 104a, 104Aa, 104Ba, ultrasonic transducers; 104b, GND; 105, 105B, backing layers; 106, 106A, 106B, 106C, 106D, 106E, piezoelectric elements; 106a, GND; 107, 107B, first acoustic impedance matching layer; 108, 108B, second acoustic impedance matching layer; 109, 109B, acoustic lens; 110, 110B, side plates; 111C, 111D, dematching layers; PD1, PD2, PD1A, PD2A, polarization directions; T1, T2, T3, thickness; W1, W2, ultrasonic waves; W3, synthesized waves.

Claims

1. An ultrasonic probe, wherein the ultrasonic probe includes: an ultrasonic transducer array in which a plurality of ultrasonic transducers for transmitting and receiving ultrasonic waves are arranged; a backing layer provided on a base end surface of the ultrasonic transducer array; and a piezoelectric body provided on a base end surface of the backing layer, the piezoelectric body having a polarization direction opposite to a polarization direction of the plurality of ultrasonic transducers to attenuate vibration of the ultrasonic transducers.

2. The ultrasonic probe according to claim 1, wherein the base end surface of the ultrasonic transducer array and the base end surface of the backing layer are surfaces on a side opposite to a direction in which the plurality of ultrasonic transducers observe with ultrasonic waves.

3. The ultrasonic probe according to claim 1, wherein the plurality of ultrasonic transducers are arranged along a circular arc, the backing layer is provided on an inner peripheral side of the circular arc.

4. The ultrasonic probe according to claim 1, wherein the plurality of ultrasonic transducers are arranged along a circumference, the backing layer is provided on an inner peripheral side of the circumference in a cylindrical shape.

5. The ultrasonic probe according to claim 1, wherein a resonance frequency of the piezoelectric body is 5 MHz or more and 12 MHz or less.

6. The ultrasonic probe according to claim 1, wherein a wavelength of an ultrasonic wave having a frequency of a resonance frequency of the piezoelectric body in the backing layer is set to λ, a thickness T1 of the backing layer in a sound axis direction that is a direction in which one of the plurality of ultrasonic transducers observes with ultrasonic waves satisfies T1 = (1 / 2 x odd number) x λ, a resonance frequency of the piezoelectric body is set to f0, a frequency constant of the piezoelectric body is set to N, and a thickness T2 of the piezoelectric body in the sound axis direction satisfies f0 = N / T2.

7. The ultrasonic probe according to claim 1, wherein the ultrasonic probe includes a de-matching layer provided on a base end surface of the piezoelectric body, the de-matching layer having a sound impedance higher than a sound impedance of the piezoelectric body.

8. The ultrasonic probe according to claim 7, wherein a wavelength of an ultrasonic wave having a frequency of a resonance frequency of the piezoelectric body in the backing layer is set to λ, a thickness T1 of the backing layer in a sound axis direction that is a direction in which one of the plurality of ultrasonic transducers observes with ultrasonic waves satisfies T1 = (1 / 2 x odd number) x λ, a resonance frequency of the piezoelectric body is set to f0, a frequency constant of the piezoelectric body is set to N, and a thickness T3 of the piezoelectric body in the sound axis direction satisfies f0 = N / (2 x T3).

9. The ultrasonic probe according to claim 1, wherein a resonance frequency of the piezoelectric body is a frequency on a low frequency side in a frequency band in which the ultrasonic transducer array can oscillate.

10. The ultrasonic probe according to claim 1, wherein the piezoelectric body is formed of a piezoelectric material that is the same as a piezoelectric material of the plurality of ultrasonic transducers.

11. The ultrasonic probe according to claim 1, wherein the piezoelectric body is composed of a plurality of piezoelectric materials formed in an elongated square shape, the plurality of piezoelectric materials are arranged in the same direction as an arrangement direction of the plurality of ultrasonic transducers.

12. The ultrasonic probe according to claim 1, wherein The piezoelectric body is formed of a high molecular material.

13. The ultrasonic probe according to claim 12, wherein The high molecular material is polyvinylidene fluoride (PVDF).

14. An ultrasonic endoscope, comprising: The ultrasonic endoscope includes: The ultrasonic probe according to claim 1; a front-end rigid portion provided with the ultrasonic probe; an illumination portion that penetrates the inner side of the backing layer, and that irradiates an illumination light from the front end of the front-end rigid portion toward a subject; a photographing portion that penetrates the inner side of the backing layer, and that photographs the inside of the subject from the front end of the front-end rigid portion; and a treatment instrument channel that penetrates the inner side of the backing layer, and that causes a treatment instrument to protrude from the front end of the front-end rigid portion.

15. The ultrasonic endoscope according to claim 14, wherein The ultrasonic probe is an ultrasonic probe of an electronic radial scanning method in which the front end portion.

16. The ultrasonic endoscope according to claim 14, wherein The ultrasonic probe is an ultrasonic probe of an electronic convex scanning method in which the front end portion.

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