Patent Publication Number: US-2018035977-A1

Title: Ultrasound transducer, ultrasound probe and method of manufacturing ultrasound transducer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of PCT international application Ser. No. PCT/JP2016/061046 filed on Apr. 4, 2016 which designates the United States, incorporated herein by reference, and which claims the benefit of priority from Japanese Patent Application No. 2015-086781, filed on Apr. 21, 2015, incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The disclosure relates to an ultrasound transducer, an ultrasound probe and a method of manufacturing an ultrasound transducer. 
     2. Related Art 
     Ultrasound is applied in some cases for observing a characteristic of a living tissue or material as an observation target. Specifically, the ultrasound transducer transmits ultrasound to the observation target, receives an ultrasound echo reflected by the observation target, and an ultrasound observation apparatus performs predetermined signal processing on the received ultrasound echo, whereby information related to the characteristic of the observation target can be obtained. 
     The ultrasound transducer includes a plurality of piezoelectric elements that converts an electrical pulse signal into an ultrasound pulse (acoustic pulse), emits the ultrasound pulse to the observation target, converts an ultrasound echo reflected on the observation target into an electrical echo signal expressed by a voltage change, and outputs the echo signal (refer to JP 2002-224104 A, for example). The ultrasound echo is obtained from the observation target, for example, by arranging the plurality of piezoelectric elements in an array pattern, electronically switching the elements related to transmission and reception, or delaying transmission and reception of the piezoelectric body of each of the ultrasound transducer. 
     Meanwhile, each of the piezoelectric elements is electrically connected by wiring to a circuit board configured to transmit a pulse signal and receive an echo signal. The piezoelectric element and the wiring are connected by soldering, for example, and the heat at the time of soldering might induce degradation of the characteristics of the piezoelectric element, in the form of depolarization, or the like. 
     As a technique for suppressing depolarization of the piezoelectric element, there is a disclosed technique of forming a conductive thin film for providing electrical connection to the circuit board on a side surface of a base material forming the piezoelectric element and then dividing the base material after formation of the thin film so as to be able to electrically connect a plurality of piezoelectric elements with a circuit board without soldering (for example, refer to JP 2007-201901 A). 
     SUMMARY 
     In some embodiments, an ultrasound transducer includes: a plurality of piezoelectric elements configured to emit ultrasound according to an input of an electric signal and to convert ultrasound incident from outside into an electric signal; a substrate configured to perform input and output of an electric signal with respect to each of the piezoelectric elements; a plurality of signal input and output electrodes where each signal input and output electrode is provided between each piezoelectric element and the substrate and is configured to electrically connect the piezoelectric element with the substrate; a plurality of first backing materials where each first backing material is provided at each of the piezoelectric elements on a side where the signal input and output electrode is arranged and is configured to attenuate ultrasound vibration generated by operation of the piezoelectric element; a plurality of sealing portions where each sealing portion is configured to seal an outer surface of at least a portion of an electrical path connecting the substrate with the signal input and output electrode; a wall configured to surround a plurality of oscillating portions including the piezoelectric element, the first backing material, the signal input and output electrode, and the sealing portion; and a second backing material provided in a hollow space formed by the wall and the plurality of oscillating portions, and configured to attenuate the ultrasound vibration. The plurality of piezoelectric elements, the plurality of first backing materials, a portion of the substrate, the plurality of signal input and output electrodes, and the plurality of sealing portions are obtained by dividing a forming member along a stacking direction of the forming member, the forming member being formed by stacking a plurality of materials, each of the plurality of materials forming the piezoelectric elements, the first backing materials, the substrate, the signal input and output electrodes, and the sealing portions. 
     In some embodiments, a method of manufacturing an ultrasound transducer includes: a stacked member production process of stacking a plurality of materials to produce a stacked member, each of the materials forming: a plurality of piezoelectric elements configured to emit ultrasound according to an input of an electric signal and to convert ultrasound incident from outside into an electric signal; a portion of a substrate configured to perform input and output of an electric signal with respect to each of the piezoelectric elements; a plurality of signal input and output electrodes where each signal input and output electrode is provided between each piezoelectric element and the substrate and is configured to electrically connect the piezoelectric element with the substrate; and a plurality of first backing materials where each first backing material is provided at each of the piezoelectric elements on a side where the signal input and output electrode is arranged and is configured to attenuate ultrasound vibration generated by operation of the piezoelectric element; a forming member production process of sealing, with respect to the stacked member, an outer surface of at least a portion of an electrical path connecting the substrate with the signal input and output electrode to produce a forming member; a forming process of dividing the produced forming member produced by the forming member production process along a stacking direction of the forming member to form the piezoelectric element, the first backing material, a portion of the substrate, the signal input and output electrode, and sealing portion; a wall arrangement process of arranging a wall surrounding a plurality of oscillating portions including the formed piezoelectric element, the formed first backing material, the formed signal input and output electrode, and the formed sealing portion, which are formed by the forming process; and a filling process of filling a second backing material in a hollow space formed by the wall and the plurality of oscillating portions. 
     The above and other features, advantages and technical and industrial significance of this disclosure will be better understood by reading the following detailed description of presently preferred embodiments of the disclosure, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram schematically illustrating an endoscope system according to a first embodiment of the disclosure; 
         FIG. 2  is a perspective view illustrating an ultrasound transducer according to the first embodiment of the disclosure; 
         FIG. 3  is a schematic diagram illustrating a configuration of a main portion of the ultrasound transducer according to the first embodiment of the disclosure; 
         FIG. 4  is a schematic diagram illustrating a configuration of a main portion of the ultrasound transducer according to the first embodiment of the disclosure; 
         FIG. 5  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer according to the first embodiment of the disclosure; 
         FIG. 6  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer according to the first embodiment of the disclosure; 
         FIG. 7  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer according to the first embodiment of the disclosure; 
         FIG. 8  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer according to the first embodiment of the disclosure; 
         FIG. 9  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer according to the first embodiment of the disclosure; 
         FIG. 10  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer according to the first embodiment of the disclosure; 
         FIG. 11  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer according to the first embodiment of the disclosure; 
         FIG. 12  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer according to the first embodiment of the disclosure; 
         FIG. 13  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a first modification of the first embodiment of the disclosure; 
         FIG. 14  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a second modification of the first embodiment of the disclosure; 
         FIG. 15  is a schematic diagram illustrating a production of a forming member of the ultrasound transducer according to the second modification of the first embodiment of the disclosure; 
         FIG. 16  is a schematic diagram illustrating a production of the forming member of the ultrasound transducer according to the second modification of the first embodiment of the disclosure; 
         FIG. 17  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a third modification of the first embodiment of the disclosure; 
         FIG. 18  is a schematic diagram illustrating a production of a forming member of the ultrasound transducer according to the third modification of the first embodiment of the disclosure; 
         FIG. 19  is a schematic diagram illustrating a configuration of a main portion of an ultrasound transducer according to a fourth modification of the first embodiment of the disclosure; 
         FIG. 20  is a schematic diagram illustrating a configuration of a main portion of an ultrasound transducer according to a fifth modification of the first embodiment of the disclosure; 
         FIG. 21  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a sixth modification of the first embodiment of the disclosure; 
         FIG. 22  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a seventh modification of the first embodiment of the disclosure; 
         FIG. 23  is a schematic diagram illustrating a configuration of an ultrasound transducer according to an eighth modification of the first embodiment of the disclosure; 
         FIG. 24  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a ninth modification of the first embodiment of the disclosure; 
         FIG. 25  is a diagram illustrating a method of manufacturing an ultrasound transducer according to a tenth modification of the first embodiment of the disclosure; 
         FIG. 26  is a schematic diagram illustrating a configuration of the ultrasound transducer according to the tenth modification of the first embodiment of the disclosure; 
         FIG. 27  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a second embodiment of the disclosure; 
         FIG. 28  is a diagram illustrating a method of manufacturing the ultrasound transducer according to the second embodiment of the disclosure; 
         FIG. 29  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer according to the second embodiment of the disclosure; 
         FIG. 30  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer according to the second embodiment of the disclosure; 
         FIG. 31  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer according to the second embodiment of the disclosure; and 
         FIG. 32  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer according to the second embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the disclosure (hereinafter, referred to as embodiment(s)) will be described with reference to the drawings. Note that the disclosure is not limited by the following embodiments. In the drawings, same reference signs are attached to the same portions. 
     First Embodiment 
       FIG. 1  is a diagram schematically illustrating an endoscope system  1  according to a first embodiment of the disclosure. The endoscope system  1  is a system for performing ultrasound diagnosis of internal portions of a subject such as a human using an ultrasound endoscope. As illustrated in  FIG. 1 , the endoscope system  1  includes an ultrasound endoscope  2 , an ultrasound observation apparatus  3 , an endoscopic examination apparatus  4 , a display device  5 , and a light source apparatus  6 . 
     The ultrasound endoscope  2 , using its distal end portion, converts an electrical pulse signal received from the ultrasound observation apparatus  3  into an ultrasound pulse (acoustic pulse) and emits it to the subject, and also converts an ultrasound echo reflected on the subject into an electrical echo signal expressed by a voltage change and outputs the signal. 
     The ultrasound endoscope  2  typically includes imaging optics and imaging elements. The ultrasound endoscope  2  can be inserted into gastrointestinal tracts (esophagus, stomach, duodenum, and large intestine) or respiratory organs (trachea, bronchus) of the subject and can capture gastrointestinal tract, respiratory organs, and their surrounding organs (pancreas, gall bladder, bile duct, biliary tract, lymph nodes, mediastinal organs, blood vessels, or the like). The ultrasound endoscope  2  includes a light guide that guides illumination light emitted to the subject at the time of imaging. The light guide is configured such that a distal end portion thereof reaches a distal end of an insertion unit of the ultrasound endoscope  2  into the subject, while a proximal end portion thereof is connected to the light source apparatus  6  that generates illumination light. 
     As illustrated in  FIG. 1 , the ultrasound endoscope  2  includes an insertion unit  21 , an operating unit  22 , a universal cable  23 , and a connector  24 . The insertion unit  21  is a portion to be inserted into the subject. As illustrated in  FIG. 1 , the insertion unit  21  includes an ultrasound transducer  7 , a rigid member  211 , a bending portion  212 , and a flexible tube portion  213 . The ultrasound transducer  7  is provided at a distal end side of the insertion unit. The rigid member  211  is coupled to a proximal end side of the ultrasound transducer  7 . The bending portion  212  is a bendable portion coupled to the proximal end side of the rigid member  211 . The flexible tube portion  213  is a flexible portion coupled to the proximal end side of the bending portion  212 . While specific illustration is omitted herein, the insertion unit  21  internally includes a light guide for transmitting illumination light supplied from the light source apparatus  6 , a plurality of signal cables for transmitting various signals, and a treatment instrument insertion passage for inserting treatment instruments. 
     The ultrasound transducer  7  may be any of a convex transducer, a linear transducer, and a radial transducer. The ultrasound endoscope  2  may be configured to cause the ultrasound transducer  7  to perform mechanical scan, or may provide, as the ultrasound transducer  7 , a plurality of piezoelectric elements in an array pattern, and may cause the ultrasound transducer  7  to perform electronic scan by electronically switching the piezoelectric elements related to transmission and reception or by imposing delay onto transmission and reception of each of the piezoelectric elements. The configuration of the piezoelectric element will be described below. 
     The operating unit  22  is coupled to the proximal end side of the insertion unit  21  and receives various types of operation from a doctor, or the like. As illustrated in  FIG. 1 , the operating unit  22  includes a bending knob  221  for performing bending operation on the bending portion  212 , and a plurality of operating members  222  for performing various types of operation. Moreover, the operating unit  22  has a treatment instrument insertion port  223  communicating with the treatment instrument insertion passage formed inside the insertion unit  21  and used for inserting treatment instruments into the treatment instrument insertion passage. 
     Extending from the operating unit  22 , the universal cable  23  includes a plurality of signal cables for transmitting various signals and an optical fiber for transmitting illumination light supplied from the light source apparatus  6 . 
     The connector  24  is provided at the distal end of the universal cable  23 . The connector  24  includes first to third connector units  241  to  243  each of which is connected with an ultrasound cable  31 , a video cable  41 , and an optical fiber cable  61 , respectively. 
     The ultrasound observation apparatus  3  is electrically connected with the ultrasound endoscope  2  via the ultrasound cable  31 , outputs a pulse signal to the ultrasound endoscope  2  via the ultrasound cable  31 , while inputting echo signals from the ultrasound endoscope  2 . Then, the ultrasound observation apparatus  3  performs predetermined processing on the echo signal and generates an ultrasound image. 
     The endoscopic examination apparatus  4  is electrically connected with the ultrasound endoscope  2  via the video cable  41 , and inputs an image signal from the ultrasound endoscope  2  via the video cable  41 . Then, the endoscopic examination apparatus  4  performs predetermined processing on the image signal and generates an endoscopic image. 
     The display device  5  is formed with liquid crystal, organic electroluminescence (EL), or the like, and displays an ultrasound image generated by the ultrasound observation apparatus  3 , an endoscopic image generated by the endoscopic examination apparatus  4 , or the like. 
     The light source apparatus  6  is connected with the ultrasound endoscope  2  via the optical fiber cable  61  and supplies illumination light for illuminating portions inside the subject, to the ultrasound endoscope  2  via the optical fiber cable  61 . 
     Subsequently, the configuration of the ultrasound transducer  7  will be described with reference to  FIGS. 2 to 4 .  FIG. 2  is a perspective view illustrating the ultrasound transducer  7  according to the first embodiment.  FIG. 3  is a schematic diagram illustrating a configuration of a main portion of the ultrasound transducer  7  according to the first embodiment.  FIG. 4  is a schematic diagram illustrating a configuration of a main portion of the ultrasound transducer  7  according to the first embodiment, illustrated as a plan view in the direction of arrow A in  FIG. 3 , in an upside down view of  FIG. 3 . While  FIG. 4  illustrates an exemplary case where ten elements  70  including the piezoelectric elements  71  are arranged for simplicity of explanation, the configuration of the ultrasound transducer  7  is not limited to this number in actual arrangement. The first embodiment is described as an exemplary case where the ultrasound transducer  7  is a convex ultrasound transducer as illustrated in  FIG. 2  including a one-dimensional array (1D array) of the plurality of piezoelectric elements  71  which is arranged in a line. In other words, in the ultrasound transducer  7  according to the first embodiment, the plurality of elements  70  is arranged along an outer surface forming a curved surface of the ultrasound transducer  7 . 
     As illustrated in  FIGS. 3 and 4 , the ultrasound transducer  7  includes the plurality of piezoelectric elements  71 , a first acoustic matching layer  72  provided on an outer surface side of the ultrasound transducer  7  with respect to the piezoelectric elements  71 , a second acoustic matching layer  73  provided on the side of the first acoustic matching layer  72  opposite to the side coming in contact with the piezoelectric element  71 , an acoustic lens  74  provided on the side of the second acoustic matching layer  73  opposite to the side coming in contact with the first acoustic matching layer  72 , a backing material  75  provided on the side of the piezoelectric element  71  opposite to the side coming in contact with the first acoustic matching layer  72 , a first electrode  76  (signal input and output electrode) provided on a main surface of the piezoelectric element  71  on the backing material  75  side, a second electrode  77  provided on the main surface of the piezoelectric element  71  on the first acoustic matching layer  72  side, a conductive thin film  78  (connecting electrode) electrically connecting the first electrode  76  with a wiring pattern on an flexible printed circuit (FPC) substrate  80  to be described below, a sealing portion  79  for sealing a connecting portion between the conductive thin film  78  and the FPC substrate  80 , and the FPC substrate  80  configured to perform input and output of electric signals on each of the piezoelectric elements  71 . Note that the first embodiment has a configuration in which the first acoustic matching layer  72  and the backing material  75  are provided for each of the piezoelectric elements  71 , and at the same time, the second acoustic matching layer  73  and the acoustic lens  74  integrally cover the plurality of piezoelectric elements  71  and the first acoustic matching layers  72 . The element  70  in the first embodiment refers to an output unit including the piezoelectric element  71 , the backing material  75 , the first electrode  76 , and the second electrode  77 , and configured to output one ultrasound pulse according to a certain pulse signal. The first embodiment describes a case where one piezoelectric element  71  is an output unit. In a case, however, where ultrasound is simultaneously emitted from the plurality of piezoelectric elements  71  by a wiring pattern formed on the FPC substrate  80 , a plurality of target piezoelectric elements  71  constitutes one element as an output unit. 
     The piezoelectric element  71  converts an electrical pulse signal into an ultrasound pulse (acoustic pulse), emits the ultrasound pulse to the subject, converts an ultrasound echo reflected on the subject into an electrical echo signal represented by a voltage change, and outputs the echo signal. 
     The piezoelectric element  71  is electrically connected with the FPC substrate  80  via the first electrode  76  by the conductive thin film  78 . Each of the first electrode  76  and the second electrode  77  is formed of a metal material or a resin material, having conductivity. 
     The piezoelectric element  71  is formed with a PMN-PT single crystal, PMN-PZT single crystal, PZN-PT single crystal, PIN-PZN-PT single crystal, or a relaxer-based material. The PMN-PT single crystal is an abbreviation of a solid solution of lead magnesium niobate and lead titanate. The PMN-PZT single crystal is an abbreviation of a solid solution of lead magnesium niobate and lead zirconate titanate. The PZN-PT single crystal is an abbreviation of a solid solution of lead zinc-niobate and lead titanate. The PIN-PZN-PT single crystal is an abbreviation of a solid solution of lead indium niobate, lead zinc-niobate, and lead titanate. The relaxer-based material is a general term of a three-component piezoelectric material obtained by adding lead-based complex perovskite as a relaxer material to the lead zirconate titanate (PZT) for the purpose of increasing the piezoelectric constant and dielectric constant. The lead-based complex perovskite is represented by Pb(B1, B2)O 3 , in which B1 is any of magnesium, zinc, indium, and scandium, while B2 is any of niobium, tantalum, and tungsten. These materials have excellent piezoelectric effects. These materials could reduce the value of the electrical impedance even in a miniaturized form, and thus, would be preferable from the viewpoint of impedance matching with a thin film electrode. 
     In order to allow the sound (ultrasound) to be efficiently transmitted between the piezoelectric element  71  and the observation target, the first acoustic matching layer  72  and the second acoustic matching layer  73  perform matching of acoustic impedance between the piezoelectric element  71  and the observation target. The first acoustic matching layer  72  and the second acoustic matching layer  73  are formed of mutually different materials. Note that while the first embodiment describes a case where there are two acoustic matching layers (first acoustic matching layer  72  and second acoustic matching layer  73 ), it is also allowable to have one layer or three layers or more, in accordance with characteristics of the piezoelectric element  71  and the observation target. Moreover, as for the acoustic matching layer, it is allowable to configure as an ultrasound transducer that does not include the acoustic matching layer as long as the acoustic impedance matching with the observation target can be achieved. 
     The acoustic lens  74  is formed with polymethylpentene, epoxy resin, polyetherimide, or the like, and has a function of narrowing the ultrasound with one side having a concave shape. Note that the material may be a material whose sound speed is slower than the sound speed of the subject, such as a silicone resin, with a convex surface that allows the ultrasound beam to converge. Whether to provide the acoustic lens  74  may be optional, and thus, it is allowable to have a configuration without the acoustic lens  74 . 
     The backing material  75  attenuates unneeded ultrasound vibration generated by operation of the piezoelectric element  71 . The backing material  75  is formed of a material having a high attenuation rate, for example, epoxy resin in which a filler such as alumina and zirconia is dispersed, or formed of a rubber in which the above-described filler is dispersed. 
     The first electrode  76  is electrically connected with the FPC substrate  80  via the above-described conductive thin film  78 . The first electrode  76  is an electrode for inputting and outputting a signal with respect to the piezoelectric element  71 . 
     The second electrode  77  is formed in the first acoustic matching layer  72  and is electrically connected to a ground electrode  72   a  grounded to the ground potential. 
     The conductive thin film  78  forms an electrical conduction path between the first electrode  76  and the FPC substrate  80 . The conductive thin film  78  is a conductive thin film formed on a side surface of the piezoelectric element  71  by a physical vapor deposition (PVD) method such as sputtering and wet plating such as electrolytic plating, and configured to electrically connect the first electrode  76  with the wiring pattern formed on the FPC substrate  80 . The conductive thin film  78  is obtained by forming a plating film on a stacked film formed of any of chromium/copper, chromium/gold, nickel-chromium/copper and chromium/copper/nickel. 
     The sealing portion  79  is formed with an insulating resin material and seals an outer surface of a portion of the backing material  75 , and an outer surface of a portion of the FPC substrate  80  and the conductive thin film  78  including the connecting portion between the FPC substrate  80  and the conductive thin film  78 . 
     The FPC substrate  80  is a substrate obtained by forming a wiring pattern formed of a conductive metal such as a copper foil on an insulating and flexible film-like base material formed of polyimide, or the like. 
     The piezoelectric element  71  vibrates with the input of the pulse signal, whereby the above-configured ultrasound transducer  7  emits ultrasound to the observation target via the first acoustic matching layer  72 , the second acoustic matching layer  73 , and the acoustic lens  74 . At this time, the piezoelectric element  71  is configured such that the backing material  75  attenuates vibration of the piezoelectric element  71  on the side opposite to the arrangement side of the first acoustic matching layer  72 , the second acoustic matching layer  73 , and the acoustic lens  74 , thereby suppressing transmission of vibration of the piezoelectric element  71  to the FPC substrate  80 , or the like. Moreover, the ultrasound reflected from the observation target is transmitted to the piezoelectric element  71  via the first acoustic matching layer  72 , the second acoustic matching layer  73 , and the acoustic lens  74 . The transmitted ultrasound causes the piezoelectric element  71  to vibrate, then, the piezoelectric element  71  converts the vibration into an electrical echo signal, and outputs the converted signal, as an echo signal, to the FPC substrate  80  via the conductive thin film  78 . 
     Subsequently, a method of manufacturing the above-described ultrasound transducer  7  will be described with reference to  FIGS. 5 to 12 .  FIGS. 5 to 10  are schematic diagrams illustrating a method of manufacturing the ultrasound transducer  7  according to the first embodiment. First, processing of producing a forming member (forming member  700  to be described below) for forming the piezoelectric element  71 , the backing material  75 , the first electrode  76 , and the second electrode  77  will be described. 
     A first thin film  760  formed with a material forming the first electrode  76  and a second thin film  770  formed with a material forming the second electrode  77  are stacked on opposing main surfaces of a rectangular parallelepiped shaped piezoelectric element base material  710  formed with a material forming the piezoelectric element  71 , and thereafter, a backing material base material  750  formed with a material forming the backing material  75  is stacked on the side of the first thin film  760  opposite to the piezoelectric element base material  710  side (refer to  FIG. 5 : stacked member production process). The backing material base material  750  is stacked while a portion of the FPC substrate  80  is embedded in the backing material base material  750 . 
     Thereafter, a masking material  90  to cover the second thin film  770  and a portion of the FPC substrate  80  is arranged (refer to  FIG. 6 ). The masking material  90  may be anything as long as it masks the second thin film  770  and a portion of the FPC substrate  80  in a region where film forming is performed by sputtering to be described below. With this processing, film forming on the second thin film  770  by sputtering is prevented. 
     After the masking material  90  is arranged, a third thin film  781  is formed by sputtering using a material forming a portion of the conductive thin film  78  (refer to  FIG. 7 ). Here, the third thin film  781  may include formation of gold (Au) with a thickness of 300 nm on an underlying layer of chromium (Cr) with a thickness of 50 nm, and include, on an underlying layer of nickel chromium (NiCr) with a thickness of 50 nm, stacks of copper (Cu) with a thickness of 100 nm and platinum (Pt) with a thickness of 400 nm, making it possible to form a conductive thin film with good adhesion. As a film forming method other than sputtering, silver (Ag) with a thickness of 1000 nm or silver palladium (AgPd) with a thickness of 700 nm may be formed by vapor deposition. By forming the third thin film  781 , the first thin film  760  can be electrically connected with the wiring pattern formed on the FPC substrate  80 . 
     After the third thin film  781  is formed, the masking material  90  is removed (refer to  FIG. 8 ), and then, a plating film  782  is formed by electrolytic plating treatment (refer to  FIG. 9 ). A stacked film (connecting member) forming the conductive thin film  78  is formed by the third thin film  781  and the plating film  782  (connection electrode member arrangement process). Materials applicable as the plating film  782  is materials forming a portion of the conductive thin film  78  formed by a sulfamic acid bath or a pyrophosphoric acid bath, such as nickel and copper. With the electrolytic plating treatment, the third thin film  781  is covered with the plating film  782 . In physical vapor deposition, it used to be difficult to increase the film thickness to lower the resistance due to an issue of film stress. More specifically, when the film stress is high, the film peels off during cutting by a precision cutting machine such as a dicing saw, making it difficult to form a thick film. In contrast, film stress can be controlled on the plating of nickel sulfamate or copper pyrophosphate, making it possible to form a thick film of 1 to 10 μm, and to ensure the thickness of the conductive film necessary as the wiring to the transducer. In other words, by using the plating film  782 , it is possible to enhance physical characteristics such as the strength and the electrical characteristics of the conductive thin film  78 . A stacked member is produced by the above-described processing, and a series of processing corresponds to the stacked member production process of the disclosure. 
     After formation of the plating film  782 , a sealing member  790  is provided on a surface of the backing material base material  750 , in which the FPC substrate  80  is embedded, so as to seal the outer surfaces of a portion of the FPC substrate  80  including the contact portion between the FPC substrate  80  and the third thin film  781 , a portion of the third thin film  781 , and a portion of the plating film  782 , with the sealing member  790  (refer to  FIG. 10 : forming member production process). The forming member  700  is produced with the above-described processing. 
       FIG. 11  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer  7  according to the first embodiment, viewed from the FPC substrate  80  side in  FIG. 10 .  FIG. 11  is a top view illustrating a state in which a first acoustic matching layer base material  720  formed by stacking the second acoustic matching layer  73  is arranged on the second thin film  770  of the forming member  700  produced by the above-described processing, with the first acoustic matching layer base material  720  being mounted on a machining tool  101 . The first acoustic matching layer base material  720  is formed of a material forming the first acoustic matching layer  72 . 
     The FPC substrate  80  includes a foil-shaped solid portion  81  formed of a conductive material for forming wiring patterns and uniformly extending to a portion of the surface of the FPC substrate  80 , and includes a pattern portion  82  in which a plurality of wiring lines  82   a  extend from the solid portion  81  in accordance with the individual wiring patterns. The solid portion  81  and the pattern portion  82  are formed of copper, for example. The above-described third thin film  781  is in contact with the solid portion  81 . 
     The FPC substrate  80  is positioned on the machining tool  101  by a positioning pin  91 . At this time, the height of an end portion of the solid portion  81  connected to the pattern portion  82  is adjusted by a height adjusting member M (refer to  FIG. 12 ) formed of machinable ceramics, or the like. Herein, the height is adjusted to the height at which a plane passing through the front surface of the FPC substrate  80 , that is, the front surface coming in contact with the height adjusting member M, passes through the first acoustic matching layer base material  720 . 
       FIG. 12  is a schematic diagram illustrating a method of manufacturing the ultrasound transducer  7  according to the first embodiment, as a side view from the arrangement direction of the individual wiring lines  82   a  of the pattern portion  82  in  FIG. 11 . As illustrated in  FIG. 12 , after arrangement of the FPC substrate  80 , the forming member  700  connected to the FPC substrate  80 , and the first acoustic matching layer base material  720  arranged on the forming member  700  and on which the second acoustic matching layer  73  is arranged, on the machining tool  101 , cutting is performed on a portion of the FPC substrate  80  including the solid portion  81 , the forming member  700 , and the first acoustic matching layer base material  720  using a dicing saw  100 . Specifically, as illustrated in  FIGS. 11 and 12 , by rotating and moving a blade of a precision cutting machine such as the dicing saw  100  along a cutting path C 1  passing through the portions between the wiring lines  82   a  of the pattern portion  82  and extending in the longitudinal direction of the FPC substrate  80 , a portion of the FPC substrate  80 , the forming member  700 , and the first acoustic matching layer base material  720  are cut and divided along a stacking direction of the forming member  700  (forming process). Note that the stacking direction herein refers to a stacking direction of the piezoelectric element base material  710 , the first thin film  760 , the second thin film  770 , and the backing material base material  750 . The solid portion  81  is divided by the dicing saw  100  in accordance with each of the wiring lines  82   a  and at the same time, the piezoelectric element  71 , the first acoustic matching layer  72 , the backing material  75 , the first electrode  76 , the second electrode  77 , the conductive thin film  78  and the sealing portion  79  are formed, and thereafter, by arranging the acoustic lens  74 , the ultrasound transducer  7  illustrated in  FIGS. 3 and 4  is obtained. 
     The piezoelectric element  71  is formed by dividing the piezoelectric element base material  710  by the dicing saw  100 . In this case, the piezoelectric element  71  has a rectangular parallelepiped shape, and when a length in the arrangement direction of the plurality of piezoelectric elements  71  in a plane orthogonal to the cut surface is w, and a length in the stacking direction of the first acoustic matching layer  72 , or the like, orthogonal to the arrangement direction is t, it is preferable that a ratio represented by w/t is 0.3 to 0.7 in that this would achieve high electricity-machine conversion efficiency. 
     As described above, the first embodiment is a case of forming the forming member  700  including the piezoelectric element base material  710 , the backing material base material  750 , the first thin film  760 , the second thin film  770 , and the third thin film  781 . The forming member  700  has a portion of the FPC substrate  80  including a contact portion between the FPC substrate  80  and the third thin film  781 , a portion of the third thin film  781 , and a portion of the plating film  782  being sealed with the sealing member  790 , and thereafter, the forming member  700  is cut in accordance with the wiring line  82   a  together with the FPC substrate  80  including the solid portion  81 . Since the piezoelectric element  71  and the FPC substrate  80  are electrically connected without using a bonding material that generates heat such as solder, it is possible to suppress degradation of the characteristics of the piezoelectric element  71  and to allow the space between the piezoelectric elements  71  to be about the thickness of the blade of the dicing saw  100 , or the like. With this configuration, it is possible to realize a narrow pitch of the plurality of piezoelectric elements. 
     Moreover, according to the above-described first embodiment, the plurality of piezoelectric elements  71  and the FPC substrate  80  are connected with each other merely by cutting and dividing the solid portion  81  using the dicing saw  100 . This configuration eliminates necessity of performing high-accuracy alignment of the piezoelectric element  71  and the wiring (for example, the wiring lines  82   a ), making it possible to perform production easily even when the pitch between the piezoelectric elements  71  is fine. This enables production of a high-quality ultrasound transducer for which narrow pitch is demanded. 
     In the first embodiment described above, it is also allowable to fix a relative relationship between the forming member  700  and the FPC substrate  80  by filling wax or the like between the forming member  700  and the FPC substrate  80 . 
     While the above-described first embodiment is a case where the forming member  700  includes the piezoelectric element base material  710 , the backing material base material  750 , the first thin film  760 , the second thin film  770 , and the third thin film  781 , the forming member  700  may further include the first acoustic matching layer base material  720 , or the like. 
     First Modification of First Embodiment 
       FIG. 13  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a first modification of the first embodiment. While the above-described first embodiment is a case where the ultrasound transducer  7  includes one backing material (backing material  75 ), the ultrasound transducer  7  includes two backing materials in the first modification. As illustrated in  FIG. 13 , in the configuration of the ultrasound transducer  7  described above, a wall  92  having a hollow rectangular prism shape is built at the first acoustic matching layer  72 , and a second backing material  75   a  is filled in a hollow space formed by the wall  92 , thereby producing an ultrasound transducer  7   a . The wall  92  encloses a plurality of oscillating portions including the piezoelectric element  71 , the backing material  75 , the first electrode  76 , the second electrode  77 , the conductive thin film  78 , and the sealing portion  79 . The second backing material  75   a  is provided in a hollow space formed by the wall  92  and the plurality of oscillating portions. 
     The acoustic impedance of the second backing material  75   a  is smaller than the acoustic impedance of the backing material  75  (first backing material). With application of the two backing materials having such a relationship, it is possible to cause the backing material  75  to hold the piezoelectric element  71  and to attenuate the unnecessary vibration with high efficiency, and to suppress transmission of vibration as a cause of crosstalk to the adjacent piezoelectric element  71  by the second backing material  75   a . Therefore, according to the first modification, it is possible to realize reduction in the pulse width and suppression of crosstalk. 
     Second Modification of First Embodiment 
       FIG. 14  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a second modification of the first embodiment. While the above-described first embodiment is a case where the ultrasound transducer  7  includes the first electrode  76  having a flat plate shape, the second modification is a case where an ultrasound transducer  7   b  includes a thick portion  76   a  on the side of first electrode  76  coming in contact with the conductive thin film  78 . 
     The thick portion  76   a  forms a portion of an electrical conduction path between the first electrode  76  and the FPC substrate  80 . For example, the thick portion  76   a  is formed of the same conductive material as that of the first electrode  76 , and comes in contact with the conductive thin film  78 .  FIGS. 15 and 16  are schematic diagrams illustrating production of a forming member of the ultrasound transducer according to the second modification of the first embodiment. As illustrated in  FIG. 15 , the forming member of the ultrasound transducer  7   b  according to the second modification is produced using a member having a structure in which a first thin film  762  having a plurality of protrusions  761  to be the thick portion  76   a  after the cutting processing is formed on one main surface of a piezoelectric element base material  711 , while a second thin film  771  is formed on the other main surface of the piezoelectric element base material  711 . Specifically, as illustrated in  FIG. 16 , after a backing material base material  751  is arranged on the first thin film  762 , cutting is performed along a cutting path C 2  passing through the protrusion  761 , thereby obtaining a stacked body for forming the forming member including the piezoelectric element base material  710 , the backing material base material  750 , and the second thin film  770 . 
     According to the second modification, by forming the thick portion  76   a , the contact area between the first electrode  76  and the conductive thin film  78  is larger than the case of the first electrode  76  without the thick portion  76   a  described above, making it possible to provide further reliable electrical connection. 
     Third Modification of First Embodiment 
       FIG. 17  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a third modification of the first embodiment. While the above-described second modification is a case where the ultrasound transducer  7   b  includes the first electrode  76  having the thick portion  76   a , the third modification is a case where an ultrasound transducer  7   c  includes a first electrode  76   b  and a second electrode  77   a  being exposed on each of opposing side surfaces. 
     The first electrode  76   b  has the thick portion  76   a  on an arrangement side of the conductive thin film  78  and is continuous to the side surface of the piezoelectric element  71  on the arrangement side of the conductive thin film  78  to be exposed to the outside, while retreating relative to the side surface of the piezoelectric element  71  on the side opposite to the side coming in contact with the conductive thin film  78 . Moreover, the second electrode  77   a  is continuous to the side surface of the piezoelectric element  71  on the side opposite to the arrangement side of the conductive thin film  78  to be exposed to the outside, while retreating relative to the side surface of the piezoelectric element  71  on the arrangement side of the conductive thin film  78 . 
       FIG. 18  is a schematic diagram illustrating production of a forming member of the ultrasound transducer according to the third modification of the first embodiment. As illustrated in  FIG. 18 , the forming member of the ultrasound transducer  7   c  according to the third modification is produced using a member having a structure in which a plurality of first thin films  764  having a protrusion  763  to be the thick portion  76   a  is formed on one main surface of the piezoelectric element base material  711 , while a plurality of second thin films  772  is formed on the other main surface of the piezoelectric element base material  711 . The first thin film  764  and the second thin film  772  are arranged in an alternating manner when viewed from the thickness direction of the piezoelectric element base material  711 , with a space (gap) between the second thin films  772  being located at a position opposing the protrusion  763 . The backing material base material  751  is arranged on the first thin film  764  having the protrusion  763 , and thereafter, cutting is performed along a cutting path C 3  passing through the protrusion  763 , thereby obtaining a stacked body for forming the forming member. 
     Fourth Modification of First Embodiment 
       FIG. 19  is a schematic diagram illustrating a configuration of a main portion of an ultrasound transducer according to a fourth modification of the first embodiment. While the above-described first embodiment is a case of the ultrasound transducer  7  in which a slit formed by cutting has a uniform width, the slit may be formed substantially in a V-shape having its width increasing toward the FPC substrate  80  side as in the fourth modification. According to the fourth modification, by widening a groove width on the FPC substrate  80  side, it is possible to facilitate casting operation of the second backing material after the cut stacked body is bent at the time of producing a convex transducer or a radial transducer. 
     Fifth Modification of First Embodiment 
       FIG. 20  is a schematic diagram illustrating a configuration of a main portion of an ultrasound transducer according to a fifth modification of the first embodiment. While the above-described first embodiment is a case of the ultrasound transducer  7  in which the slit formed by cutting has a uniform width, the slit may be formed in a stepped shape having its width increasing toward the FPC substrate  80  side as in the fifth modification. 
     Sixth Modification of First Embodiment 
       FIG. 21  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a sixth modification of the first embodiment, and is a diagram illustrating a configuration of a forming member. While the above-described first embodiment is a case where the backing material  75  has a prismatic shape, the backing material  75  may be a backing material  75   b  having a chamfered outer edge on the surface of the side holding the FPC substrate  80  as illustrated as an ultrasound transducer  7   d  according to the sixth modification. With this chamfering, it is possible to suppress damage on the conductive thin film  78 . 
     Seventh Modification of First Embodiment 
       FIG. 22  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a seventh modification of the first embodiment, and is a diagram illustrating a configuration of a forming member. While the above-described first embodiment is a case where the backing material  75  has a prismatic shape, the backing material  75  may be a backing material  75   c  having a trapezoidal shape in side view with the width decreasing toward the side holding the FPC substrate  80  as illustrated as an ultrasound transducer  7   e  according to the seventh modification. 
     Eighth Modification of First Embodiment 
       FIG. 23  is a schematic diagram illustrating a configuration of an ultrasound transducer according to an eighth modification of the first embodiment and is a diagram illustrating a configuration of a forming member. While the above-described first embodiment is a case where the backing material  75  has a prismatic shape, the backing material  75  may be a backing material  75   d  having a curved surface on the side holding the FPC substrate  80  as illustrated as an ultrasound transducer  7   f  according to the eighth modification. 
     Ninth Modification of First Embodiment 
       FIG. 24  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a ninth modification of the first embodiment. While the above-described first embodiment is a case where the FPC substrate  80  is embedded in the backing material  75  and connected to the first electrode  76  via the conductive thin film  78 , it is allowable to directly connect the first electrode  76  with the solid portion  81  after the division of the FPC substrate  80  by arranging the FPC substrate  80  on the side surface of the backing material  75  as in an ultrasound transducer  7   g  according to the ninth modification. In this case, a sealing portion  79   a  is formed at a connecting portion between the first electrode  76  and the FPC substrate  80 . 
     Note that by applying the configuration of the ultrasound transducer  7   b  according to the above-described second modification also to the ninth modification, the contact region with the FPC substrate  80  is increased due to the thick portion  76   a , making it possible to make the electrical connection further easy and stable. 
     Tenth Modification of First Embodiment 
       FIG. 25  is a diagram illustrating a method of manufacturing an ultrasound transducer according to a tenth modification of the first embodiment.  FIG. 26  is a schematic diagram illustrating a configuration of the ultrasound transducer according to the tenth modification of the first embodiment. While the above-described first embodiment is an exemplary case of using a 1D array, application is also possible to a 1.25D array, a 1.5D array, or a 1.75D array in which a plurality of piezoelectric elements (oscillating portions) is arranged in a direction (elevation direction) substantially orthogonal to the scanning direction (arrangement direction of piezoelectric elements in the 1D array, the arrangement direction of piezoelectric elements along which the forming member  700  is divided) of the ultrasound transducer. Note that in a convex ultrasound transducer, the plurality of piezoelectric elements (oscillating portions) is arranged in a direction along a spherical surface in the arrangement direction of the piezoelectric elements, that is, a direction perpendicular to the scanning direction. For example, with a method of manufacturing a 1.25D-array ultrasound transducer illustrated in  FIG. 25 , there are provided three forming members as described above, for example, a first forming member  701 , a second forming member  702 , and a third forming member  703 , respectively connected to mutually different FPC substrates  80   a  to  80   c . The forming members  701  to  703  are arranged in the moving direction of the dicing saw  100  and thereafter individually divided along a cutting path C 4  using the dicing saw  100 , thereby achieving production of a 1.25D-array ultrasound transducer  7   h  having elements  70   a  to  70   c  as illustrated in  FIG. 26 . 
     Alternatively, the 1.25D-array ultrasound transducer  7   h  illustrated in  FIG. 26  may be formed by building a wall serving as a weir at the time of casting of the backing material as illustrated in the first modification (refer to  FIG. 13 ), and then, casting a portion between the groove and the wall divided by the dicing saw  100  using a liquid backing material and solidifying the backing material, so as to obtain a 1.25D-array ultrasound transducer. Examples of the liquid backing material include liquid materials obtained by mixing alumina (Al 2 O 3 ), zirconia (ZrO 2 ), or the like, as a filler, with epoxy resin or silicone resin that can maintain flexibility after being cured. This also applies to ultrasound transducers with 1.5D array and 1.75D array in a similar manner. 
     Second Embodiment 
       FIG. 27  is a schematic diagram illustrating a configuration of an ultrasound transducer according to a second embodiment. While the above-described first embodiment is a case where the second electrode  77  is connected to the ground electrode  72   a  provided in the first acoustic matching layer  72 , the second embodiment is configured such that the second electrode  77  is electrically connected to a ground pattern  83  formed on the FPC substrate  80 . 
     As illustrated in  FIG. 27 , an ultrasound transducer  7   i  according to the second embodiment includes a second conductive thin film  78   a  configured to connect the ground pattern  83  provided on a surface of the FPC substrate  80  opposite side of the connection surface of the conductive thin film  78  with the second electrode  77 , in contrast with the above-described ultrasound transducer  7 . Note that, in the second embodiment, the first acoustic matching layer  72  does not include the ground electrode  72   a.    
     Next, a method of manufacturing the ultrasound transducer  7   i  will be described with reference to  FIGS. 28 to 32 .  FIGS. 28 to 32  are schematic diagrams illustrating a method of manufacturing the ultrasound transducer according to the second embodiment. Herein, production of a forming member for forming the piezoelectric element  71 , the backing material  75 , the first electrode  76 , the second electrode  77 , the conductive thin film  78  (first conductive thin film) and the second conductive thin film  78   a  will be described. 
     First, as described above, the first thin film  760  and the second thin film  770  are formed on opposing main surfaces of the piezoelectric element base material  710 , and thereafter, backing material base material  750  is provided on a side opposite to the piezoelectric element base material  710  side of the first thin film  760  (refer to  FIG. 5 ). 
     Thereafter, a masking material  93  to cover the second thin film  770  and a portion of the FPC substrate  80  is arranged and a thin film formation prevention member  765  configured to prevent thin film formation by sputtering is arranged on a side of the first thin film  760 , the side opposite to the formation surface of the conductive thin film  78  (refer to  FIG. 28 ). A fourth thin film  783  is formed by sputtering using the material of the stacked film, being one constituent material of the conductive thin film  78  and the second conductive thin film  78   a  (refer to  FIG. 29 ). 
     After formation of the fourth thin film  783 , the masking material  93  is removed (refer to  FIG. 30 ), leading to a state where the fourth thin film  783  is divided into the third thin film  781  connecting the first thin film  760  with the wiring pattern formed on the FPC substrate  80 , and a fifth thin film  784  connecting the second thin film  770  with the ground pattern formed on the FPC substrate  80 . Thereafter, the plating film  782  covering the third thin film  781  and a second plating film  785  covering the fifth thin film  784  are formed by electroplating treatment (refer to  FIG. 31 ). 
     After formation of the plating film  782  and the second plating film  785 , a sealing member  791  is provided on a surface of the backing material base material  750 , on which the FPC substrate  80  is embedded, so as to seal a portion of the FPC substrate  80  including the contact portion between the FPC substrate  80  and each of the third thin film  781  and the fifth thin film  784 , a portion of the third thin film  781  and a portion the fifth thin film  784 , and a portion of the plating film  782  and a portion of the second plating film  785 , by the sealing member  791  (refer to  FIG. 32 ). A forming member  700 A is produced by the above-described processing. 
     Thereafter, similarly to the above-described processing, the first acoustic matching layer base material  720  on which the second acoustic matching layer  73  is stacked is arranged on the second thin film  770  of the forming member  700 A, so as to be mounted on the machining tool  101 , and then, by rotating and moving the dicing saw  100  along the cutting path C 1  (refer to  FIGS. 11 and 12 ) extending in the longitudinal direction of the FPC substrate  80 , a portion of the FPC substrate  80 , the forming member  700 A, and the first acoustic matching layer base material  720  are cut. The solid portion  81  and the ground pattern  83  are cut by the dicing saw  100  according to each of the wiring lines  82   a  and at the same time, the piezoelectric element  71 , the first acoustic matching layer  72 , the backing material  75 , the first electrode  76 , the second electrode  77 , the conductive thin film  78 , the second conductive thin film  78   a , and a sealing portion  79   b  are formed, and thereafter, the acoustic lens  74  is arranged, thereby obtaining the ultrasound transducer  7   i  illustrated in  FIG. 27 . Note that a second sealing portion  76   c  formed by the thin film formation prevention member  765  is formed on the first electrode  76  on the second conductive thin film  78   a  side, thereby insulating between the first electrode  76  and the second conductive thin film  78   a.    
     As described above, the second embodiment is a case of forming the forming member  700 A including the piezoelectric element base material  710 , the backing material base material  750 , the first thin film  760 , the second thin film  770 , the fifth thin film  784 , and the second plating film  785 . The forming member  700 A has a portion of the FPC substrate  80  including the contact portions between the FPC substrate  80  and each of the third thin film  781  and the fifth thin film  784 , a portion of the third thin film  781  and a portion of the fifth thin film  784 , and a portion of the plating film  782  and a portion of the second plating film  785  being sealed with the sealing member  791 , and thereafter, the forming member  700 A is cut in accordance with the wiring line  82   a  together with the FPC substrate  80  including the solid portion  81  and the ground pattern  83 . Since the piezoelectric element  71  and the FPC substrate  80  are electrically connected without using a bonding material that generates heat such as solder, it is possible to suppress degradation of the characteristics of the piezoelectric element  71  and to allow the space between the piezoelectric elements  71  to be about the thickness of the blade of the dicing saw  100 , or the like. With this configuration, it is possible to realize a narrow pitch of the plurality of piezoelectric elements. 
     Note that by applying the configuration of the ultrasound transducer  7   c  according to the third modification of the first embodiment described above also to the second embodiment, the backing material  75  (backing material base material  750 ) suppresses exposure of the side of the first electrode  76   b  opposite to the side coming in contact with the conductive thin film  78  to the outside. With this configuration, there is no need to provide the thin film formation prevention member  765 , making it possible to produce an ultrasound transducer with the reduced number of components. 
     According to some embodiments, it is possible to suppress, in an ultrasound transducer, degradation of characteristics of the piezoelectric element in manufacture and to realize a narrow pitch in the plurality of piezoelectric elements. 
     Embodiments of the disclosure have been described hereinabove, however, the disclosure is not intended to be limited to the above-described embodiments and the modification example. The disclosure is not intended to be limited to the above-described embodiments and modification example but may include various forms of embodiments without deviating from the technical spirit and scope of the general inventive concept as defined in the appended claims of this application. Furthermore, the components described in each of the embodiments and modification examples may be appropriately combined with each other. 
     In this manner, the disclosure may include various forms of embodiments without deviating from the technical spirit and scope of the general inventive concept as defined in the appended claims of this application.