Patent Publication Number: US-2021169313-A1

Title: Endoscope

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Continuation of PCT International Application No. PCT/JP2019/033255 filed on Aug. 26, 2019 claiming priority under 35 U.S.C § 119(a) to Japanese Patent Application No. 2018-169147 filed on Sep. 10, 2018. Each of the above applications is hereby expressly incorporated by reference, in its entirety, into the present application. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an endoscope including a treatment tool delivery port and an elevator on a distal end side of an insertion part. 
     2. Description of the Related Art 
     As an ultrasound endoscope, there is known one in which an electronic scanning type ultrasound transducer is provided at a distal end part of an insertion part of the endoscope and a treatment tool delivery port is disposed on a proximal end side of the ultrasound transducer in the distal end part. In endoscopy using this ultrasound endoscope, for example, while acquiring an ultrasound image of a treatment target region (including an observed region, an examined region, and the like) with the ultrasound transducer, cells are collected by puncturing a treatment target region with a puncturing treatment tool delivered into the body through a treatment tool insertion channel and a treatment tool delivery port. Also, in order to treat a desired position with such a treatment tool, it is necessary to change the delivery direction of the treatment tool delivered from the treatment tool delivery port formed at the distal end part of the insertion part. For this reason, a treatment tool elevating mechanism is provided inside the treatment tool delivery port of the distal end part of the insertion part (refer to JP1996-126643A (H08-126643A), JP1996-126643A (H08-126604A), and JP2005-287526A). 
     The treatment tool elevating mechanism includes an elevator housing chamber, an elevator, an elevator rotating mechanism, and the like. The elevator housing chamber is provided in the treatment tool delivery port of the distal end part of the insertion part. The elevator is supported in the elevator housing chamber so as to be rotatable about a rotation shaft. The elevator rotating mechanism rotates the elevator depending on the rotational operation of the elevator, which is performed by the operating part of the ultrasound endoscope. 
     In addition to the already-described treatment tool delivery port, an observation window for observing the treatment target region, and an illumination window for emitting illumination light toward the treatment target region and the like are provided on an outer surface of the distal end part of the insertion part. 
     For example, in ultrasound endoscopes described in JP1996-126643A (H08-126643A) and JP1996-126643A (H08-126604A), in a case where a direction parallel to the rotation shaft of the elevator is the width direction of the treatment tool delivery port, the observation window and the illumination window are provided at a position on one direction side of the treatment tool delivery port in the width direction at the outer periphery of the distal end part of the insertion part. Additionally, in an ultrasound endoscope described in JP2005-287526A, the observation window and a first illumination window are provided at a position on the one direction side in the width direction with respect to the treatment tool delivery port at the distal end part of the insertion part, and a second illumination window is provided at a position on the other direction side opposite to the one direction side with respect to the treatment tool delivery port. 
     SUMMARY OF THE INVENTION 
     In recent years, a therapeutic procedure has been performed in which a stent (corresponding to the treatment tool) is placed in a lumen, for example, the stomach by using an ultrasound endoscope. In a case where the stent is placed in the stomach, it is important for therapeutic safety to optically observe the stent not only by an ultrasound image but also by an endoscope image. For example, in a case where the intrahepatic bile duct and the stomach are connected to each other with a stent in order to relieve the jaundice symptom, it is necessary to confirm in real time that the stent is accurately released in the stomach on the basis of the endoscope image. For this reason, it is necessary to reliably illuminate the treatment tool such as a stent delivered from the treatment tool delivery port and the treatment target region with the illumination light. 
     In the ultrasound endoscopes described in JP1996-126643A (H08-126643A) and JP1996-126643A (H08-126604A), the treatment tool and the treatment target region are illuminated only by the illumination window disposed on one direction side of the treatment tool delivery port. For this reason, in a case where the treatment target region enters the shadow of the elevator and the treatment tool, there is a concern that the illumination light does not hit the treatment target region. Additionally, since the way the illumination light hits the treatment tool changes due to the displacement of the treatment tool accompanying the rotation of the elevator, there is a concern that the endoscope image is not easily seen and the treatment tool delivered from the treatment tool delivery port and the treatment target region may be out of the illumination range of the illumination light. 
     Additionally, in the ultrasound endoscope described in JP2005-287526A, the treatment target region is illuminated from two directions by the first illumination window and the second illumination window, and the illumination light amount is also increased as compared to the ultrasound endoscopes described in JP1996-126643A (H08-126643A) and JP1996-126643A (H08-126604A). Therefore, the treatment target region does not easily enter the shadow of the elevator and the treatment tool. However, also in the ultrasound endoscope described in JP2005-287526A, there is a concern that the treatment tool delivered from the treatment tool delivery port and the treatment target region thereof may be out of the illumination range of the illumination light depending on the rotational position of the elevator. 
     The present invention has been made in view of such circumstances, and an object of the present invention is to provide an endoscope capable of reliably illuminating a treatment tool delivered from a treatment tool delivery port and a treatment target region thereof. 
     An endoscope for achieving the object of the present invention is an endoscope comprising a distal end part body that is provided on a distal end side of an insertion part and has a distal end, a proximal end, and a longitudinal axis; a treatment tool delivery port that is formed in the distal end part body and delivers a treatment tool inserted into the insertion part; an elevator that is rotatably supported in the treatment tool delivery port of the distal end part body and controls a delivery direction of the treatment tool delivered from the treatment tool delivery port, and a first illumination window that is provided on the distal end part body. The first illumination window is provided in a proximal end side region at a position shifted from the treatment tool delivery port to a proximal end side of the distal end part body in the distal end part body. 
     According to this endoscope, the treatment tool delivered from the treatment tool delivery port and the treatment target region thereof can always be illuminated from the proximal end side region with the illumination light emitted from the first illumination window. Thus, it is possible to reliably illuminate the treatment tool and the treatment target region thereof with the illumination light from the first illumination window. 
     In the endoscope according to another aspect of the present invention, in a case where a direction perpendicular to both the longitudinal axis and a normal direction of an opening surface of the treatment tool delivery port is a width direction of the treatment tool delivery port, the proximal end side region is a region in the distal end part body, which is located closer to the proximal end side of the distal end part body than the treatment tool delivery port and is present within a range in which the treatment tool delivery port is formed in the width direction. Accordingly, it is possible to reliably illuminate the treatment tool and the treatment target region thereof with the illumination light from the first illumination window. 
     The endoscope according to another aspect of the present invention further comprises an elevator support member that is coupled to one end part of the elevator and rotatably supports the elevator between an elevated position and a lodged position. The other end part of the elevator opposite to the one end part is provided at a position closer to a distal end side of the distal end part body than the first illumination window at least in a case where the elevator is at the lodged position. Accordingly, it is possible to reliably illuminate the treatment tool and the treatment target region thereof with the illumination light from the first illumination window. 
     In the endoscope according to another aspect of the present invention, in a case where a direction perpendicular to both the longitudinal axis and a normal direction of an opening surface of the treatment tool delivery port is a width direction of the treatment tool delivery port, a first illumination axis of the first illumination window is inclined toward a distal end side of the distal end part body from a posture perpendicular to both the width direction and the longitudinal axis, and the proximal end side region is an inclined surface having the first illumination axis as a normal line. Accordingly, it is possible to reliably illuminate the treatment tool and the treatment target region thereof with the illumination light from the first illumination window. 
     The endoscope according to still another aspect of the present invention further comprises an observation window that is provided at a position closer to the proximal end side of the distal end part body than the treatment tool delivery port in the distal end part body, and a first illumination range of illumination light emitted from the first illumination window includes an observation range of the observation window. Accordingly, the visibility of the observation range of the observation window can be improved. 
     In the endoscope according to still another aspect of the present invention, in a case where a direction perpendicular to both the longitudinal axis and a normal direction of an opening surface of the treatment tool delivery port is a width direction of the treatment tool delivery port, the observation window is provided at a position on one direction side in the width direction with respect to the proximal end side region in the distal end part body. By disposing the observation window and the first illumination window at substantially the same position in the direction along the longitudinal axis, the observation range of the observation window can be illuminated with the illumination light emitted from the first illumination window. 
     The endoscope according to still another aspect of the present invention further comprises a second illumination window provided at a position on the other direction side opposite to the one direction side with respect to the proximal end side region in the distal end part body, and the second illumination window illuminates a second illumination range that partially overlaps the first illumination range and includes the observation range. Accordingly, the observation range of the observation window can be illuminated with the illumination light emitted from both the first illumination window and the second illumination window. 
     In the endoscope according to still another aspect of the present invention, both a first illumination axis of the first illumination window and a second illumination axis of the second illumination window are inclined toward the distal end side of a distal end part body from a posture perpendicular to both the width direction and the longitudinal axis, and a second illumination axis angle is smaller than a first illumination axis angle in a case where an inclination angle of the first illumination axis with respect to a reference axis parallel to the longitudinal axis as seen from the width direction side is the first illumination axis angle and an inclination angle of the second illumination axis with respect to the reference axis as seen from the width direction side is the second illumination axis angle. Accordingly, the visibility (forward visibility) of the insertion part  20  on the insertion direction side can be improved. 
     In the endoscope according to still another aspect of the present invention, an observation axis of the observation window is inclined toward the distal end side of the distal end part body from the posture perpendicular to both the width direction and the longitudinal axis, and an observation axis angle is equal to the first illumination axis angle in a case where an inclination angle of the observation axis with respect to the reference axis as seen from the width direction side is the observation axis angle. Accordingly, the observation range of the observation window can be included in the first illumination range of the first illumination window. 
     The endoscope according to still another aspect of the present invention further comprises an ultrasound transducer that is provided in the distal end part body and is located closer to a distal end side of the distal end part body than the treatment tool delivery port. 
     The present invention can reliably illuminate the treatment tool delivered from the treatment tool delivery port and the treatment target region thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of an ultrasound examination system to which an endoscope of the present invention is applied. 
         FIG. 2  is a schematic view illustrating a pipe line configuration of an ultrasound endoscope. 
         FIG. 3  is an external perspective view of a distal end part of an insertion part. 
         FIG. 4  is a right side view of the distal end part of the insertion part. 
         FIG. 5  is an exploded perspective view of the distal end part of the insertion part. 
         FIG. 6  is a perspective view of an elevating case. 
         FIG. 7  is a front view of the elevating case in a case where the elevating case is viewed from an exterior case distal end side. 
         FIG. 8  is a schematic view illustrating an example of an elevator operating mechanism. 
         FIGS. 9A and 9B  are explanatory views for explaining the rotation of the elevator according to the operation of an operating lever. 
         FIG. 10  is a top view of the exterior case. 
         FIG. 11  is an explanatory view for explaining an observation axis and an observation range of the observation window, a first illumination axis and a first illumination range of a first illumination window, and a second illumination axis and a second illumination range of a second illumination window. 
         FIG. 12  is a side view of the distal end part of the insertion part inserted into a lumen. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     [Configuration of Ultrasound Examination System and Ultrasound Endoscope] 
       FIG. 1  is a schematic view of an ultrasound examination system  2  to which an endoscope of the present invention is applied. As illustrated in  FIG. 1 , the ultrasound examination system  2  includes an ultrasound endoscope  10  that images the inside of a lumen  154  (also referred to as a body cavity, refer to  FIG. 12 ) of a subject, an ultrasound processor device  12  that generates an ultrasound image, an endoscope processor device  14  that generates an endoscope image, a light source device  16  that supplies illumination light for illuminating the inside of the lumen  154  to the ultrasound endoscope  10 , and a monitor  18  for displaying the ultrasound image and the endoscope image. 
     The ultrasound endoscope  10  corresponds to the endoscope of the present invention and includes an insertion part  20 , an operating part  22 , and a universal cord  24 . 
     The insertion part  20  is inserted into various lumens  154  (refer to  FIG. 12 ). The operating part  22  is continuously provided on a proximal end side of the insertion part  20  and receives an operation of a surgeon. 
     The operating part  22  is connected to one end side of the universal cord  24 . Additionally, an ultrasound connector  27  connected to the ultrasound processor device  12 , an endoscope connector  28  connected to the endoscope processor device  14 , and a light source connector  30  connected to the light source device  16  are provided on the other end side of the universal cord  24 . A water supply tank  118  is connected to the light source connector  30  via an air and water supply tube  32 , and a suction pump  124  is connected to light source connector  30  via a suction tube  34 . 
     The ultrasound processor device  12  generates an ultrasound image on the basis of an ultrasound detection signal output from the ultrasound endoscope  10 . Additionally, the endoscope processor device  14  also generates an endoscope image on the basis of an imaging signal output from the ultrasound endoscope  10 . 
     The light source device  16  is connected to the insertion part  20 , the operating part  22 , the universal cord  24 , and an incident end of a light guide  128  (refer to  FIG. 2 ) inserted into the light source connector  30 . The light source device  16  supplies illumination light to the incident end of the light guide  128 . The illumination light is emitted from the light guide  128  to treatment target regions through respective illumination windows  90 A and  90 B (refer to  FIG. 3 ) described below. 
     The monitor  18  is connected to both the ultrasound processor device  12  and the endoscope processor device  14  and displays an ultrasound image generated by the ultrasound processor device  12  and the endoscope image generated by the endoscope processor device  14 . With regard to the display of the ultrasound image and the endoscope image, only any one of the images can be selectively displayed or both of the images can be simultaneously displayed. 
     An air and water supply button  36  and a suction button  38  and are provided side by side on the operating part  22 , which is provided with a pair of angle knobs  42 , an operating lever  43 , a treatment tool insertion port  44 , and the like. 
     The insertion part  20  has a distal end, a proximal end, and a longitudinal axis and has a distal end part  50 , a bending part  52 , and a flexible part  54  in order toward the proximal end side from the distal end side. The distal end part  50  is formed of a hard member and is also referred to as a distal end hard part. An ultrasound transducer  62  is provided on the distal end part  50  on which a balloon  64  that covers the ultrasound transducer  62  is attachably and detachably mounted. 
     The bending part  52  has one end continuously provided on the proximal end side of the distal end part  50  and the other end continuously provided on the distal end side of the flexible part  54 . The bending part  52  is configured to be bendable and is operated to be remotely bent by performing the rotational movement operation of the pair of angle knobs  42 . Accordingly, the distal end part  50  can be oriented in a desired direction. 
     The flexible part  54  has a small diameter, a long length, and flexibility and couples the bending part  52  to the operating part  22 . 
       FIG. 2  is a schematic view illustrating a pipe line configuration of the ultrasound endoscope  10 . As illustrated in  FIG. 2 , a treatment tool insertion channel  100 , an air and water supply pipe line  102 , and a balloon pipe line  104  having one end leading to an internal space of the balloon  64  are provided inside the insertion part  20  and the operating part  22 . 
     One end side of the treatment tool insertion channel  100  is connected to an elevating case  200  (refer to  FIG. 3 ) described below, and the other end side of the treatment tool insertion channel  100  is connected to the treatment tool insertion port  44  in the operating part  22 . Accordingly, the treatment tool insertion port  44  and the treatment tool delivery port  94  (refer to  FIG. 3 ) described below communicate with each other via the treatment tool insertion channel  100 . Additionally, a suction pipe line  106  is branched from the treatment tool insertion channel  100 , and the suction pipe line  106  is connected to the suction button  38 . 
     One end side of the air and water supply pipe line  102  is connected to an air and water supply nozzle  92  (refer to  FIG. 3 ) described below, and the other end side of the air and water supply pipe line  102  is branched into an air supply pipe line  108  and a water supply pipe line  110 . The air supply pipe line  108  and the water supply pipe line  110  are connected to the air and water supply button  36 , respectively. 
     One end side of the balloon pipe line  104  is connected to a supply and discharge port  70  that opens at a position inside the balloon  64  in an outer peripheral surface of the distal end part  50 , and the other end side of the balloon pipe line  104  is branched to a balloon water supply pipeline  112  and a balloon drainage pipeline  114 . The balloon water supply pipeline  112  is connected to the air and water supply button  36 , and the balloon drainage pipe line  114  is connected to the suction button  38 . 
     In addition to the air supply pipe line  108 , the water supply pipe line  110 , and the balloon water supply pipe line  112 , one end side of an air supply source pipe line  116  leading to an air supply pump  129  and one end side of a water supply source pipe line  120  leading to the water supply tank  118  are connected to the air and water supply button  36 . The air supply pump  129  always operates during ultrasound observation. 
     A branch pipe line  122  is branched from the air supply source pipe line  116 , and the branch pipe line  122  is connected to an inlet (above a liquid surface) of the water supply tank  118 . Additionally, the other end side of the water supply source pipe line  120  is inserted into the water supply tank  118  (below the liquid surface). Then, in a case where the internal pressure of the water supply tank  118  rises due to the air supply from the air supply pump  129  via the branch pipe line  122 , the water in the water supply tank  118  is supplied to the water supply source pipe line  120 . 
     As the air and water supply button  36 , a publicly known two-stage switchable button is used. The air and water supply button  36  switches between the leak of air sent from the air supply source pipe line  116 , the jetting of air from the air and water supply nozzle  92 , the jetting of water supply from the air and water supply nozzle  92 , and the supply of water into the balloon  64 , depending on the surgeon&#39;s operation. In addition, since a specific switching method is a known technique, the description thereof will be omitted here. 
     In addition to the suction pipe line  106  and the balloon drainage pipe line  114 , one end side of a suction source pipe line  126  is connected to the suction button  38 . A suction pump  124  is connected to the other end side of the suction source pipe line  126 . The suction pump  124  also always operates during the ultrasound observation. The suction button  38  is a two-stage switchable button similar to the air and water supply button  36 . 
     The suction button  38  switches between the communication of the suction source pipe line  126  with the outside (atmosphere), the suction of various suctioned materials from the treatment tool delivery port  94  (refer to  FIG. 3 ), and the drainage of water in the balloon  64 , depending on the surgeon&#39;s operation. In addition, since a specific switching method is a known technique, the description thereof will be omitted here. 
     Returning to  FIG. 1 , although the operating lever  43  of the operating part  22  is described in detail below, the operating lever  43  is used for the operation of changing the delivery direction of a treatment tool (not illustrated, the same applies below) delivered from the treatment tool delivery port  94  (refer to  FIG. 3 ). 
     [Configuration of Distal End Part of Insertion Part] 
       FIG. 3  is an external perspective view of the distal end part  50  of the insertion part  20 .  FIG. 4  is a right side view of the distal end part  50  of the insertion part  20 .  FIG. 5  is an exploded perspective view of the distal end part  50  of the insertion part  20 . In addition, illustration of the balloon  64  is omitted in  FIGS. 3 and 5 . Additionally, in  FIG. 5 , illustration of the light guide  128  is omitted. 
     As illustrated in  FIGS. 3 to 5 , the distal end part  50  includes an exterior case  72  (also referred to as a housing) corresponding to a distal end part body of the present invention. The exterior case  72  has a distal end that constitutes the distal end of the insertion part  20 , a proximal end that is connected to the bending part  52 , and a longitudinal axis LA. Hereinafter, a distal end side of the exterior case  72  is referred to as an “exterior case distal end side”, and a proximal end side of the exterior case  72  is referred to as an “exterior case proximal end side”. 
     An ultrasound observation part  60  that acquires an ultrasound detection signal, a treatment tool delivery port  94  for treatment tools, a first inclined surface  86 A and a second inclined surface  86 B, and an endoscope observation part  80  that acquires an imaging signal are provided from the exterior case distal end side toward the exterior case proximal end side in the exterior case  72 . Additionally, an elevator housing chamber  94   a  and an elevator  96  located inside the treatment tool delivery port  94 , and a metallic elevating case  200  (also referred to as an elevator assembly) that rotatably supports the elevator  96  are provided inside the exterior case  72 . Moreover, the exterior case  72  includes a lever housing lid  76 . 
     The treatment tool delivery port  94  opens on an outer surface of the exterior case  72  and at a position between the ultrasound observation part  60  and the endoscope observation part  80  (first inclined surface  86 A). The treatment tool inserted into the treatment tool insertion channel  100  of the insertion part  20  is delivered from the treatment tool delivery port  94 . Hereinafter, as illustrated in  FIG. 3 , a direction perpendicular to both the longitudinal axis LA and a normal direction NV of an opening surface of the treatment tool delivery port  94  is defined as a width direction WD of the treatment tool delivery port  94 , and one direction side in the width direction WD is defined as an L direction side, and the other direction side opposite to the one direction side in the width direction WD is defined as an R direction side. 
     The first inclined surface  86 A and the second inclined surface  86 B are inclined surfaces that are inclined toward the exterior case proximal end side from a posture that is parallel to the width direction WD and perpendicular to the longitudinal axis LA. In addition, although described in detail below, the inclination angle of the first inclined surface  86 A and the inclination angle of the second inclined surface  86 B are different from each other. 
     On the outer surface of the exterior case  72 , the first inclined surface  86 A is formed at a position closer to the exterior case proximal end side than the treatment tool delivery port  94  in a direction along the longitudinal axis LA and is formed from a formation region for the treatment tool delivery port  94  to a region on the L direction side in the width direction WD. An observation window  88 , a first illumination window  90 A, and an air and water supply nozzle  92  of the endoscope observation part  80  are provided on the first inclined surface  86 A. In addition, the first inclined surface  86 A may be divided into a region where the observation window  88  is provided, a region where the first illumination window  90 A is provided, and a region where the air and water supply nozzle  92  is provided. 
     On the outer surface of the exterior case  72 , the second inclined surface  86 B is formed closer to the exterior case distal end side than the first inclined surface  86 A in the direction along the longitudinal axis LA and formed in a region closer to the R direction side than the formation region for the treatment tool delivery port  94  in the width direction WD. A second illumination window  90 B is provided on the second inclined surface  86 B. In addition, the second inclined surface  86 B may be formed, in the direction along the longitudinal axis LA, at the same position as the first inclined surface  86 A or at a position closer to the exterior case proximal end side than the first inclined surface  86 A. 
     The ultrasound observation part  60  is provided at a position closer to the exterior case distal end side than the treatment tool delivery port  94  in the exterior case  72 . The ultrasound observation part  60  includes an ultrasound transducer  62  constituted of a plurality of ultrasound vibration elements. Each ultrasound vibration element of the ultrasound transducer  62  are sequentially driven on the basis of a drive signal input from the ultrasound processor device  12 . Accordingly, each ultrasound vibration element sequentially generates an ultrasound toward a treatment target region and receives an ultrasound echo (echo signal) reflected by the treatment target region. Then, each ultrasound vibration element outputs an ultrasound detection signal (electrical signal) according to the received ultrasound echo to the ultrasound processor device  12  via a signal cable (not illustrated) inserted into the insertion part  20 , the universal cord  24 , and the like. As a result, an ultrasound image is generated in the ultrasound processor device  12 . 
     The balloon  64  is attached to the exterior case distal end side with respect to the treatment tool delivery port  94  on the exterior case  72 , is formed in a bag shape that covers the ultrasound transducer  62 , and prevents attenuation of an ultrasound and an ultrasound echo. The balloon  64  is formed of, for example, a stretchable elastic material such as latex rubber, and a stretchable locking ring  66  is provided at an opening end on the exterior case proximal end side. A locking groove  68  is provided between the ultrasound observation part  60  and the treatment tool delivery port  94  over the entire circumference in the circumferential direction of the exterior case  72  in the exterior case  72 . Then, by fitting the locking ring  66  into the locking groove  68 , the balloon  64  is attachably and detachably mounted on the exterior case  72 . 
     The endoscope observation part  80  has the observation window  88  provided on the first inclined surface  86 A. Although not illustrated, an observation optical system (objective lens or the like), and a charge coupled device (CCD) type or complementary metal oxide semiconductor (CMOS) type imaging element, and the like, which constitute the endoscope observation part  80 , are disposed in the exterior case  72  and behind the observation window  88 . The imaging element captures an observation image taken from the observation window  88 . Then, the imaging element outputs an imaging signal of the observation image to the endoscope processor device  14  via the signal cable (not illustrated) inserted into the insertion part  20 , the universal cord  24 , and the like. As a result, the endoscope processor device  14  generates an endoscope image. 
     The first illumination window  90 A and the second illumination window  90 B emit illumination light toward the front thereof, which will be described in detail below. Emitting ends of the already-described respective light guides  128  are disposed in the exterior case  72  and behind the respective illumination windows  90 A and  90 B. Therefore, by coupling the light source connector  30  to the light source device  16  as illustrated in the already-described  FIG. 2 , the illumination light emitted from the light source device  16  is guided to each of the illumination windows  90 A and  90 B via the light guide  128 , and the illumination light is emitted from each of the illumination windows  90 A and  90 B. 
     The air and water supply nozzle  92  is provided at a position in the vicinity of the observation window  88  on the first inclined surface  86 A. The air and water supply nozzle  92  is connected to one end side of the air and water supply pipe line  102  illustrated in the already-described  FIG. 2  and jets a fluid such as water or air toward the observation window  88  in order to clean foreign matters and the like adhering to the surface of the observation window  88 . 
     The exterior case  72  houses the respective parts of the already-described ultrasound observation part  60  and the endoscope observation part  80 , and the elevator  96  and the elevating case  200 , which will be described below. A portion of the exterior case  72  closer to the exterior case proximal end side than the ultrasound observation part  60  is divided into two parts in an upward-downward direction in the figure with a plane parallel to both the longitudinal axis LA and the width direction WD as a boundary. For this reason, the exterior case  72  is constituted of the exterior case body  72   a  located on a lower side in the figure and an exterior case lid  72   b  located on an upper side in the figure. 
     The exterior case body  72   a  houses the ultrasound observation part  60  and has the locking groove  68 , at a distal end portion closer to the exterior case distal end side than the treatment tool delivery port  94 . Additionally, the exterior case body  72   a  has an opening part  71  that is provided at a portion closer to the exterior case proximal end side than the locking groove  68  and is covered with the exterior case lid  72   b  (refer to  FIG. 5 ). Also, the exterior case body  72   a  houses a portion of each of the elevator  96  and the elevating case  200  in the opening part  71 . 
     A groove part  74  (refer to  FIG. 4 ) formed along the longitudinal axis LA and a supply and discharge port  70  opening at an end part of the groove part  74  on the case proximal end side are formed on a side surface of the distal end portion of the exterior case body  72   a  on the L direction side. Accordingly, water can be supplied to the inside of the balloon  64  through the supply and discharge port  70 , or the water inside the balloon  64  can be discharged. 
     The exterior case lid  72   b  is attachably and detachably attached to the opening part  71  of the exterior case body  72   a . The exterior case lid  72   b  is formed with the already-described treatment tool delivery port  94 , first inclined surface  86 A, and second inclined surface  86 B from the exterior case distal end side toward the exterior case proximal end side. Additionally, the exterior case lid  72   b  covers the endoscope observation part  80  and the two light guides  128  that guide illumination light to the respective illumination windows  90 A and  90 B. 
     In a case where the exterior case lid  72   b  is attached to the opening part  71  of the exterior case body  72   a , the elevator housing chamber  94   a  that is a housing space for the elevator  96  is formed inside the treatment tool delivery port  94 . Additionally, the exterior case body  72   a  and the exterior case lid  72   b  are formed with a partition wall  73  (refer to  FIG. 5 ) that forms a side surface on the L direction side of the elevator housing chamber  94   a  so as to straddle both. 
     A fitting hole  75  (refer to  FIG. 5 ) into which the lever housing lid  76  is fitted is formed so as to straddle the exterior case body  72   a  and the exterior case lid  72   b  at the position of the elevating case  200  facing a lever housing chamber  212  to be described below (refer to  FIG. 5 ) on the side surfaces of the exterior case body  72   a  and the exterior case lid  72   b  on the R direction side. 
     The elevator housing chamber  94   a  communicates with the treatment tool insertion port  44  via the already-described treatment tool insertion channel  100  (refer to  FIG. 2 ). For this reason, the treatment tool inserted into the treatment tool insertion port  44  is introduced into the lumen  154  (refer to  FIG. 12 ) from the treatment tool delivery port  94  via the treatment tool insertion channel  100 , the elevator housing chamber  94   a , and the like. 
     The elevator  96  is rotatably supported (pivotally supported) on the elevating case  200  via a rotation shaft  216  (refer to  FIG. 6 ) in the elevator housing chamber  94   a . The elevator  96  has an arcuate guide surface  96   a  that guides a treatment tool guided into the elevator housing chamber  94   a  toward the treatment tool delivery port  94 . Accordingly, the elevator  96  changes the direction of the treatment tool guided into the elevator housing chamber  94   a  from the treatment tool insertion channel  100  and delivers the treatment tool from the treatment tool delivery port  94 . Also, although described in detail below, the elevator  96  rotates about a rotation shaft  216  in the elevator housing chamber  94   a  depending on the operation of the operating lever  43  and thereby changes the delivery direction of a treatment tool introduced into the lumen  154  (refer to  FIG. 12 ) from the treatment tool delivery port  94 . Therefore, the elevator  96  controls the delivery direction of the treatment tool from the treatment tool delivery port  94 . 
     The lever housing lid  76  is fitted into the fitting hole  75  on the outer surface of the exterior case  72 . The lever housing lid  76  is attachably and detachably attached to the elevating case  200  by a bolt  77  penetrating the lever housing lid  76  in a state where the lever housing lid  76  is fitted in the fitting hole  75  (refer to  FIG. 5 ). 
     [Configuration of Elevating Case] 
       FIG. 6  is a perspective view of the elevating case  200 , and  FIG. 7  is a front view of the elevating case  200  in a case where the elevating case  200  is viewed from the exterior case distal end side. As illustrated in  FIGS. 6 and 7  and the already-described  FIG. 5 , the elevating case  200  corresponds to an elevator support member of the present invention and is formed of, for example, a metal material having corrosion resistance. The elevating case  200  has a base  202  and a partition wall  204  extending from the base  202  to the exterior case distal end side. 
     A distal end surface of the base  202  on the exterior case distal end side constitutes a side surface of the elevator housing chamber  94   a  on the exterior case proximal end side. Additionally, the base  202  is formed with a through hole  202   a  that is parallel to the longitudinal axis LA and communicates with the elevator housing chamber  94   a  and the treatment tool insertion channel  100 . Accordingly, the treatment tool insertion channel  100  and the elevator housing chamber  94   a  communicate with each other via the through hole  202   a.    
     Two light guide holding grooves  203 A and  203 B are formed on an upper surface (a surface on the delivery direction side of the treatment tool) of outer wall surfaces of the base  202 . Here, since the illumination windows  90 A and  90 B are disposed on an upward side (a side perpendicular to both the longitudinal axis LA and the width direction WD) of the elevating case  200 , the two light guides  128  corresponding to the illumination windows  90 A and  90 B, respectively, are disposed along an upper surface of the base  202 . Accordingly, each of the light guide holding grooves  203 A and  203 B allows one emitting end of each light guide  128  to be held at a position facing the first illumination window  90 A and allows the emitting end of each light guide  128  to be held at a position facing the second illumination window  90 B. 
     The partition wall  204  is provided between the elevator  96  (elevator housing chamber  94   a ) and an elevator elevating lever  210  (lever housing chamber  212 ) described below. The partition wall  204  has a side wall surface  206  that is a side surface on the R direction side, and a facing wall surface  208  that is a side surface on the L direction side and faces the elevator  96 . 
     The lever housing chamber  212  that houses the elevator elevating lever  210  is formed on the side wall surface  206 . A holding hole  214  (refer to  FIG. 6 ), which penetrates the partition wall  204  in the width direction WD (an axis direction of the rotation shaft  216 ), is formed in a bottom surface of the lever housing chamber  212  on the elevator  96  side. The holding hole  214  allows the lever housing chamber  212  and the elevator housing chamber  94   a  to communicate with each other. Also, the holding hole  214  rotatably and pivotably supports the rotation shaft  216 . In addition, since the elevator elevating lever  210  in the lever housing chamber  212  rotates (rocks) about the rotation shaft  216 , the lever housing chamber  212  is formed in a fan shape about the rotation shaft  216 . 
     A wire insertion hole  224  (refer to  FIG. 6 ) through which an operating wire  222  is inserted is formed on the side wall surface of the lever housing chamber  212  on the exterior case proximal end side. 
     A bolt hole  220  into which the already-described bolt  77  is screwed is formed in a peripheral region of the lever housing chamber  212  and a region covered with the lever housing lid  76 , in the side wall surface  206 . In addition, the numbers of bolts  77  and bolt holes  220  are not particularly limited. 
     The facing wall surface  208  constitutes a side surface of the elevator housing chamber  94   a  on the R direction side. A holding hole  214  opens in the facing wall surface  208 . Additionally, the facing wall surface  208  is formed with a cutout part  208   a  (refer to  FIG. 7 ) into which a portion of the elevator  96  is inserted. 
     The elevator elevating lever  210  rotates the elevator  96  about the rotation shaft  216  depending on the operation of the operating lever  43 . One end part of the elevator elevating lever  210  is provided with one of the rotation shafts  216  having a two-split structure, and the operating wire  222  is coupled to the other end part of the elevator elevating lever  210 . 
     One of the rotation shaft  216  having a two-split structure is provided at one end part of the elevator elevating lever  210  as already described, and the other thereof is provided at one end part of the elevator  96 . Also, the elevator elevating lever  210  and the elevator  96  are coupled to each other via the rotation shafts  216  having a two-split structure. For example, in the present embodiment, by using the bolt  211  penetrating one end side of the elevator elevating lever  210  to couple one and the other side of the rotation shafts  216  having a two-split structure, the elevator elevating lever  210  and the elevator  96  are coupled to each other via the rotation shaft  216  (refer to  FIG. 6 ). Accordingly, the elevator elevating lever  210  rotates (rocks) integrally with the elevator  96  about the rotation shaft  216 . 
     The operating wire  222  has a distal end side coupling part  222   a  (refer to  FIG. 5 ) that is coupled to the elevator elevating lever  210  inside the lever housing chamber  212 , at one end side thereof. Additionally, the other end side of the operating wire  222  is coupled to an elevator operating mechanism  226  (refer to  FIG. 8 ) in the operating part  22  through the insertion part  20  from a wire insertion hole  224  of the lever housing chamber  212 . 
       FIG. 8  is a schematic view illustrating an example of the elevator operating mechanism  226 . As illustrated in  FIG. 8 , the operating wire  222  has a proximal end side coupling part  222   b  coupled to the elevator operating mechanism  226 , on the proximal end side thereof. The elevator operating mechanism  226  includes the operating lever  43 , a rotating drum  226 A that is coupled to the operating lever  43  and is rotatable within a certain angle range, a crank member  226 B coupled to the rotating drum  226 A, and a slider  226 C coupled to the crank member  226 B. The proximal end side coupling part  222   b  is coupled to the slider  226 C. 
     In a case where the operating lever  43  is operated to rotate the rotating drum  226 A, the operating wire  222  is pushed and pulled via the crank member  226 B and the slider  226 C, whereby the elevator elevating lever  210  rocks, and the elevator  96  rotates (rocks) about the rotation shaft  216  depending on the rocking of the elevating lever  210 . 
       FIGS. 9A and 9B  are an explanatory views for explaining the rotation of the elevator  96  according to the operation of the operating lever  43 . As indicated by reference numeral IXA in  FIG. 9A , in a case where the operating lever  43  is operated to rotate the rotating drum  226 A in one direction, the operating wire  222  is pushed, and thereby, the elevator elevating lever  210  moves about the rotation shaft  216  in an SW 1  direction. Accordingly, the elevator  96  is rotated in a lodged position along with this rotation. 
     As indicated by reference numeral IXB in  FIG. 9B , in a case where the operating lever  43  is operated to rotate the rotating drum  226 A in the opposite direction, the operating wire  222  is pulled, and the elevator elevating lever  210  rotates about the rotation shaft  216  in an SW 2  direction opposite to the SW 1  direction. Accordingly, the elevator  96  is rotated to an elevated position along with this rotation. In this way, by rotating the rotation shaft  216  via the operating wire  222 , the elevator elevating lever  210 , and the like through the operation of the operating lever  43 , the elevator  96  can be displaced (elevated and lodged). 
     [First Illumination Window, Second Illumination Window, and Observation Window] 
       FIG. 10  is a top view of the exterior case  72 . As illustrated in  FIG. 10 , the first illumination window  90 A is formed in a proximal end side region ER in the already-described first inclined surface  86 A. The proximal end side region ER is a region on the outer surface of the exterior case  72 , which is located at a position shifted from the treatment tool delivery port  94  to the exterior case proximal end side. 
     More specifically, the proximal end side region ER is a region of the exterior case  72 , which is located closer to the exterior case proximal end side than the treatment tool delivery port  94  in the direction along the longitudinal axis LA and is a region within a range where the treatment tool delivery port  94  is formed in the width direction WD. Accordingly, the treatment tool delivered from the treatment tool delivery port  94  and the treatment target region thereof can be illuminated with the illumination light emitted from the first illumination window  90 A. 
     Moreover, in a case where an end part opposite to one end part on the side where the rotation shaft  216  of the elevator  96  is provided is the other end part of the elevator  96 , the first illumination window  90 A is provided at a position closer to the exterior case proximal end side than the other end part of the elevator  96  in the exterior case  72  (proximal end side region ER) at least in a case where the elevator  96  is in the lodged position. In other words, at least in a case where the elevator  96  is in the lodged position, the other end part of the elevator  96  is located closer to the exterior case distal end side than the first illumination window  90 A. Accordingly, the treatment tool delivered from the treatment tool delivery port  94  and the treatment target region thereof can be illuminated with the illumination light emitted from the first illumination window  90 A. 
     In addition, it is more preferable that the first illumination window  90 A is provided closer to the exterior case proximal end side than the other end part of the elevator  96  even in a case where the elevator  96  is in the elevated position (that is, regardless of the rotational position of the elevator  96 ). Accordingly, even in a case where the elevator  96  is rotated (pulled up) to the elevated position, the treatment tool delivered from the treatment tool delivery port  94  and the treatment target region thereof can be illuminated with the illumination light emitted from the first illumination window  90 A. 
     The observation window  88  is provided on the first inclined surface  86 A as already described. The observation window  88  is provided at a position closer to the exterior case proximal end side than the treatment tool delivery port  94  in the exterior case  72 , similar to the first illumination window  90 A, in the direction along the longitudinal axis LA. Accordingly, a treatment tool delivered from the treatment tool delivery port  94  and a treatment target region thereof can be observed through the observation window  88 . 
     Additionally, the observation window  88  is provided at a position on the L direction side with respect to the proximal end side region ER in the first inclined surface  86 A. In this way, by disposing the observation window  88  and the first illumination window  90 A in the same first inclined surface  86 A, that is, at substantially the same position in the direction along the longitudinal axis LA, an observation range  150 B of the observation window  88  (refer to  FIG. 11 ) can be illuminated with the illumination light emitted from the first illumination window  90 A. 
     The second illumination window  90 B is provided on the second inclined surface  86 B of the already-described exterior case  72 . Although described in detail below, the second illumination window  90 B is different from the first illumination window  90 A in the emission direction of the illumination light. 
     The air and water supply nozzle  92  is provided at a position closer to the L direction side than the observation window  88  in the first inclined surface  86 A. As already described, the air and water supply nozzle  92  cleans the observation window  88  by jetting a fluid such as water or air onto the observation window  88 . In this case, the formation position of the first illumination window  90 A in the proximal end side region ER and the formation position of the second illumination window  90 B within the second inclined surface  86 B are respectively adjusted such that both the illumination windows  90 A and  90 B are included in the jetting range of a fluid jetted from the air and water supply nozzle  92 . Accordingly, the illumination windows  90 A and  90 B and the light guide distal end part of each light guide  128  can be cooled by a fluid jetted from the air and water supply nozzle  92 . 
       FIG. 11  is an explanatory view for explaining an observation axis  150 A and an observation range  150 B of the observation window  88 , a first illumination axis  151 A and a first illumination range  151 B of the first illumination window  90 A, and a second illumination axis  152 A and a second illumination range  152 B of the second illumination window  90 B. In addition, in  FIG. 11  (the same applies to  FIG. 12  described below), in order to prevent the drawing from becoming complicated, the respective axes and the respective ranges will be described assuming that the observation window  88  and the illumination windows  90 A and  90 B are at the same position. 
     As illustrated in  FIG. 11 , the observation axis  150 A is an axis extending from the observation window  88  in a normal direction thereof, the first illumination axis  151 A is an axis extending from the first illumination window  90 A in the normal direction thereof, and the second illumination axis  152 A is an axis extending from the second illumination window  90 B in the normal direction thereof. Additionally, each of the observation axis  150 A, the first illumination axis  151 A, and the second illumination axis  152 A is an inclined axis that is inclined toward the exterior case distal end side from the posture perpendicular to both the width direction WD and the longitudinal axis LA. In addition, the observation axis  150 A and the first illumination axis  151 A are parallel to a normal line of the first inclined surface  86 A, and the second illumination axis  152 A is parallel to a normal line of the second inclined surface  86 B. 
     An observation axis angle θ 0  is the inclination angle of the observation axis  150 A with respect to a reference axis LB parallel to the longitudinal axis LA as seen from the width direction WD side (the side perpendicular to the paper surface). A first illumination axis angle θ 1  is the inclination angle of the first illumination axis  151 A with respect to the reference axis LB as seen from the width direction WD side. A second illumination axis angle θ 2  is the inclination angle of the second illumination axis  152 A with respect to the reference axis LB as seen from the width direction WD side. In addition, the reference axis LB is an axis that intersects the observation axis  150 A in the case of the observation axis angle θ 0 , an axis that intersects the first illumination axis  151 A in the case of the first illumination axis angle θ 1 , and an axis that intersects the second illumination axis  152 A in the case of the second illumination axis angle θ 2 . 
     As seen from the width direction WD side, the observation axis angle θ 0  and the observation range  150 B are respectively set to values such that an angle range from one to the other of the exterior case distal end side of the exterior case  72  [the insertion direction side of the insertion part  20  (the traveling direction side)] and the treatment tool the delivered from the treatment tool delivery port  94  and the treatment target region thereof can be observed through the observation window  88 . In addition, it is preferable that the observation axis angle θ 0  and the observation range  150 B are values that allow observation of the treatment tool delivered from the treatment tool delivery port  94  and the treatment target region thereof in a state where the elevator  96  is rotated to the elevated position. 
     Since the first illumination axis angle θ 1  and the observation axis angle θ 0  are equal to each other (including substantially equal), the first illumination axis  151 A and the observation axis  150 A are parallel to each other (including substantially parallel). Also, the first illumination range  151 B includes at least the observation range  150 B as seen from the width direction WD side. Accordingly, the first illumination window  90 A can illuminate the above-described angle range (observation range  150 B) with illumination light. 
     Since the second illumination axis angle θ 2  is smaller than the first illumination axis angle θ 1 , the second illumination axis  152 A is inclined toward the exterior case distal end side with respect to the first illumination axis  151 A. In other words, the second inclined surface  86 B has an inclination angle closer to an angle perpendicular to the reference axis LB than the first inclined surface  86 A. 
     In a case where the difference between the first illumination axis angle θ 1  and the second illumination axis angle θ 2  is Δθ, the second illumination range  152 B is inclined toward the exterior case distal end side by a difference Δθ with respect to the first illumination range  151 B. Therefore, the second illumination range  152 B partially overlaps the first illumination range  151 B. 
     In this case, the second illumination axis angle θ 2  (difference Δθ) is set to a value such that the observation range  150 B is included in at least the second illumination range  152 B as seen from the width direction WD side. For this reason, the second illumination window  90 B can also be illuminated with the illumination light in the above-described angle range (observation range  150 B). 
       FIG. 12  is a side view of the distal end part  50  of the insertion part  20  inserted into the lumen  154 . As illustrated in  FIG. 12  and the already-described  FIG. 11 , by inclining the second illumination window  90 B (the second illumination axis  152 A and the second illumination range  152 B) toward the exterior case distal end side by the difference Δθ with respect to the first illumination window  90 A (the first illumination axis  151 A and the first illumination range  151 B), it is possible to increase the illumination light amount of the illumination light with which the second illumination window  90 B illuminates the insertion direction side of the insertion part  20 . As a result, for example, in a case where the insertion part  20  is inserted into the narrow lumen  154 , the visibility (forward visibility) of an inner wall of the lumen  154  on the insertion direction side of the insertion part  20  is improved. 
     Moreover, by inclining the second illumination window  90 B toward the exterior case distal end side by the difference Δθ with respect to the first illumination window  90 A, for example, in a case where an inner wall surface of the narrow lumen  154  such as the duodenum is illuminated, the illumination light amount of the illumination light emitted from the second illumination window  90 B to the inner wall surface can be made smaller than the illumination light amount of the illumination light emitted from the first illumination window  90 A to the inner wall surface. Accordingly, it is possible to reduce the illumination light amount of the illumination light with which the inner wall surface of the lumen  154  is irradiated, as compared to a case where the second illumination axis angle θ 2  has the same size as the first illumination axis angle θ 1 . As a result, it is possible to prevent the occurrence of halation in the endoscope image due to the excessive illumination light amount of the illumination light on the inner wall surface of the lumen  154 . In addition, the illumination only by the second illumination window  90 B may be selectively performed as necessary. 
     Since the first illumination window  90 A is disposed in the already-described proximal end side region ER, the treatment tool delivered from the treatment tool delivery port  94  and the treatment target region thereof can be illuminated always from one direction side (the proximal end side region ER side) by the first illumination window  90 A. Accordingly, it is possible to prevent the treatment target region from entering the shadow of the elevator  96 , the treatment tool, and the like as seen from the first illumination window  90 A. Additionally, since the way that the illumination light hits the treatment tool does not change due to the displacement of the treatment tool accompanying the rotation of the elevator  96 , the endoscope image is prevented from being not easily seen, and the treatment tool delivered from the treatment tool delivery port  94  and the treatment target region is prevented from coming off the first illumination range  151 B. As a result, since it is possible to reliably illuminate the treatment tool delivered from the treatment tool delivery port  94  and the treatment target region thereof with the illumination light emitted from the first illumination window  90 A, the visibility of the treatment tool and the treatment target region can be improved. 
     Moreover, by inclining the first illumination window  90 A (the first illumination axis  151 A and the first illumination range  151 B) toward the exterior case proximal end side by the difference Δθ with respect to the second illumination window  90 B (the second illumination axis  152 A and the second illumination range  152 B), it is possible to increase the illumination light amount of the illumination light with which the first illumination window  90 A illuminates the treatment tool delivered from the treatment tool delivery port  94  and the treatment target region thereof. As a result, since the treatment tool and the treatment target region can be reliably illuminated with the illumination light, the visibility of the treatment tool and the treatment target region can be improved. 
     In this way, by combining the first illumination window  90 A with the second illumination window  90 B, it is possible to improve the forward visibility of the insertion part  20  and the visibility of the treatment tool and the treatment target region. 
     Effects of Present Embodiment 
     As described above, in the present embodiment, the first illumination window  90 A is disposed in the proximal end side region ER of the exterior case  72 . Thus, it is possible to always illuminate the treatment tool delivered from the treatment tool delivery port  94  and the treatment target region thereof from the proximal end side region ER side with the illumination light emitted from the first illumination window  90 A. As a result, it is possible to reliably illuminate the treatment tool and the treatment target region thereof with the illumination light regardless of the rotational position of the elevator  96 . Accordingly, the visibility of the treatment tool and the treatment target region can be improved. 
     Additionally, in the present embodiment, the observation window  88  is disposed at the position of the treatment tool delivery port  94  of the exterior case  72  on the exterior case proximal end side. Thus, the treatment tool and the treatment target region can be observed through the observation window  88  regardless of the rotational position of the elevator  96 . Accordingly, the visibility of the treatment tool and the treatment target region can be improved. 
     [Others] 
     In the above-described embodiment, the entire first illumination window  90 A fits within the proximal end side region ER in the width direction WD. However, a portion of the first illumination window  90 A may protrude to the L direction side or the R direction side of the proximal end side region ER. However, in order to reliably illuminate the treatment tool and the treatment target region thereof with the illumination light regardless of the rotational position of the elevator  96 , the entire first illumination window  90 A fits within the proximal end side region ER in the width direction WD, preferably. 
     In the above embodiment, the first illumination axis angle θ 1  of the first illumination axis  151 A of the first illumination window  90 A is less than 90°. However, the first illumination axis angle θ 1  may be 90 (including approximately 90°) depending on the size of the first illumination range  151 B of the first illumination window  90 A. That is, the proximal end side region ER (the first inclined surface  86 A) may be a surface parallel to the longitudinal axis LA. 
     In the above-described embodiment, the observation window  88  is formed at the position of the proximal end side region ER on the L direction side in the first inclined surface  86 A. However, the formation position of the observation window  88  is not particularly limited. However, in order to always observe the treatment tool delivered from the treatment tool delivery port  94  and the treatment target region thereof, it is preferable that the observation window  88  is provided at a position closer to the exterior case proximal end side than the treatment tool delivery port  94  in the exterior case  72 . 
     In the above embodiment, the second illumination window  90 B is formed on the second inclined surface  86 B. However, the formation position of the second illumination window  90 B is not particularly limited. Additionally, in the above embodiment, the second illumination axis angle θ 2  is smaller than the first illumination axis angle θ 1 . However, the second illumination axis angle θ 2  may be larger than the first illumination axis angle θ 1  or both may be equal to each other. Moreover, in the above-described embodiment, the second illumination window  90 B is provided at a position closer to the exterior case distal end side than the proximal end side region ER in the exterior case  72  but may be provided at a position closer to the exterior case proximal end side than the treatment tool delivery port  94 . Moreover, the second illumination window  90 B may be omitted as long as the already-described forward visibility and the visibility of the treatment tool and the treatment target region can be ensured only with the first illumination window  90 A. 
     In the above embodiment, the observation axis  150 A and the first illumination axis  151 A are parallel to each other but both may not be parallel to each other. For example, the observation axis angle θ 0  may be an angle between the first illumination axis angle θ 1  and the second illumination axis angle θ 2 . 
     In the above-described embodiment, an example in which the elevator  96  is rotated via the operating wire  222  and the elevator elevating lever  210  has been described. However, the method of rotating the elevator  96  is not particularly limited, and a publicly known method can be adopted. 
     In the above embodiment, the first inclined surface  86 A is parallel to the observation window  88  and the first illumination window  90 A. However, the observation window  88  and the first illumination window  90 A may be provided not to be parallel to the first inclined surface  86 A. Additionally, similarly, the second illumination window  90 B may be provided not to be parallel to the second inclined surface  86 B. 
     In the above embodiment, the ultrasound endoscope  10  including the ultrasound observation part  60  (ultrasound transducer  62 ) has been described as an example. However, the present invention can also be applied to an endoscope including the elevator  96  that guides the treatment tool, for example other side-view endoscopes such as a duodenoscope. 
     EXPLANATION OF REFERENCES 
     
         
         
           
               2 : ultrasound examination system 
               10 : ultrasound endoscope 
               12 : ultrasound processor device 
               14 : endoscope processor device 
               16 : light source device 
               18 : monitor 
               20 : insertion part 
               22 : operating part 
               24 : universal cord 
               27 : ultrasound connector 
               28 : endoscope connector 
               30 : light source connector 
               32 : tube 
               34 : tube 
               36 : air and water supply button 
               38 : suction button 
               42 : angle knob 
               43 : operating lever 
               44 : treatment tool insertion port 
               50 : distal end part 
               52 : bending part 
               54 : flexible part 
               60 : ultrasound observation part 
               62 : ultrasound transducer 
               64 : balloon 
               66 : locking ring 
               68 : locking groove 
               70 : supply and discharge port 
               71 : opening part 
               72 : exterior case 
               72   a : exterior case body 
               72   b : exterior case lid 
               73 : partition wall 
               74 : groove part 
               75 : fitting hole 
               76 : lever housing lid 
               77 : bolt 
               80 : endoscope observation part 
               86 A: first inclined surface 
               86 B: second inclined surface 
               88 : observation window 
               90 A: first illumination window 
               90 B: second illumination window 
               92 : air and water supply nozzle 
               94 : treatment tool delivery port 
               94   a : elevator housing chamber 
               96 : elevator 
               96   a : guide surface 
               100 : treatment tool insertion channel 
               102 : air and water supply pipe line 
               104 : balloon pipe line 
               106 : suction pipeline 
               108 : air supply pipe line 
               110 : water supply pipe line 
               112 : balloon water supply pipe line 
               114 : balloon drainage pipe line 
               116 : air supply source pipe line 
               118 : water supply tank 
               120 : water supply source pipe line 
               122 : branch pipe line 
               124 : suction pump 
               126 : suction source pipe line 
               128 : light guide 
               129 : air supply pump 
               150 A: observation axis 
               150 B: observation range 
               151 A: first illumination axis 
               151 B: first illumination range 
               152 A: second illumination axis 
               152 B: second illumination range 
               154 : lumen 
               200 : elevating case 
               202 : base 
               202   a : through hole 
               203 A: light guide holding groove 
               203 B: light guide holding groove 
               204 : partition wall 
               206 : side wall surface 
               208 : facing wall surface 
               208   a : cutout part 
               210 : elevator elevating lever 
               211 : bolt 
               212 : lever housing chamber 
               214 : holding hole 
               216 : rotation shaft 
               220 : bolt hole 
               222 : operating wire 
               222   a : distal end side coupling part 
               222   b : proximal end side coupling part 
               224 : wire insertion hole 
               226 : elevator operating mechanism 
               226 A: rotating drum 
               226 B: crank member 
               226 C: slider 
             ER: proximal end side region 
             LA: longitudinal axis 
             LB: reference axis 
             NV: normal direction 
             WD: width direction 
             Δθ: difference 
             θ 0 : observation axis angle 
             θ 1 : first illumination axis angle 
             θ 2 : second illumination axis angle