Patent Publication Number: US-2021177249-A1

Title: Endoscope

Description:
TECHNICAL FIELD 
     The present invention relates to an endoscope having a convex observation optical system at the distal end of an insertion portion inserted into a body. 
     BACKGROUND ART 
     Conventionally, in an endoscope, an observation optical system for imaging a subject is provided at the distal end of an insertion portion to be inserted into a body. Dirt such as mucus, blood and residue is likely to adhere to the surface of such an observation optical system. As described above, if the observation optical system is dirty or the like, it is difficult to take a clear image of the subject. 
     On the other hand, Patent Literature 1 discloses an endoscope in which a fluid is spread over the entire convex lens by spraying the fluid from diagonally above toward an inclined surface around the convex lens. 
     Patent Literature 2 discloses a lens cleaning sheath for an endoscope that cleans the entire lens by using a wall surface surrounding the lens for a lens having a large diameter. 
     Patent Literature 3 discloses an air supply/water supply nozzle of an endoscope which has a plurality of outlet ports and makes each jet smaller to give the jet momentum. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 2012-115421 A 
     Patent Literature 2: JP 2018-094016 A 
     Patent Literature 3: JP 2002-85339 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     The Coanda effect is known in which the fluid flowing near the wall surface is attracted to the wall surface by the effect of fluid viscosity. Due to such a Coanda effect, in a convex lens, when a fluid flows along a surface (curved surface), the fluid is concentrated toward the center of the curved surface. The fluid concentrated in this way separates from the curved surface of the convex lens. Therefore, when the cleaning fluid is injected onto the convex lens from one nozzle, the cleaning fluid does not reach the side opposite to the nozzle side where the fluid directly hits, resulting in insufficient cleaning. 
     However, the above-mentioned endoscope of Patent Literature 1, the lens cleaning sheath for the endoscope of Patent Literature 2, and the air supply/water supply nozzle of the endoscope of Patent Literature 3 have not been devised to solve such a problem, and are not able to solve it. 
     The invention has been made in view of such circumstances, and an object of the invention is to provide an endoscope in which a cleaning fluid can be distributed to the side opposite to the side of the nozzle injecting the fluid, and sufficient cleaning can be performed in a convex observation optical system. 
     Solution to Problem 
     An endoscope according to the invention has a convex observation optical system at a distal end of an insertion portion, and includes a nozzle for injecting a cleaning fluid toward the observation optical system. The nozzle includes a plurality of outlets from which the fluid is emitted in directions not intersecting with each other. 
     In the invention, the nozzle that injects the cleaning fluid toward the observation optical system has a plurality of outlets each emitting the fluids in directions not intersecting with each other. Therefore, it is possible to suppress the fluids from the outlets from merging after emission and concentrating toward the center of the observation optical system, and it is possible to prevent the fluid from leaving the curved surface of the observation optical system. 
     Advantageous Effects of Invention 
     According to the invention, in a convex observation optical system, a cleaning fluid can be distributed to the side opposite to the side of the nozzle injecting the fluid, and sufficient cleaning can be performed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an external view of an endoscope according to a first embodiment of the invention. 
         FIG. 2  is an external view of a distal end portion of the endoscope according to the first embodiment of the invention. 
         FIG. 3  is a diagram illustrating an air supply/water supply nozzle of the endoscope according to the first embodiment of the invention. 
         FIG. 4  is a result of simulating the flow path of air or water ejected by the air supply/water supply nozzle in the endoscope according to the first embodiment of the invention. 
         FIG. 5  is a result of simulating the flow path of air or water ejected by the air supply/water supply nozzle in the endoscope according to the first embodiment of the invention. 
         FIG. 6  is an exemplary view illustrating a case where the distal end surface is a flat surface in the endoscope according to the first embodiment of the invention. 
         FIG. 7  is a diagram illustrating an air supply/water supply nozzle of an endoscope according to a second embodiment of the invention. 
         FIG. 8  is a diagram illustrating an air supply/water supply nozzle of an endoscope according to a third embodiment of the invention. 
         FIG. 9  is a cross-sectional view taken along line IX-IX in  FIG. 8C . 
         FIG. 10  is a cross-sectional view taken along line X-X of  FIG. 8C . 
         FIG. 11  is a cross-sectional view taken along line XI-XI of  FIG. 9 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an endoscope according to embodiments of the invention will be described in detail with reference to the drawings. 
     First Embodiment 
       FIG. 1  is an external view of an endoscope  10  according to the first embodiment of the invention. The endoscope  10  according to this embodiment includes an insertion portion  14 , an operation unit  20 , a universal cord  25 , and a connector portion  24 . The operation unit  20  includes a button  201  and a bending knob  21  for receiving a user operation, and a channel inlet  22  provided in a case  205  having a substantially cylindrical shape. A forceps plug  23  having an insertion port for inserting a treatment tool or the like is fixed to the channel inlet  22 . 
     The insertion portion  14  is inserted into the body of a subject. The insertion portion  14  is long and has a distal end portion  13 , a bending section  12 , and a soft section  11  in this order from one end of the distal end. The other end of the insertion portion  14  is connected to the operation unit  20  via a folding portion  16 . The bending section  12  is bent according to an operation of the bending knob  21 . The distal end portion  13  is composed of a distal end portion  13   a  and a distal end portion  13   b  (see  FIG. 9 ), and the distal end portion  13   a  is provided on the distal end side of the insertion portion  14  with respect to the distal end portion  13   b.    
     In the following description, a longitudinal direction of the insertion portion  14  is also referred to as an insertion direction. Further, in the insertion direction, the other end side close to the operation unit  20  is referred to as the operation unit side, and the one end side close to the distal end portion  13  is also referred to as the distal end portion side. 
     The universal cord  25  is long, and has one end connected to the operation unit  20  and the other end connected to the connector portion  24 . The universal cord  25  is soft. The connector portion  24  is connected to a processor for an endoscope (not illustrated), a light source device, a display device, an air and water supply device, and the like. By appropriately operating the operation unit  20 , the cleaning fluid (air or water) sent through the connector portion  24  is sent to the distal end portion  13  via the folding portion  16 . 
       FIG. 2  is an external view of the distal end portion  13   a  of the endoscope  10  according to the first embodiment of the invention.  FIG. 2A  is a perspective view of the distal end portion  13   a .  FIG. 2B  is a diagram illustrating the distal end portion  13   a  when viewed from a direction of arrow B of  FIG. 2A .  FIG. 2C  is a diagram illustrating the distal end portion  13   a  when viewed from a direction of arrow C of  FIG. 2A . 
     The distal end portion  13   a  is substantially elliptical in cross section, and has the distal end protruding in a substantially conical shape. The distal end surface  131  of the distal end portion  13   a  is provided with an observation optical system  132 , an air supply/water supply nozzle  140 , a channel outlet  18 , and the like. 
     Further, the distal end portion  13   a  has a cylindrical storage cylinder  19  which houses an image sensor (not illustrated) or the like that captures the image light of the subject via the observation optical system  132  and performs imaging. The distal end surface  131  of the distal end portion  13   a  extends from the edge of the storage cylinder  19 . Air and water transmission paths injected through the air supply/water supply nozzle  140  are formed in the storage cylinder  19 , the bending section  12 , and the soft section  11 . 
     The observation optical system  132  is provided at the central part of the distal end surface  131  of the distal end portion  13   a , and is a circular convex lens. Further, in the distal end surface  131  of the distal end portion  13   a , the air supply/water supply nozzle  140  and the channel outlet  18  are provided adjacent to each other around the observation optical system  132 . 
     The distal end surface  131  of the distal end portion  13   a  looks like a truncated cone. That is, the distal end surface  131  is an inclined surface that is inclined in the tangential direction from the edge portion of the observation optical system  132 , and the air supply/water supply nozzle  140  and the channel outlet  18  are formed on such an inclined surface. 
       FIG. 3  is a diagram illustrating the air supply/water supply nozzle  140  of the endoscope  10  according to the first embodiment of the invention.  FIG. 3A  is a perspective view illustrating the appearance of the air supply/water supply nozzle  140 ,  FIG. 3B  is a cross-sectional view taken along line MB- 111 B of  FIG. 2B , and  FIG. 3C  is a cross-sectional view taken along line IIIC-IIIC of  FIG. 2B . 
     The air supply/water supply nozzle  140  injects air or water toward the observation optical system  132  along the distal end surface  131 . The air supply/water supply nozzle  140  has a plurality of outlets  141  from which air or water is emitted. Air and water are emitted toward the observation optical system  132  through each outlet  141 . 
     In this embodiment, a case where the air supply/water supply nozzle  140  has two outlets  141  will be described as an example. The invention is not limited to this, and may be configured to have three or more outlets  141 . 
     Each outlet  141  is open in different directions. That is, air or water is emitted through each outlet  141  in a direction that does not intersect with each other. Each outlet  141  has an oval shape with the direction along the distal end surface  131  as the long axis direction. Most part of the air supply/water supply nozzle  140  (the chain line portion in  FIG. 3A ) is inserted and fixed in a recess provided on the distal end surface  131 . 
     As described above, the observation optical system  132  is provided at the distal end of the distal end portion  13   a , and the distal end surface  131  forms a slope so as to surround the circular edge of the observation optical system  132 . The air supply/water supply nozzle  140  is provided on the distal end surface  131  separated from the observation optical system  132 . That is, in the endoscope  10  according to the first embodiment of the invention, in the longitudinal direction of the insertion portion  14  (see the arrow in  FIG. 2C ), the air supply/water supply nozzle  140  is arranged at a position closer (the operation unit  20  side) to the other end of the insertion portion  14  rather than the observation optical system  132 . 
     Since the observation optical system  132  is a convex lens and has a wide viewing angle (180 degrees or more), when the air supply/water supply nozzle  140  is arranged at the same position as the observation optical system  132  in the longitudinal direction of the insertion portion  14 , the air supply/water supply nozzle  140  appears in the captured image of the observation optical system  132 . However, in the endoscope  10  according to the first embodiment of the invention, as described above, the air supply/water supply nozzle  140  is arranged at a position closer to the other end of the insertion portion  14  than the observation optical system  132 . Therefore, the air supply/water supply nozzle  140  does not appear in the captured image of the observation optical system  132 , and does not interfere with the image capturing by the observation optical system  132 . 
     The air supply/water supply nozzle  140  has a cylinder portion  147  and a lid portion  148  that seals one open end of the cylinder portion  147 . The lid portion  148  and the cylinder portion  147  are integrally formed. The lid portion  148  has a substantially disk shape and is inclined with respect to the longitudinal direction of the cylinder portion  147 . The air supply/water supply nozzle  140  is provided with the outlet  141  at one end portion on the lid portion  148  side. The air supply/water supply nozzle  140  has a connecting pipe portion  142  extending along the longitudinal direction of the cylinder portion  147  inside the cylinder portion  147 . The connecting pipe portion  142  sends air or water sent through the connector portion  24  and the folding portion  16  to each outlet  141 . That is, the connecting pipe portion  142  connects an air supply tube  121  and a water supply tube  122  (see  FIG. 10 ) with the outlet  141 , and sends air or water flowing into the connecting pipe portion  142  through the opening at one end of the connecting pipe portion  142  toward the outlet  141  on the other end side (the lid portion  148  side). 
     In the end portion (the end portion on the lid portion  148  side) on the downstream side in the connecting pipe portion  142 , there is provided a divergence portion  144  that divides the flow of air or water flowing through the connecting pipe portion  142  corresponding to the number of outlets  141 . That is, the downstream side of the connecting pipe portion  142  is divided into two flow paths (the flow divergence portion  144 ) having a smaller diameter than the connecting pipe portion  142 . Each divergence portion  144  is provided so as to correspond to any one of the outlets  141 , and the air or water flowing into each divergence portion  144  is emitted through the corresponding outlet  141 . 
     Further, a funnel-shaped or tapered diameter-reduced portion  143  is formed on the downstream side of the connecting pipe portion  142  and on the upstream side of the divergence portion  144 . The diameter of the connecting pipe portion  142  on the upstream side of the divergence portion  144  is reduced by the diameter-reduced portion  143 . Therefore, the pressure of air or water flowing into each divergence portion  144  through the diameter-reduced portion  143  is reduced, and the flow speed is increased. The air or water having a higher flow speed flows out into a space wider than the divergence portion  144  (see  FIGS. 3B and 3C ), and flows toward the outlet  141 . At this time, air or water forms a vortex having vectors in various directions, and is emitted from the outlet  141 . Therefore, the air or water injected from each outlet  141  spreads over a wide range, and can secure an injection force and range at the time of injection.  FIG. 3C  illustrates the flow path of air or water with a broken line. 
     As described above, in the air supply/water supply nozzle  140 , the directions of the outlets  141  are different from each other, and the air or water from each outlet  141  is emitted in a direction that does not intersect with each other. That is, if air or water is emitted linearly through the outlet  141  and maintains the linearity even after the emission, each outlet  141  is provided such that the air or water from each outlet  141  does not intersect with each other. 
     With such a configuration, the endoscope  10  according to this embodiment can clearly clean the observation optical system  132  up to the opposite side of the air supply/water supply nozzle  140  side, where the air or water directly hits in the observation optical system  132  which is a convex lens, even using one air supply/water supply nozzle  140 . Hereinafter, the portion opposite to the air supply/water supply nozzle  140  side in the observation optical system  132  is referred to as the nozzle opposite side. 
     In general, the fluid flowing near the wall surface is attracted to the wall surface by the effect of fluid viscosity (called the Coanda effect). Due to such a Coanda effect, when a fluid flows along the surface (curved surface) of a convex lens, the fluid exhibits a behavior of concentrating toward the center of the curved surface. The fluid concentrated in this way separates from the curved surface of the convex lens. Therefore, when air or water (cleaning fluid) is injected to the observation optical system from one air supply/water supply nozzle (outlet), the air or water does not reach the nozzle opposite side in the observation optical system, and the cleaning of the observation optical system becomes insufficient. 
     Even if the outlet of the air supply/water supply nozzle is widened and air or water is sprayed over a wide range of the observation optical system, the air or water emitted from the outlet is concentrated toward the center of the observation optical system. Therefore, as described above, the separation from the curved surface of the observation optical system occurs. 
     Further, even when the air supply/water supply nozzle has a plurality of outlets and air or water is injected from the plurality of outlets, the air or water from one outlet starts to spread after the emission, and the air or water from the other outlets merge together. Therefore, as described above, the air or water concentrates toward the center, and are separated from the curved surface of the observation optical system. 
     On the other hand, in the endoscope  10  according to the first embodiment of the invention, the air supply/water supply nozzle  140  has two outlets  141  having different orientations. Therefore, it is possible to suppress the air or water emitted from one outlet  141  from merging with the air or water emitted from the other outlet  141 . Therefore, it is possible to prevent the air or water from concentrating toward the center of the observation optical system  132  and separating from the curved surface of the observation optical system  132  in advance, and the air or water for cleaning can flow to the nozzle opposite side in the observation optical system  132 . 
     Further, since air or water from each outlet  141  approaches the center of the observation optical system  132  due to the Coanda effect, the entire observation optical system  132  can be sufficiently cleaned including the center portion of the observation optical system  132  where air or water is not directly injected. 
       FIGS. 4 and 5  are the results of simulating the flow path of air or water ejected by the air supply/water supply nozzle  140  in the endoscope  10  according to the first embodiment of the invention.  FIG. 4  mainly illustrates the upstream side of the flow path, and  FIG. 5  mainly illustrates the downstream side. That is,  FIG. 5  illustrates the flow path on the nozzle opposite side in the observation optical system  132 . Further, in  FIG. 4 , the chain line indicates the direction of each outlet  141 , and the solid line indicates the flow path of air or water emitted from the outlet  141 . 
     As can be seen from  FIGS. 4 and 5 , in the endoscope  10  according to the first embodiment of the invention, the air or water emitted from one outlet  141  starts to spread after the emission (see arrow in  FIG. 4 ). However, there is almost no merging with air or water emitted from the other outlet  141 , no concentration in the center of the observation optical system  132  is found, and the separation from the curved surface of the observation optical system  132  does not occur. Air or water is flowing to the nozzle opposite side in the observation optical system  132  (see  FIG. 5 ). 
     In the above description, the case where the distal end surface  131  is inclined with respect to the longitudinal direction of the insertion portion  14  has been described as an example, but the invention is not limited to this. 
       FIG. 6  is an exemplary view illustrating the case where a distal end surface  131 A is a flat surface in the endoscope  10  according to the first embodiment of the invention. As illustrated in  FIG. 6 , even in a case where the distal end surface  131 A is a flat surface, it is a matter of course that the above-mentioned effect is obtained. 
     Second Embodiment 
       FIG. 7  is a diagram illustrating an air supply/water supply nozzle  140  of the endoscope  10  according to the second embodiment of the invention.  FIG. 7A  is a perspective view illustrating the appearance of the air supply/water supply nozzle  140 ,  FIG. 7B  is a cross-sectional view taken along line B-B of  FIG. 7A , and  FIG. 7C  is a diagram seen from the arrow direction of  FIG. 7B . In  FIG. 7A , the portion inserted into the recess provided in the distal end surface  131  is indicated by a chain line, and in  FIG. 7B , the distal end surface  131  is indicated by a broken line. 
     The air supply/water supply nozzle  140  according to the second embodiment of the invention has five outlets  141 . Each outlet  141  has a circular shape. The five outlets  141  are arranged side by side in a row, and each outlet  141  has a different orientation. 
     The air supply/water supply nozzle  140  has a cylinder portion  147  and a lid portion  148  that seals one open end of the cylinder portion  147 . The lid portion  148  and the cylinder portion  147  are integrally formed. The lid portion  148  has a substantially disk shape and is inclined with respect to the longitudinal direction of the cylinder portion  147 . The air supply/water supply nozzle  140  is provided with the outlet  141  at one end portion on the lid portion  148  side. The air supply/water supply nozzle  140  has a connecting pipe portion  142  extending along the longitudinal direction of the cylinder portion  147  inside the cylinder portion  147 . The connecting pipe portion  142  sends air or water sent through the connector portion  24  and the folding portion  16  to each outlet  141 . 
     On the downstream side (the lid portion  148  side) of the connecting pipe portion  142 , there is provided a divergence portion  144 A for dividing the flow of air or water in the connecting pipe portion  142  corresponding to the number of outlets  141 . The divergence portion  144 A is composed of five recesses provided on the inner surface of the lid portion  148 . These five recesses are connected in series, and each recess extends to the outlet  141  side. The bottom of each recess is curved, and the dimension of the bottom is shorter as it goes to the outside. Each recess corresponds to any one of the outlets  141 . 
     Air or water is divided into five flow paths on the downstream side of the connecting pipe portion  142  by the divergence portion  144 A. That is, each recess of the flow divergence portion  144 A constitutes a flow path to the corresponding outlet  141 . Therefore, the air or water that has flowed into the divergence portion  144 A flows into the corresponding outlet  141  by each recess, and is emitted through the corresponding outlet  141 . 
     Further, a funnel-shaped or tapered diameter-reduced portion  143  is formed on the downstream side in the connecting pipe portion  142  and on the upstream side of the divergence portion  144 A. The diameter of the connecting pipe portion  142  on the upstream side of the divergence portion  144 A is reduced by the diameter-reduced portion  143 . Therefore, the speed of air or water flowing into each divergence portion  144 A through the diameter-reduced portion  143  becomes fast, and the injection force at the time of injection from each outlet  141  can be secured. 
     As described above, in the endoscope  10  according to the second embodiment of the invention, since the air supply/water supply nozzle  140  has five outlets  141  having different orientations, it is possible to prevent the separation from the curved surface of the observation optical system  132  in advance by air or water concentrating toward the center of the observation optical system  132 , and it is possible to clean the observation optical system  132  up to the nozzle opposite side with air or water. 
     The same portions as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. 
     Third Embodiment 
       FIG. 8  is a diagram illustrating an air supply/water supply nozzle  140 B of the endoscope  10  according to the third embodiment of the invention.  FIG. 8A  is a perspective view illustrating the appearance of the air supply water supply nozzle  140 B,  FIG. 8B  is a side view of the air supply water supply nozzle  140 B, and  FIG. 8C  illustrates a case where the air supply/water supply nozzle  140 B is attached to the distal end portion  13   a . In  FIGS. 8A and 8B , the portion to be inserted into the recess provided on the distal end surface  131  is indicated by a chain line, and the distal end surface  131  is indicated by a broken line. 
     The air supply/water supply nozzle  140 B of the endoscope  10  according to the third embodiment of the invention has a semi-cylindrical portion  146  inserted into a recess provided on the distal end surface  131 , and one open end of the semi-cylindrical portion  146  is sealed by the lid portion  148 . The lid portion  148  and the semi-cylindrical portion  146  are integrally formed. 
     The lid portion  148  has a peripheral wall  148   b  extending from the periphery of a substantially disc-shaped plate portion  148   a . The peripheral wall  148   b  is provided with a predetermined dimension in the direction intersecting the plate portion  148   a . The lid portion  148  is inclined with respect to the longitudinal direction of the semi-cylindrical portion  146 . The area of the plate portion  148   a  is larger than the cross-sectional area in the radial direction of the semi-cylindrical portion  146 , and a part of the lid portion  148  protrudes from the semi-cylindrical portion  146  in the radial direction of the semi-cylindrical portion  146 . 
     Two outlets  141 B are formed in the peripheral wall  148   b  relating to a part of the lid portion  148  with an interval therebetween. The outlet  141 B has a semi-elliptical shape. In other words, the outlet  141 B is formed in the part of the lid portion  148  by cutting out the peripheral wall  148   b  in a semi-circular shape. Therefore, the outlet  141 B forms a hole together with the distal end surface  131 . Air or water is injected into the observation optical system  132  through such a hole. 
     A fin-shaped guide portion  145  is projected from the inner surface of the plate portion  148   a . The guide portion  145  guides air or water from a divergence portion  134 , which will be described later, to the outlet  141 B. The guide portion  145  is provided on the downstream side in the flow path of air or water from the divergence portion  134  to each outlet  141 B, that is, closer to the outlet  141 B. The guide portion  145  is provided in the vicinity of the two outlets  141 B and between the two outlets  141 B. 
     As described above, since the endoscope  10  according to the third embodiment of the invention includes the guide portion  145 , the emission direction (injection direction) of air or water emitted from the outlet  141 B can be accurately adjusted. 
     Unlike the first and second embodiments, in the third embodiment, the connecting pipe portion, the divergence portion, and the diameter-reduced portion are provided at the distal end portion  13 . The details will be described below. 
       FIG. 9  is a cross-sectional view taken along line IX-IX of  FIG. 8C ,  FIG. 10  is a cross-sectional view taken along line X-X of  FIG. 8C , and  FIG. 11  is a cross-sectional view taken along line XI-XI of  FIG. 9 . 
     Inside the distal end portion  13 , a connecting pipe portion  136  extending along the longitudinal direction of the insertion portion  14  is provided. The connecting pipe portion  136  sends the air or water sent through the air supply tube  121  and the water supply tube  122  (fluid channel) to each outlet  141 B. The air supply tube  121  (air supply channel) and the water supply tube  122  (water supply channel) penetrate the insertion portion  14  in the longitudinal direction, and are provided so as to straddle the bending section  12  and the distal end portion  13 . The air supply tube  121  and the water supply tube  122  communicate with one end of the connecting pipe portion  136 , and send the air or water from the folding portion  16  side to the connecting pipe portion  136 . That is, the air or water that has flowed into the connecting pipe portion  136  via the air supply tube  121  and the water supply tube  122  is sent to the outlet  141 B of the air supply/water supply nozzle  140 B. 
     At the other end of the connecting pipe portion  136  on the downstream side, there is provided the divergence portion  134  that divides the flow of air or water flowing through the connecting pipe portion  136  corresponding to the number of outlets  141 B. That is, the downstream side of the connecting pipe portion  136  is divided into two flow paths (the divergence portion  134 ) having a smaller diameter than the connecting pipe portion  136 . The divergence portion  134  is open to the distal end surface  131  on both sides of the guide portion  145  (see  FIG. 11 ). In this way, each divergence portion  134  is provided so as to correspond to any one of the outlets  141 B. The air or water flowing out from each divergence portion  134  changes its direction by the plate portion  148   a  of the air supply/water supply nozzle  140 B, and is emitted through the corresponding outlet  141 B. 
     Further, a funnel-shaped or tapered diameter-reduced portion  135  is formed on the downstream side of the connecting pipe portion  136  and on the upstream side of the divergence portion  134 . That is, the diameter of the connecting pipe portion  136  on the upstream side of the divergence portion  134  is reduced by the diameter-reduced portion  135 . Therefore, the pressure of air or water flowing into each divergence portion  134  through the diameter-reduced portion  135  is reduced, and the flow speed is increased. The air or water having a higher flow speed flows out into a space wider than the divergence portion  134  (see  FIGS. 9 and 10 ), and flows toward the outlet  141 B. At this time, air or water forms a vortex having vectors in various directions, and is emitted from the outlet  141 B. Therefore, the air or water injected from each outlet  141 B spreads over a wide range, and can secure an injection force and range at the time of injection.  FIG. 9  illustrates the flow path of air or water with a broken line. 
     In the endoscope  10  according to the third embodiment of the invention, the air or water sent to the connecting pipe portion  136  via the air supply tube  121  and the water supply tube  122  passes through the diameter-reduced portion  135  and the flow divergence portion  134  and is sent to the outlet  141 B of the air supply/water supply nozzle  140 B. As described above, the guide portion  145  is provided on the downstream side of the flow path of air or water from the divergence portion  134  to the outlet  141 B, that is, near the outlet  141 B. Therefore, the guide portion  145  guides the air or water to the outlet  141 B. Air or water is emitted through the hole including the outlet  141 B and the distal end surface  131 . 
     As described above, in the endoscope  10  according to the third embodiment of the invention, the connecting pipe portion  136 , the diameter-reduced portion  135 , and the divergence portion  134  are provided inside the distal end portion  13 , so that it is possible to provide the air supply/water supply nozzle  140 B with a simple configuration. 
     The same portions as those in the first and second embodiments are designated by the same reference numerals, and detailed description thereof will be omitted. 
     The endoscope  10  according to the invention is not limited to the above description. 
     The size, shape, and the like of all the outlets  141  and  141 B do not be necessarily the same. 
     Further, the plurality of outlets  141  and  141 B may communicate with each other, but preferably does not communicate with each other. 
     It is desirable that the outlets  141  and the outlets  141 B are spaced at a distance of 50% or less of their heights (dimensions in a direction perpendicular to the distal end surface  131 ). 
     In the above description, the case where the air supply tube  121  and the water supply tube  122  are connected to the connecting pipe portions  136  and  142 , and the connecting pipe portions  136  and  142  are connected to the air supply/water supply nozzles  140  and  140 B has been described. The endoscope  10  according to the invention, however, is not limited to the above description. 
     The air supply/water supply nozzles  140  and  140 B for air supply directly connected to the air supply tube  121  and the air supply/water supply nozzles  140  and  140 B for water supply directly connected to the water supply tube  122  may be provided, individually. 
     REFERENCE SIGNS LIST 
     
         
           10  endoscope 
           14  insertion portion 
           121  air supply tube (fluid channel) 
           122  water supply tube (fluid channel) 
           132  observation optical system 
           134 ,  144 ,  144 A divergence portion 
           135 ,  143  diameter-reduced portion 
           136 ,  142  connecting pipe portion 
           140 ,  140 B air supply/water supply nozzle 
           141 ,  141 B outlet 
           145  guide portion