Abstract:
An endoscope adapter for use with an endoscope is provided. The endoscope includes an endoscopic insertion section subject to be inserted into an object subject to inspection and the endoscope adapter so that the endoscopic insertion section has an insertion section electrodes; the endoscope adapter comprises a lighting section for emitting light to the object and an adapter electrode section connected to the lighting section. The adapter electrode section comprises: an elongated hollow casing having an opening section at one end in the longitudinal direction of the casing; and a columnar electrode terminal configured to be movable in the longitudinal direction in the hollow casing and capable of projecting from the longitudinal direction end of the hollow casing. The inner diameter of the opening section is equalized to the outer diameter of the electrode terminal. It is possible to provide an endoscopic apparatus and an endoscope adapter having an endoscope adapter and an endoscopic insertion section not so significant in sizes; being capable of closing an opening section in a state where the endoscope adapter is attached to the endoscopic insertion section; and being capable of maintaining the electrode terminal clean for a prolonged period.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an endoscopic apparatus for observing an object subject to inspection and an endoscope adapter. 
     2. Description of the Related Art 
     A variously operable endoscopic apparatus for use in various fields, e.g., medical field or industrial field is provided with an elongated endoscopic insertion section subject to be inserted into an object subject to inspection; and an endoscope main body section. An endoscope adapter provided with a lighting section, etc., is detachably attached at the tip of the endoscopic insertion section in some of commonly known endoscopic apparatus (see, for example, Japanese Unexamined Patent Application, First Publication No. 2004-341546). 
     Provided at the tip of the endoscopic insertion section of the endoscopic apparatus is a cylindrical insertion electrode section connected to a power supply section. In addition, an adapter electrode section connected to the lighting section is provided to the endoscope adapter. The adapter electrode section is provided with a round electrode terminal disposed in an attaching hole having a compression spring. The electrode terminal is disposed movably along the longitudinal direction of the attaching hole so as to extend from and retract into the opening section of attaching hole. Attaching the endoscope adapter onto the tip of the endoscopic insertion section electrically connects the adapter electrode section to an insertion electrode section, thus supplying electric power from the power supply section to the lighting section. 
     Formed on the tip of the endoscopic insertion section of the endoscopic apparatus is an attaching surface onto which the adapter is attached. The attaching surface has a cylindrical electrode thereon which is connected to the power supply system. Also, the adapter has an electrode connected to the lighting section, etc. Attaching consequently the adapter onto the tip of the endoscopic insertion section electrically connects the electrode disposed to the adapter and the electrode disposed to the insertion section, thereby supplying electric power to the lighting section. 
     It is an object of the present invention to provide an endoscopic apparatus and an endoscope adapter having an endoscope adapter and an endoscopic insertion section not so significant in sizes; being capable of closing an opening section in a state where the endoscope adapter is attached to the endoscopic insertion section; and being capable of maintaining the electrode terminal clean for a prolonged period. 
     SUMMARY OF THE INVENTION 
     The present invention provides the following components. 
     A first aspect of the present invention is an endoscope adapter for use with an endoscope. The endoscope includes an endoscopic insertion section subject to be inserted into an object subject to inspection and the endoscope adapter so that the endoscopic insertion section has an insertion section electrode; the endoscope adapter comprises a lighting section for emitting light to the object and an adapter electrode section connected to the lighting section. The adapter electrode section comprises: an elongated hollow casing having an opening section at one end in the longitudinal direction of the casing; and a columnar electrode terminal configured to be movable in the longitudinal direction in the hollow casing and capable of projecting from the longitudinal direction end of the hollow casing. The inner diameter of the opening section is equalized to the outer diameter of the electrode terminal. 
     Attaching the endoscope adapter to the endoscopic insertion section in the endoscope adapter according to the present invention thrusts the electrode terminal innermore toward the endoscope adapter. The electrode terminal having a columnar shape maintains the constant distance between the inner wall of the opening section and the exterior wall of the electrode terminal irrespective of position of the electrode terminal in the longitudinal direction as long as the electrode terminal is disposed within the opening section. Equalizing the inner diameter of the opening section to the outer diameter of the electrode blocks the interspace between the inner wall of the opening section and the exterior wall of the electrode terminal irrespective of the position of the electrode terminal in the longitudinal direction. 
     This prevents the occurrence of an interspace between the inner wall of the opening section and the exterior wall of the electrode terminal when coupled to the endoscopic insertion section. Accordingly, this prevents dust from entering and sticking to the inside of the adapter electrode section. 
     In a second aspect of the present invention, one of the adapter electrode section and the insertion electrode section is provided with the hollow casing and the electrode terminal, and the electrode terminal is configured to be movable in the longitudinal direction in the hollow casing and capable of projecting from the longitudinal direction end of the hollow casing. 
     In the endoscopic apparatus according to the present invention, detaching the endoscope adapter from the endoscopic insertion section projects the electrode terminal from one longitudinal end of the hollow casing, and coupling the endoscope adapter to the endoscopic insertion section thrusts the electrode terminal toward the adapter electrode section or the insertion electrode section, thereby moving the electrode terminal innermore toward the hollow casing. 
     This provides a reliable connection between the adapter electrode section and the insertion electrode section when the endoscope adapter is coupled to the endoscopic insertion section. 
     In a third aspect of the present invention, the hollow casing of the endoscopic apparatus is electrically conductive. 
     Electrical power can be efficiently supplied to the lighting section disposed in the endoscope adapter since the hollow casing of the endoscopic apparatus according to the present invention is electrically conductive. 
     In a fourth aspect of the present invention, an attaching section subject to attaching to the hollow casing is provided to one of the endoscope adapter and the endoscopic insertion section, and the adapter further has an insulative unit for insulating the hollow casing from the attaching section. 
     The insulative unit isolates the hollow casing from the attaching section in the endoscopic apparatus according to the present invention. 
     This reduces the electrical loss in the adapter electrode section or the insertion electrode section. 
     A fifth aspect of the present invention is an endoscopic apparatus for use in observing an object subject to inspection. The apparatus includes: an endoscopic insertion section subjected to be inserted into the object subject to inspection, the endoscopic insertion section having insertion section electrodes; and an endoscope adapter having an adapter electrode section electrically connected to a lighting section for emitting light to the object, the endoscope adapter being subjected to being detachably attached to the endoscopic insertion section. The endoscopic insertion section is provided with an insertion electrode section electrically connected to the adapter electrode section when the endoscope adapter is attached to the endoscopic insertion section. The insertion electrode section includes: an elongated hollow casing having an opening section at one end in the longitudinal direction of the casing; and a columnar electrode terminal configured to be movable in the longitudinal direction in the hollow casing and capable of projecting from the longitudinal direction end of the hollow casing, and the inner diameter of the opening section is equalized to the outer diameter of the electrode terminal. 
     Attaching the endoscope adapter of the endoscopic apparatus to the endoscopic insertion section electrically connects the adapter electrode section to the insertion electrode section. In this state, the electrode terminal is thrusted by the adapter electrode section innermore toward the endoscopic insertion section. The electrode terminal having a columnar shape maintains the constant distance between the inner wall of the opening section and the exterior wall of the electrode terminal irrespective of position of the electrode terminal in the longitudinal direction as long as the electrode terminal is disposed within the opening section. Equalizing the inner diameter of the opening section to the outer diameter of the electrode blocks the interspace between the inner wall of the opening section and the exterior wall of the electrode terminal irrespective of the position of the electrode terminal in the longitudinal direction. 
     This prevents the occurrence of an interspace between the inner wall of the opening section and the exterior wall of the electrode terminal when the endoscope adapter is coupled to the endoscopic insertion section. Accordingly, this prevents dust from entering and sticking to the inside of the insertion electrode section. 
     As sixth aspect of the present invention is an endoscopic apparatus including: an endoscopic insertion section subjected to be inserted into an object subject to inspection; an attaching surface disposed to the endoscopic insertion section, the surface being subjected to be detachably attached to the adapter having the adapter electrode section; and the insertion section electrode disposed to the endoscopic insertion section, the electrode being subjected to being electrically connected to the adapter electrode section when the adapter is attached to the attaching surface. The insertion section electrode is disposed innermore toward the endoscopic insertion section relative to the attaching surface. 
     In the endoscopic apparatus according to the present invention, attaching the adapter to the attaching surface of the endoscopic insertion section electrically connects the insertion section electrode to the adapter electrode. On the other hand, the insertion section electrode detached therefrom is concealed from the surface of the attaching surface since the insertion section electrode is disposed innermore relative to the attaching surface. 
     This prevents the insertion section electrode from projecting relative to the attaching surface when the adapter is detached from the endoscopic insertion section. 
     In a seventh aspect of the present invention, a recess accommodating the insertion section electrode is formed in the attaching surface. 
     Accordingly, the insertion section electrode is reliably prevented from projecting from the surface of the attaching surface in the endoscopic apparatus according to the present invention since the insertion section electrode is disposed in the recess. 
     An eighth aspect of the present invention is an endoscopic apparatus including: an endoscopic insertion section subjected to be inserted into an object subject to inspection; an attaching surface disposed to the endoscopic insertion section, the surface being subjected to being detachably attached to the adapter having the adapter electrode section; and the insertion section electrode disposed to the endoscopic insertion section, the electrode being subjected to being electrically connected to the adapter electrode section when the adapter is attached to the attaching surface; and projecting sections disposed in the vicinity of the insertion section electrode on the attaching surface and projecting from the attaching surface. The insertion section electrode is disposed innermore toward the attaching surface relative to the tip of the projecting sections. 
     In the endoscopic apparatus according to the present invention, attaching the adapter to the attaching surface of the endoscopic insertion section electrically connects the insertion section electrode to the adapter electrode. On the other hand, at least a portion of the insertion section electrode is concealed by the projecting sections when the adapter is detached since the insertion section electrode is disposed closer to the attaching surface than the tip of the projecting sections. 
     This prevents the projection of the insertion section electrode when the adapter is detached from the endoscopic insertion section. 
     In a ninth aspect of the present invention, the projecting sections are provided with a hollow section extending in the projecting direction, the insertion section electrode being disposed in the hollow section. 
     Accordingly, the insertion section electrode is reliably prevented from projecting from the surface of the attaching surface in the endoscopic apparatus according to the present invention since the insertion section electrode is disposed in the recess. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates first and fifth embodiments of the endoscopic apparatus according to the present invention in a schematic view. 
         FIG. 2  illustrates the tip of the insertion section of the endoscopic apparatus of  FIG. 1  in an enlarged perspective view. 
         FIG. 3  is an enlarged view of the optical adapter shown in  FIG. 1  viewed from the base end including an attaching hood approximately half of which is illustrated in a cutout view. 
         FIG. 4  illustrates the adapter electrode section of  FIG. 3  in an enlarged perspective view. 
         FIG. 5  is a half-cutaway view of a hollow casing shown in  FIG. 4 . 
         FIG. 6  is a half-cutaway view of a hollow casing shown in  FIG. 3 . 
         FIG. 7  illustrates the substantial peripheral part of the adapter electrode section shown in  FIG. 6  in a cross sectional view. 
         FIG. 8  illustrates a modified example of the adapter electrode section shown in  FIG. 5  in a perspective view additionally having a resilient member. 
         FIG. 9  illustrates another modified example of the adapter electrode section shown in  FIG. 5  in a perspective view using air as a resilient member. 
         FIG. 10  illustrates another modified example of the adapter electrode section shown in  FIG. 5  in a perspective view additionally having a sealing member. 
         FIG. 11  illustrates another modified example of the adapter electrode section shown in  FIG. 5  in a perspective view additionally having a columnar electrode terminal. 
         FIG. 12  illustrates another modified example of the adapter electrode section shown in  FIG. 5  in a perspective view additionally showing a large diameter portion at the tip of the terminal. 
         FIG. 13  illustrates modified examples of the hollow casing, the insulative casing, and inner peripheral wall section shown in  FIG. 6  where an outward flange section is disposed to the hollow casing. 
         FIG. 14  illustrates the substantial peripheral part of the adapter electrode section shown in  FIG. 13  in a cross sectional view. 
         FIG. 15  illustrates modified examples of the hollow casing, the insulative casing, inner peripheral wall section that are shown in  FIG. 14 , and the substantial peripheral part of the adapter electrode section. 
         FIG. 16  illustrates other modified examples of the hollow casing, the insulative casing, inner peripheral wall section that are shown in  FIG. 14 , and the substantial peripheral part of the adapter electrode section. 
         FIG. 17  illustrates modified examples of the hollow casing, the insulative casing, and inner peripheral wall section, where a counterpart terminal is disposed to the hollow casing. 
         FIG. 18  illustrates the substantial peripheral part of the adapter electrode section shown in  FIG. 17  in a cross sectional view. 
         FIG. 19  shows a substantial part of the endoscopic apparatus including the tip of the insertion section according to the second embodiment of the present invention. 
         FIG. 20  shows a substantial part of the endoscopic apparatus of the second embodiment in a perspective view including a half cutaway view of the attaching hood of the optical adapter viewed from the base end. 
         FIG. 21  is a perspective half-cutaway view of the insertion section shown in  FIG. 19 . 
         FIG. 22  illustrates the substantial peripheral part of the insertion electrode section shown in  FIG. 21  in a cross sectional view. 
         FIG. 23  shows a substantial part of the endoscopic apparatus including the tip of the insertion section according to the third embodiment of the present invention. 
         FIG. 24  shows a substantial part of the endoscopic apparatus of the third embodiment in a perspective view including a half cutaway view of the attaching hood of the optical adapter viewed from the base end. 
         FIG. 25  illustrates the adapter electrode section of  FIG. 24  in an enlarged perspective view. 
         FIG. 26  is a half-cutaway view of a hollow casing shown in  FIG. 24 . 
         FIG. 27  illustrates a modified example of the adapter electrode section shown in  FIG. 25 . 
         FIG. 28  shows a substantial part of the endoscopic apparatus including the tip of the insertion section according to the fourth embodiment of the present invention. 
         FIG. 29  shows a substantial part of the endoscopic apparatus of the fourth embodiment in a perspective view including a half cutaway view of the attaching hood of the optical adapter viewed from the base end. 
         FIG. 30  is a perspective half-cutaway view of the insertion section shown in  FIG. 28 . 
         FIG. 31  illustrates the insertion section of the endoscopic apparatus shown in  FIG. 1  including the attaching surface to which the optical adapter is detachably attached. 
         FIG. 32  is an enlarged view of the optical adapter shown in  FIG. 1  viewed from the base end including an attaching hood approximately half of which is illustrated in a cutout view. 
         FIG. 33  illustrates the substantial peripheral part of the adapter electrode section shown in  FIG. 32  in a cross sectional view. 
         FIG. 34  is an enlarged half cutaway view of the tip of the insertion section viewed from the tip. 
         FIG. 35  illustrates the substantial peripheral part of the insertion electrode section shown in  FIG. 34  in a cross sectional view. 
         FIG. 36  illustrates a modified example of the insertion section electrode shown in  FIG. 34  in a perspective view including a half cutaway view of a cylindrical main body. 
         FIG. 37  illustrates another modified example of the insertion section electrode shown in  FIG. 34  in a perspective view including a half cutaway view of the cylindrical main body. 
         FIG. 38  illustrates modified examples of a recess and the insertion section electrode that are shown in  FIG. 31 . 
         FIG. 39  illustrates modified examples of the recess and the insertion section electrode that are shown in  FIG. 31  and a notch section formed on the recess shown in  FIG. 38 . 
         FIG. 40  illustrates modified examples of two recesses and the insertion section electrode that are shown in  FIG. 31  and a notch section formed on each recess shown in  FIG. 31 . 
         FIG. 41  illustrates modified examples of  FIG. 31  having a recess having a plurality of insertion section electrodes. 
         FIG. 42  illustrates modified examples of the recess and the insertion section electrodes that are shown in  FIG. 31  and a notch section formed on the recess shown in  FIG. 41 . 
         FIG. 43  shows a substantial part of the endoscopic apparatus including a half cutaway view of the tip of the insertion section according to the sixth embodiment of the present invention. 
         FIG. 44  illustrates the substantial peripheral part of the insertion electrode section shown in  FIG. 43  in a cross sectional view. 
         FIG. 45  shows a substantial part of the endoscopic apparatus including a half cutaway view of the tip of the insertion section according to the seventh embodiment of the present invention. 
         FIG. 46  illustrates the substantial peripheral part of the insertion electrode section shown in  FIG. 45  in a cross sectional view. 
         FIG. 47  illustrates a modified example of a groove shown in  FIG. 45  in a perspective view including a half cutaway view of the tip of the insertion section. 
         FIG. 48  illustrates the substantial peripheral part of the insertion electrode section shown in  FIG. 47  in a cross sectional view. 
         FIG. 49  illustrates substantial parts of the eighth embodiment of the endoscopic apparatus according to the present invention in a perspective view. 
         FIG. 50  illustrates the optical adapter viewed from the base end according to an embodiment including a half cutaway view of the base end section. 
         FIG. 51  illustrates modified examples of a projecting section and the insertion section electrode that are shown in  FIG. 49 . 
         FIG. 52  illustrates modified examples of the recess and the insertion section electrodes that are shown in  FIG. 49  and a notch section formed on the recess shown in  FIG. 51 . 
         FIG. 53  is a perspective view illustrating modified examples of two projecting sections and the insertion section electrode that are shown in  FIG. 49  and a notch section formed on each projecting section. 
         FIG. 54  illustrates modified examples of  FIG. 49  having a projecting section having a hollow section accommodating a plurality of the insertion section electrodes. 
         FIG. 55  illustrates modified examples of the projecting section and the insertion section electrodes that are shown in  FIG. 49  and a notch section formed on the projecting section shown in  FIG. 54 . 
         FIG. 56  illustrates modified examples of a projecting section and the insertion section electrodes that are shown in  FIG. 49  where a columnar projecting section is provided between the electrodes. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     (Embodiment 1) 
     An endoscopic apparatus according to a first embodiment of the present invention will be explained with reference to the attached drawings. 
       FIG. 1  illustrates the endoscope device according to the first embodiment of the present invention. 
     An endoscope apparatus  1  is provided with an insertion section  2  (endoscopic insertion section) having a bending section  7  capable of bending; and a main body section  3  variously operable when used with the insertion section  2  inserted thereinto. 
     The approximately box-shaped main body section  3  has a side wall section onto which an operation panel  6  used for carrying out various operations is disposed. In addition, a monitor  8  for exhibiting an observed image is disposed on a ceiling of the main body section  3 . Furthermore, a power supply section  9  for supplying electric power is disposed to the main body section  3 . 
     Also, the base end section of the insertion section  2  is configured to be detachably attached to the main body section  3  through a connecting section which is not shown in the drawings. Meanwhile an observing unit using a CCD  16  is disposed onto the tip thereof as shown in  FIG. 2 . In addition, a fitting-protrusion section  17  is disposed over the circumference of the insertion section  2  while protruding outwardly in a radial direction. An insertion section-mounting surface  13  is disposed on the tip of the insertion section  2  so that an optical adapter  12  (shown in  FIG. 1 ) having an object lens which is not shown in the drawing is detachably attached onto the surface  13 . Fixed onto the insertion section-mounting surface  13  is an insertion section electrode section  32  which is electrically connected to the power supply section  9  shown in  FIG. 1 . The insertion section electrode section  32  will be explained afterwards. 
     As illustrated in  FIG. 3 , the optical adapter (endoscope adapter)  12  is provided with an adapter main body  27  having an approximate columnar shape; and an attachment hood section  23  having an approximate cylindrical shape and being coaxially joined to the base end of the adapter main body  27 . 
     Provided onto the side wall section of the adapter main body  27  is a lighting section  11  having, for example LEDs. In addition, formed on the bottom surface section  27   a  of the adapter main body  27  is an adapter-mounting surface  29  by way of which the optical adapter  12  is attached to the insertion section  2 . Provided onto the adapter-mounting surface  29  is a movable adapter electrode section  18  electrically connected to the lighting section  11 . The adapter electrode section  18  will also be explained afterwards. 
     Furthermore, formed on the inner periphery of the attachment hood section  23  is a mounting groove  26  extending over the circumference of the hood  23 . 
     Squeezing the optical adapter  12  into the insertion section-mounting surface  13  as shown in  FIG. 2  fits the fitting-protrusion section  17  with the mounting groove  26 , and this configuration allows detachable attaching of the optical adapter  12  onto the tip of the insertion section  2  while maintaining the insertion section-mounting surface  13  to face the adapter-mounting surface  29 . 
     Furthermore, as shown in  FIGS. 4 and 5 , the adapter electrode section  18  according to the present embodiment is provided with a hollow casing  30  having a bottom section and a cylindrical section and an approximate columnar electrode terminal  31 . 
     The hollow casing  30  possesses electrical conductivity and is made from nonferrous metals and ferrous metals, e.g., iron. In addition, an inward flange section  34  formed on one end of the hollow casing  30  in a longitudinal direction L is inwardly directed in a radial direction of the casing  30 . Crimping the end of the hollow casing  30  provides the inward flange section  34 . The inward flange section  34  also defines a circular opening section  35  on the end of the hollow casing  30 . 
     Also, highly conductive plating or painting is applied to the surface of the electrode terminal  31  made of metal. The electrode terminal  31  is further provided with a columnar terminal tip section  37  and a terminal base end section  38 . The terminal tip section  37  is coaxially jointed to the terminal base end section  38  in one unit. The terminal tip section  37  projects from the hollow casing  30  through the opening section  35  formed at the end of the casing  30 . The inner diameter of the opening section  35  is set to be the same as the outer diameter of the terminal tip section  37 , so disposing the terminal tip section  37  into the opening section  35  blocks the opening section  35 . 
     It should be noted that, in the present invention, the same dimensions with respect to the inner diameter of the opening section and the outer diameter of the tip of the terminal indicate that there is a clearance that allows the tip of the terminal to slidably move through the opening section. 
     Also, the terminal base end section  38  greater than the terminal tip section  37  in diameter is configured to slidably move in the tubular hole  39  (hollow casing) of the hollow casing  30  in the longitudinal direction L. The movement of the terminal base end section  38  in the tubular hole  39  allows the terminal tip section  37  to project from and retract into the opening section  35  formed at the end of the hollow casing  30 . Furthermore, the terminal base end section  38  makes contact with the inward flange section  34  before the terminal base end section  38  moves out of the opening section  35 . That is, the inward flange section  34  works as a retainer against the electrode terminal  31 . 
     Provided between the terminal base end section  38  and the bottom section inside the hollow casing  30  is a coil spring (urging member)  42 . The force exerted by the coil spring  42  presses the terminal base end section  38  at the end of the hollow casing  30 , thereby maintaining the terminal tip section  37  to project outward from the end of the hollow casing  30 . The coil spring  42  is made from electrically conductive metal. 
     In this configuration, provided further around the adapter electrode section  18  is an insulative casing (insulative unit)  47  surrounding the hollow casing  30  as shown in  FIGS. 6 and 7 . To be more specific, the insulative casing  47  has a bottom section, a cylinder section, and a cylindrical hole into which the adapter electrode section  18  is inserted and fixed there. The bottom surface of the hollow casing  30  makes contact with the bottom surface section  47   a  of the insulative casing  47 . Formed at the end of the insulative casing  47  is a flange section  48  extending outward in the radial direction of the insulative casing  47 . A through hole  49  is formed in the center of the bottom surface section  47   a  of the insulative casing  47 . 
     The endoscope adapter is inserted into the insulative casing  47  inserted in the adapter electrode section  18  is attached in the electrode-mounting hole  43  formed in the optical adapter  12 . That is, the inner peripheral wall section  44  defining the electrode-mounting hole  43  works as an attaching portion accommodating the hollow casing  30  and the insulative casing  47  thereon. The terminal tip section  37  projects from the adapter-mounting surface  29  while the adapter electrode section  18  is mounted in the electrode-mounting hole  43 . 
     A portion of the bottom surface section  27   a  disposed at one longitudinal end of the inner peripheral wall section  44  has a step section  52  with which the outward-extending flange section  48  makes contact. 
     The force needed to push the adapter electrode section  18  into the optical adapter  12  is supported by the bottom surface section  47   a  of the insulative casing  47 , thereby restraining the movement of the hollow casing  30  inward, i.e., toward the inside of the optical adapter  12  in this configuration. Furthermore, the force pushing the insulative casing  47  into the optical adapter  12  is supported by the step section  52 , thereby restraining the movement of the insulative casing  47  into the optical adapter  12 . That is, the bottom surface section  47   a  of the insulative casing  47  serves for restraining the movement of the hollow casing; and the step section  52  and the outward-extending flange section  48  serve for restraining the movement of the insulative member. 
     The insulative casing  47  furthermore serves for providing insulation to the hollow casing  30  and the inner peripheral wall section  44 . 
     An end of a cable  53  inserted through the through hole  49  into the insulative casing  47  is electrically soldered to the outer surface of the bottom of the hollow casing  30 . The other end of the cable  53  is electrically connected to the lighting section  11 . Reference numeral  50  indicates the soldered portion. 
     As shown in  FIG. 2 , the insertion section-mounting surface  13  of the insertion section  2  furthermore has recesses  54  accommodating insertion section electrode sections  32  each having a bottom and a cylinder section. The innermost section of each insertion section electrode section  32  is bent inner more in the radial direction than the recess  54 . To be more specific, each insertion section electrode section  32  subsides inward of the insertion section  2  relative to the insertion section-mounting surface  13 . Each insertion section electrode section  32  is concealed from the insertion section-mounting surface  13  by a sidewall section of the recess  54 . Also, highly conductive plating or painting is applied to the surface of the insertion section electrode section  32  made of metal. 
     The operation of the endoscope apparatus  1  thus configured in the present embodiment will be explained next. 
     The optical adapter  12  is first attached onto the insertion section-mounting surface  13  of the insertion section  2 . The terminal tip section  37  is subsequently disposed in the recess  54  and makes contact with the outer surface of the bottom of the insertion section electrode section  32 . This electrically connects the adapter electrode section  18  to the insertion section electrode section  32 , thereby supplying electric power to the lighting section  11  from the power supply section  9 . The lighting section  11  of the insertion section  2  introduced into an object subject to inspection emits light. The light reflected by the object subject to inspection passes through object lenses in the optical adapter  12  and an image thereof is formed on a CCD  16 . A signal output from the CCD  16  is supplied to a monitor  8  through a predetermined circuit. This provides an observed image exhibited on the monitor  8  used for a predetermined inspection of the object. 
     The adapter electrode section  18  is electrically connected to the insertion section electrode section  32  upon coupling the optical adapter  12  to the insertion section-mounting surface  13 . 
     To be more specific, the optical adapter  12  is brought to the tip of the insertion section  2  and pushed thereinto while the insertion section-mounting surface  13  faces the adapter-mounting surface  29 . The terminal tip section  37  is subsequently disposed in the recess  54  and makes contact with the insertion section electrode section  32 . Pushing furthermore the optical adapter  12  thereinto causes the insertion section electrode section  32  to press the terminal tip section  37  innermore toward the optical adapter  12 . The terminal tip section  37  moves in the subsiding direction into the hollow casing  30  through the opening section  35 . Simultaneously, the terminal base end section  38  resisting the force exerted by the coil spring  42  moves in the hollow casing  30  into the optical adapter  12 . 
     The constant interspace is maintained between the exterior wall of the terminal tip section  37  and the inner wall of the opening section  35  when the cylindrical terminal tip section  37  moves into the hollow casing  30  through the opening section  35 . Configuring the outer diameter of the terminal tip section  37  to be the same as the inner diameter of the opening section  35  blocks the interspace between the exterior wall of the terminal tip section  37  and the inner wall of the opening section  35  irrespective of the position of the terminal tip section  37 . 
     The fitting-protrusion section  17  of the insertion section  2  fits with a mounting groove  26  while the terminal tip section  37  is depressed; thus, the optical adapter  12  is attached onto the tip of the insertion section  2 . The projection of the terminal tip section  37  in length from the adapter-mounting surface  29  through the opening section  35  reduces according to the depression caused by the insertion section electrode section  32 . The terminal tip section  37  is further pressed toward the insertion section electrode section  32  by the force exerted by the coil spring  42 . The contact between the terminal tip section  37  and the insertion section electrode section  32  is therefore maintained. This configuration allows the adapter electrode section  18  to be electrically connected to the insertion section electrode section  32 . 
     Although the hollow casing  30  and the insulative casing  47  subject to the pressing force are apt to move into the optical adapter  12  when the optical adapter  12  is attached onto the tip of the insertion section  2 , the movements of these casings  30  and  47  are restrained by making contacts with the bottom surface section  47   a  of the insulative casing  47  and the step section  52 . 
     Since the interspace between the exterior wall of the terminal tip section  37  and the inner wall of the opening section  35  can be continuous irrespective of the position of the terminal tip section  37  in the endoscope apparatus  1 , the present embodiment does not allow the interspace between the exterior wall of the terminal tip section  37  and the inner wall of the opening section  35  while the optical adapter  12  is attached to the insertion section  2 . 
     This prevents dust from entering and sticking inside of the adapter electrode section  18 . Poor contact can be prevented accordingly, thus the cleanness of the adapter electrode section  18  can be maintained in the long term. Also preventing the entry of dust reduces the cleaning cycle; thus facilitating regular care. 
     The circular shapes of the opening section  35  and the terminal tip section  37  not only allow smooth movement of the terminal tip section  37  through the opening section  35  but provide a uniform block between the inner wall of the opening section  35  and the exterior wall of the terminal tip section  37 . 
     The terminal tip section  37  mounted in the hollow casing  30  through the opening section  35  is pushed by the force exerted by the coil spring  42 ; thus coupling the optical adapter  12  into the insertion section  2  results in secure connection between the adapter electrode section  18  and the insertion section electrode section  32 . 
     The electric power supplied by the power supply section  9  can be further supplied to the lighting section  11  through the coil spring  42  and the hollow casing  30  that are electrically conductive. The efficiency thus increases in supplying electricity. Although the electrical resistance of the coil spring  42  is significant because of its insignificant cross sectional area and significant longitudinal length, insignificant electrical resistance in the hollow casing  30  having a significant cross sectional area and insignificant longitudinal length connected to the cable  53  help to efficiently supply the electric power in the present embodiment. 
     The isolation between the hollow casing  30  and the inner peripheral wall section  44  obtained by the insulative casing  47  can lower the electrical loss of the adapter electrode section  18 . 
     The insertion section electrode section  32  subsides from the insertion section-mounting surface  13 , i.e., is concealed from the insertion section-mounting surface  13 , thereby resisting damage of the insertion section electrode section  32  and preventing dust from entering or sticking there with the optical adapter  12  detached. The cleanness of the insertion section electrode section  32  can be thus maintained effectively. 
     The inward flange section  34  formed to the hollow casing  30  prevents the removal of the electrode terminal  31  from the hollow casing  30  while allowing smooth movement of the electrode terminal  31 . 
     Furthermore, the bottom surface section  47   a  and the step section  52  that are formed to the insulative casing  47  restrain the hollow casing  30  and the insulative casing  47  from moving inward into the optical adapter  12 , thereby facilitating fixing the hollow casing  30  and the insulative casing  47  to the inner peripheral wall section  44  and maintaining suitable contact between the adapter electrode section  18  and the insertion section electrode section  32  in the long term. 
     Also coupling the optical adapter  12  to the insertion section  2  connects the the radially-inner surface of the insertion section electrode section  32  to an end surface of the terminal tip section  37 , thereby providing an interfacial contact between the insertion section electrode section  32  and the adapter electrode section  18 . The electrical conductivity between the insertion section electrode section  32  and the adapter electrode section  18  can be obtained in the case of lower component quality or lower assembly accuracy. 
     The highly conductive plating or painting provided onto the insertion section electrode section  32  and the electrode terminal  31  lowers the electrical loss between the insertion section electrode section  32  and the adapter electrode section  18 . 
     The hollow casing  30 , electrode terminal  31 , coil spring  42 , and insulative casing  47  provided in the present embodiment are susceptible to modifications in arbitrary shape and material. 
     For example, an elastic member (urging member)  57  may be provided as shown in  FIG. 8  in place of the coil spring  42 . The elastic member  57  made of conductive resin allows supplying the electrical power efficiently in an improved manner. 
     The configuration free of the coil spring  42  as shown in  FIG. 9  may also be desirable. This case requires the hollow casing  30  to be of an airtight construction. The reciprocation of the electrode terminal  31  expands and contracts the air in the tubular hole  39 , thereby rendering the air an urging member. 
     Furthermore, a rubber sealing material  58  may be provided to the tip of the hollow casing  30  as shown in  FIG. 10 . This prevents water from entering into the adapter electrode section  18 , thereby preventing corrosion and failure due to the submergence. 
     The electrode terminal  31  may be a column having an identical diameter over the longitudinal length as shown in  FIG. 11 . This facilitates the production of the electrode terminal  31 . This case requires to fix the tip of the coil spring  42  to the rear end of the electrode terminal  31  and to fix the rear end of the coil spring  42  to the inner bottom surface of the hollow casing  30 . This configuration eliminates the need of the inward flange section  34 , thereby simplifying the configuration. 
     A large-diameter tip section  59  having a larger diameter than that of the terminal tip section  37  may be formed at the tip of the terminal tip section  37  as shown in  FIG. 12 . This provides contact between the large-diameter tip section  59  and the insertion section electrode section  32 , thereby increasing the area contacting the insertion section electrode section  32 . Therefore, superior conductivity can be obtained between the adapter electrode section  18  and the insertion section electrode section  32  in the case of lower component quality or lower assembly accuracy. 
     Furthermore, as shown in  FIGS. 13 and 14 , an outward flange section  62  may be provided to the tip of the hollow casing  30 , and a step section  63  contacting the outward flange section  62  may be provided to the tip of the insulative casing  47 . The outward flange section  62  and the step section  63  serve for restraining the movement of the hollow casing. Also, an engagement step section  64  is disposed in the vicinity of the base end section of the insulative casing  47 ; and a counter-engagement step section  66  engaging the engagement step section  64  is formed to the inner peripheral wall section  44  near a coupling part. The engagement step section  64  and the counter-engagement step section  66  serve for restraining the movement of the insulative component. 
     Furthermore, the insulative casing  47  may be cylindrical and the hollow casing  30  may have a bottom section and a cylinder section as shown in  FIG. 15  in place of providing a step section or an outer flange section to the inner peripheral wall section  44 , insulative casing  47 , and hollow casing  30 . This case requires the insulative casing  47  to be fixed to the hollow casing  30  using adhesives, etc. 
     Also, as shown in  FIG. 16 , the adapter electrode section  18  may be directly mounted into the inner peripheral wall section  44 , i.e., without the insulative casing  47 . In this case, the hollow casing  30  may be made of an insulative material, and the hollow casing  30  may be anodized so as to provide insulation on the surface thereof. In addition, the inner peripheral wall section  44  may be made of an insulative material and the surface of the inner peripheral wall section  44  may be treated to impart insulation there. 
     An inward flange section  34  defining the circular other counterpart opening section  68  may be provided to the other end in the longitudinal direction L of the hollow casing  30 . In this case, provided to the other end of the hollow casing  30  is another columnar end terminal  69 . The other end terminal  69  having a configuration similar to that of the electrode terminal  31  is provided with a columnar connection terminal section  70  and a terminal base plate section  71 . 
     The connection terminal section  70  projects from the other end of the hollow casing  30  through the other counterpart opening section  68 . The inner diameter of the other counterpart opening section  68  is set to be the same as the outer diameter of the connection terminal section  70 , so disposing the connection terminal section  70  into the other counterpart opening section  68  blocks the other counterpart opening section  68 . This prevents dusts from entering there through the other counterpart opening section  68 . 
     The terminal base plate section  71  is movable in the longitudinal direction L of the tubular hole  39  in the hollow casing  30 . The movement of the terminal base plate section  71  in the tubular hole  39  similarly to the electrode terminal  31  enables the reciprocation of the connection terminal section  70  from the other end of the hollow casing  30  through the other counterpart opening section  68 . 
     The force exerted by the coil spring  42  presses the terminal base plate section  71  at the other end of the hollow casing  30 , thereby urging the connection terminal section  70  outward from the other end of the hollow casing  30 . 
     The insulative casing  47  mounted into the electrode-mounting hole  43  is configured to be detachable from the mounted condition. To be more specific, the insulative casing  47  including the adapter electrode section  18  is configured to be replaceably mounted in the electrode-mounting hole  43 . 
     Inserting and pushing the adapter electrode section  18  into the insulative casing  47  at a predetermined position allow the connection terminal section  70  to project through the through hole  49  in this configuration. In addition, equalizing the outer diameter of the connection terminal section  70  to the inner diameter of the through hole  49  blocks the through hole  49 . 
     Pushing the insulative casing  47  having a projecting connection terminal section  70  as described above through the connection terminal section  70  into the electrode-mounting hole  43  to the predetermined position contacts the connection terminal section  70  to the connecting section  73  disposed at the tip of the cable  53 , thereby pushing the connection terminal section  70  into the hollow casing  30  while resisting the force exerted by the coil spring  42 . The electrical connection between the other end terminal  69  and the connecting section  73  is maintained because the connection terminal section  70  is pushed by the force exerted by the coil spring  42  toward the connecting section  73 . 
     In the case of failure of the adapter electrode section  18 , the adapter electrode section  18  is removed together with the insulative casing  47 , and another set of adapter electrode section  18  and insulative casing  47  is mounted to the inner peripheral wall section  44  as described above. 
     In addition, the adapter electrode section  18  may be replaceably mounted in the insulative casing  47 . 
     The incorporation of the adapter electrode section  18  regardless of its direction is facile in the above configuration. Also, the reciprocation of the other end terminal  69  absorbs dimensional error in each component. Also, the replaceable adapter electrode section  18  facilitates repairing the optical adapter  12 . The absence of necessity for fixing the other end terminal  69  to the connecting section  73  also facilitates replacing the adapter electrode section  18 . 
     (Embodiment 2) 
     A second embodiment of the present invention will be next explained. 
       FIGS. 19 to 22  illustrate the second embodiment of the present invention. 
     The same reference numerals are added to the elements illustrated in  FIGS. 19 to 22  that are the same as those illustrated in  FIGS. 1 to 18  so as to omit duplicate explanation. 
     The fundamental configuration of the present embodiment is the same as that of the first embodiment; only the differences will be hereafter explained. 
     The adapter electrode section  18  and the insertion section electrode section  32  illustrated in the first embodiment are interchangeably disposed in the endoscope apparatus  1  of the present embodiment. To be more specific, an insertion section electrode section  74  according to the present embodiment has the same configuration as that of the adapter electrode section  18  according to the above first embodiment; and the adapter electrode section  75  according to the present embodiment has the same configuration as that of the insertion section electrode section  32  according to the above first embodiment. Accordingly, the adapter electrode section  75  is of a fixed type, and the insertion section electrode section  74  is of a movable type as explained above. 
     The adapter electrode section  75  is electrically connected to the insertion section electrode section  74  upon coupling the optical adapter  12  to the insertion section  2 . The opening section  35  is closed in this state. 
     As described above, the effect similar to that of the above first embodiment can be obtained by the endoscope apparatus  1  according to the present embodiment. 
     The modified examples illustrated in  FIGS. 8 to 18  based on the above first embodiment are applicable to the present embodiment. 
     (Embodiment 3) 
     A third embodiment of the present invention will be next explained. 
       FIGS. 23 to 26  illustrate the third embodiment of the present invention. 
     As shown in  FIGS. 23 and 24 , an insertion section electrode section  78  is of a fixed type, and an adapter electrode section  79  is of a movable type according to the present embodiment. To be more specific, the insertion section electrode section  78  is provided with a projecting terminal (electrode terminal)  80  which is fixed on and projects from the insertion section-mounting surface  13 . The adapter electrode section  79  is provided with a columnar inner-casing connection terminal  83  as illustrated in  FIGS. 25 and 26  in place of the electrode terminal  31 . 
     Also, highly conductive plating or painting is applied to the surface of the inner-casing connection terminal  83  made of metal. The inner-casing connection terminal  83  movable in the longitudinal direction L is also urged by the coil spring  42  toward the opening section  35 . 
     The inner diameter of the opening section  35  and the outer diameter of the projecting terminals  80  are configured to be the same. 
     Coupling the optical adapter  12  to the insertion section  2  in this configuration inserts the projecting terminals  80  into the hollow casing  30  through the recess  54  and the opening section  35 . The contact between the projecting terminals  80  and the inner-casing connection terminal  83  provides electrical connection between the adapter electrode section  79  and the insertion section electrode section  78 . 
     As described above, the effect similar to that of the above first embodiment can be obtained by the endoscope apparatus  1  according to the present embodiment; and the rigidity of the fixed projecting terminals  80  can be significant. 
     The configuration of the present invention is not limited to the use of the inner-casing connection terminal  83 , that is, the configuration free of the inner-casing connection terminal  83  is also practicable. In this case, the projecting terminals  80  make contact with the tip of the coil spring  42  through the opening section  35 . This configuration allows the adapter electrode section  79  to be electrically connected to the insertion section electrode section  78 . 
     In addition, it is obvious that the modified examples illustrated in  FIGS. 8 to 19  based on the above first embodiment are applicable to the present embodiment. 
     (Embodiment 4) 
     A fourth embodiment of the present invention will be next explained. 
       FIGS. 28 to 30  illustrate the fourth embodiment of the present invention. 
     The fundamental configuration of the present embodiment is the same as that of the third embodiment; only the differences will be hereafter explained. 
     The adapter electrode section  79  and the insertion section electrode section  78  illustrated in the third embodiment are interchangeably disposed in the endoscope apparatus  1  of the present embodiment. To be more specific, an insertion section electrode section  85  according to the present embodiment has the same configuration as that of the adapter electrode section  79  according to the above third embodiment; and the adapter electrode section  86  according to the present embodiment has the same configuration as that of the insertion section electrode section  78  according to the above third embodiment. Accordingly, the adapter electrode section  86  is of a fixed type, and the insertion section electrode section  85  is of a movable type. 
     The adapter electrode section  86  is electrically connected to the insertion section electrode section  85  upon coupling the optical adapter  12  to the insertion section  2 . The opening section  35  is closed in this state. 
     As stated above, the effect similar to that of the above third embodiment can be obtained by the endoscope apparatus  1  according to the present embodiment. 
     In addition, it is obvious that the modified examples illustrated in  FIGS. 8 to 19  based on the above first embodiment are applicable to the present embodiment. 
     Arbitrary modifications are practicable in the forms of the opening section  35  and other counterpart opening section  68  that are circular through the above first to fourth embodiments; and the electrode terminal  31 , the other end terminal  69 , and projecting terminals  80  that are columnar through the above embodiments. For example, the transverse cross section of the electrode terminal  31 , etc. may be oval, and the electrode terminal  31  may be a rectangular parallelepiped. 
     Arbitrary modifications are also practicable to the coil spring  42 , serving as an urging member, and the hollow casing  30  with respect to electrical conductivity; that is, at least one of them may have electrical conductivity. 
     It is understood that the adapter electrode sections  18 ,  75 ,  79 , and  86  according to the present invention are not limited to be connected to the lighting section  11 . These may rather be connected to other sensors and electronic components, e.g., adapter recognition sensors and temperature humidity sensors. 
     It is in addition understood that the present invention is not limited to the optical adapter  12  of a lateral view type having the lighting section  11  on a side wall section. The lighting section  11  may rather be of a direct view type provided onto the tip of the optical adapter  12 . 
     The present invention is not limited to the first to fourth embodiments, and various modifications may be made without departing from the spirit of the present invention. 
     For example, the first to fourth embodiments above having disclosed the electrodes disposed to one of the adapter and the insertion section may include the configuration of one electrode to the adapter and the other one to the insertion section. The adapter and the insertion section may each have two electrodes in another configuration. This configuration advantageously maintains an adapter and an insertion section to be small in outside shape. 
     (Embodiment 5) 
     An endoscopic apparatus according to a fifth embodiment of the present invention will be explained with reference to the attached drawings. 
       FIG. 1  illustrates the endoscope device according to the fifth embodiment of the present invention. 
     The endoscope apparatus  1  is provided with an insertion section  2  (endoscopic insertion section) having a bending section  7  capable of bending; and a main body section  3  (endoscope main body section) variously operable when used with the insertion section  2  inserted thereinto. 
     The approximately box-shaped main body section  3  has a side wall section onto which an operation panel  6  is disposed used for carrying out various operations. In addition, a monitor  8  for exhibiting an observed image is disposed on a ceiling of the main body section  3 . Furthermore, a power supply section  9  for supplying electric power is disposed to the main body section  3 . 
     Also, the base end section of the insertion section  2  is configured to be detachably attached to the main body section  3  through a connecting section which is not shown in the drawings. Meanwhile an observing unit using a CCD  16  is disposed onto the tip thereof as shown in  FIG. 31 . In addition, a fitting-protrusion section  17  is disposed extending over the circumference of the insertion section  2 . An insertion section-mounting surface  13  is disposed on the tip of the insertion section  2  so that an optical adapter (adapter)  12  having an object lens which is not shown in the drawing is detachably attached onto the surface  13 . 
     The optical adapter  12  is provided with an approximately columnar adapter main body  27  and an approximately cylindrical attachment hood section  23  as shown in  FIG. 32 . The adapter main body  27  is coaxially and rotatably coupled to the attachment hood section  23 . 
     Provided onto the side wall section of the adapter main body  27  is a lighting section  11  having, for example, LEDs. Provided on a bottom surface section  27   a  of the adapter main body  27  is an adapter electrode section  18  connected to the lighting section  11  through a cable  21  shown in  FIG. 33 . Highly conductive plating or painting is applied to the surface of the adapter electrode section  18  made of nonferrous metals or ferrous metals, e.g., iron. The adapter electrode section  18  is also provided with protrusion electrode sections  28  projecting from the bottom surface section  27   a  outward in the longitudinal direction of the optical adapter  12 . Provided around the adapter electrode section  18  is an insulative member  22 . 
     A first female thread section  25  and a second female screw section  126  are cut fully on the inner periphery of the attachment hood section  23  so that a predetermined interval is disposed between the screw sections. 
     Inserting the tip of the insertion section  2  from the rear end of the optical adapter  12  and rotating the attachment hood section  23  screw first the male thread section  17  into the first female thread section  25 . Rotating further the attachment hood section  23  screws the male thread section  17  into the second female screw section  126  across the first female thread section  25 , thereby causing the optical adapter  12  to be detachably coupled to the mounting surface  13 . That is, the first female thread section  25  works as a retainer restraining the optical adapter  12  from removing from the insertion section  2 . 
     Provided on the mounting surface  13  of the insertion section  2  in the present embodiment as shown in  FIG. 34  are two recesses  131  each accommodating thereinside an insertion section electrode section  32  having a bottom section and a cylinder section. To be more specific, in a recess  131  formed by a side wall section  31   a  and a bottom surface section  31   b  as shown in  FIG. 35 , an end surface section  32   a  of the insertion section electrode section  32  is disposed to be flush with the bottom surface section  31   b . The insertion section electrode section  32  is therefore disposed recessed relative to the mounting surface  13  toward the insertion section  2 . 
     Also, highly conductive plating or painting is applied to the surface of the insertion section electrode section  32  made of nonferrous metals or ferrous metals, e.g., iron. The insertion section electrode section  32  is further connected to the power supply section  9  as shown in  FIG. 1  through the cable  21 . Attaching then the optical adapter  12  to the mounting surface  13  provides contact between the protrusion electrode section  28  and the end surface section  32   a  of the insertion section electrode section  32 , thereby providing electrical connection between the adapter electrode section  18  and the insertion section electrode section  32  and thus supplying electrical power from the power supply section  9  to the lighting section  11 . Provided around the insertion section electrode section  32  is an insulative member  33 . 
     The operation of the endoscope apparatus  1  thus configured in the present embodiment will be explained next. 
     A selected one of desirable optical adapter  12  is attached first to the mounting surface  13  of the insertion section  2  as explained previously. This electrically connects the adapter electrode section  18  to the insertion section electrode section  32 , thereby supplying electric power to the lighting section  11  from the power supply section  9 . The lighting section  11  of the insertion section  2  introduced into a object subject to inspection emits light. The light reflected by the object subject to inspection passes through object lenses in the optical adapter  12  and an image thereof is formed on a CCD  16 . 
     A signal output from the CCD  16  is supplied to a monitor  8  through a predetermined circuit. This provides an observed image exhibited on the monitor  8  used for a predetermined inspection of the object. The optical adapter  12  attached to the mounting surface  13  is detached and replaced by another optical adapter  12  required for inspecting another object. Another selected one of the optical adapter  12  is then attached to the mounting surface  13 . This is how the optical adapters  12  are exchanged. 
     The insertion section electrode section  32  accommodated in the recess  131  is surrounded by the side wall section  31   a  forming the recess  131  while the optical adapter  12  is in the detached state in the present embodiment. This conceals the insertion section electrode section  32  behind the mounting surface  13 . 
     As described above, the endoscope apparatus  1  according to the present embodiment advantageously prevents the appearance of the insertion section electrode section  32  from the mounting surface  13  with the optical adapter  12  detached. Accordingly, the insertion section electrode section  32  can be protected from short circuit, failure, and dust entry, thereby maintaining the insertion section electrode section  32  clean with the optical adapter  12  detached from the insertion section  2 . 
     The insertion section electrode section  32  having the bottom section, the cylinder section, and the end surface section  32   a  directed outward is effectively protected from dust entry. 
     Also, coupling the optical adapter  12  to the mounting surface  13  connects the end surface section  32   a  of the insertion section electrode section  32  to the tip of the protrusion electrode section  28 , thereby providing an interfacial contact between the insertion section electrode section  32  and the adapter electrode section  18 . The electrical conductivity between the insertion section electrode section  32  and the adapter electrode section  18  can be obtained in the case of lower component quality or lower assembly accuracy. 
     The highly conductive plating or painting provided onto the insertion section electrode section  32  and the adapter electrode section  18  lowers the electrical loss between the insertion section electrode section  32  and the adapter electrode section  18 . 
     Incidentally, the present embodiment is not limited to the configuration disclosing the protrusion electrode section  28  fixed to the adapter electrode section  18  and the end surface section  32   a  fixed to the insertion section electrode section  32 , i.e., at least one of them may be movable. 
     For example, the insertion section electrode section  32  as shown in  FIG. 36  may comprise a main body cylinder section  137  having a bottom section and a cylinder section; a spring  138  disposed in the main body cylinder section  137 ; and a columnar electrode terminal section  139  disposed to the tip of the spring  138  so as to be movable in the longitudinal direction of the main body cylinder section  137 . The tip of the main body cylinder section  137  is then disposed at the bottom surface section  31   b  forming the recess  131 . 
     Coupling the optical adapter  12  to the mounting surface  13  in this configuration inserts the protrusion electrode section  28  into the main body cylinder section  137  through the opening  41  disposed at the tip of the main body cylinder section  137 . The electrode terminal section  139  moves accordingly while resisting the thrust force exerted by the spring  138 . This facilitates the connection between the protrusion electrode section  28  and the end surface section  32   a , and the resilience of the spring  138  absorbs manufacturing error in the adapter electrode section  18  and the insertion section electrode section  32 , etc. Equalizing the outer diameter of the protrusion electrode section  28  to the inner diameter of the opening  41  provides the constant blockage of the interspace between the protrusion electrode section  28  and the opening  41  irrespective of the position of the protrusion electrode section  28  inserted into the insertion section electrode section  32 , thereby more effectively preventing dust entry. 
     Also, another configuration having only a spring  138  in the main body cylinder section  137 , i.e., without the electrode terminal section  139  may be practicable. Coupling the optical adapter  12  to the mounting surface  13  in this configuration inserts the protrusion electrode section  28  into the main body cylinder section  137  through the opening  41  disposed at the tip of the main body cylinder section  137 . The spring  138  contacting the tip of the protrusion electrode section  28  is then thrusted. This simple configuration facilitates the electrical connection between the protrusion electrode section  28  and the spring  138 . 
     The number of the recesses  131  and insertion section electrode sections  32  disposed in the present embodiment may be modified arbitrarily irrespective of the previously described disposition in which one recess  131  has one insertion section electrode section  32 . 
     For example, three or more insertion section electrode sections  32  may practicably be disposed. 
       FIG. 38  illustrates an example in which a recess  131  disposed on the mounting surface  13  has an insertion section electrode section  32 , and an insertion section electrode  32 ′ is disposed on a portion of the mounting surface  13  except the recess  131 . 
     Furthermore,  FIG. 41  practicably shows an example in which two insertion section electrodes  32   a  are disposed in a recess  131 . The simple and low cost configuration that can be shortly obtained facilitates cleaning inside the recess  131 . The number of insertion section electrode sections  32  disposed in the recess  131  in this case may not be limited to two, i.e., it can be arbitrarily modified. That is, a plurality of insertion section electrode sections  32  may be disposed in one common recess  131  formed on the mounting surface  13 ; and some of the insertion section electrode sections  32  may be separately disposed at a plurality of recesses  131 . Alternatively, some of the insertion section electrode sections  32  may be disposed in the recess  131 . 
     Also,  FIG. 40  practicably shows an example in which two recesses  131  each has a notch section  142 . 
     Furthermore,  FIG. 41  practicably shows an example in which two insertion section electrodes  32   a  are disposed in a recess  131 . The simple and low cost configuration that can be shortly obtained facilitates cleaning inside the recess  131 . The number of insertion section electrodes  32  disposed in the recess  131  in this case may not be limited to two, i.e., it can be arbitrarily modified. That is, a plurality of insertion section electrodes  32  may be disposed in one common recess  131  formed on the mounting surface  13 ; and some of the insertion section electrodes  32  may be separately disposed at a plurality of recesses  131 . Alternatively, some of the insertion section electrodes  32  may be disposed in the recess  131 . 
     Also,  FIG. 42  practicably shows an example in which the recess  131  accommodates a plurality of insertion section electrode sections  32  and has a notch section  142 . 
     (Embodiment 6) 
     A sixth embodiment of the present invention will be next explained. 
       FIGS. 33 to 44  illustrate the sixth embodiment of the present invention. 
     The same reference numerals are added to the elements illustrated in  FIGS. 43 and 44  that are the same as those illustrated in  FIGS. 1 to 31  so as to omit duplicate explanation. 
     The fundamental configuration of the present embodiment is the same as that of the fifth embodiment; only the differences will be hereafter explained. 
     A side wall section  31   a  of the recess  131  is configured to incline so as to gradually expand in a radial direction outward relative to the recess  131 . In other words, the side wall section  31   a  is a tapered section (recess section&#39;s tapered section)  143 . The inclination of the tapered section  143  prevents dusts from entering the recess  131  and sticking thereto. 
     The configuration described above prevents dusts from clogging in the vicinity of the insertion section electrode section  32 , thereby improving the workability in cleaning inside the recess  131 . 
     (Embodiment 7) 
     A seventh embodiment of the present invention will be next explained. 
       FIGS. 45 and 46  illustrate the seventh embodiment of the present invention. 
     An end surface section  32   a  of the insertion section electrode section  32  projects more frontward relative to a bottom surface section  31   b  of the recess  131  in the present embodiment. That is, a groove (groove in a recess)  46  extends around and in the vicinity of the circumference of the insertion section electrode section  32 . 
     If dust has entered the recess  131 , it would access the groove  46  in this configuration. Therefore, dust accumulates in the groove  46  instead of clogging in the insertion section electrode section  32 . 
     As described above, poor electrical contact due to dust accumulating on the insertion section electrode section  32  can be prevented. 
     The present invention is not limited to the configuration in which the groove  46  extending over the circumference of the insertion section electrode section  32  is disposed, that is, the groove  46  may be arbitrarily modified with respect to its size and position. 
       FIGS. 47 and 48  show an example in which a groove  46  is disposed along the length of the notch section. 
     (Embodiment 8) 
     An eighth embodiment of the present invention will be next explained. 
       FIGS. 49 and 50  illustrate the eighth embodiment of the present invention. 
     Provided onto the mounting surface  13  according to the present embodiment shown in  FIG. 49  are projecting sections  147  projecting from the mounting surface  13  along an axial line of the insertion section  2 . The projecting sections  147  are cylindrical in shape. To be more specific, provided in the center of the projecting sections  147  is a hollow section  148  projecting in the same direction as that of the projecting sections  147 . Provided in the hollow section  148  is an insertion section electrode section  32 . The end surface section  32   a  of the insertion section electrode section  32  is configured to be flush with the mounting surface  13 , thus the insertion section electrode section  32  is located more frontward, i.e., closer to the mounting surface  13  relative to the tip of the projecting sections  147 . 
     As shown in  FIG. 50 , provided on the bottom surface section  27   a  of the optical adapter  12  is an adapter-recessing section  51  accommodating a protrusion electrode section  28 . 
     Coupling the optical adapter  12  to the mounting surface  13  in this configuration disposes the projecting sections  147  into the adapter-recessing section  51 , thereby contacting the protrusion electrode section  28  to the end surface section  32   a  of the insertion section electrode section  32  through the hollow section  148 . This configuration allows the adapter electrode section  18  to be electrically connected to the insertion section electrode section  32 . Since the insertion section electrode section  32  accommodated in the hollow section  148  is surrounded by the projecting sections  147 , and the insertion section electrode section  32  is disposed closer to the mounting surface  13  relative to the tip of the projecting sections  147 , this conceals the insertion section electrode  32  behind the mounting surface  13 . 
     As described above, the endoscope apparatus  1  according to the present embodiment advantageously prevents the appearance of the insertion section electrode section  32  from the mounting surface  13  with the optical adapter  12  detached. The present embodiment can exhibit substantially the same effect as that of the previously described fifth embodiment. 
     The number of adapter-recessing sections  51  in the present embodiment may be modified arbitrarily irrespective of one piece of the adapter-recessing section  51  previously described. 
     The number of projecting sections  147  and insertion section electrode sections  32  disposed in the present embodiment may be modified arbitrarily irrespective of the previously described disposition in which one projecting section  147  has one insertion section electrode section  32 . 
     For example, three or more insertion section electrode sections  32  may practicably be disposed. 
       FIG. 51  furthermore illustrates an example in which a projecting section  147  disposed on the mounting surface  13  has an insertion section electrode section  32  in its hollow section  148 , and an insertion section electrode  32 ′ is disposed on a portion of the mounting surface  13  except the hollow section  148 . 
     Furthermore,  FIG. 52  shows an example in which a projecting section  147  has a notch (notched recess)  152  formed by cutting a portion of the projecting sections  147 . If dust has entered the hollow section  148 , it would be discharged from the notch section  152  without difficulty. This prevents dust from clogging in the hollow section  148 , thereby improving the workability in cleaning inside the recess  148 . 
     Also,  FIG. 53  practicably shows an example in which two projecting sections  147  each has a notch section  152 . 
     Furthermore,  FIG. 54  practicably shows an example in which two insertion section electrode sections  32  are disposed in a projecting section  147 . The simple and low cost configuration that can be shortly obtained facilitates cleaning inside the hollow section  148 . The number of insertion section electrode sections  32  disposed in the hollow section  148  in this case may not be limited to two, i.e., it can be arbitrarily modified. That is, a plurality of insertion section electrode sections  32  may be disposed in one common hollow section  148  formed on the mounting surface  13 ; and some of the insertion section electrode sections  32  may be separately disposed at a plurality of hollow sections  148 . Alternatively, some of the insertion section electrode sections  32  may be disposed in the hollow section  148 . 
     Also,  FIG. 55  practicably shows an example in which a hollow section  148  accommodates a plurality of insertion section electrode sections  32  and has a notch section  152  in the projecting sections  147 . 
     Furthermore, a configuration free of a hollow section  148  may be desirable. To be more specific, projecting sections (projecting sections)  153  projecting in manner of a rectangular parallelepiped shape may be provided between (in the vicinity of) the insertion section electrode sections  32  as shown in  FIG. 56 . Detaching the optical adapter  12  conceals a part of the insertion section electrode  32  behind the mounting surface  13  because the rectangular parallelepiped protrusion section  153  is disposed in the vicinity of the insertion section electrode sections  32 . Accordingly, the simple configuration according to the present embodiment provides an effect similar to that of the previously described fifth embodiment. 
     In addition, a tapered section (tapered section used for projecting sections) similar to the above configuration and grooves (projecting sections used with a groove), etc., may be provided in the vicinity of the insertion section electrode section  32  in the present embodiment in which the insertion section electrode sections  32  are disposed on the mounting surface  13 . 
     The adapter electrode section  18  according to the above fifth to eighth embodiments is not limited to be connected to the lighting section  11 . This may rather be connected to other sensors and electronic components, e.g., adapter recognition sensors and temperature/humidity sensors. 
     It is in addition understood that the present invention is not limited to the optical adapter  12  of a lateral view type having the lighting section  11  on a side wall section. The lighting section  11  may rather be of a direct view type provided onto the tip of the optical adapter  12 . 
     The insulative member  33  disposed on surfaces of the adapter electrode section  18  and the insertion section electrode section  32  may be anodized instead. Alternatively, the component of the insertion section  2  itself may be of an insulative material, and it may be subjected to an insulation process. This eliminates the necessity of the insulative member  33  covering the adapter electrode section  18  and the insertion section electrode section  32 . 
     The present invention is not limited to the first to fourth embodiments, and various modifications may be made without departing from the spirit of the present invention. 
     The present invention prevents the generation of an interspace between the inner wall of the opening section and the exterior wall of the electrode terminal with the endoscope adapter attached to the endoscopic insertion section, thereby providing a blockage to the opening section in the attached state of the endoscope adapter without expanding the endoscope adapter and the endoscopic insertion section in size, thus maintaining cleanliness of the electrode terminal in the long term. 
     Short circuit, failure, and dust entry in the insertion section electrode can be prevented according to the present invention because the insertion section electrode is prevented from projecting from the attaching surface; therefore, the cleanliness of the insertion section electrode can be maintained in the detached state of the adapter from the endoscopic insertion section. 
     The present invention is effective for use not only in electrical connection to the lighting section but also electrical contacts of sensors and motors, etc. The present invention is also effective for use in electrical contacts of apparatuses subject to electrical connection with respect to optional retrofit requirement.