Abstract:
The present invention aims to provide an endoscope and its manufacturing method enabling to reduce a diameter of the endoscope required to have airtightness and facilitate a connecting work between a cable and a connector. A first tube body and a second tube body constituting an airtight container are relatively moved to extend and contract, so that it is possible to extend cables from a proximal end part of the second tube body by contracting the container, thereby enabling a connecting work between the cables and an airtight connector. After the completion of connecting work between the cables and the airtight connector, it is possible to store an extra length of the cables in the second tube body as well as to allow the airtight connector to engage with the proximal end part of the second tube body by extending the first tube body and the second tube body.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The patent application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2013-204750, filed on Sep. 30, 2013. Each of the above application(s) is hereby expressly incorporated by reference, in its entirety, into the present application. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an endoscope and a method for manufacturing an endoscope, and more particularly to an endoscope and a method for manufacturing an endoscope for which high airtightness is required. 
         [0004]    2. Description of the Related Art 
         [0005]    An endoscope used for surgery or endoscopy requires sterilization treatment to prevent infection among patients. In recent years, a sterilization method, with which an endoscope is put in a high pressure steam sterilizer such as an autoclave to be sterilized by high pressure steam, is gradually becoming the mainstream. 
         [0006]    Conventionally, there is proposed a technique for forming a distal end of an endoscope, in which an optical unit and an imaging device unit are stored, so that the distal end has an airtight structure that can cope with the autoclave (Japanese Patent Application Laid-Open No. 2002-301016). 
         [0007]    An endoscope described in Japanese Patent Application Laid-Open No. 2002-301016 includes a lens unit and a solid imaging element, which are provided in a pipe-shaped element frame as shown in FIG. 2 in Japanese Patent Application Laid-Open No. 2002-301016. A lens on the tip of the lens unit is fixed to a distal end part of the element frame in an airtight manner, and a connector is fixed to a proximal end part of the element frame in an airtight manner, thereby allowing the element frame to have an airtight structure. The solid imaging element is electrically connected to a hybrid IC (hybrid integrated circuit) through an element lead pin, and the hybrid IC is fixed to the connector through a connection terminal. That is, the solid imaging element is fixed to the connector through the hybrid IC. 
         [0008]    An endoscope of another embodiment shown in FIG. 13 in Japanese Patent Application Laid-Open No. 2002-301016 includes two bodies of a first element frame in which a lens unit is provided and a second element frame in which a solid imaging element is provided. The first element frame and the second element frame are joined with each other by metal joining or the like in an airtight manner. 
         [0009]    The first element frame and the second element frame are relatively movable in an axial direction, so that it is possible to perform focus adjustment by changing relative positions of the first element frame and the second element frame before the joining. 
       SUMMARY OF THE INVENTION 
       [0010]    In the endoscope described in Japanese Patent Application Laid-Open No. 2002-301016, the solid imaging element is connected to the connector through the element lead pin and the hybrid IC, and has a structure in which cables are not arranged between the solid imaging element (or the hybrid IC) and the connector. Thus, a connecting work between cables that connect the hybrid IC and the connector is unnecessary; however, the invention described in Japanese Patent Application Laid-Open No. 2002-301016 is not applicable to an endoscope of a type in which a hybrid IC is connected to a connector by cables. 
         [0011]    Furthermore, in the invention described in Japanese Patent Application Laid-Open No. 2002-301016, since the solid imaging element is connected to the connector through the element lead pin and the hybrid IC, the solid imaging element and the connector are fixed to the element frame so as to be parallel to each other. Thus, the solid imaging element to be applied to the endoscope described in Japanese Patent Application Laid-Open No. 2002-301016 is limited to a longitudinally mounted solid imaging element that is provided in a direction orthogonal to a longitudinal direction of the element frame (endoscope). Therefore, the invention described in Japanese Patent Application Laid-Open No. 2002-301016 has a problem that it is not applicable to a transversely mounted imaging device which is advantageous for reducing a diameter of an endoscope. 
         [0012]    The present invention has been made in light of the above-mentioned circumstances, and the present invention aims to provide an endoscope and a method for manufacturing an endoscope capable of reducing a diameter of the endoscope required to have airtightness and facilitating a connecting work for connecting cables to a connector. 
         [0013]    In order to achieve the object above, an endoscope according to one aspect of the present invention includes: a first tube body that is provided with an optical window joined to a distal end thereof in an airtight manner, and that stores an optical unit and an imaging device unit; a second tube body that is movable by sliding on an inner circumferential surface or an outer circumferential surface of the first tube body; and an airtight connector that is joined to a proximal end part of the second tube body in an airtight manner, and that is connected to cables extending from the imaging device unit, wherein the first tube body and the second tube body are joined together in an airtight manner at least after the cables and the airtight connector are connected. 
         [0014]    According to one aspect of the present invention, the first tube body and the second tube body constituting an airtight container can extend and contract by relatively moving to each other. When the first tube body and the second tube body are relatively moved so that a length from the distal end of the first tube body to the proximal end part of the second tube body is shortened, it is possible to extend the cables from proximal end part of the second tube body, thereby enabling a connecting work for connecting the cables and the airtight connector. After the connecting work for connecting the cables and the airtight connector is finished, it is possible to store an extra length of the cables in the second tube body by relatively moving the first tube body and the second tube body so that the length from the distal end of the first tube body to the proximal end part of the second tube body is increased, as well as to allow the airtight connector to engage with the proximal end part of the second tube body. The optical window to be joined to the distal end of the first tube body in an airtight manner is not limited to a transparent parallel flat plate, but a plate serving as a lens is available. 
         [0015]    In an endoscope according to another aspect of the present invention, it is preferable that the cables have a length corresponding to a distance from the imaging device unit to the airtight connector. Accordingly, it is possible to minimize inner diameters of the first and second tube bodies for allowing the cables to be stored in the tube bodies, so that a diameter of the endoscope can be reduced. 
         [0016]    In an endoscope according to yet another aspect of the present invention, it is preferable that one of the first tube body and the second tube body has a fitting part in which the other of the first tube body and the second tube body is fitted with a fixed gap, and the fitting part has a length in which an extra length of the cables is adjustable. Accordingly, in a case where the extra length of the cables is stored in the second tube body by relatively moving the first tube body and the second tube body so that length from the distal end of the first tube body to the proximal end part of the second tube body is increased after the connecting work between the cables and the airtight connector is finished, even if there are variations in the extra length of the cables, it is possible to join the first and second tube bodies with the fitting part having the fixed gap at the time of joining a part between the first and second tube bodies in an airtight manner, because an end part of the first tube body or the second tube body is brought into contact with an inner circumferential surface or an outer circumferential surface the other tube body within a range of the length of the fitting part. If the length of the fitting part is so long that resistance at the time of sliding is increased, it is impossible to smoothly perform extension and contraction movement of the first tube body and the second tube body. Thus, the fitting part cannot have a length longer than a length in which the extension and contraction movement of the first tube body and the second tube body can be smoothly performed. 
         [0017]    In an endoscope according to yet another aspect of the present invention, it is preferable that the airtight connector includes a plurality of pins penetrating through a connector body in an airtight manner, and that the cable and the airtight connector are electrically connected through pipe-shaped conductive members in which the pins are fitted, that is, one end of each of the cables is inserted into one end of each of the pipe-shaped conductive members to be fixed, and each of the pins of the airtight connector is inserted into the other end of each of the conductive members, whereby it is possible to easily connect the cables to the airtight connector. 
         [0018]    In an endoscope according to yet another aspect of the present invention, it is preferable that a maximum movement amount by which the first tube body and the second tube body are relatively movable is twice or more as large as a length from the airtight connector to an end part of each of the conductive members connected to the airtight connector on a side connected to each of the cables, in order to secure flexibility of the conductive members when each of the pins of the airtight connector is inserted into each of the pipe-shaped conductive members is inserted. 
         [0019]    In an endoscope according to yet another aspect of the present invention, it is preferable that the optical unit includes a folded optical system, and the imaging device unit is arranged to be parallel to a longitudinal direction of the first tube body. For the imaging device unit, a transversely mounted type arranged to be parallel the longitudinal direction of the first tube body is used so that the diameter of the endoscope can be reduced as compared with a longitudinally mounted type. 
         [0020]    In an endoscope according to yet another aspect of the present invention, it is preferable that the first tube body includes a third tube body that is provided with the optical window fixed to a distal end thereof in an airtight manner, and that stores the optical unit and the imaging device unit; and a fourth tube body that is joined to the third tube body in an airtight manner. Thus, it is possible to shorten the length of the third tube body that stores the optical unit and the imaging device unit by dividing the first tube body into two tube bodies of the third tube body and the fourth tube body. Accordingly, an operation of providing the optical unit and the imaging device unit in the third tube body is facilitated. In addition, the fourth tube body is joined to the third tube body so that a movement amount by which the fourth tube body and the second tube body can be relatively moved can be secured in a part between the fourth tube body and the second tube body. 
         [0021]    A method for manufacturing an endoscope according to yet another aspect of the present invention includes: preparing a first tube body storing an optical unit and an imaging device unit, a second tube body movable by sliding on an inner circumferential surface or an outer circumferential surface of the first tube body, and an airtight connector to which cables extending from the imaging device unit are connected; extending the cables from a proximal end part of the second tube body by relatively moving the first tube body and the second tube body so that a length from a distal end of the first tube body to the proximal end part of the second tube body is shortened; electrically connecting the cables extending from the proximal end part of the second tube body and the airtight connector; engaging the airtight connector with the proximal end part of the second tube body by relatively moving the first tube body and the second tube body so that the length from the distal end of the first tube body to the proximal end part of the second tube body is increased after the cables and the airtight connector are connected; joining the optical window to the distal end of the first tube body in an airtight manner; joining the first tube body and the second tube body in an airtight manner; and joining the proximal end part of the second tube body and the airtight connector in an airtight manner. 
         [0022]    Although it is possible to perform joining operations of joining the optical window to the distal end of the first tube body in an airtight manner, joining the first tube body and the second tube body in an airtight manner, and joining the proximal end part of the second tube body and the airtight connector in an airtight manner in any order and timing, it is necessary that the joining the first tube body and the second tube body in an airtight manner, and joining the proximal end part of the second tube body and the airtight connector in an airtight manner, are performed at least after the cables and the airtight connector are connected. 
         [0023]    In a method for manufacturing an endoscope according to yet another aspect of the present invention, it is preferable that after the cables and the airtight connector are connected, the first tube body and the second tube body are relatively moved so that the length from the distal end of the first tube body to the proximal end part of the second tube body is increased, and the airtight connector is joined to the proximal end part of the second tube body, and that the cables have a length corresponding to a distance from the imaging device unit to the airtight connector at a time when the airtight connector is joined to the proximal end part of the second tube body. 
         [0024]    In a method for manufacturing an endoscope according to yet another aspect of the present invention, it is preferable that the airtight connector includes a plurality of pins penetrating through a connector body in an airtight manner, and that, in the step of electrically connecting the cables and the airtight connector, the cables and the airtight connector are electrically connected through pipe-shaped conductive members in which the pins are fitted. 
         [0025]    In a method for manufacturing an endoscope according to yet another aspect of the present invention, it is preferable that a maximum movement amount by which the first tube body and the second tube body are relatively movable is twice or more as large as a length of a rigid part of the pins of the airtight connector and the conductive members. 
         [0026]    In a method for manufacturing an endoscope according to yet another aspect of the present invention, it is preferable that the first tube body includes a third tube body and a fourth tube body, and that the method further includes: storing the optical unit and the imaging device unit in the third tube body; fitting the fourth tube body in the third tube body; and joining the third tube body and the fourth tube body in an airtight manner. 
         [0027]    According to the present invention, since the first tube body storing the optical unit and the imaging device unit and the subsequent second tube body are configured to be relatively movable (extendable), it is possible to extend the cables from the proximal end part of the second tube body by relatively moving the first tube body and the second tube body so that the length from the distal end of the first tube body to the proximal end part of the second tube body is shortened, thereby enabling the connecting work between the cables and the airtight connector to be facilitated. In addition, it is possible to store an extra length of the cables in the second tube body by relatively moving the first tube body and the second tube body so that the length from the distal end of the first tube body to the proximal end part of the second tube body is increased after the connecting work between the cable and the airtight connector is completed, whereby it is possible to minimize a space for storing the cables so that a diameter of the endoscope can be reduced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is a whole configuration diagram showing a first embodiment of the endoscope according to the present invention; 
           [0029]      FIG. 2  is an external view of a distal end rigid part of the endoscope shown in  FIG. 1  showing a contracted state; 
           [0030]      FIG. 3  is an external view of the distal end rigid part of the endoscope shown in  FIG. 1  showing an extended state; 
           [0031]      FIG. 4  is a cross-sectional view of an enlarged main section of the distal end rigid part of the endoscope shown in  FIG. 2 ; 
           [0032]      FIG. 5  is a cross-sectional view of an enlarged main section of the distal end rigid part of the endoscope shown in  FIG. 3 ; 
           [0033]      FIG. 6  is a front view of the airtight connector; 
           [0034]      FIG. 7  is a cross-sectional view of the airtight connector shown in  FIG. 6  taken along the line  7 - 7 ; 
           [0035]      FIG. 8  is a perspective view showing a state in which the cables and the airtight connector are connected; 
           [0036]      FIGS. 9A ,  9 B,  9 C, and  9 D show a procedure of connecting the cable and the airtight connector; 
           [0037]      FIG. 10  is an external view showing a second embodiment of the endoscope according to the present invention in a state in which the distal end rigid part of an insertion section of the endoscope is contracted; 
           [0038]      FIG. 11  is an external view showing a second embodiment of the endoscope according to the present invention in a state in which the distal end rigid part of the insertion section of the endoscope is extended; 
           [0039]      FIG. 12  is a cross-sectional view of an enlarged main section of the distal end rigid part of the endoscope shown in  FIG. 10 ; and 
           [0040]      FIG. 13  is a cross-sectional view of an enlarged main section of the distal end rigid part of the endoscope shown in  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0041]    Referring to accompanying drawings, preferable embodiments of the endoscope and the method for manufacturing an endoscope according to the present invention will be described. 
       First Embodiment 
       [0042]      FIG. 1  is a whole configuration diagram showing a first embodiment of the endoscope according to the present invention. 
         [0043]    An endoscope  10  shown in  FIG. 1  is an electronic endoscope applied to surgery, and includes an insertion section  12  to be inserted in a body cavity of a patient, and an operation section  14  to be held by a surgeon. The insertion section  12  includes a distal end rigid part  16 - 1  that stores an optical unit, an imaging device unit, and the like, which will be described. The distal end rigid part  16 - 1  is provided inside an exterior case of the insertion section  12 . 
         [0044]    A universal cable  18  is connected to the operation section  14 , and a light guide (LG) connector  20  is provided at a tip of the universal cable  18 . The LG connector  20  is detachably coupled to a light source device (not shown). Accordingly, illumination light is emitted from the light source device to the distal end of the insertion section  12  through a light guide (not shown) in the endoscope  10  so that it is possible to illuminate the inside of the body cavity. Furthermore, a video connector  22  is connected to the LG connector  20 , and the video connector  22  is detachably coupled to a processor (not shown) for performing image processing and the like. 
         [0045]      FIGS. 2 and 3  are external views of the distal end rigid part  16 - 1  of the endoscope  10  showing a state in which the distal end rigid part  16 - 1  is contracted and a state in which the distal end rigid part  16 - 1  is extended, respectively. 
         [0046]      FIGS. 4 and 5  are cross-sectional views showing enlarged main sections of the distal end rigid part  16 - 1  shown in  FIGS. 2 and 3 , respectively. 
         [0047]    As shown in  FIGS. 2 to 5 , the distal end rigid part  16 - 1  is mainly composed of a first tube body  110  that stores an optical unit  140  and an imaging device unit  150 , a second tube body  120  that is joined to the first tube body  110 , and an airtight connector  130 . 
         [0048]    The first tube body  110  and the second tube body  120  are main members constituting an airtight container, and each of the first tube body  110  and the second tube body  120  is a metal tube made of stainless steel (SUS). The tube bodies can be formed of kovar (trademark), titanium or the like, instead of the SUS. 
         [0049]    A slide part  122  (a part in which a diameter of an outer circumferential surface thereof is smaller than a diameter of an outer circumferential surface of a part other than the slide part  122 ) is formed in a distal end side of the second tube body  120 , so that the outer circumferential surface of the slide part  122  is slidably fitted into an inner circumferential surface of the first tube body  110 . Accordingly, the first tube body  110  and the second tube body  120  can be extended and contracted by relatively moving to each other, that is, the first tube body  110  and the second tube body  120  form a telescopic structure such as a telescope. 
         [0050]    In the first tube body  110 , the optical unit  140  and the imaging device unit  150  are stored, and fixed to the inside of the first tube body  110 . The optical unit  140  includes an objective lens  142  and a prism (folded optical system)  143 . The imaging device unit  150  includes an imaging element  152  such as a charge coupled device (CCD), a complementary metal oxide semiconductor (CMOS), and the like, and a circuit board  154  on which the imaging element  152 , a driving circuit component, an integrated circuit component, and the like are mounted. 
         [0051]    A picture imaged by the objective lens  142  is imaged on a light receiving surface of the imaging element  152  through the prism  143 , and then is converted into an electric signal. The optical unit  140  including the prism  143  is used as above so that a transversely mounted type of an imaging device unit, which can be arranged parallel to a longitudinal direction (an optical axis direction of the objective lens  142 ) of the first tube body  110 , is used for the imaging device unit  150 . The transversely mounted type is advantageous for reducing a diameter of the endoscope  10  as compared with a longitudinally mounted type. 
         [0052]    In the distal end of the first tube body  110 , the optical window  144  is joined in an airtight manner. The optical window  144  is a parallel flat plate formed of transparent sapphire, quartz, and the like, and a metal film is evaporated (metalized) onto a surface of the optical window to secure a joining property, and is joined to the distal end of the first tube body  110  by soldering in an airtight manner. In the present embodiment, although the optical window  144  is a transparent parallel flat plate, a part of a lens included in the optical unit  140  may be used. 
         [0053]    The other ends of the cables (seventeen cables in the present embodiment)  160  wired to the imaging device unit  150  (the circuit board  154 ) are connected to the airtight connector  130  attached to a proximal end part of the second tube body  120 . 
         [0054]    It is preferable that a connecting work between the cables  160  and the airtight connector  130  is performed in a state in which the first tube body  110  and the second tube body  120  are most contracted. Thus, it is possible to increase an extra length of the cables  160  extending outside from the proximal end of the second tube body  120  by relatively moving the first tube body  110  and the second tube body  120  so that a length (overall length) from the distal end of the first tube body  110  to the proximal end of the second tube body  120  is most shortened. Accordingly, flexibility of the cables  160  at the time of the connecting work is secured to enable the connecting work. 
         [0055]      FIG. 6  is a front view of the airtight connector  130 , and  FIG. 7  is a sectional view of the airtight connector  130  shown in  FIG. 6  taken along the line  7 - 7 . 
         [0056]    As shown in  FIGS. 6 and 7 , the airtight connector  130  is composed of: a connector body (base)  130   b  made of kovar, in which through-holes  130   a  are formed; pins  132  made of kovar arranged in the through-holes  130   a ; and sealing glass  134  made of borosilicate glass or the like, which fixes the base  130   b  and the pins  132  in a mutually insulted manner. The structure enables the airtight connector  130  to maintain airtightness between the base  130   b  and the pins  132 . 
         [0057]    The base  130   b  of the airtight connector  130  is formed into a shape to be inserted and fitted in the proximal end part of the second tube body  120 , and has a flange part  130   c  that is brought into contact with an end face of the proximal end part of the second tube body  120 . 
         [0058]    The base  130   b  can be formed of borosilicate glass or the like other than the kovar, and the pins  132  can be formed of copper, brass, or the like other than the kovar. In addition, the sealing glass  134  can be formed of ceramic-based sealant or the like other than the borosilicate glass. A raw material and a structure of the airtight connector  130  are not limited to the embodiment above, so that various materials and structures are applicable. 
         [0059]    [Connecting Method of Cables and Airtight Connector] 
         [0060]    Next, a connecting method of the cables  160  and the airtight connector  130  will be described. 
         [0061]      FIG. 8  is a perspective view showing a state in which the cables  160  and the airtight connector  130  are connected. 
         [0062]    As shown in  FIG. 8 , the cables  160  and the airtight connector  130  are electrically connected through pipe-shaped conductive members  170 . 
         [0063]      FIGS. 9A ,  9 B,  9 C, and  9 D show a procedure of connecting the cable  160  and the airtight connector  130  by using the pipe-shaped conductive member  170 . 
         [0064]    As shown in  FIG. 9A , first the pipe-shaped conductive member  170  is prepared. 
         [0065]    Next, the inside of one end of the conductive member  170  is filled with conductive adhesive  172 , and then a core wire of the cable  160  is inserted into the inside of the conductive member  170  ( FIG. 9B ). The conductive adhesive  172  is cured at a room temperature for about 24 hours to connect and fix the core wire to the inside of the conductive member  170 . 
         [0066]    Subsequently, the inside of the other end of the conductive member  170  to which the cable  160  is connected and fixed is filled with the conductive adhesive  172 , and then the conductive member  170  is moved so that the pin  132  is inserted into the other end of the conductive member  170  ( FIGS. 9B ,  9 C, and  9 D). 
         [0067]    Finally, the conductive adhesive  172  is cured at the room temperature for about 24 hours to connect and fix the pin  132  to the inside of the conductive member  170  ( FIG. 9D ). As the conductive adhesive  172 , Aremco-Bond 525 (trademark) (a heat-resistant temperature of 170° C.) and Aremco-Bond 556 (a heat-resistant temperature of 170° C.), (made by Aremco Products Inc.). Duralco 120 (trademark) (a heat-resistant temperature of 260° C.) (made by Cotronics Corp.), and the like, are available. 
         [0068]    Using the conductive adhesive  172  having a high heat-resistance (a heat-resistant temperature of 130° C. or more) enables adhesion to be maintained even in a high temperature environment, thereby making the endoscope  10  applicable to a high pressure and high temperature steam sterilizer (autoclave). 
         [0069]      FIGS. 2 and 4  show a state in which the connecting work between the cables  160  and the airtight connector  130  has been performed in a manner as described above. A part of the cables  160  in the state is extended from the proximal end part of the second tube body  120  by a predetermined amount (corresponding to a maximum movement amount by which the first tube body  110  and the second tube body  120  are relatively movable). 
         [0070]    From the state, the first tube body  110  and the second tube body  120  are relatively moved so that a length from the distal end of the first tube body  110  to the proximal end part of the second tube body  120  is increased, whereby the airtight connector  130  is fitted to the proximal end part of the second tube body  120  as shown in  FIGS. 3 and 5 . 
         [0071]    Subsequently, as shown in  FIG. 5 , a fitting part A between the optical window  144  provided with a surface on which a metal film is evaporated and the distal end of the first tube body  110  is sealed by soldering. 
         [0072]    Next, the first tube body  110  and the second tube body  120  are joined in an airtight manner. In the embodiment, a fitting part B (whole circumference of a proximal end part of the first tube body  110 ) in which the first tube body  110  and the second tube body  120  are fitted is sealed by laser welding. 
         [0073]    Finally, the proximal end part of the second tube body  120  and the airtight connector  130  are joined in an airtight manner. In the embodiment, a fitting part C (whole circumference of the proximal end part of the second tube body  120 ) in which the proximal end part of the second tube body  120  and the airtight connector  130  are fitted is sealed by laser welding. 
         [0074]    Accordingly, it is possible to maintain airtightness of the inside of the distal end rigid part  16 - 1  (the first tube body  110  and the second tube body  120 ) storing the optical unit  140  and the imaging device unit  150 , and the endoscope  10  provided with the distal end rigid part  16 - 1  can cope with autoclave sterilization. The fitting parts may be sealed by not only the laser welding but another metal welding. 
         [0075]    Order of sealing operations in three fitting parts A, B, and C is not limited to the order described above. The sealing operation for the fitting part A between the optical window  144  and the distal end of the first tube body  110  may be performed before the connecting work between the cables  160  and the airtight connector  130 . 
         [0076]    According to the first embodiment of the present invention, as shown in  FIGS. 2 and 4 , the cables  160  are extended from the proximal end part of the second tube body  120  by relatively moving the first tube body  110  and the second tube body  120  so that the length from the distal end of the first tube body  110  to the proximal end part of the second tube body  120  is shortened, thereby enabling the connecting work between the cable  160  and the airtight connector  130 . 
         [0077]    As shown in  FIGS. 3 and 5 , after the connecting work is finished, the extra length of the cables  160  is stored in the second tube body  120  by relatively moving the first tube body  110  and the second tube body  120  so that the length from the distal end of the first tube body  110  to the proximal end part of the second tube body  120  is increased so that it is possible to wire the plurality of (seventeen cables in the present embodiment) cables  160  over a section from the imaging device unit  150  (circuit board  154 ) to the airtight connector  130  in a substantially linear (including a case of being bent) state, whereby it is possible to minimize an inner diameter (an inner diameter for storing the cables  160 ) of each of the first tube body  110  and the second tube body  120  so that a diameter of the endoscope  10  can be reduced. That is, the cables  160  are made to have a length corresponding to a distance from the imaging device unit  150  to the airtight connector  130  so that it is possible to wire the cables  160  over the section from the imaging device unit  150  to the airtight connector  130  in a substantially linear state. 
       Second Embodiment 
       [0078]      FIGS. 10 and 11  are external views showing a second embodiment of the endoscope according to the present invention in states in which the distal end rigid part  16 - 2  of an insertion section  12  of the endoscope  10  is contracted and that is extended, respectively. 
         [0079]      FIGS. 12 and 13  show enlarged main sections of the distal end rigid part  16 - 2  shown in  FIGS. 10 and 11 , respectively. In  FIGS. 10 to 13 , a part common to that in the distal end rigid part  16 - 1  shown in  FIGS. 2 to 5  is indicated by the same reference numeral, and a detailed description of the part is omitted. 
         [0080]    As shown in  FIGS. 10 to 13 , the distal end rigid part  16 - 2  is mainly composed of a first tube body  210 , a second tube body  220  that is joined to the first tube body  210 , and the airtight connector  130 . 
         [0081]    The first tube body  210  is composed of a third tube body  212 , and a fourth tube body  214  that is joined to the third tube body  212 . 
         [0082]    In the third tube body  212 , as shown in  FIGS. 12 and 13 , the optical unit  140  and the imaging device unit  150  are stored. The first tube body  210  is divided into the third tube body  212  and the fourth tube body  214 , and a length of the third tube body  212  is made shorter. This makes it possible to facilitate an operation of inserting the optical unit  140  and the imaging device unit  150  from a proximal end part side of the third tube body  212  and fastening them in the third tube body  212 . 
         [0083]    If the fourth tube body  214  is lengthened enough, it is possible to secure a movement amount in which the fourth tube body  214  and the second tube body  220  can be moved while relatively sliding them to each other. 
         [0084]    After the optical unit  140  and the imaging device unit  150  are inserted and fixed in the third tube body  212 , a distal end part of the fourth tube body  214  is fitted to the proximal end part of the third tube body  212  to constitute the first tube body  210 . The first tube body  210  corresponds to the first tube body  110  shown in  FIGS. 2 to 5 , and is longer than the first tube body  110 . 
         [0085]    The second tube body  220  includes a sliding part  222  as shown in  FIGS. 11 and 13 . The sliding part  222  has a fitting part  222 A that is slidably fitted in an inner circumferential surface of the fourth tube body  214  with a fixed gap, and a reduced diameter part  222 B having an outer diameter slightly smaller than that of the fitting part  222 A. The second tube body  220  having the sliding part  222  is capable of moving (sliding) inside the fourth tube body  214  within a range of a maximum movement amount LB shown in  FIG. 11 . 
         [0086]    It is required that a length L A  of the fitting part  222 A is set at an appropriate length. 
         [0087]    If the length L A  of the fitting part  222 A is too long, sliding resistance increases to make the movement difficult. On the other hand, if the length L A  of the fitting part  222 A is too short, as shown in  FIG. 13 , when the second tube body  220  is moved so that the second tube body  220  and the airtight connector  130  are fitted to each other, a proximal end part of the first tube body  210  (fourth tube body  214 ) and the reduced diameter part  222 B of the second tube body  220  are overlapped with each other. As a result, a gap occurs between the inner circumferential surface of the proximal end part of the fourth tube body  214  and an outer circumferential surface of the reduced diameter part  222 B. The gap is obstruction when laser welding is performed on the proximal end part of the first tube body  210  and a distal end part of the second tube body  220 . 
         [0088]    The movement amount La of the second tube body  220  varies as shown in  FIGS. 10 and 11  due to a variation and the like of the extra length of the cables  160  extended from the proximal end part of the second tube body  220  as shown in  FIG. 10 . The length L A  of the fitting part  222 A is secured to allow the fitting part  222 A of the second tube body  220  to be fitted at a position of an end face of the proximal end part of the first tube body  210  even in the case above. That is, it is preferable that the length L A  of the fitting part  222 A is shorter than a length in which movement is difficult due to sliding resistance as well as is a length in which the extra length of the cables  160  is adjustable. 
         [0089]    As shown in  FIG. 10 , the distal end rigid part  16 - 2  of the present embodiment is capable of exposing the cables  160  with a length enough for the connecting work between the cables  160  and the airtight connector  130  by moving the second tube body  220  so that the sliding part  222  ( FIG. 11 ) of the second tube body  220  is stored in the first tube body  210  (fourth tube body  214 ). 
         [0090]    As illustrated in  FIG. 9 , a core wire of one end of the exposed cable  160  and the pin  132  of the airtight connector  130  are electrically connected through the pipe-shaped conductive member  170  ( FIG. 12 ). 
         [0091]    It is preferable that the maximum movement amount LB in which the first tube body  210  (fourth tube body  214 ) and the second tube body  220  are relatively movable is twice or more a length (a length of the rigid part) from the airtight connector  130  (a contact face of the flange part  130   c ) to an end part of each of the conductive members  170  connected to the airtight connector  130  on a side connected to each of the cables. As a result, it is possible to facilitate the connecting work between the cables  160  and the airtight connector  130 . 
         [0092]    When the connecting work between the cables  160  and the airtight connector  130  is finished, the first tube body  210  and the second tube body  220  are relatively moved so that the airtight connector  130  is fitted to the proximal end part of the second tube body  220  as shown in  FIGS. 11 and 13 . 
         [0093]    Subsequently, as shown in  FIG. 13 , a fitting part A of the optical window  144  provided with a surface on which a metal film is evaporated and the distal end of the third tube body  212  is scaled by soldering. 
         [0094]    Next, the third tube body  212  and the fourth tube body  214  are joined in an airtight manner. In the embodiment, a fitting part D (whole circumference of a proximal end part of the third tube body  212 ) in which the proximal end part of the third tube body  212  and the distal end part of the fourth tube body  214  are fitted is sealed by laser welding. 
         [0095]    Next, the fourth tube body  214  and the second tube body  220  are joined in an airtight manner. In the embodiment, a fitting part B (whole circumference of a proximal end part of the fourth tube body  214 ) in which the proximal end part of the fourth tube body  214  and the distal end part of the second tube body  220  are fitted is sealed by laser welding. 
         [0096]    Finally, the proximal end part of the second tube body  220  and the airtight connector  130  are joined in an airtight manner. In the embodiment, a fitting part C (whole circumference of the proximal end part of the second tube body  220 ) in which the proximal end part of the second tube body  220  and the airtight connector  130  are fitted is sealed by laser welding. 
         [0097]    Accordingly, it is possible to maintain airtightness of the inside of the distal end rigid part  16 - 2  (the first tube body  210  (the third tube body  212 +the fourth tube body  214 ) and the second tube body  220 ) storing the optical unit  140  and the imaging device unit  150 , so that the endoscope provided with the distal end rigid part  16 - 2  can cope with autoclave sterilization. 
         [0098]    Order of sealing operations in four fitting parts A, B. C, and D is not limited to the order described above. The sealing operations for the fitting part A between the optical window  144  and the distal end of the third tube body  212 , and for the fitting part D between the proximal end part of the third tube body  212  and the distal end part of the fourth tube body  214 , may be performed before the connecting work between the cables  160  and the airtight connector  130 . 
         [0099]    [Others] 
         [0100]    Although the first and second tube bodies and the like of the present embodiment have a cylindrical shape, the bodies are not limited to the cylindrical shape, but may have a cross section formed into a shape in which a part of a circle is linear such as a D-shape, or may be a polygon tube and the like. The slide part between the first and second tube bodies is provided in the second tube body side, but it may be provided in the first tube body side. 
         [0101]    In addition, in the present embodiment, although the endoscope having the imaging device unit of a transversely mounted type is described, the present invention is also applicable to an endoscope having an imaging device of a longitudinally mounted type. 
         [0102]    Further, in the present embodiment, although the endoscope applied to surgery is described, the present invention is not limited to a type of an endoscope, but is applicable to various endoscopes, such as a transnasal endoscope, a colonoscope, and an industrial endoscope. 
         [0103]    The present invention is not limited to the embodiments described above, and therefore it is needless to say that a variety of modifications is possible within a range without departing from the spirit of the present invention.