Abstract:
An electronic endoscope in accordance with the present invention consists broadly of an operation unit, an elongated insertion unit, and a universal cord. The operation unit has a treatment appliance insertion port and various operation switches and fills the role of a hand-held unit. The insertion unit extends from the lower end of the operation unit in a direction substantially corresponding to the longitudinal direction of the operation unit. The universal cord extends in a direction crossing the longitudinal direction of the operation unit at an acute angle, and accommodates at least a signal cable extending from the top of the operation unit.

Description:
This application claims benefit of Japanese Application No. Hei 11-280432 filed in Japan on Sep. 30, 1999, the contents of which are incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electronic endoscope having a treatment appliance insertion port and various operation switches formed in and on an operation unit thereof, and having a universal cord extended from the operation unit. 
     2. Description of the Related Art 
     In recent years, endoscopes having an elongated insertion unit inserted into a body cavity and having, if necessary, a treatment appliance passed through a treatment appliance channel so as to enable various kinds of examinations and treatments have widely been adopted. The endoscopes include an electronic endoscope having a solidstate imaging device such as a charge-coupled device (CCD) incorporated as an imaging means therein. The electronic endoscope converts an optical image of an object converged on the CCD into an electric signal and the electric signal into an image signal, displays an image of the object on the screen of a monitor, and thus enables observation of a lesion or the like. 
     A type of electronic endoscope has a soft insertion unit that includes a bending portion formed by concatenating a plurality of bending pieces. The bending portion can be angled vertically and laterally. The insertion unit can therefore be inserted into a tortuous body cavity through the oral cavity or anus. Angling the bending portion is controlled using an angling knob that is one of operation switches formed on an operation unit communicating with the proximal end of the insertion unit and filling the role of a hand-held unit. 
     Moreover, a universal cord accommodating a signal cable extended from the CCD or operation switch and a light guide fiber bundle is extended from a flank of the operation unit. A connector is attached to one end of the universal cord. Consequently, the universal cord is coupled to a camera control unit (hereinafter a CCU) that is an external apparatus through the connector so that the universal cord can be uncoupled freely. 
     The CCU has a light source and a signal processor, which are not shown, incorporated therein. The light source supplies illumination light to the electronic endoscope. The signal processor processes an electric signal photoelectrically converted from an optical image of an object by the solid-state imaging device incorporated in the distal part of the insertion unit. When the universal cord is coupled to the CCU through the connector, it becomes possible to transfer the electric signal or supply illumination light. 
     As shown in FIG. 1, an operation unit  100  of a conventional electronic endoscope consists of a hand-held portion  101  and an operator portion  102  located proximally to the hand-held portion  101  (upside in the drawing). The operator portion  102  has a suction button  103 , an aeration/perfusion button  104 , and other pushbutton switches included in operation switches, and angling knobs  105  and  106  that are also referred to as operation switches and used to angle the bending portion, which is not shown, of an insertion unit  111 . Control switches  107 ,  108 ,  109 , and  110  that are also referred to as operation switches are formed near the end of the hand-held portion  101  and used to control display of an endoscopic image on a display device that is not shown. 
     The operation unit  100  is designed to be preferably held with the left hand. A user holds the middle portion, which is not shown, of the insertion unit  111  with his/her right hand. The user introduces the distal part of the insertion unit  111  to a region to be observed in a body cavity while handling the angling knobs  105  and  106  with the fingers of his/her left hand. Otherwise, a user holds the insertion unit  111  with his/her right hand, and handles the suction button  103 , aeration/perfusion button  104 , and various control switches  107 ,  108 ,  109 , and  110  with his/her left hand. 
     A user can handle the operation switches with the fingers of his/her left hand without parting his/her right hand from the insertion unit  111 . The user can efficiently introduce the insertion unit  111  to a region to be observed. Moreover, since it is unnecessary to handle the various operation switches on the operator portion  102  with the wet right hand, the insertion unit  111  remains sanitary. 
     However, as shown in FIG. 1, a universal cord  112  having high springiness extends in a direction substantially orthogonal to the longitudinal direction of the operation unit  100 . When the insertion unit  111  is introduced into a body cavity, if the insertion unit  111  is, as shown in FIG. 2, twisted in a direction of arrow A, the universal cord  112  is bent to wind about the operation unit  100 . Since the universal cord  112  has springiness, the universal cord  112  bent to wind about the operation unit imposes a load, which constrains the operation unit  100  to return to its original position, on the operation unit  100 . At this time, an operator must handle the operation unit  100  against the load. An unnecessarily large magnitude of force is therefore needed to manipulate the endoscope. 
     A discussion will be made of a case where a connector  113  attached to the proximal end of the universal cord  111  as shown in FIG.  3 A and FIG. 3B is mated with a light source connector  115  formed on a CCU  114 . 
     For example, assume that the CCU  114  is, as shown in FIG. 3A, installed to the left side of the electronic endoscope. For matching the upper and lower sides of the connector  113  attached to the universal cord  112  with those of the light source connector  115  formed on the CCU  114 , the universal cord  112  must be turned 180° to form a twist  116 . The formation of the twist  116  brings about a fear that an unnecessarily large magnitude of force may be required to introduce the endoscope into a body cavity, thus invariably increasing the burden on the operator. For overcoming this drawback, the CCU  114  must be installed to have the positional relationship relative to the electronic endoscope shown in FIG.  3 B. 
     Furthermore, when an attempt is made to handle any of the various control switches  107 ,  108 ,  109 , and  110 , aeration/perfusion button  104 , suction button  103 , and angling knobs  105  and  106  formed on the operation unit  100 , a force with which the hand-held portion  101  is held may be gone. This poses a problem in that the held state of the operation unit  100  can become unstable. 
     A treatment appliance insertion port  117  (see FIG. 1) formed in the operation unit  100  and used to introduce a treatment appliance into a body cavity is located distally to the various control switches  107 ,  108 ,  109 , and  110 , suction button  103 , and aeration/perfusion button  104  with the hand-held portion  101  between them. Therefore, when the insertion unit  111  is held with the right hand and the operation unit  100  is held with the left hand, it is hard to manipulate a treatment appliance such as forceps introduced into a body cavity through the treatment appliance insertion port  117 . For manipulating the treatment appliance, a nurse or the like is usually asked to hold the insertion unit  111 . However, when a nurse holds the insertion unit  111 , an endoscopic image of an operator-intended region to be observed is hard to produce. 
     In efforts to improve maneuverability of an endoscope, various proposals have been disclosed in, for example, Japanese Unexamined Patent Application Publication Nos. 8-19507 and 7-100105, Japanese Unexamined Utility Model Publication No. 60-171403, and Japanese Examined Utility Model Publication No. 63-23042. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide an electronic endoscope having the characteristics of a stable hold, excellent user-friendliness, and superb maneuverability. 
     Briefly, an electronic endoscope in accordance with the present invention consists broadly of an operation unit, an elongated insertion unit, and a universal cord. The operation unit has a treatment appliance insertion port and various operation switches and fills the role of a hand-held unit. The insertion unit extends from the lower end of the operation unit in a direction substantially corresponding to the longitudinal direction of the operation unit. The universal cord extends from an upper part of the operation unit in a direction crossing the longitudinal direction of the operation unit at an acute angle, and accommodates at least a signal cable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 to FIG. 3 are explanatory diagrams concerning a conventional electronic endoscope; 
     FIG. 1 is an explanatory diagram concerning the components of an operation unit of the electronic endoscope; 
     FIG. 2 is an explanatory diagram concerning the relationship between the operation unit and a universal cord established when an insertion unit is twisted; 
     FIG.  3 A and FIG. 3B are explanatory diagrams concerning the state of the universal cord that varies depending on the positional relationship between the electronic endoscope and a CCU; 
     FIG. 3A shows a positional relationship causing the universal cord to form a twist; 
     FIG. 3B shows a positional relationship causing the universal cord to form no twist; 
     FIG. 4 to FIG. 8 are concerned with the first embodiment of the present invention; 
     FIG. 4A to FIG. 4C are explanatory diagrams concerning the components of an electronic endoscope; 
     FIG. 4A is an oblique view for explaining the components of the electronic endoscope; 
     FIG. 4B is an explanatory diagram concerning the appearance of an operation unit of the electronic endoscope and its surroundings with the endoscope viewed from its frontal direction; 
     FIG. 4C is an explanatory diagram concerning the appearance of the operation unit of the electronic endoscope and its surroundings with the endoscope viewed from its lateral direction; 
     FIG.  5 A and FIG. 5B are explanatory diagrams concerning the structure of a joint between a universal cord and the operation unit; 
     FIG. 5A is a sectional view for explaining the structure of the joint between the universal cord and operation unit; 
     FIG. 5B is a cross-sectional view showing a plane A—A shown in FIG. 5A; 
     FIG.  6 A and FIG. 6B are explanatory diagrams concerning an operation to be exerted by the electronic endoscope having a cord twist correcting means; 
     FIG. 6A is an explanatory diagram concerning the twisted state of the universal cord; 
     FIG. 6B is an explanatory diagram concerning the universal cord whose twisted state has been corrected; 
     FIG. 7 is an explanatory diagram concerning an operation to be exerted by the electronic endoscope when the insertion unit is twisted; 
     FIG. 8 is an explanatory diagram concerning an operation to be exerted by the electronic endoscope having a treatment appliance insertion port formed between an aeration/perfusion button and a suction button; 
     FIG. 9A to FIG. 9C are explanatory diagrams concerning the structure of a joint between an operation unit and a universal cord included in an electronic endoscope in accordance with the second embodiment of the present invention; 
     FIG. 9A is an oblique view for explaining the components of the electronic endoscope; 
     FIG. 9B is an explanatory diagram concerning the appearance of an operation unit of the electronic endoscope and its surroundings with the endoscope viewed from its frontal direction; 
     FIG. 9C is an explanatory diagram concerning the appearance of. the operation unit of the electronic endoscope and its surroundings with the endoscope viewed from its lateral direction; 
     FIG.  10 A and FIG. 10B are explanatory diagrams concerning the structure of a joint between the operation unit of the electronic endoscope and a universal cord thereof; 
     FIG. 10A shows a case where the operation unit and universal cord share the same plane; 
     FIG. 10B shows another case where the operation unit and universal cord share the same plane; 
     FIG.  11 A and FIG. 11B are explanatory diagrams concerning the structure of another joint between the operation unit of the electronic endoscope and the universal cord thereof; 
     FIG. 11A is an oblique view showing the operation unit and its surroundings; and 
     FIG. 11B is a diagram for practically explaining an operation to be exerted by the universal cord. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, embodiments of the present invention will be described below. 
     The first embodiment of the present invention will be described with reference to FIG. 4A to FIG.  8 . 
     An electronic endoscope (hereinafter simply an endoscope)  1  in accordance with the present embodiment shown in FIG. 4A is designed for, for example, medical use. The endoscope  1  consists mainly of an elongated insertion unit  2  to be inserted into a body cavity, an elongated operation unit  3  formed proximally to the insertion unit  2  and filling the role of a hand-held unit, and a universal cord  4  extending from the operation unit  3 . 
     The insertion unit  2  is extended from the distal end of the operation unit  3  in a direction substantially corresponding to the longitudinal direction of the operation unit  3 . The insertion unit  2  has a rigid distal part  21 , a bending portion  22 , and a flexible tube  23  arranged in that order from the distal end thereof. The distal part  21  has a built-in imaging device that is not shown. The bending portion  22  has a plurality of bending pieces concatenated and can be angled vertically and laterally. The flexible tube  23  has flexibility. 
     The operation unit  3  consists of a hand-held portion  3   a  to be held by an operator and an operator portion  3   b  located proximally to the hand-held portion  3   a  (upside in the drawing). The operator portion  3   b  has operation switches formed thereon in a watertight fashion. The operation switches include an angling knob  31  used to angle the bending portion  22 , pushbutton switches such as a suction button  32  and an aeration/perfusion button  33 , and control switches  34 ,  35 , and  36  used to control display of an endoscopic image on a display device that is not shown. 
     A treatment appliance insertion port  37  through which a treatment appliance such as forceps is introduced into a body cavity over a suction channel is formed between the aeration/perfusion button  33  and suction button  32 . 
     Moreover, a cord juncture  38  at which the universal cord  4  is coupled and fixed to the operation unit  3  is projected from one flank of the operation unit  3 . The cord juncture  38  meets the operation unit  3  at an acute angle (θ) with respect to the longitudinal direction of the operation unit  3 . 
     A crossed-axes angle θ 1  shall be, as shown in FIG. 4B, an angle formed on a plane containing the face of the endoscope between the longitudinal axis of the operation unit and the longitudinal axis of the universal cord on the assumption that the universal cord  4  is extended straight. A crossed-axes angle θ 2  shall be, as shown in FIG. 4C, an angle formed,on a plane containing one flank of the endoscope between the longitudinal axis of the operation unit and the longitudinal axis of the universal cord. The crossed-axes angles θ 1  and θ 2  are acute angles. 
     Consequently, the insertion unit  2  and universal cord  4  are extended downwards in FIG. 4A, FIG. 4B, and FIG.  4 C. 
     An operator&#39;s left hand with which the operation unit  3  is held is rested on part of one flank of the operation unit  3  between the operation unit  3  and the cord juncture  38  and a coupling fixture  40  attached to an end of the universal cord  4 . The cord juncture  38  and coupling fixture  40  therefore traverses the back of the operator&#39;s left hand. According to the present embodiment, the cord juncture  38  and coupling fixture  40  constitute a hold assistant against which the operator&#39;s left hand is rested. 
     The coupling fixture  40  attached to one end of the universal cord  4  serves as an integral part of not only the hold assistant but also a cord twist correcting means. The coupling fixture  40  is joined to the cord juncture  38  formed on the operation unit  3 , whereby the universal cord  4  can be rotated 180° or more as mentioned later. Moreover, a connector  4   a  is attached to the other end of the universal cord  4 . The connector  4   a  is coupled to a camera control unit  5  (see FIG. 6) (hereinafter a CCU) that is an external apparatus so that it can be uncoupled freely. 
     A signal line and a light guide fiber bundle or the like are passed through the universal cord  4 , operation unit  3 , and insertion unit  2 . The signal line links an imaging device that is not shown and the CCU  5 . Illumination light emanating from a light source, which is not shown, incorporated in the CCU  5  is propagated to the distal part  21  of the insertion unit  2  over the light guide fiber bundle. Moreover, anti-break members  6   a  and  6   b  are used to protect the insertion unit  2  and universal cord  4  respectively from buckling. 
     Referring to FIG.  5 A and FIG. 5B, a description will be made of the structure of the cord twist correcting means composed of the cord juncture  38  and coupling fixture  40 , and an operation to be exerted by the cord twist correcting means. 
     As shown in FIG. 5A, the cord juncture  38  projects from an operation unit body  30  of the operation unit  3 . The light guide fiber bundle and signal line are passed through a hollow  38   c  of the cord juncture  38 . A screw hole  38   d  having a female screw threaded on the inner wall thereof is bored at the end of the cord juncture  38 . The female screw is mashed with a lock screw  7 . 
     As shown in FIG.  5 A and FIG. 5B, the coupling fixture  40  consists of a first coupling member  41  and a second coupling member  42 . The first coupling member  41  is shaped like a pipe and composed of a rotator portion  41   a  and a joint portion  41   b.  The second coupling member  42  is a pile member having a small-diameter portion  42   a,  which is joined to the joint portion  41   b  of the first coupling member  41  and has a small diameter, and a large-diameter portion having a large diameter. 
     The rotator portion  41   a  of the first coupling member  41  is engaged with the hollow  38   c  of the cord juncture  38 . The joint portion  41   b  is formed to project from the hollow  38   c,  and has, for example, a male screw  41   c,  which serves as a joint, threaded on the periphery thereof. The small-diameter portion  42   a  of the second coupling member  42  has a female screw  42   c,  which is meshed with the male screw  41   c  threaded on the joint portion  41   b,  threaded thereon. The large-diameter portion is a juncture shield  42   b  engaged with the periphery of the cord juncture  38 . The large-diameter portion has a through hole  42   d,  through which the lock screw  7  is fitted into the screw hole  38   d,  formed at a predetermined position thereon. 
     A rotation groove  43  extending circumferentially is bored in the periphery of the rotator portion  41   a  of the first coupling member  41 . The rotation groove  43  enables the universal, cord  4  to rotate substantially 180° or more relative to the operation unit. 
     A circumferential groove  41   d  in which an O ring  44  is fitted in order to maintain watertightness between the hollow of the cord juncture  38  and the periphery of the rotator portion  41   a  and induce a predetermined magnitude of resistance to a turn is formed on both sides of the rotation groove  43 . 
     A cord member  4   b  that is an integral part of the universal cord  4  is locked in the hollow of the first coupling member  41 , and the anti-break member  6   b  is mounted on the small-diameter portion  42   a  of the second coupling member  42  as an integral part thereof. 
     The male screw  41   c  threaded on the first coupling member  41  having the cord member  4   b  locked therein as an integral part thereof and having the O rings  44  fitted in the circumferential grooves  41   d  is meshed with the female screw  42   c  threaded on the second coupling member  42  having the anti-break member  6   b  mounted thereon as an integral part thereof. The coupling fixture  40  attached to one end of the universal cord  4  is thus realized. 
     Now, how to join the coupling fixture  40  and cord juncture  38  will be described below. 
     For joining the coupling fixture  40  to the cord juncture  38 , first, the rotator portion  41   a  of the first coupling member  41  is thrust into the hollow  38   c  of the cord juncture  38  against constraining force exerted by the O rings  44 . 
     Thereafter, the rotation groove  43  bored in the first coupling member  41  is substantially aligned with the screw hole  38   d  bored in the cord juncture  38  through the through hole  42   d  bored in the second coupling member  42 . 
     The lock screw  7  is then fitted into the screw hole  38   d  through the through hole  42   d,  meshed with the female screw threaded on the wall of the screw hole  38   d,  and then tightened. The tip of the lock screw  7  is thus put in the rotation groove  43 . Consequently, the rotator portion  41   a  is located at a predetermined position so that it can rotate freely. 
     Consequently, the second coupling member  42  having the anti-break member  6   b  mounted thereon as an integral part thereof is rotated. The first coupling member  41  joined to the second coupling member  42  is therefore guided to rotate by an angle determined with the length of the rotation groove  43  owing to the lock screw  7 . Thus, the coupling fixture  40  rotates 180° or more. 
     Operations to be executed by the endoscope  1  having the foregoing structure will be described below. 
     To begin with, an operation to be performed when the connector  4   a  attached to the end of the universal cord  4  extending from the operation unit  3  of the endoscope  1  is mated with a light source connector  5   a  of the CCU  5  will be described with reference to FIG.  6 A and FIG.  6 B. 
     When an attempt is made to connect the endoscope  1  to the CCU  5 , the orientation of the connector  4   a  attached to the universal cord  4  may be reversed as indicated with dashed lines in FIG. 3A depending on the positional relationship between the endoscope  1  and CCU  5 . When an attempt is made to adjust the orientation of the connector  4   a  as indicated with solid lines, the universal cord  4  may be twisted to form a twist  4   c.  This may hinder manipulation of the endoscope. 
     In the endoscope  1  of the present embodiment, the second coupling member  42  included in the coupling fixture  40  attached to one end of the universal cord  4  and having the anti-break member  6   b  mounted thereon as an integral part thereof is rotated 180° in a direction of arrow B. Consequently, the twist  4   c  of the universal cord  4  is unraveled as shown in FIG.  6 B. The connector  4   a  can be smoothly mated with the light source connector  5   a  of the CCU  5 . 
     As mentioned above, the coupling fixture  40  attached to the universal cord is joined to the cord juncture  38  formed on the operation unit so that the coupling fixture can rotate at least 180°. It will therefore not happen when the connector of the electronic endoscope is mated with the light source connector of the CCU, that the universal cord is twisted to form a twist. This contributes to improvement in the maneuverability of the electronic endoscope. 
     Next, an operation to be performed when an operator holds the endoscope  1  and inserts the insertion unit  2  into a body cavity will be described with reference to FIG.  7 . 
     When an operator holds the endoscope, the operator&#39;s left hand is rested on the part of one flank of the operation unit  3  between the flank and the combination of the cord juncture  38  and coupling fixture  40  attached to one end of the universal cord  4 . At this time, when the state of the left hand with which the operation unit is held is changed, the back of the operator&#39;s left hand rests against a rigid support structure defined by the combination of the cord juncture  38  and coupling fixture  40 . The endoscope  1  is therefore held on a stable basis while being supported at two points, that is, with the palm of the left hand with which the operation unit  3  is held and the back of the left hand resting against the end of the universal cord  4 . 
     With the operation unit held in this say, the distal part  21  of the insertion unit  2  is inserted into a region to be observed at the sight of an endoscopic image displayed on the screen of a monitor that is not shown. At this time, if necessary, an operator twists the insertion unit  2  in a direction of arrow C as shown in FIG.  7 . 
     The cord juncture  38  formed on the operation unit  3  is extended at an acute angle θ with respect to the longitudinal axis of the operation unit  3 . The universal cord  4  coupled to the cord juncture  38  with the coupling fixture  40  between them so that the universal cord  4  can rotate freely is extended with the acute angle θ retained with respect to the longitudinal axis of the operation unit  3 . Therefore, even when the insertion unit  2  is twisted, the universal cord  4  will not be bent to impose a load on the operation. unit  3  but will move towards the insertion unit  2  as indicated with an arrow D. 
     In other words, when the insertion unit  2  is twisted, the universal cord  4  merely moves around the insertion unit  2 . The endoscope can therefore be manipulated with the operation unit  3  free from any load stemming from the springiness of the universal cord  4 . 
     As mentioned above, the cord juncture to which the coupling fixture attached to one end of the universal cord is joined is formed at the acute angle θ with respect to the longitudinal axis of the operation unit so that the universal cord will extend in a direction substantially corresponding to the direction of extension of the insertion unit (downside in the drawing). A drawback attributable to the fact that when the insertion unit is twisted, a load is imposed on the operation unit because of the springiness of the universal cord can be overcome. 
     Moreover, the cord juncture is formed at the acute angle θ with respect to the longitudinal axis of the operation unit, and the coupling fixture attached to one end of the universal cord is joined to the cord juncture. When an operator holds the operation unit, the cord juncture and coupling fixture are located near the back of the operator&#39;s left hand and serve as a hold assistant. The electronic endoscope can therefore be supported at two points, that is, with the back and palm of the left hand. This contributes to great improvement in the stability of a hold on the electronic endoscope. 
     Next, an operation to be executed when a treatment appliance is passed through the treatment appliance insertion port  37  interposed between the suction button  32  and aeration/perfusion button  33  will be described with reference to FIG.  8 . 
     When the distal part  21  of the insertion unit  2  of the endoscope  1  is opposed to a region to be observed, an endoscopic image of the region to be observed displayed on the screen of a monitor that is not shown is viewed. A treatment is then performed if necessary. At this time, an operator parts his/her right hand from the insertion unit  2  and passes a treatment appliance  8  through the treatment appliance insertion port  37 . 
     When the treatment appliance has reached a predetermined position, the operator holds the insertion unit  2  with his/her right hand and visualizes the region to be observed on the screen of the monitor. 
     With the treatment appliance  8  borne with the index and middle fingers of the left hand, the treatment appliance  8  is advanced or withdrawn as indicated with the double-sided arrow in FIG. 8 so that it will be visualized on the screen of the monitor. When the treatment appliance  8  is opposed to an intended region, the treatment appliance  8  is manipulated with the index and middle fingers of the left hand in order to perform a predetermined treatment. 
     In other words, an operator can swiftly introduce the treatment appliance  8  to a predetermined position so as to perform a treatment while holding the insertion unit  2  with his/her right hand without the necessity of parting his/her left hand from the operation unit  3 . Namely, the operator can swiftly introduce the treatment appliance  8  without disturbing an endoscopic image displayed on the screen of the monitor. 
     The treatment appliance insertion port through which a treatment appliance is introduced into a body cavity is interposed between the suction button and aeration/perfusion button to be handled with the index and middle fingers respectively. A treatment appliance put into the treatment appliance insertion port can be manipulated with the index and middle fingers without the necessity of changing the positions of the operator&#39;s right and left hands. This contributes greatly to improvement in the maneuverability of the endoscope. 
     Referring to the drawing concerning the present embodiment, the suction button  32 , aeration/perfusion button  33 , and treatment appliance insertion port  37  are juxtaposed straight on the surface of the operation unit illustrated upside in the drawing. The positional relationship among the suction button  32 , aeration/perfusion button  33 , and treatment appliance insertion port  37  is determined in consideration of maneuverability. Their location is not limited to the surface of the operation unit illustrated in the drawing, and their layout is not limited to the straight juxtaposition. 
     Moreover, when it is intended to manipulate the treatment appliance  8 , if the endoscope  1  is held with the back of the left hand rested against the hold assistant, the treatment appliance  8  can be manipulated more smoothly. 
     The first embodiment has been described on the assumption that the endoscope is an electronic endoscope for medical use. The endoscope is not limited to the one for medical use but may be the one for industrial use. 
     The second embodiment of the present invention will be described with reference to FIG. 9A to FIG.  9 C. 
     In the endoscope  1  of the first embodiment, the cord juncture  38  is projected from the middle point of the operation unit  3 . In contrast, in an endoscope  1 A of the present embodiment, a cord juncture  38   a  is projected from the proximal end of the operation unit  3  as shown in FIG. 9A, FIG. 9B, and FIG.  9 C. At this time, the longitudinal axes of the cord juncture and operation unit form an acute angle θ 1  on a plane containing the face of the endoscope. Moreover, the longitudinal axes of the cord juncture and operation unit form an acute angle θ 2  on a plane containing one flank of the endoscope. The coupling fixture  40  attached to one end of the universal cord  4  is joined to the cord juncture  38   a.    
     A joystick  31 A used to angle the bending portion  22  is formed instead of the angling knob  31 , which is one of the operation switches, on one flank of the operation unit  3 . The other components are identical to those of the first embodiments. The same reference numerals are assigned to the identical components, and the description of the components is omitted. 
     As mentioned above, the cord juncture to which the coupling fixture attached to one end of the universal cord is joined is projected from the proximal end of the operation unit at an acute angle. Consequently, the insertion unit extending from the operation unit and the universal cord can be balanced easily. 
     As shown in FIG.  10 A and FIG. 10B, in an endoscope  1 B, a cord juncture  38   b  projected from the operation unit  3  and the operation unit  3  share the same plane. The insertion unit  2  extending from the operation unit  3  and the universal cord  4  can be balanced more easily. 
     Moreover, as shown in FIG.  11 A and FIG. 11B, in an endoscope  1 C, the operation unit  3  and a cord juncture  38   c  are joined using a hinge  8  serving as an angle varying means so that the cord juncture  38   c  can pivot freely. This results in a hold assistant composed of the cord juncture  38   c  and coupling fixture  40  that are located at any desired position by varying an angle θ depending on the size of an operator&#39;s hand or operator&#39;s likes or dislikes. Thus, the endoscope  1 C offers further improved maneuverability. 
     According to the present invention, it is apparent that a wide range of different embodiments can be constructed based on the invention without a departure from the spirit and scope of the invention. The present invention will be limited by the appended claims but not restricted to any specific embodiment.