Patent Publication Number: US-2017360289-A1

Title: Examination tool

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2016-122823, filed Jun. 21, 2016. The contents of this application are incorporated herein by reference in their entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to an examination tool to observe an inner part of an ear such as an ear canal and an eardrum. 
     2. Description of Related Arts 
     Maintenance of an inner part of an ear is necessary not only for a human but also for a small/medium animal. Ear canal cleaning of a human is routinely performed with various cleaning methods. A structure of an ear canal of a human is horizontal. A structure in a straight line is normal. Some people have structures curved in some degree. On the other hand, a structure of an ear canal of a small/medium animal is in a curved line toward a lower inner surface. An eardrum is at a leading end and an ear canal is narrow. In an inner part of an ear, earwax in various conditions such as dry earwax, wet earwax, and dandruff-type earwax is generated. Specifically, an inner part of an ear in a small/medium animal is likely to be parasitized by an animalcule such as a tick and louse. Thus, an ear canal, an eardrum, and a part near the eardrum are likely to be contaminated. A disease of the eardrum is caused very frequently. Thus, in order to detect abnormality in an inner part of an ear early in a human and a small/medium animal, it is desirable that the inner part of the ear is examined regularly and that the inner part of the ear is taken care of. 
     In Japanese Patent Application Laid-Open No. 2014-138858, an otoscope with which it is possible to diagnose inflammation or infection in an inner part of an ear by imaging of a three-dimensional image or a spectrum image in an inner part of an earhole is disclosed. 
     SUMMARY 
     The otoscope disclosed in Japanese Patent Application Laid-Open No. 2014-138858 can improve a diagnosis of inflammation or infection in an inner part of an ear. However, a device itself as the otoscope is large-scaled and cannot be easily used by an ear, nose and throat hospital or an animal hospital. Also, since there is no low-cost examination tool, with which a part near an ear canal or an eardrum can be easily examined, for treatment of an eardrum of a small/medium animal, a high cost is necessary to introduce the above otoscope. Thus, it is difficult for a small-scale ear, nose and throat hospital or animal hospital to purchase the above otoscope. 
     Many hospitals have a desire to introduce such otoscope. However, there are many hospitals hesitating to introduce the otoscope since the otoscope is a large-scale device and requires a high introduction cost. 
     Also, many animal hospitals have a desire to observe an inner part of an ear with a clear image. However, even with the otoscope disclosed in Japanese Patent Application Laid-Open No. 2014-138858, it is difficult to observe an inner part of an ear of an animal, humidity in an ear canal of which is higher than that of a human, without fogging of a lens of a camera. 
     Furthermore, in order to prevent infection, the otoscope usually requires work to disinfect a part inserted into the ear canal after use. For this reason, it cannot be said that working efficiency is good, and there is a concern about reliability in terms of hygiene. 
     The present invention is provided to respond to such various conventional demands and is to provide an examination tool with high reliability in terms of hygiene which tool is simple in structure and inexpensive to introduce and with which tool it is possible to observe an inner part of an ear with a clear image. 
     An examination tool according to an aspect of the present invention for achieving the above object is an examination tool including: an imaging tube that is inserted into an ear canal to image an inner part of an ear; and a main body part from a leading end part of which the imaging tube protrudes, wherein the imaging tube includes, at a leading end part thereof, an imaging lens that images the inner part of the ear and an illumination unit that is provided adjacent to the imaging lens and that illuminates the inner part of the ear, a cap part including a penetration part in which the imaging tube penetrates is included at the leading end part of the main body part, a protective tube that protects an entire circumference of the imaging tube is attached to the imaging tube, a holding part that holds an end part of the protective tube with the imaging tube is formed in the penetration part of the cap part, and the cap part is moved in a direction opposite to a protruding direction of the imaging tube and is fixed to the leading end part when being rotated in a first direction along a circumferential direction of the main body part, and is moved in the protruding direction of the imaging tube, is detached from the leading end part, and moves the protective tube held by the holding part in the protruding direction of the imaging tube when being rotated in a second direction opposite to the first direction. 
     An examination tool according to another aspect of the present invention for achieving the above object is an examination tool including: an imaging tube that is inserted into an ear canal to image an inner part of an ear; and a main body part from a leading end part of which the imaging tube protrudes, wherein the imaging tube includes, at a leading end part thereof, an imaging lens that images the inner part of the ear and an illumination unit that is provided adjacent to the imaging lens and that illuminates the inner part of the ear, a cap part including a protective part in which the imaging tube penetrates and which protects an entire circumference of the imaging tube is included at the leading end part of the main body part, and the cap part is moved in a direction opposite to a protruding direction of the imaging tube and is fixed to the leading end part when being rotated in a first direction along a circumferential direction of the main body part, and is moved in the protruding direction of the imaging tube and detached from the leading end part when being rotated in a second direction opposite to the first direction. 
     According to the examination tool according to the present invention, an introduction cost becomes low with a simple structure, an inner part of an ear can be observed with a clear image, and high reliability can be secured in terms of hygiene. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a configuration diagram of an ear canal examination device including an examination tool according to a first embodiment; 
         FIG. 2  is a side view of an imaging tube and a main body part of the examination tool according to the first embodiment; 
         FIG. 3A  is a view illustrating a partly-broken side surface of the examination tool according to the first embodiment; 
         FIG. 3B  is a cross section of a cap part of the examination tool according to the first embodiment; 
         FIG. 4  is a perspective view of the examination tool according to the first embodiment; 
         FIG. 5A  is a view illustrating the examination tool according to the first embodiment in a perspective manner; 
         FIG. 5B  is a cross section of a penetration part of the cap part according to the first embodiment; 
         FIG. 6  is a cross-sectional view of the main body part and the imaging tube of the examination tool according to the first embodiment; 
         FIG. 7  is a view for describing operation of the examination tool according to the first embodiment; 
         FIG. 8  is a view for describing the operation of the examination tool according to the first embodiment; 
         FIG. 9  is a view for describing the operation of the examination tool according to the first embodiment; 
         FIG. 10  is a view for describing the operation of the examination tool according to the first embodiment; 
         FIG. 11  is a view for describing the operation of the examination tool according to the first embodiment; 
         FIG. 12  is a view for describing the operation of the examination tool according to the first embodiment; 
         FIG. 13  is a configuration diagram of an examination tool according to a second embodiment; 
         FIG. 14A  is a view illustrating a partly-broken side surface of the examination tool according to the second embodiment; 
         FIG. 14B  is a cross section of a cap part of the examination tool according to the second embodiment; 
         FIG. 15  is a perspective view of the examination tool according to the second embodiment; 
         FIG. 16  is a view for describing operation of the examination tool according to the second embodiment; 
         FIG. 17  is a view for describing the operation of the examination tool according to the second embodiment; and 
         FIG. 18  is a view for describing the operation of the examination tool according to the second embodiment; 
         FIG. 19A  is a cross section of a cap part of the examination tool according to the third embodiment; 
         FIG. 19B  is a Left side view of a cap part of the examination tool according to the third embodiment; 
         FIG. 19C  is a Right side view of a cap part of the examination tool according to the third embodiment; 
         FIG. 20  is a configuration diagram of an examination tool according to third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following, a [first embodiment] and a [second embodiment] of an examination tool according to the present invention will be described in detail. 
     First Embodiment 
     The first embodiment is an examination tool with which it is possible to observe an inner part of an ear such as an ear canal and an eardrum with a clear image and in which a protective tube can be replaced after observation of the inner part of the ear. 
     Configuration of Ear Canal Examination Device 
       FIG. 1  is a configuration diagram of an ear canal examination device including an examination tool according to the first embodiment. As illustrated in  FIG. 1 , an ear canal examination device  100  includes an examination tool  200 , a control device  300 , and a display  400 . 
     With the examination tool  200 , it is possible to examine (observe) an inner part of an ear of a human or an animal. The examination tool  200  includes an imaging tube  210  that is inserted into the ear canal to image an inner part of an ear, and a main body part  220  from a leading end part of which the imaging tube  210  protrudes. 
     Although not illustrated in  FIG. 1 , the imaging tube  210  includes an imaging lens, which images an inner part of an ear, at a leading end part on a side inserted into an ear canal and an illumination unit that illuminates the inner part of the ear. The illumination unit is provided adjacent to the imaging lens at the leading end. This is to warm the imaging lens with residual heat of the illumination unit and to prevent fogging of the imaging lens. A detachable cylindrical protective tube  212  is attached to the imaging tube  210 . The protective tube  212  protects the entire circumference of the imaging tube  210 . The length of the protective tube  212  is longer than the length of a protruding part of the imaging tube  210 . This is to prevent the imaging lens and the illumination unit from contacting the ear canal. Also, it is preferable that the protective tube  212  is formed of a flexible and soft material so as not to damage an inner wall of the ear canal. 
     To the leading end part of the main body part  220  from which end part the imaging tube  210  protrudes, a cap part  230  that can be attached to/detached from the leading end part by a rotation is attached. The cap part  230  includes a penetration part where the imaging tube  210  penetrates. A holding part  235  that holds an end part of the protective tube  212  with the imaging tube  210  is formed in the penetration part. When the protective tube  212  is slid from a leading end direction of the imaging tube  210  to cover the imaging tube  210  and a leading end of the protective tube  212  is inserted into the holding part  235 , the protective tube  212  is held by the holding part  235 . 
     When being rotated in a first direction along a circumferential direction of the main body part  220  (such as rightward direction), the cap part  230  is moved in a direction opposite to a protruding direction of the imaging tube  210  (direction of arrow P) and is fixed to the leading end part of the main body part  220 . When being rotated in a second direction (such as leftward direction) opposite to the first direction, the cap part  230  is moved in the protruding direction of the imaging tube  210  (direction of arrow P), is detached from the leading end part of the main body part  220 , and moves the protective tube  212  held by the holding part in the protruding direction of the imaging tube. 
     A camera (not illustrated) is built in the main body part  220 . The camera and the imaging lens are connected to each other by an optical fiber. Thus, an image of an inner part of an ear which image is captured by the imaging lens is transmitted to the camera via the optical fiber. The camera is connected to the control device  300  via a cable  250  drawn out from a rear end part of the main body part  220 . Note that the camera is provided in the main body part  220  in the first embodiment. However, the camera may be directly attached to the imaging lens. In that case, an external dimension of the camera is about  2  to  4  mm. 
     The control device  300  includes a control unit  330  and an image processing unit  360 . The control unit  330  totally controls operations of the camera and the illumination unit included in the main body part  220 , and the image processing unit  360 . The image processing unit  360  processes an image transmitted from the camera and displays the image on the display  400 . 
     [Operation of Ear Canal Examination Device] 
     When the examination tool  200  according to the first embodiment is used, the cap part  230  is attached to the leading end part of the main body part  220 , the protective tube  212  is put on the imaging tube  210 , and the protective tube  212  is held by the holding part  235  of the cap part  230 . The leading end part of the imaging tube  210  is inserted into an ear canal in this state, and a state of an inner part of an ear is observed with reference to an image displayed on the display  400 . 
     When the observation of the state of the inner part of the ear is over, the cap part  230  is detached from the leading end part of the main body part  220 , the protective tube  212  moved in the protruding direction of the imaging tube  210  is detached from the imaging tube  210 , and the cap part  230  is detached from the main body part  220 . 
     As described above, a structure of the examination tool  200  according to the first embodiment is simple. Also, inexpensive general-purpose products can be used as the control device  300  and the display  400 . Thus, the examination tool  200  and the ear canal examination device  100  according to the first embodiment have simple structures and an introduction cost thereof becomes low. In addition, since fogging of the imaging lens can be prevented with heat of the illumination unit, the inner part of the ear can be observed with a clear image. Furthermore, since the protective tube  212  can be replaced each time being used, high reliability can be secured in terms of hygiene. [Configuration of Examination Tool] 
     Next, with reference to  FIGS. 2 to 6 , the configuration of the examination tool  200  according to the first embodiment will be described in detail. 
       FIG. 2  is a side view of the imaging tube  210  and the main body part  220  of the examination tool  200  according to the first embodiment. 
     The imaging tube  210  protrudes from the leading end part  222  of the main body part  220 . The leading end part  222  includes a first tapered part  224  having a gentle taper angle, and a second tapered part  226  having a taper angle steeper than that of the first tapered part. In the first tapered part  224 , locking pieces  228  are provided at constant angular intervals in the circumferential direction of the leading end part  222 . 
       FIG. 3A  is a view illustrating a partly-broken side surface of the examination tool  200  according to the first embodiment.  FIG. 3B  is a cross section of the cap part  230  of the examination tool  200  according to the first embodiment. 
     The cap part  230  includes a bowl-shaped hollow shape formed along a shape of the leading end part  222  illustrated in  FIG. 2 . In the cap part  230 , a penetration part  232  where the imaging tube  210  illustrated in  FIG. 2  penetrates is formed. In the penetration part  232 , the holding part  235  that holds the protective tube  212  (see  FIG. 1 ) with the imaging tube  210  is formed. 
     The holding part  235  is a protrusion that protrudes in the protruding direction of the imaging tube  210  from the penetration part  232  of the cap part  230 . The diameter of the penetration part  232  is equal to the diameter of the imaging tube  210  or larger than the diameter of the imaging tube  210 . The penetration part  232  includes an abutment part  238  to which an end part of the protective tube  212  illustrated in  FIG. 1  is abutted. The distance from a surface of the holding part  235  to a surface of the imaging tube  210  is equal to the thickness of the protective tube  212  or shorter than the thickness of the protective tube  212 . 
     Engagement grooves  234  that engage with the locking pieces  228  illustrated in  FIG. 2  are included at constant angular intervals in the circumferential direction in the inner peripheral part of the cap part  230 . 
     Thus, when the cap part  230  is abutted to the leading end part  222  illustrated in  FIG. 2  and the cap part  230  is rotated in the first direction (such as rightward direction), the locking pieces  228  are engaged with the engagement grooves  234  and the cap part  230  is moved in the direction opposite to the protruding direction of the imaging tube  210  (rightward direction in  FIG. 2 ) and is firmly fixed to the leading end part  222  of the main body part  220 . 
     On the other hand, when the cap part  230  is rotated in the second direction (such as leftward direction) opposite to the first direction, the cap part  230  is moved in the protruding direction of the imaging tube  210  (leftward direction in  FIG. 2 ) until the engagement grooves  234  are detached from the locking pieces  228 . 
     Anti-slip grooves  236  are formed in an end part with the largest diameter of the cap part  230 . The anti-slip grooves  236  are provided in the entire circumference of the cap part  230  as illustrated in an A-A cross section. 
       FIG. 4  is a perspective view of the examination tool  200  according to the first embodiment.  FIG. 5A  is a view illustrating the examination tool  200  according to the first embodiment in a perspective manner.  FIG. 5B  is a cross section of a penetration part of the cap part  230  according to the first embodiment.  FIG. 6  is a cross-sectional view of the main body part  220  and the imaging tube  210  of the examination tool  200  according to the first embodiment. 
     The cap part  230  is attached to the leading end part  222  of the main body part  220 . The cap part  230  is firmly attached to the main body part  220  by the locking pieces  228  provided at the leading end part  222  and the engagement grooves  234  in the cap part  230  itself. The imaging tube  210  protruding from the main body part  220  penetrates the penetration part  232  of the cap part  230 . As illustrated in a B-B cross section, three holding parts  235  provided with angular differences of 120 degrees in the circumferential direction are provided in the penetration part  232 . The protective tube  212  protects the entire circumference of the imaging tube  210  from the abutment part  238  of the penetration part  232  in the cap part  230  to the leading end part of the imaging tube  210 . 
     As illustrated in  FIG. 5A, 5B , the protective tube  212  is held by the holding parts  235  with an end part thereof being abutted to the abutment part  238  and being inserted into a space between the imaging tube  210  and the holding parts  235 . The protective tube  212  is longer than the imaging tube  210 . As illustrated in  FIG. 4 , the protective tube  212  protects the entire circumference of the imaging tube  210  in a state of protruding more than the leading end part of the imaging tube  210 . 
     When the cap part  230  is rotated in the second direction (such as leftward direction) opposite to the first direction (such as rightward direction), the cap part  230  and the protective tube  212  are moved in the protruding direction of the imaging tube  210  (leftward direction in drawing). 
     Thus, the end part of the protective tube  212  is pushed by the abutment part  238 , the leading end part of the protective tube  212  is greatly deviated from the leading end part of the imaging tube  210 , and it becomes easier to pinch the leading end part of the protective tube  212 . Thus, replacement of the protective tube  212  becomes easy. 
     As illustrated in  FIGS. 5 and 6 , a camera  240  to image an inner part of an ear is built in the main body part  220 . An optical fiber  245  is attached to the camera  240 . The optical fiber  245  is connected, through the imaging tube  210 , to an imaging lens  260  provided at the leading end part of the imaging tube  210 . Thus, the camera  240  is connected to the imaging lens  260  via the optical fiber  245 . Also, the imaging lens  260  and an LED  270 , which functions as the illumination unit, are arranged side by side in a radial direction in the leading end part of the imaging tube  210 . 
     Thus, the imaging lens  260  is prevented, with the heat generated by the LED  270 , from being fogged due to the humidity inside an ear canal. Note that the inner part of the ear is irradiated only with the LED  270  in the first embodiment. However, an LED may be arranged along an outer periphery of the leading end part of the imaging tube  210  in addition to the LED  270 . 
     [Operation of Examination Tool] 
       FIGS. 7 to 12  are views for describing the operation of the examination tool  200  according to the first embodiment. As illustrated in  FIGS. 7 and 8 , when the examination tool  200  is used, first, the imaging tube  210  is inserted into the penetration part  232  of the cap part  230 , and the cap part  230  is slid along the imaging tube  210  in a direction of an illustrated arrow until the cap part  230  is abutted to the leading end part  222 . 
     When the cap part  230  is abutted to the leading end part  222 , the cap part  230  is rotated in the first direction (rightward direction in drawing) as illustrated in  FIG. 9 . Then, the engagement grooves  234  illustrated in  FIG. 3A, 3B  are engaged with the locking pieces  228  in  FIG. 2  and the cap part  230  is further moved in the direction of the illustrated arrow and is firmly attached to the main body part  220 . In this state, as illustrated in  FIG. 10 , the protective tube  212  is moved in the direction of the illustrated arrow until being abutted to the abutment part  238  illustrated in  FIG. 5A, 5B  in such a manner that the end part of the protective tube  212  is held by the holding parts  235 . 
     In this state, since the imaging tube  210  is covered and protected by the protective tube  212 , the imaging tube  210  is inserted into the ear canal and a state of the inner part of the ear is observed. During the observation of the state of the inner part of the ear, the LED  270  illustrated in  FIG. 6  is on and the state of the inner part of the ear is imaged by the camera  240 . Although humidity inside the ear canal is high depending on a kind of an animal, the imaging lens  260  is not fogged since the imaging lens  260  is warmed by the heat of the LED  270 . 
     When the observation of the state of the inner part of the ear is over, the cap part  230  is rotated in the second direction (leftward direction in drawing) as illustrated in  FIG. 11 . Then, the engagement grooves  234  illustrated in  FIG. 3A, 3B  are detached from the locking pieces  228  in  FIG. 2  and the cap part  230  is moved in a direction of an illustrated arrow. Thus, the protective tube  212  is moved in the direction of the illustrated arrow as the abutment part  238  of the cap part  230  illustrated in  FIG. 5A, 5B  is moved, and it becomes easier to detach the protective tube  212  from the imaging tube  210 . 
     By an operator, the protective tube  212  that becomes easier to be detached is moved in the direction of the illustrated arrow with an end thereof being pinched and is detached from the imaging tube  210  as illustrated in  FIG. 12 . 
     As described above, according to the examination tool of the first embodiment, an introduction cost becomes low since a structure thereof is simple compared to a conventional one. Since fogging of the imaging lens  260  is designed to be prevented, it is possible to observe an inner part of an ear with a clear image. Moreover, since the protective tube  212  can be replaced, high reliability can be secured in terms of hygiene. 
     Second Embodiment 
     In the second embodiment, a part corresponding to the protective tube  212  of the first embodiment is integrated with the cap part  230 . With an examination tool of the second embodiment, it is also possible to observe an inner part of an ear with a clear image. Also, it is possible to replace a protective tube after observation of the inner part of the ear. 
       FIG. 13  is a configuration diagram of the examination tool according to the second embodiment An examination tool  200 A of the second embodiment is different from the examination tool  200  of the first embodiment only in a structure of a cap part  230 A. Configurations of the other parts are the same as those of the first embodiment. 
     As illustrated in  FIG. 13 , the examination tool  200 A includes an imaging tube  210 A that is inserted into an ear canal to image an inner part of an ear and a main body part  220 A from a leading end part of which an imaging tube  210 A protrudes. 
     Although not illustrated in  FIG. 13 , the imaging tube  210 A includes an imaging lens, which images an inner part of an ear, at a leading end part on a side inserted into an ear canal and an illumination unit that illuminates the inner part of the ear. The illumination unit is provided adjacent to the imaging lens. This is to warm the imaging lens with heat of the illumination unit and to prevent fogging of the imaging lens. A cap part  230 A including a protective part  237 A in which the imaging tube  210 A penetrates and which protects the entire circumference of the imaging tube  210 A is included at the leading end part of the main body part.  220 A. The protective part  237 A is formed integrally with the cap part  230 A. 
     The protective part  237 A of the cap part  230 A protects the entire circumference of the imaging tube  210 A in a state of protruding more than the leading end part of the imaging tube  210 A. This is to prevent the imaging lens and the illumination unit provided at the leading end part of the imaging tube  210 A from contacting an ear canal. 
     When being rotated in a first direction (such as rightward direction) along a circumferential direction of the main body part  220 A, the cap part  230 A is moved in a direction opposite to a protruding direction of the imaging tube  210 A (direction of arrow P) and is fixed to the leading end part of the main body part  220 A. When being rotated in a second direction (such as leftward direction) opposite to the first direction, the cap part  230 A is moved in the protruding direction of the imaging tube  210 A (direction of arrow P) and is detached from the leading end part of the main body part  220 A. 
     A camera (not illustrated) is built in the main body part  220 A. The camera and the imaging lens are connected to each other by an optical fiber. Thus an image of an inner part of an ear which image is captured by the imaging lens is transmitted to the camera via the optical fiber. 
       FIG. 14A  is a view illustrating a partly-broken side surface of the examination tool  200 A according to the second. embodiment.  FIG. 14B  is a a cross section of the cap part  230 A of the examination tool  200 A according to the second embodiment. 
     The cap part  230 A has a bowl-like hollow shape formed along a shape of the leading end part  222  illustrated in  FIG. 2 . The cap part  230 A includes a protective part  237 A in which the imaging tube  210  illustrated in  FIG. 2  penetrates and which protects the entire circumference of the imaging tube  210 A. 
     Engagement grooves  234 A that engage with the locking pieces  228  illustrated in  FIG. 2  are included at constant angular intervals in a circumferential direction in an inner peripheral part of the cap part  230 A. 
     Thus, when the cap part  230 A is abutted to the leading end part  222  illustrated in  FIG. 2  and the cap part  230 A is rotated in the first direction (such as rightward direction), the locking pieces  228  are engaged with the engagement grooves  234 A and the cap part  230 A is moved in the direction opposite to the protruding direction of the imaging tube  210 A and is firmly fixed to the leading end part of the main body part  220 A. 
     On the other hand, when the cap part  230 A is rotated in the second direction (such as leftward direction) opposite to the first direction, the cap part  230 A is moved in the protruding direction of the imaging tube  210 A until the engagement grooves  234 A are detached from the locking pieces  228 . 
     Anti-slip grooves  236 A are formed in an end part with the largest diameter of the cap part  230 A. The anti-slip grooves  236 A are provided in the entire circumference of the cap part  230 A as illustrated in a C-C cross section. 
       FIG. 15  is a perspective view of the examination tool  200 A according to the second embodiment. 
     The cap part  230 A is attached to the leading end part of the main body part  220 A. The cap part  230 A is firmly attached to the main body part  220 A by the locking pieces  228  provided at the leading end part and the engagement grooves  234 A in the cap part  230 A itself. The imaging tube  210 A protruding from the main body part  220 A penetrates the protective part  237 A of the cap part  230 A. The protective part  237 A protects the entire circumference of the imaging tube  210 A. 
     A camera  240 A that images an inner part of an ear is built in the main body part  220 A. An optical fiber  245 A is attached to the camera  240 A. The optical fiber  245 A is connected, through the imaging tube  210 A, to an imaging lens  260 A provided at the leading end part of the imaging tube  210 A. Thus, the camera  240 A is connected to the imaging lens  260 A via the optical fiber  245 A. Also, the imaging lens  260 A and an LED  270 A, which functions as the illumination unit, are arranged side by side in a radial direction in the leading end part of the imaging tube  210 A. 
     Thus, the imaging lens  260 A is prevented, with heat generated by the LED  270 A, from being fogged due to humidity inside an ear canal. 
     [Operation of Examination Tool] 
       FIGS. 16 to 18  are views for describing the operation of the examination tool  200 A according to the second embodiment. As illustrated in  FIG. 16 , when the examination tool  200 A is used, first, the protective part  237 A of the cap part  230 A is inserted into the imaging tube  210 A, and the cap part  230 A is slid along the imaging tube  210 A in a direction of an illustrated arrow until the cap part  230 A is abutted to the leading end part of the main body part  220 A. 
     When the cap part  230 A is abutted to the leading end part, the cap part  230 A is rotated in the first direction (rightward direction in drawing) as illustrated in  FIG. 17 . Then, the engagement grooves  234 A illustrated in  FIG. 14A, 14B  are engaged with the locking pieces  228  in  FIG. 2 , and the cap part  230 A is further moved in the direction of the illustrated arrow and is firmly attached to the main body part  220 A. 
     In this state, since the imaging tube  210 A is covered and protected by the protective part  237 A, the imaging tube  210 A is inserted into an ear canal and a state of an inner part of an ear is observed. During the observation of the state of the inner part of the ear, the LED  270 A illustrated in  FIG. 15  is on and the state of the inner part of the ear is imaged by the camera  240 A. Although humidity inside the ear canal is high depending on a kind of an animal, the imaging lens  260 A is not fogged since the imaging lens  260 A is warmed by the heat of the LED  270 A, 
     When the observation of the state of the inner part of the ear is over, the cap part  230 A is rotated in the second direction (leftward direction in drawing) as illustrated in  FIG. 18 . Then, the engagement grooves  234 A illustrated in  FIG. 14A, 14B  are detached from the locking pieces  228  in  FIG. 2  and the cap part  230 A is moved in a direction of an illustrated arrow. Thus, it becomes easier to detach the cap part  230 A from the imaging tube  210 A, 
     By an operator, the cap part  230 A that becomes easier to be detached is moved in the direction of the illustrated arrow and is detached from the imaging tube  210 A illustrated in  FIG. 18 . 
     As described above, according to the examination tool of the second embodiment, an introduction cost becomes low since a structure thereof is simple compared to a conventional one. Since fogging of the imaging lens  260 A is designed to be prevented, it is possible to observe an inner part of an ear with a clear image. Moreover, since the cap part  230 A can be replaced, high reliability can be secured in terms of hygiene. 
     Third Embodiment 
     In the third embodiment, a through hole penetrating the cap portion in the longitudinal direction provided in the cap portion according to the second embodiment. 
       FIG. 19A  is a cross section of a cap part of the examination tool according to the third embodiment.  FIG. 19B  is a Left side view of a cap part of the examination tool according to the third embodiment.  FIG. 19C  is a Right side view of a cap part of the examination tool according to the third embodiment. 
     As shown in FIG. 19 A,  19 B,  19 C, a through hole  253  is formed so as to pass through the protective portion  237 B in the longitudinal direction of the cap portion  230 B. 
     In the through hole  253 , for example, a medical instrument such as a forceps is inserted and held so as to be movable along the through hole  253 . 
       FIG. 20  is a configuration diagram of an examination tool according to third embodiment. 
     As shown in  FIG. 20 , the forceps  255  is passed through the through hole  253  shown in  FIG. 19 . The outer diameter of the forceps  255  is slightly smaller than the inner diameter of the through hole  253 . Therefore, the forceps  255  can be moved in the longitudinal direction of the cap portion  230 B. 
     As described above, according to the examination tool of the third embodiment, the examination tool  200 B can be provided with a medical device such as forceps  255 .