Patent Publication Number: US-2019175002-A1

Title: Endoscope

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of PCT/JP2016/081897 filed on Oct. 27, 2016, the entire contents of which are incorporated herein by this reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an endoscope including, on a rigid distal end portion, an image pickup unit including a stack of a plurality of semiconductor devices including an image pickup device. 
     2. Description of the Related Art 
     An endoscope acquires an image of an inside of a body of a patient, for example, by inserting an insertion section having a rigid distal end portion in which an image pickup unit is arranged into the inside of the body. Japanese Patent Application Laid-Open Publication No. 2005-334509 discloses an image pickup unit in which a wiring board on which electronic components such as a capacitor, a resistor, and an IC configuring a drive circuit are mounted is bonded to a rear surface of an image pickup device. 
     A length of an image pickup unit including a wiring board on which electronic components are mounted in an optical axis direction becomes long. Therefore, it is not easy to cause the rigid distal end portion of the endoscope to be short and small. 
     In recent years, semiconductor devices in which planar devices (thin film parts) having the same functions as electronic components such as a capacitor are formed have been developed. The image pickup unit can be caused to be short and small by a stack obtained by stacking a plurality of semiconductor devices in which the planar devices are formed with an image pickup device. 
     SUMMARY OF THE INVENTION 
     According to an embodiment of the present invention, there is provided an endoscope including: an insertion section including a rigid distal end portion; and a grip section arranged on a rear portion of the insertion section, in which: a first through hole and a second through hole are formed in the rigid distal end portion; an image pickup unit inserted in the first through hole and including a stack of a plurality of optical elements and a plurality of semiconductor devices including an image pickup device includes: a first block including the image pickup device; and a second block having an area in a direction orthogonal to an optical axis that is smaller than an area of the first block in the direction orthogonal to the optical axis; and a part of a component including a distal end portion inserted in the second through hole is arranged in an accommodation space in which a space obtained by extending the first block in an optical axis direction and a space obtained by extending the second block in the direction orthogonal to the optical axis are superimposed on each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an endoscope of a first embodiment; 
         FIG. 2  is a perspective view of a rigid distal end portion of the endoscope of the first embodiment; 
         FIG. 3  is a cross-sectional view of the rigid distal end portion of the endoscope of the first embodiment taken along line of  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of the rigid distal end portion of the endoscope of the first embodiment taken along line IV-IV of  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of the rigid distal end portion of the endoscope of the first embodiment taken along line V-V of  FIG. 3 ; 
         FIG. 6  is a perspective view of an image pickup unit of the endoscope of the first embodiment; 
         FIG. 7  is a cross-sectional view of a rigid distal end portion of an endoscope of a second embodiment; 
         FIG. 8  is a cross-sectional view of the rigid distal end portion of the endoscope of the second embodiment taken along line VIII-VIII of  FIG. 7 ; 
         FIG. 9  is a perspective view of an image pickup unit of an endoscope of a third embodiment; and 
         FIG. 10  is a front view of a rigid distal end portion of the endoscope of the third embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     First Embodiment 
     As illustrated in  FIG. 1 , an endoscope  90  of this embodiment includes an insertion section  9 B in which an image pickup unit  10  is accommodated in a rigid distal end portion  9 A, a grip section  9 C arranged on a rear portion of the insertion section  9 B, and a universal cord  9 D extending from the grip section  9 C. A signal cable  38  connected to the image pickup unit  10  passes through the universal cord  9 D. 
     As illustrated in  FIG. 2  to  FIG. 5 , in the rigid distal end portion  9 A of the endoscope  90 , not only the image pickup unit  10  but also a water feeding and air feeding tube  40  that is a component is arranged. Note that, as described below, the component arranged in the rigid distal end portion  9 A is not limited to the water feeding and air feeding tube  40 . 
     Note that, in the following description, the drawings based on each embodiment are schematic, and a relationship between a thickness and a width of each portion, a thickness ratio and a relative angle of each portion, and the like are different from actual relationships, thickness ratios, relative angles, and the like. Portions having different size relationships and ratios may also be included throughout the drawings. Further, drawing of some components may be omitted. 
     In the optical axis direction, a direction (Z-axis value increasing direction) in which a first block  20  is placed is referred to as a distal end side or a front side, and a direction (Z-axis value decreasing direction) in which a second block  30  is placed is referred to as a rear side. 
     A first through hole H 10  and a second through hole H 40  are formed in the rigid distal end portion  9 A formed by a metal or a rigid resin. The image pickup unit  10  is inserted in the first through hole, and the water feeding and air feeding tube  40  is inserted in the second through hole H 40 . 
     The image pickup unit  10  includes a lens unit including a plurality of optical members  21  to  26 , and a stack of a plurality of semiconductor devices  31  to  36  including an image pickup device  11 . 
     Further, as illustrated in  FIG. 6 , the image pickup unit  10  includes the first block  20  having a rectangular parallelepiped shape and including the lens unit and the image pickup device  11 , and the second block  30  having a rectangular parallelepiped shape. The second semiconductor device  32  that is a front surface of the second block  30  is bonded to the first semiconductor device  31  that is a rear surface of the first block  20 . The second block  30  is smaller than the first block  20  in terms of an area (a dimension in planar view) in a direction orthogonal to an optical axis. Therefore, an accommodation space S 40  in which a space S 20  obtained by extending the first block  20  in the optical axis direction and a space S 30  obtained by extending the second block  30  in the direction orthogonal to the optical axis are superimposed on each other is provided. 
     In other words, in the image pickup unit  10 , the second block  30  that is smaller than the first block  20  in terms of the dimension in planar view has three side surfaces that are respectively in the same planes as three side surfaces of the first block  20 , and has one side surface located on the optical axis side with respect to a side surface of the first block  20 . The first block  20  and the second block  30  both have a rectangular shape in planar view, and have the same width (dimension in an X direction) and different heights (dimension in a Y-axis direction). Further, the first block  20  and the second block  30  are bonded to each other so that sides in a height direction overlap with each other. 
     The water feeding and air feeding tube  40  includes a water feeding pipe  41  that is a first cylindrical member inserted in the second through hole H 40 , a flexible water feeding tube  42  that is a second cylindrical member put in an outer periphery of a rear end portion of the water feeding pipe  41 , and a thread member  43  wound around a connection portion between the water feeding pipe  41  and the water feeding tube  42 . In other words, the water feeding tube  42  is connected to a rear portion of the water feeding pipe  41 . 
     The water feeding tube  42  is firmly fixed to the water feeding pipe  41  by fixing the thread member  43  by an adhesive (not shown). A material of the thread member  43  is polyimide, PET (polyethylene terephthalate), or polyvinylidene fluoride, for example. The adhesive is an epoxy resin adhesive, for example. The thread member  43  has a diameter of from 0.05 mm to 0.3 mm, for example. 
     A part of the thread member  43  and a part of the water feeding tube  42  that are parts of the water feeding and air feeding tube  40 , a distal end portion of which is inserted in the second through hole H 40 , are arranged in the accommodation space S 40 . In other words, a cross-sectional shape of the water feeding and air feeding tube  40  is circular in the direction orthogonal to the optical axis, and the thread member  43  and the like that are parts of an outer peripheral portion of the water feeding and air feeding tube  40  are arranged in the accommodation space S 40 . 
     Now, the accommodation space S 40  is a space formed by the configuration of the image pickup unit  10 , but a part of the water feeding and air feeding tube  40  that is a component that is not directly related to the image pickup unit  10  is arranged in the accommodation space S 40 . In other words, the water feeding and air feeding tube  40  is not electrically connected to the image pickup unit  10 . 
     On the rigid distal end portion, components other than the image pickup unit such as a water feeding and air feeding tube are arranged. The water feeding and air feeding tube includes a water feeding pipe inserted in a through hole in the rigid distal end portion, a flexible water feeding tube connected to a rear portion of the water feeding pipe, and a thread member wound around a connection portion between the water feeding pipe and water feeding tube. When the layout of the water feeding and air feeding tube in the rigid distal end portion is designed in accordance with a winding portion having a largest outer diameter, an outer diameter of the rigid distal end portion becomes large. 
     However, a part of the water feeding and air feeding tube  40  is arranged in the accommodation space S 40 , and hence the rigid distal end portion  9 A of the endoscope  90  is small in diameter and minimally invasive. 
     For example, in an endoscope in which the outer diameter of the rigid distal end portion  9 A is about 3 mm, the outer diameter of the outer diameter of the rigid distal end portion  9 A can be reduced by from about 0.1 mm to about 0.5 mm by the configuration of the present invention. 
     Next, components of the endoscope  90  are described in detail. 
     The first block  20  of the image pickup unit  10  includes a concave lens  21  on the distal end, a transparent plate  22  in which an aperture is arranged, a spacer  23 , a transparent plate  24  configuring a convex lens, a spacer  25 , a cover glass  26 , the image pickup device  11 , and the first semiconductor device  31 . 
     Light that has entered the image pickup device  11  that is a CCD or a CMOS light receiving element via the concave lens  21  to the cover glass  26  is converted to an image pickup signal through photoelectric conversion, and the image pickup signal is transmitted to an electrode on the rear surface via through wiring (not shown). The image pickup device  11  and the first semiconductor device  31  are connected to each other via bonding portions such as bumps (not shown). 
     The second block  30  of the image pickup unit  10  includes the second semiconductor device  32 , the third semiconductor device  33 , the fourth semiconductor device  34 , the fifth semiconductor device  35 , and the sixth semiconductor device  36 . The second semiconductor device  32  to the sixth semiconductor device  36  are also connected via wiring and bumps (not shown). Note that spaces between the devices are sealed with sealing resin layers (underfilling). The sealing resin layer is formed by an insulating resin such as an epoxy resin, an acrylic resin, a polyimide resin, a silicone resin, or a polyvinyl resin. 
     In each of the first semiconductor device  31  to the sixth semiconductor device  36 , a planar device configuring an electronic component function circuit such as a capacitor, a resistor, or a buffer, or a signal processing circuit such as a noise reduction circuit or an analog-to-digital converter circuit is formed. The signal cable  38  is connected to a rear surface of the sixth semiconductor device  36  via a wiring board  37 . 
     A thickness of each of the semiconductor devices  31  to  36  is from about 30 μm to about 100 μm. The planar device may be formed on one surface or both surfaces of each of the semiconductor devices  31  to  36 . The number of the semiconductor devices  31  to  36  only needs to be two or more, and is not limited to six as in this example. 
     The first block  20  and the second block  30  are so-called wafer-level structures. For example, the first block  20  is manufactured by cutting stacked wafers obtained by bonding a plurality of optical wafers respectively including a plurality of optical members  21  to  26 , an image pickup device wafer including a plurality of the image pickup devices  11 , and a plurality of semiconductor wafers including a plurality of the first semiconductor devices  31 . The first block  20  and the second block  30  having different areas in the direction orthogonal to the optical axis are bonded to each other after the respective stacked wafers are cut. 
     Needless to say, although the productivity is not good, the first block  20  and the like may be manufactured by bonding a plurality of elements after cutting an element wafer including the plurality of elements. In contrast, the accommodation space S 40  may be manufactured by manufacturing stacked wafers in which all of the wafers are stacked, and grinding a region in which the planar device and the like are not formed through so-called step-cut dicing. The accommodation space S 40  may also be manufactured by removing a region in which the planar device and the like are not formed by etching. 
     Note that the first block  20  only needs to include the image pickup device  11 , and the first semiconductor device  31  may be included in the second block  30 . In contrast, a plurality of semiconductor devices may be included in the first block  20 . Further, the second block  30  only needs to include at least one semiconductor device. 
     As illustrated in  FIG. 5 , in the rigid distal end portion  9 A of the endoscope  90 , a rear portion of the first through hole H 10  that is located behind a rear opening of the second through hole H 40  is a groove T 20 , one surface of which is an opening. Further, a part of the groove T 20  configures the accommodation space S 40 . Therefore, by inserting the water feeding and air feeding tube  40  in the second through hole H 40  after inserting the image pickup unit  10  in the first through hole H 10  and the groove T 20 , the thread member  43  having a large outer diameter can be arranged in the accommodation space S 40 . Therefore, the endoscope  90  is easy to manufacture. 
     Second Embodiment 
     An endoscope  90 A of a second embodiment is similar to and has the same effect as the endoscope  90 , and hence components having the same functions are denoted by the same reference characters and description of those components are omitted. 
     As illustrated in  FIG. 7  and  FIG. 8 , in the endoscope  90 A, a metal member  45  made of copper, for example, is arranged on the water feeding pipe  41  made of metal of the water feeding and air feeding tube  40  that is a component. The metal member  45  is in abutment against the rear surface of the first block  20 . In other words, the endoscope  90 A is configured so that heat generated by the image pickup unit  10  is transferred to the water feeding and air feeding tube  40  via the metal member  45 . 
     An abutting surface between the metal member  45  and the rear surface of the first block  20  is large, and hence heat can be efficiently transferred. Note that, instead of the metal member  45  made of copper, a highly heat-conductive member formed by a highly heat-conductive material such as aluminum, silicon, AIN, or a graphite-metal composite material may be used. 
     Third Embodiment 
     An endoscope  90 B of a third embodiment is similar to and has the same effect as the endoscope  90 , and hence components having the same functions are denoted by the same reference characters and description of the components is omitted. 
     As illustrated in  FIG. 9 , in an image pickup unit  10 B of the endoscope  90 B, there are four accommodation spaces S 40 A, S 50 A, S 60 A, and S 70 A on a periphery of a second block  30 B. In other words, in the image pickup unit  10 B, the second block  30 B having a smaller dimension in planar view as compared to a first block  20 B is bonded to approximately a center of a rear surface of the first block  20 B. Further, as illustrated in  FIG. 10 , five through holes  1110 , H 40 , H 50 ,  1160 , and H 70  are formed in the rigid distal end portion  9 A. 
     The image pickup unit  10 B is inserted in the through hole H 10  in the center having a rectangular shape in planar view. The water feeding and air feeding tube  40  is inserted in the through hole  1140  having a circular shape in planar view. Light guides  50  and  60  are respectively inserted in the through holes H 50  and H 60  having a circular shape in planar view. A treatment instrument channel  70  is inserted in the through hole H 70  having a circular shape in planar view. 
     In each of the light guides  50  and  60 , a plurality of thin optical fibers are bundled, and an outer periphery is covered with a covering. The covering is removed from distal end portions inserted in the through holes H 50  and H 60 . On a rear portion of the distal end portion, the thread member is wound around the plurality of optical fibers. A part of the thread member is arranged in the accommodation spaces S 50 A and S 60 A. 
     The treatment instrument channel  70  inserted in the through hole H 70  has approximately the same configuration as the water feeding and air feeding tube  40 , and includes a distal end pipe, a flexible channel tube, and a thread member wound around a connection portion. A part of the thread member is arranged in the accommodation space S 70 A. 
     As described above, in the endoscope  90 B, at least the third through hole H 50  is further formed in the rigid distal end portion  9 A, and a part of the light guide  50 , which is a second component and has a distal end portion that is inserted in the third through hole H 50 , is arranged in the accommodation space S 50 A. 
     Needless to say, the second component may be a treatment instrument channel in the endoscopes  90  and  90 A, as well. A component having a distal end portion that is inserted in the through hole H 40  may be the treatment instrument channel. Further, as in the endoscope  90 B, four or more through holes may be formed in the rigid distal end portion  9 A, or a plurality of components may have the same configuration. Accommodation spaces may be above two side surfaces or above three side surfaces of the second block. 
     In the first to third embodiments, all the components having a distal end portion inserted in a through hole have a circular shape in terms of a cross-sectional shape (shape in planar view) of an outer peripheral surface in the direction orthogonal to the optical axis, but the components may be members having a rectangular shape, a polygonal shape, or the like. A component arranged in an accommodation space may be a member protruding from a part of the outer periphery of a component as with the metal member  45 . 
     The endoscope  90  and the like are soft endoscopes, but may be rigid endoscopes, and may be medical endoscopes or industrial endoscopes. 
     The present invention is not limited to the abovementioned embodiments, and various modifications, changes, and the like can be made within the range in which the gist of the present invention is not changed.