JP6744119B2 - Endoscope - Google Patents

Description

The present invention relates to an endoscope.

2. Description of the Related Art Conventionally, an endoscope for imaging the inside of a patient's body, equipment, or structure has prevailed in the medical field or industrial field. In this type of endoscope, the light from the imaging site is imaged on the light-receiving surface of the image sensor by the objective lens system at the insertion portion inserted into the observation target. The endoscope converts the image formation light into an electric signal and transmits it as an image signal to an external image processing device or the like via a signal cable.

For example, in an endoscope used in the medical field, in order to reduce the burden on the subject, it is important to further reduce the outer diameter of the insertion portion on the distal end side that is inserted into the body of the subject. ing. Conventionally, a normal diameter oral endoscopy has a maximum outer diameter of about 8 to 9 mm. Therefore, the base of the tongue is easily touched during insertion, which may cause nausea and dyspnea on the subject. Therefore, in recent years, small-diameter transnasal endoscopes have rapidly become popular. The narrow outer diameter endoscope has a maximum outer diameter of about 5 to 6 mm, which is about half that of a conventional oral endoscope. For this reason, a small-diameter nasal endoscope can be inserted nasally, and in combination with its thinness of about 5 mm, the vomiting reflex is small, and insertion is often not very bothersome.

For example, the electronic endoscope system 501 of Patent Document 1 shown in FIG. 31 mainly includes an endoscope 503, a light source device 505, a video processor 507, and a monitor 509. The endoscope 503 is configured to have a long and slender insertion portion 511, an operation portion 513, and a universal cable 515 which is an electric cable. The insertion portion 511 of the endoscope 503 is configured to have a distal end portion 517, a bending portion 519, and a flexible tube portion 521 in order from the distal end side to be inserted into the subject. The operation section 513 includes an operation section body 523 and a treatment instrument channel insertion section 525 that inserts various treatment instruments into the insertion section 511. A bending operation knob 527 for bending the bending portion 519 is provided on the operation portion main body 523. The bending operation knob 527 includes a UD bending operation knob 529 for bending the bending portion 519 in the up-down direction and an RL bending operation knob 531 for bending the bending portion 519 in the left-right direction.

Further, the endoscope 533 of Patent Document 2 shown in FIG. 32 includes an outer cylinder 535 at the tip portion. The outer cylinder 535 is provided with an imaging mechanism 539 covered with the filled light-shielding material 537. The image pickup mechanism 539 is optically coupled to the image pickup element 543 having the light receiving section 541 on one surface, the cover member 545 covering the surface of the image pickup element 543 on which the light receiving section 541 is provided, and the light receiving section 541 of the image pickup element 543. A lens unit 547 and a flexible printed wiring board 549 are provided. The lens unit 547 includes an objective cover member 551, a diaphragm 553, a plano-convex lens 555, a plano-convex lens 557, and a lens barrel 559 fixing these members from the objective side. The plano-convex lens 557 and the cover member 545 are fixed with an adhesive 561.

International Publication No. 2013/031276 International Publication No. 2013/146091

By the way, the endoscope is required to have a further smaller outer diameter (for example, the outer diameter of the insertion portion, which is the distal end side of Patent Document 1 or the objective side of Patent Document 2, is reduced). This is not for the existing small-diameter nasal endoscope described above, but for the existing small-diameter nasal endoscope, it is difficult to insert it into the body of the recipient (for example, a very thin tube such as a blood vessel). It is based on the medical demand to insert it into a hole and observe the details inside.

However, the endoscope 503 disclosed in Patent Document 1 has the appearance shown in FIG. 1 of the document and a description of an application example (for example, the insertion portion 511 for insertion into the digestive organs of the upper or lower part of the living body is It is presumed that it is mainly inserted into the digestive tract of the human body from a flexible so-called flexible endoscope). Therefore, it is difficult to insert the tube into a tube or hole having a very small diameter such as a blood vessel of a human body and observe the inside thereof.

Further, in the endoscope 533 disclosed in Patent Document 2, in the image pickup mechanism 539, the image pickup element 543 and the flexible printed wiring board 549 are larger than the outer diameter of the lens barrel 559 in the radial direction. In addition to this, the endoscope 533 has a configuration in which an imaging mechanism 539 made of these members is housed in the outer cylinder 535, and the imaging mechanism 539 is covered with the light shielding material 537 filled in the outer cylinder 535. For this reason, the distance between the image pickup element 543 and the flexible printed wiring board 549 protruding outside the lens barrel 559 in the radial direction, and the thickness of the outer cylinder 535 are structures that are disadvantageous for downsizing. Further, since the outer cylinder 535 is required, the number of parts is increased and the cost is increased.

The present invention has been made in view of the above circumstances, and provides an endoscope that can be downsized (for example, the outer diameter of the insertion portion on the distal end side can be reduced) and the cost can be reduced. To do.

According to the present invention, a single lens having a quadrangular outer shape in a direction perpendicular to the optical axis and a square outer shape in a direction perpendicular to the optical axis, one side of which has the longest length of the single lens. and an imaging element have a length than the sides to cover the imaging plane of the imaging element, the same element cover glass and the outer shape of the outer shape in a direction perpendicular to the optical axis the image sensor, of said single lens An outer peripheral surface, a mold portion for covering and fixing the element cover glass and the image pickup device with a molding resin, and the single lens and the single lens in which the optical axis of the single lens is aligned with the center of the image pickup surface. The element cover glass and the element cover glass are fixed by an adhesive resin, and the single lens is formed into a prismatic shape, and the first surface on the subject side is a flat surface and the second surface on the imaging side is a convex surface. The central portion of the one lens has a convex curved surface that bulges in a substantially spherical shape that constitutes the lens surface of the convex surface on the imaging side, and the peripheral portion of the single lens has a flat end surface and the end surface. and in the whole have a bonding surface of the element cover glass in contact with said single lens, and a frame-shaped surface of the element cover glass exposed protrudes from said single lens is covered with the mold portion To provide an endoscope.

Further, according to the present invention, an octagonal single lens in which the long side and the short side are alternately arranged and the outer shape in the direction perpendicular to the optical axis is opposed, and the outer shape in the direction perpendicular to the optical axis is a square. And an outer shape in a direction perpendicular to the optical axis that covers an image pickup surface of the image pickup element and an image pickup element whose one side length is the same as a distance between a pair of long sides facing each other of the single lens. Has an element cover glass having the same outer shape as the image pickup element, an outer peripheral surface of the single lens, and a mold part for covering and fixing the element cover glass and the image pickup element with a mold resin. The single lens having the optical axis of the single lens aligned with the center of the element cover glass and the element cover glass are fixed by an adhesive resin, and the single lens is formed in an octagonal prism shape, and the first surface on the object side. Is a plane, and the second surface on the image pickup side is a lens having a convex surface, and the central portion of the single lens has a convex curved surface that is raised in a substantially spherical shape that constitutes the lens surface of the convex surface on the image pickup side. and peripheral edge portions of said single lens is an end planar and have a bonding surface between the element cover glass in the entire of the end surfaces in contact with said single lens, and the octagonal each short entrance corner surfaces of the element cover glass exposed protrudes from the side, the Ru-covered molded part, provides an endoscope.

According to the present invention, it is possible to reduce the size and cost of an endoscope.

Overall configuration diagram showing an example of an endoscope system using the endoscope of the present embodiment FIG. 3 is a perspective view showing a state in which the distal end portion of the endoscope of the present embodiment is viewed from the front side. Sectional drawing which shows the structural example of the front-end|tip part of the endoscope of this embodiment. Sectional drawing which shows the structural example of the state in which the lens and imaging element in the endoscope of this embodiment were directly attached via the adhesive resin. FIG. 3 is a perspective view showing a state in which an image pickup device in which a transmission cable is connected to a conductor connecting portion of the endoscope of the present embodiment is viewed from the rear side. The figure which shows the 1st example of the lens shape in the endoscope of this embodiment. The figure which shows the 1st example of the lens shape in the endoscope of this embodiment. The figure which shows the 1st example of the lens shape in the endoscope of this embodiment. The figure which shows the 2nd example of the lens shape in the endoscope of this embodiment. The figure which shows the 2nd example of the lens shape in the endoscope of this embodiment. The figure which shows the 2nd example of the lens shape in the endoscope of this embodiment. The figure which shows the 3rd example of the lens shape in the endoscope of this embodiment. The figure which shows the 3rd example of the lens shape in the endoscope of this embodiment. The figure which shows the 3rd example of the lens shape in the endoscope of this embodiment. The figure which shows the 3rd example of the lens shape in the endoscope of this embodiment. The figure which shows the structural example of the adhesive surface with the element cover glass in the lens of the endoscope of this embodiment. The figure which shows the 1st example of the image pick-up element in the endoscope of this embodiment. The figure which shows the 1st example of the image pick-up element in the endoscope of this embodiment. The figure which shows the 2nd example of the image sensor in the endoscope of this embodiment. The figure which shows the 2nd example of the image sensor in the endoscope of this embodiment. The figure which shows the 3rd example of the image pick-up element in the endoscope of this embodiment. The figure which shows the 3rd example of the image pick-up element in the endoscope of this embodiment. Side sectional view in which the sheath in the endoscope of the present embodiment extends to the distal end A perspective view showing an example in which the lens of the endoscope of the present embodiment has a quadrangular shape and the imaging surface has a square shape Side view of FIG. 24 A perspective view showing an example in which the lens of the endoscope of the present embodiment is rectangular and the image sensor is square. 26 is a perspective view of the rectangular lens shown in FIG. 26 in the endoscope of the present embodiment. Front view of the rectangular lens shown in FIG. 26 in the endoscope of the present embodiment. A perspective view showing an example in which the lens of the endoscope of the present embodiment has an octagonal shape and the image pickup element has a square shape. The side view of FIG. Overall configuration diagram of an electronic endoscope system including a conventional endoscope Partial cross-sectional view showing an example of a conventional endoscope end structure

Hereinafter, an embodiment (hereinafter referred to as the present embodiment) in which the endoscope according to the present invention is specifically disclosed will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed description of well-known matters and repeated description of substantially the same configuration may be omitted. This is for avoiding unnecessary redundancy in the following description and for facilitating understanding by those skilled in the art. It should be noted that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the claimed subject matter by these.

First, a basic configuration example common to the endoscope of the present embodiment will be described. In addition, the configuration example is a configuration requirement that can be included in the endoscope according to the present invention. The endoscope according to the present invention does not exclude that the following respective configuration examples are overlapped with each other.

<Basic configuration example>
FIG. 1 is an overall configuration diagram showing an example of an endoscope system using the endoscope of this embodiment.
FIG. 1 is a perspective view showing the entire configuration of the endoscope system 13 including the endoscope 11 and the video processor 19.

It should be noted that the directions used in the description in this specification follow the description of the directions in the drawings. Here, "upper" and "lower" correspond to the upper and lower sides of the video processor 19 placed on a horizontal plane, respectively, and "front (forward)" and "rear" refer to the endoscope body (hereinafter referred to as "endoscope 11"). ") corresponding to the distal end side of the insertion portion 21 and the proximal end side of the plug portion 23 (in other words, the video processor 19 side).

As shown in FIG. 1, the endoscope system 13 converts a still image or a moving image obtained by photographing the inside of an observation target (for example, a blood vessel of a human body) and the endoscope 11 that is a flexible endoscope for medical use. On the other hand, the configuration includes a video processor 19 that performs well-known image processing and the like. The endoscope 11 includes an insertion portion 21 that extends substantially in the front-rear direction and is inserted into an observation target, and a plug portion 23 to which the rear portion of the insertion portion 21 is connected.

The video processor 19 has a socket portion 27 that opens to the front wall 25. The rear portion of the plug portion 23 of the endoscope 11 is inserted into the socket portion 27, whereby the endoscope 11 can transmit and receive power and various signals (video signal, control signal, etc.) to and from the video processor 19. Is.

The power and various signals described above are guided from the plug portion 23 to the flexible portion 29 via the transmission cable 31 (see FIG. 3 or 4) inserted through the flexible portion 29. The image data output by the image sensor 33 provided at the tip portion 15 is transmitted from the plug portion 23 to the video processor 19 via the transmission cable 31. The video processor 19 performs well-known image processing such as color correction and gradation correction on the image data transmitted from the plug unit 23, and outputs the image data after the image processing to a display device (not shown). The display device is, for example, a monitor device having a display device such as a liquid crystal display panel, and displays an image of a subject imaged by the endoscope 11 (for example, image data showing the inside of a blood vessel of a person who is the subject).

The insertion portion 21 has a flexible flexible portion 29 whose rear end is connected to the plug portion 23, and a distal end portion 15 which is continuous with the distal end of the flexible portion 29. The flexible portion 29 has an appropriate length corresponding to various types of endoscopy, endoscopic surgery, and the like. The flexible portion 29 is formed by, for example, covering the outer circumference of a metal thin plate spirally wound with a net and further covering the outer circumference thereof with sufficient flexibility. The flexible portion 29 connects between the tip portion 15 and the plug portion 23.

The endoscope 11 of the embodiments described below can be inserted into a body cavity having a small diameter by forming the insertion portion 21 with a small diameter. The small-diameter body cavity is not limited to a blood vessel of the human body and includes, for example, a ureter, a pancreatic duct, a bile duct, a bronchiole. That is, the endoscope 11 can be inserted into a blood vessel, a ureter, a pancreatic duct, a bile duct, a bronchiole, etc. of a human body. In other words, the endoscope 11 can be used for observing a lesion in a blood vessel. The endoscope 11 is effective in identifying arteriosclerotic plaque. Further, it can be applied to observation with an endoscope at the time of cardiac catheter inspection. Further, the endoscope 11 is also effective for detecting thrombus and arteriosclerotic yellow plaque. In the arteriosclerotic lesion, a color tone (white, light yellow, yellow) and a surface (smooth, irregular) are observed. Colors (red, white, dark red, yellow, brown, mixed colors) are observed in the thrombus.

In addition, the endoscope 11 can be used for diagnosis and treatment of renal pelvis/ureteral cancer and idiopathic renal hemorrhage. In this case, the endoscope 11 can be inserted into the bladder through the urethra and further advanced into the ureter to observe the inside of the ureter and renal pelvis.

In addition, the endoscope 11 can be inserted into the Vater papilla that opens into the duodenum. Bile is drained from the liver and through the bile ducts, and pancreatic juice from the pancreas and through the ducts and from the Vater papilla in the duodenum. The endoscope 11 can be inserted through the papilla of Vater, which is the opening of the bile duct and the pancreatic duct, and enables observation of the bile duct or the pancreatic duct.

Furthermore, the endoscope 11 can be inserted into the bronchus. The endoscope 11 is inserted through the oral cavity or nasal cavity of the sample (that is, the subject) in the supine position. The endoscope 11 passes through the pharynx and the larynx and is inserted into the trachea while observing the vocal cords. The bronchus becomes thinner each time it branches. For example, with the endoscope 11 having the maximum outer diameter Dmax of less than 2 mm, it is possible to confirm the lumen up to the subsegmental bronchus.

Next, various configuration examples of the endoscope of this embodiment will be described. The endoscope 11 of the present embodiment can have each configuration of the first configuration example to the thirteenth configuration example.

In the following description, the term “adhesive” does not have a strict meaning of a substance used to bond the surfaces of solid objects to each other, but also a substance that can be used to bond two objects or a cured material. When the adhesive has a high barrier property against gas and liquid, it is broadly used as a substance having a function as a sealant.

<First configuration example>
FIG. 2 is a perspective view showing a state in which the distal end portion 15 of the endoscope 11 of the present embodiment is viewed from the front side. FIG. 3 is a cross-sectional view showing a configuration example of the distal end portion 15 of the endoscope 11 of this embodiment. In the endoscope 11 shown in FIG. 2, the maximum outer diameter Dmax of the distal end portion 15 shown in FIG. 3 is formed within a range of a finite diameter to 1.0 mm corresponding to the diameter of the circumscribed circle of the substrate of the dicing imageable element 33. can do.

In the endoscope 11 of the present embodiment, as the image pickup element 33 having a square cross section in a direction perpendicular to the axial direction passing through the optical axis or the lens center, one having a side dimension of 0.5 mm or less is used. .. As a result, in the endoscope 11, the diagonal dimension of the image pickup element 33 is about 0.7 mm, and the maximum outer diameter Dmax is 1.0 mm or less including the light guide 57 (for example, φ50 μm) as the illumination means. It will be possible.

As described above, according to the endoscope 11 of the first configuration example, by setting the maximum outer diameter Dmax to be less than 1.0 mm, insertion into a blood vessel of a human body can be further facilitated.

<Second configuration example>
In the endoscope 11 of the second configuration example, in the endoscope 11 of the present embodiment, as shown in FIG. 5, the substrate of the image pickup element 33 is formed in a square shape, and the conductor connection part 49 is formed in the image pickup element 33. It is located at the four corners of the board. One conductor connecting portion 49 is formed, for example, in a circular shape. The four conductor connecting portions 49 are arranged at the four corners of the square, so that they can be arranged at the maximum distance from each other.

In the transmission cable 31, the conductors of the power line and the signal line, which are the electric wires 45, are covered with an insulating coating. The four electric wires 45 are arranged in two rows on the left and right and in two steps on the upper and lower sides, and the outer circumference of the insulating coating is further bundled by the jacket to form a single transmission cable 31. Each conductor is formed into four parallel straight lines with the insulating coating removed. In the electric wire 45, the tip of this conductor is connected to the conductor connecting portion 49 by soldering. The image pickup element 33 and the transmission cable 31 are covered with the mold resin 17, as shown in FIG. Therefore, the conductor connecting portion 49, the conductor, the insulating coating of the electric wire 45, and the jacket of the transmission cable 31 are embedded in the molding resin 17.

As described above, according to the endoscope 11 of the second configuration example, since the four conductor connecting portions 49 can be arranged at the four corners of the substrate of the image pickup element 33, the four conductor connecting portions 49 can be arranged in the square image pickup element 33. On the substrate, as shown in FIG. 5, they can be evenly spaced from each other with a maximum distance. As a result, the two adjacent conductor connecting portions 49 are not connected by solder in the soldering process, the insulation distance is easily secured, and the diameter of the tip portion 15 can be easily reduced. ..

<Third configuration example>
FIG. 4 is a cross-sectional view showing a configuration example in a state where the lens 93 and the image pickup device 33 in the endoscope 11 of the present embodiment are directly attached via the adhesive resin 37. As shown in FIG. 4, the endoscope 11 of the third configuration example includes an objective cover glass 91, an element cover glass 43, an image pickup element 33 whose image pickup surface 41 is covered with the element cover glass 43, and an objective cover glass 91. Lens 93, which is sandwiched between the element cover glass 43 and the element cover glass 43, and whose optical axis coincides with the center of the imaging surface 41, the diaphragm 51 provided between the objective cover glass 91 and the lens 93, the lens 93 and the element cover glass. An adhesive resin 37 for fixing 43 to each other and an air layer 95 provided between the lens 93 and the element cover glass 43 are provided.

The image pickup device 33 is formed of, for example, a small CCD (Charge Coupled Device) or CMOS (Complementary Metal-Oxide Semiconductor) image pickup device having a square shape when viewed from the front-rear direction. That is, the image sensor 33 has a square outer shape in a direction perpendicular to the optical axis of the lens 93 or the axial direction passing through the lens center. In the image sensor 33, the light incident from the outside passes through the diaphragm 51 provided between the objective cover glass 91 and the lens 93, and the passed light is imaged on the imaging surface 41 by the lens 93. Further, in the image pickup element 33, the image pickup surface 41 is covered with the element cover glass 43. The element cover glass 43 has a square outer shape in the direction perpendicular to the optical axis, and the length of one side thereof is the same as the length of one side of the image pickup element 33.

The adhesive resin 37 is made of, for example, UV/thermosetting resin. The adhesive resin 37 is preferably transparent and has a refractive index close to that of air. When a UV/thermosetting resin is used as the adhesive resin 37, the outer surface portion can be cured by ultraviolet irradiation, and the inside of the filled adhesive that cannot be irradiated with ultraviolet light can be cured by heat treatment. The adhesive resin 37 fixes the lens 93 whose optical axis is aligned with the center of the imaging surface 41 to the element cover glass 43. As a result, the lens 93 and the image pickup element 33 are directly bonded and fixed by the adhesive resin 37, that is, the lens 93 and the image pickup element 33 are directly attached via the adhesive resin 37. The adhesive resin 37 is, for example, a type of adhesive that requires heat treatment in order to obtain the final hardness, but is cured to a certain degree of hardness even when irradiated with ultraviolet rays.

In the endoscope 11 of this embodiment, the lens 93 and the element cover glass 43 are directly attached via the adhesive resin 37. As a result, in the endoscope 11, the adhesive resin 37 becomes substantially linear in a side view (see FIG. 5). FIG. 5 is a perspective view showing a state in which the image pickup device 33 in which the transmission cable 31 is connected to the conductor connection portion 49 of the endoscope 11 of the present embodiment is viewed from the rear side. Further, in the endoscope 11 of the present embodiment, the lens 93 and the element cover glass 43 are directly attached to the edge portions on both ends of the lens 93 by the adhesive resin 37, and the adhesive resin 37 is attached to the edge portion. Only applied.

The lens 93 is, for example, a single lens, is formed in the same prismatic shape as the outer shape of the image sensor 33, and has a square cross section in a direction perpendicular to the optical axis or the axis passing through the lens center. The lens 93 forms an image of incident light from the subject that has passed through the objective cover glass 91 on the image pickup surface 41 of the image pickup device 33 via the element cover glass 43. A concave portion is formed on the surface of the lens 93 on the element cover glass 43 side. A convex curved surface portion 97 that is raised in a substantially spherical shape is formed on the bottom surface of the concave portion. The lens 93 has a function as an optical element that focuses light by the convex curved surface portion 97. The protruding tip of the convex curved surface portion 97 is slightly separated from the element cover glass 43. On the other hand, in the lens 93, a rectangular annular end surface surrounding the recess is bonded to the element cover glass 43 via the bonding resin 37. As a result, air is sealed in the concave portion between the lens 93 and the element cover glass 43. It is preferable that the air enclosed in the recessed space is dry air. Further, nitrogen may be filled in the recess. Thus, the air layer 95 having the concave portion as the internal volume is formed between the lens 93 and the element cover glass 43. A convex curved surface portion 97 is arranged in the air layer 95. That is, in the lens 93, the light emitting surface of the convex curved surface portion 97 is in contact with air.

In the endoscope 11 having the maximum outer diameter Dmax of 1.0 mm, whether or not the number of lenses can be reduced is an important requirement for reducing the diameter. Therefore, when the lens 93, which is a single lens, is provided in the endoscope 11, it is important how to make the refractive index difference with the lens 93 in a minute region in the width direction parallel to the optical axis direction. Thus, the endoscope 11 of the third configuration example is characterized in that an air layer capable of obtaining a large refractive index difference with the lens 93 is provided on the optical element surface.

As described above, according to the endoscope 11 of the third configuration example, the concave portion is formed in the lens 93, the convex curved surface portion 97 is formed on the bottom surface, and the square annular end surface is bonded to the element cover glass 43. An air layer 95 for increasing the refractive index difference with the lens 93 can be secured in such a region. At the same time, the lens 93 can easily align the optical axis with the imaging surface 41. Since the lens 93 can secure the air layer 95, a large lens power can be obtained between the lens 93 and the lens 93. As a result, the number of lenses in the endoscope 11 can be reduced to one. As a result, it is possible to reduce the size and cost of the endoscope 11.

<Fourth configuration example>
In the endoscope 11 of the fourth configuration example, in the endoscope 11 of the present embodiment, as shown in FIG. 3, the outer peripheral surface of the objective cover glass 91 excluding the objective surface, the outer peripheral surface of the lens 93, and the imaging element 33 are provided. A mold portion 65 which is covered and fixed by the mold resin 17 and which forms the outer shell of the tip portion 15 and is exposed to the outside; and a mold portion 65 which is formed with the same outer diameter as the tip portion 15 and covers at least a part of the mold portion 65. And a tubular sheath 61 to be connected.

The sheath 61 is made of a flexible resin material. The sheath 61 can be provided with a single wire, a plurality of wires, or a braided tensile strength wire on the inner peripheral side for the purpose of imparting strength. Examples of the tensile strength wire include aramid fiber such as poly-p-phenylene terephthalamide fiber, polyarylate fiber, polyparaphenylene benzbisoxazole fiber, polyester fiber such as polyethylene terephthalate fiber, nylon fiber, fine wire of tungsten, or stainless steel. As an example, a thin line can be cited. The sheath 61 is made of a flexible resin material as described above. Further, the sheath 61 can be provided with a single wire, a plurality of wires, or a braided tensile strength wire on the inner peripheral side for the purpose of imparting strength as described above. The material of the tensile strength wire is the same as above.

In the endoscope 11, the objective cover glass 91, the lens 93, the element cover glass 43, the entire image pickup element 33, a part of the transmission cable 31, and a part of the light guide 57 are covered with the mold resin 17 and fixed. The mold resin 17 is exposed to the outside. The distal end portion 15 of the endoscope 11 may include a radiopaque marker. This makes it easy to confirm the tip position of the endoscope 11 under fluoroscopy.

In the endoscope 11, an illumination unit is provided along the objective cover glass 91, the lens 93, the element cover glass 43, and the image pickup element 33. That is, the endoscope 11 of the fourth configuration example has the light guide 57 as an example of the illumination means. Hereinafter, the case where the illuminating means is the light guide 57 will be described as an example, but in addition to this, the illuminating means may be an LED directly attached to the insertion tip surface of the tip portion 15. In this case, the light guide 57 becomes unnecessary.

The light guide 57 is composed of one optical fiber 59. As the optical fiber 59, for example, a plastic optical fiber (POF: Plastic Optical Fiber) is preferably used. The plastic optical fiber has a core and a clad made of plastic by using silicon resin or acrylic resin as a material. Further, the optical fiber 59 may be, for example, a bundle fiber in which a plurality of optical fiber strands are bundled and terminal fittings are attached to both ends thereof. The tip end of the optical fiber 59 serves as the emitting end face at the tip portion 15, and the base end is connected to the ferrule of the plug portion 23. The light source is, for example, an LED provided in the socket portion 27 or the like. In the endoscope 11, by connecting the plug portion 23 to the socket portion 27, the light from the LED propagates through the optical fiber 59 of the light guide 57 and is emitted from the tip. According to this configuration, it is possible to configure from the light source to the emission end of the illumination light with one optical fiber, and it is possible to reduce the optical loss.

As described above, according to the endoscope 11 of the fourth configuration example, by including the light guide 57, it is possible to use the endoscope 11 alone to enable photographing in a dark part.

Further, as shown in FIG. 2, in the endoscope 11 of the fourth configuration example, the light guide 57 as an example of the illumination means includes the objective cover glass 91, the lens 93, the element cover glass 43, and the imaging element 33. It is a configuration in which a plurality is provided in the periphery. For example, four light guides 57 can be evenly provided at equal intervals. As a result, according to the endoscope 11 of the fourth configuration example, the four light guides 57 are evenly spaced around the objective cover glass 91, the lens 93, the element cover glass 43, and the imaging element 33. Since it is provided, shadows are less likely to occur on the top, bottom, left, and right of the subject. As a result, the endoscope 11 can obtain a clear captured image as compared with the configuration having one light guide 57 or the configuration having two light guides 57.
Further, in the endoscope 11 of the present embodiment, the image pickup element 33 is formed in a rectangular shape. The optical fibers 59 of the four light guides 57 are arranged substantially in the center of each side of the substrate of the image pickup element 33 in the space between the substrate of the image pickup element 33 and the circumscribed circle of the substrate of the image pickup element 33. There is.

As described above, according to the endoscope 11 of the fourth configuration example, the space sandwiched between the square image pickup device 33 and the circular mold part 65 that is substantially circumscribed with the image pickup device 33 can be effectively used, and the distal end portion 15 can be effectively used. It is possible to easily dispose a plurality of (especially four) optical fibers 59 without increasing the outer diameter. As a result, the endoscope 11 can obtain a clear image while facilitating the manufacture without increasing the outer diameter of the distal end portion 15.

In the endoscope 11, the objective cover glass 91, the lens 93, the element cover glass 43, the image pickup element 33, a part of the transmission cable 31, and a part of the light guide 57 (image pickup unit) are covered with the mold resin 17 and fixed. Therefore, there are few intervening parts when fixing these members. As a result, the diameter of the distal end portion 15 of the endoscope 11 can be reduced, and even when the diameter is further reduced, the diameter can be minimized. Also, the cost of parts can be reduced. For example, it is possible to realize the endoscope 11 which can be applied so as to be able to image a diseased part having a very small diameter such as a blood vessel of a human body. As a result, the size and cost of the endoscope 11 can be reduced.

Further, since the mold resin 17 is molded so as to cover the image pickup device 33 to the objective cover glass 91, it contributes to increase the fixing strength of these image pickup units. Further, the mold resin 17 also enhances the airtightness (that is, there is no fine gap), the watertightness, and the light shielding property of the air layer 95. Further, the molding resin 17 also enhances the light blocking effect when the optical fiber 59 for the light guide 57 is embedded.

Further, since the light guide 57 is molded on the distal end portion 15 of the endoscope 11 by the molding resin 17, the light guide 57 acts as a structural material, and even in the small-diameter endoscope 11, the flexible portion 29 and the distal end thereof are combined. The connection strength with the part 15 can be improved. Further, in the endoscope 11, when the distal end portion 15 is viewed from the insertion-side outermost surface (see, eg, FIG. 2), the mold resin 17 covers the objective cover glass 91 of the distal end portion 15 and the four optical fibers 59. Therefore, there is no clearance around each of the objective cover glass 91 and the four optical fibers 59 (that is, a clearance around each). Therefore, when the endoscope 11 is subjected to a sterilizing action (that is, washed) after being used in an examination or an operation, uncleaned residue such as unnecessary liquid may adhere to the endoscope 11. It is reduced, and it is possible to have a higher degree of convenience in terms of hygiene when it is used for the next examination or surgery.

Further, in the conventional endoscope 533 shown in Patent Document 2, the axis line of the distal end portion and the optical axis of the lens unit 547 are eccentric. Therefore, the distance to the subject easily changes depending on the rotation angle of the tip portion, and it is difficult to stably obtain a good image. Further, when the axis of the tip portion and the optical axis of the lens unit 547 are eccentric, the degree of interference between the inner wall of the tube and the tip portion changes depending on the rotation angle of the tip portion, and especially when entering a hole having a small diameter. Sex decreases. On the other hand, according to the endoscope 11, the objective cover glass 91, the lens 93, the element cover glass 43, and the imaging element 33 are coaxially connected. That is, the objective cover glass 91 is arranged concentrically with the tip portion 15. As a result, in the endoscope 11 of the fourth configuration example, the diameter can be easily reduced, a good image can be stably obtained, and the insertion operability can be improved.

<Fifth configuration example>
In the endoscope 11 of the fifth configuration example, it is preferable that the thickness of the sheath 61 be in the range of 0.1 to 0.3 mm.

The mold portion 65 of the endoscope 11 has a small-diameter extension portion 71 shown in FIG. 3 that extends rearward from the rear end that covers the imaging element 33. The small-diameter extending portion 71 is formed in a columnar shape and has four optical fibers 59 embedded therein. The small-diameter extending portion 71 has the transmission cable 31 embedded inside the four optical fibers 59. The inner diameter side of the sheath 61 is fixed to the outer periphery of the small diameter extension portion 71 with an adhesive or the like. That is, the mold portion 65 and the sheath 61 are continuous with a maximum outer diameter Dmax of 1.0 mm that is coaxial.

As described above, according to the endoscope 11 of the fifth configuration example, since the thickness of the sheath 61 can be increased to 0.3 mm, it becomes easy to increase the tensile strength of the sheath 61. The minimum outer diameter of the transmission cable 31 is currently about 0.54 mm. When the maximum outer diameter Dmax of the tip portion 15 is 1.0 mm, the thickness of the sheath 61 is 0.23 mm. Thereby, the endoscope 11 makes it possible to set the maximum outer diameter Dmax of the distal end portion 15 to 1.0 mm by setting the thickness of the sheath 61 in the above range of 0.1 to 0.3 mm. be able to.

<Sixth configuration example>
The sixth configuration example shows a configuration example of a lens shape as a specific example of the configuration of the lens 93 in the endoscope 11. 6, 7, and 8 are diagrams showing a first example of the lens shape in the endoscope 11 of the present embodiment.

The lens 93A of the first example is configured by a single lens in which the first surface LR1 on the subject side is a flat surface and the second surface LR2 on the imaging side is a convex surface. On the imaging side of the lens 93A, an optical element unit 201 having a circular dome-shaped convex curved surface portion 97 which is convex in a substantially spherical shape and which forms the lens surface of the convex second surface LR2 is formed in the central portion, and the peripheral portion is formed. The edge portion 202 is integrally formed as a frame body having an end face having a flat adhesive surface 203. The edge portion 202 has a larger dimension in the thickness direction (optical axis direction) than the central portion of the convex curved surface portion 97 of the optical element portion 201, and the bonding surface 203 of the edge portion 202 has a shape protruding from the convex curved surface portion 97. The adhesive resin 37 adheres to the entire area of the adhesive surface 203 and is fixed to the element cover glass 43. The bonding surface 203 of the edge portion 202 has a substantially square shape in which the outer peripheral portion is square and the inner peripheral portion is rounded square, and the four sides excluding the corner portions have substantially the same width. In the bonding surface 203 of the edge portion 202, the bonding width Wa of the equal width portion of the four sides is, for example, 50 μm or more. On the inner side of the edge portion 202, an air layer 95 is formed between the convex curved surface portion 97 serving as the lens surface of the second surface LR2 and the element cover glass 43.

The dimension of the lens 93 in the thickness direction (thickness SRt) is, for example, 100 μm to 500 μm. In the illustrated example, the thickness TE of the edge portion 202 is 200 μm, and the thickness TL to the first surface LR1 in the outer peripheral portion of the convex curved surface portion 97 (second surface LR2) of the optical element portion 201 is 110 μm to 120 μm. Further, from the outer peripheral portion of the convex curved surface portion 97 of the optical element portion 201 to the inner peripheral portion of the adhesive surface 203 of the edge portion 202, there is an inclined surface 204 that spreads from the lens center toward the outer periphery. The angle θA of the inclined surface 204 is, for example, θA=60° when the angle θA of the opening viewed from the center of the lens is set.

9, 10, and 11 are diagrams showing a second example of the lens shape in the endoscope 11 of the present embodiment. The lens 93B of the second example is an optical element in which, on the imaging side of the lens 93B, the central portion has a convex dome-shaped convex curved surface portion 97 that is raised in a substantially spherical shape that constitutes the lens surface of the convex second surface LR2. The portion 201 is formed, and the peripheral portion is integrally formed with the edge portion 202 which is a frame body having an adhesive surface 203 having a flat end surface. Here, the description will focus on the configuration of the parts different from the first example, and the description of the parts similar to the first example will be omitted. The adhesive surface 203 of the edge portion 202 is a circular shape having a square outer peripheral portion and an inner peripheral portion concentric with the convex curved surface portion 97 having a circular dome shape, and the minimum portion adhesive width Wa is, for example, 50 μm. There is. In addition, the width Wc of the flat surface portion 205 formed on the outer peripheral portion of the convex curved surface portion 97 (second surface LR2) of the optical element portion 201 is, for example, 13 μm. Further, from the flat surface portion 205 of the outer peripheral portion of the optical element portion 201 to the inner peripheral portion of the bonding surface 203 of the edge portion 202, there is an inclined surface 204 that spreads from the lens center toward the outer periphery. The angle θA of the inclined surface 204 is, for example, θA=60° when the angle θA of the opening viewed from the center of the lens is set.

12, 13, 14, and 15 are diagrams showing a third example of the lens shape in the endoscope 11 of the present embodiment. The lens 93C of the third example is an optical element in which, on the imaging side of the lens 93C, the central portion has a convex dome-shaped convex curved surface portion 97 that is raised in a substantially spherical shape that constitutes the lens surface of the convex second surface LR2. The portion 201 is formed, and the peripheral portion is integrally formed with the edge portion 202 which is a frame body having an adhesive surface 203 having a flat end surface. Here, the description will focus on the configuration of the parts different from the first example, and the description of the parts similar to the first example will be omitted. The optical element unit 201 in the central portion has a barrel shape in which four portions 206 on the circumference corresponding to the four sides of the square of the lens outer shape are partially cut out in the outer peripheral portion of the convex curved surface portion 97 of the circular dome shape. Has become. In the peripheral edge portion 202, an inclined surface 204 is formed from the inner peripheral portion of the adhesive surface 203 to the outer peripheral portion of the barrel-shaped optical element portion 201. As shown in FIG. 15, the lens 93C of the third example is an unnecessary portion of the image circle 212 of the circular lens 93C, that is, outside the four sides of the imaging surface 211, with respect to the imaging surface 211 of the square imaging element 33. It has a shape obtained by cutting the four outer peripheral areas 214 on which the light rays that are focused on the area 213 are incident. The angle θA of the inclined surface 204 at the inner peripheral portion of the edge portion 202 is, for example, θA=90° when the angle θA of the opening viewed from the center of the lens is set, and the inclination is smaller than that in the first and second examples. It can be formed gently. On the other hand, similarly to the first example and the second example, when the angle θA of the inclined surface 204 of the inner peripheral portion of the edge portion 202 is θA=60°, the adhesive width Wa of the adhesive surface 203 of the edge portion 202 becomes larger. Can be taken.

The lens 93 is manufactured by, for example, nanoimprint, injection molding, or the like. The lens 93 is formed by forming a lens group in which a plurality of minute lenses having the same shape are arranged by using a mold such as an original plate of nanoimprint, and after releasing the lens group of the molded product, individual lenses are formed by dicing or the like. It is made by cutting. When manufacturing the lens 93, it is necessary to provide a draft for removing the lens 93 from the mold, and the inclined surface 204 of the lens 93 acts as a draft. Since it is better in terms of releasability that the draft of the molded product is made as large as possible, from the standpoint of releasability, the inclined surface 204 of the lens 93 is gentle to the plane perpendicular to the optical axis of the lens 93. Is preferable. On the other hand, in order to reduce the outer dimensions of the lens 93, it is preferable to make the inclined surface 204 of the lens 93 stand up as much as possible. Further, when the lens 93 is bonded to the element cover glass 43 by the adhesive resin 37, it is preferable that the adhesive surface 203 of the edge portion 202 to which the adhesive resin 37 adheres has as large an adhesive area as possible from the viewpoint of adhesive strength.

For this reason, in consideration of the factors such as the thinning of the lens 93, the releasability, and the adhesive strength comprehensively, the lens 93 and the element cover glass 43 can be reliably adhered to each other at the edge portion 202. The size of the adhesive surface 203 of is set. For example, as an example of the size of the lens 93 having an outer shape of a quadrangular prism, when the size of one side of a square of a cross section perpendicular to the optical axis direction or the axial direction passing through the lens center is 0.5 mm, the bonding surface of the edge portion 202 is The adhesive width Wa of 203 is, for example, 50 μm or more. In this case, in the endoscope 11 in which the maximum outer diameter Dmax of the tip portion 15 is 1.0 mm or less, the dimension of one side of the outer shape of the lens 93 is 0.5 mm or less, and the bonding width Wa of the bonding surface 203 of the edge portion 202 is Wa. Is ensured to be 50 μm or more. Further, in order to make the lens 93 both compact and easy to release, the angle θA of the inclined surface 204 is, for example, 60°≦θA≦90° when the angle θA of the opening viewed from the center of the lens is set. In this case, the angle of the inclined surface 204 is 30° or more and 45° or less with respect to the optical axis direction of the lens 93 (direction parallel to the mold release direction), and the axial direction passing through the optical axis of the lens 93 or the lens center. The angle is 60° or less and 45° or more with respect to the plane perpendicular to.

As described above, according to the endoscope 11 of the sixth configuration example, it is possible to realize the lens 93 having a small diameter capable of setting the maximum outer diameter Dmax of the distal end portion 15 to 1.0 mm or less. Further, in the lens 93 having a reduced diameter, by setting the bonding width Wa of the bonding surface 203 of the edge portion 202 to 50 μm or more, a sufficient bonding area between the lens 93 and the element cover glass 43 can be secured, so that it is ensured. It becomes possible to adhere and fix. Further, as an angle of the inclined surface 204 between the optical element portion 201 in the central portion and the edge portion 202 in the peripheral portion of the lens 93, the angle θA of the opening viewed from the center of the lens is 60°≦θA≦90°. Thereby, the releasability at the time of manufacturing the lens can be improved.

<Seventh configuration example>
The seventh configuration example shows a configuration example of the bonding surface between the lens 93 and the element cover glass 43 in the endoscope 11.

FIG. 16 is a diagram showing a configuration example of a bonding surface of the lens 93 of the endoscope 11 of the present embodiment with the element cover glass 43. The lens 93 is fixed by aligning the outer shape of the quadrangular prism with the element cover glass 43 of the image pickup element 33 and adhering the lens cover glass 43 with the adhesive resin 37 to easily align the optical axis with the image pickup surface 41 of the image pickup element 33. can do. The adhesive surface 203 of the edge portion 202 of the lens 93 is not a plane parallel to the end surface of the element cover glass 43 but is inclined so as to have a predetermined angle in a state where the adhesive surface 203 faces the element cover glass 43 for adhesive fixation. It may have the portion 207. The inclined portion 207 of the adhesive surface 203 has a taper shape that is inclined from the inner peripheral portion of the edge portion 202 toward the outer peripheral portion, and the thickness dimension of the outer peripheral portion is slightly reduced. The inclination angle of the inclined portion 207 of the adhesive surface 203 is, for example, 0.5° or more. When the adhesive resin 37 is finely applied to the adhesive surface 203 of the edge portion 202 in order to adhere the lens 93 to the element cover glass 43, the inclined portion 207 of the adhesive surface 203 causes the adhesive resin 37 on the adhesive surface to move to the outer periphery. It is easy for the adhesive resin 37 to move to the side and is less likely to enter the edge portion 202 than the edge portion 202, and it is possible to prevent the adhesive resin 37 from interfering with the air layer 95 formed in the optical element portion 201.

As described above, according to the endoscope 11 of the seventh configuration example, it is possible to prevent the adhesive resin 37 from entering the air layer 95 between the lens 93 and the element cover glass 43, and to secure the air layer 95. The lens 93 and the element cover glass 43 can be securely bonded and fixed.

<Eighth configuration example>
The eighth configuration example shows a specific example of the configuration of the optical system in the endoscope 11.

A specific example of the configuration of the optical system including the objective cover glass 91, the lens 93, and the element cover glass 43 will be shown below.
・Objective cover glass 91
Thickness of objective cover glass 91 TGt: TGt=0.1 to 0.5 mm
An example of the material of the objective cover glass 91: BK7 (manufactured by Schott), nd=1.52, νd=64.2
Refractive index ndF of objective cover glass 91: 1.3 ≤ ndF
Abbe number of objective cover glass 91 νdF: 30 ≦νdF
・Element cover glass 43
Thickness of element cover glass 43 SGt: SGt=0.1 to 0.5 mm
An example of the material of the element cover glass 43: BK7 (manufactured by Schott), nd=1.52, νd=64.2
Refractive index ndR of element cover glass 43: 1.3 ≤ ndR ≤ 2.0, ndF ≤ ndR
Abbe number of element cover glass 43 νdR: 40 ≤νdR, νdF ≤νdR
・Lens 93
Focal length f of lens 93: 0.1 mm ≤ f ≤ 1.0 mm
F number of lens 93 FNO: 1.4 ≤ FNO ≤ 8.0

<Ninth configuration example>
The ninth configuration example shows a specific example of the configuration of the image sensor 33 in the endoscope 11. 17 and 18 are diagrams showing a first example of the image sensor 33 in the endoscope 11 of the present embodiment.

The image pickup device 33A of the first example has a quadrangular cross-section taken along a plane perpendicular to the optical axis of the lens 93 or the axial direction passing through the lens center. In this case, the outer shapes of the image pickup surface on the element cover glass 43A side and the terminal surface on the transmission cable 31 side are quadrangular, and the outer shape of the image pickup element 33A and the element cover glass 43A is formed in a quadrangular prism shape. Further, the image pickup device 33A and the device cover glass 43A, and the lens 93 (not shown) are formed into a quadrangular prism having the same outer shape.

An electric circuit 99A having a circuit pattern is provided on a substrate (terminal surface) provided on the rear end side of the image pickup device 33A, and conductor connecting portions (connection lands) 49 are provided at four corners, respectively. The transmission cable 31 by the electric wire 45 is connected by soldering or the like. That is, four electric wires 45 are connected at four corners of the terminal surface of the image pickup device 33A. The four electric wires 45 are positioned and connected at the four corners of the terminal surface of the image pickup device 33A in a state where the ends are formed in a crank shape. Here, the external shape width (length of one side of the quadrangular cross section) SQL of the image pickup device 33A is, for example, 0.5 mm or less, and the inter-wire pitch PC between the four electric wires 45 is, for example, 0.3 mm. That is all.

19 and 20 are diagrams showing a second example of the image sensor 33 in the endoscope 11 of the present embodiment. In the image sensor 33B of the second example, the shape of the cross section taken along a plane perpendicular to the optical axis of the lens 93 or the axial direction passing through the lens center is formed into an octagonal shape, and the outer shapes of the image sensor 33B and the element cover glass 43B. Are formed in an octagonal column shape. The image sensor 33B, the element cover glass 43B, the electric circuit 99B, and the lens 93 (not shown) are formed into an octagonal prism having the same outer shape. Here, the description will focus on the configuration of the parts different from the first example, and the description of the parts similar to the first example will be omitted.

The second example is an example having an octagonal shape in which four corners (four corners) of a quadrangle in the cross-sectional shape of the image sensor 33B are cut (chamfered) by one cutting surface 221B. As for the size of the cut-out portion of the outer shape of the image sensor 33B, the size CS to the end of the cut-off surface 221B with respect to the apex of the quadrangle is, for example, 20 to 50 μm. In this way, by cutting the four corners of the outer shape of the image sensor 33B by the cut surface 221B, the wire pitch Pc of the four electric wires 45 is separated as much as possible, and the outer dimension of the image sensor 33B in the diagonal direction is determined. The size can be reduced, which can contribute to further reduction in diameter of the endoscope. For example, when the dimension CS of the cutout portion is 21.2 μm, the outer dimension of the image pickup element 33B in the diagonal direction is reduced by 15 μm at one place, and is reduced by 30 μm at both ends in the diagonal direction. When this configuration of the cut surface 221B is applied to an image pickup element having a square outer shape with an outer dimension SQL of 0.5 mm on one side and an outer dimension of 0.705 mm in the diagonal direction, the outer dimension in the diagonal direction is chamfered. Becomes as small as 0.675 mm, and a small-diameter endoscope having a diameter of 0.7 mm or less can be realized.

21 and 22 are diagrams showing a third example of the image sensor 33 in the endoscope 11 of the present embodiment. The image pickup device 33C of the third example has a dodecagonal cross section cut along a plane perpendicular to the optical axis of the lens 93 or the axial direction passing through the lens center, and the outer shapes of the image pickup device 33C and the element cover glass 43C. The shape is a dodecagonal column. Further, the image pickup device 33C, the device cover glass 43C, the electric circuit 99C, and the lens 93 (not shown) are formed in an octagonal column shape having the same outer shape. Here, the description will focus on the configuration of the parts different from the first example, and the description of the parts similar to the first example will be omitted. The third example is an example having a dodecagonal shape in which four corner portions of a quadrangle are cut by two cut surfaces 221C in the cross-sectional shape of the image sensor 33C. As for the size of the cut-out portion of the outer shape of the image pickup element 33C, the size CS up to the end of the cut-off surface with respect to the apex of the quadrangle can be made larger by cutting the outer surface of the image pickup device 33C as compared with the second example. Therefore, the diameter of the image pickup device can be further reduced.

The sectional shape of the image sensor 33 in the direction perpendicular to the axial direction passing through the lens optical axis or the lens center is not limited to a quadrangle, an octagon, and a dodecagon, and is a hexagon such as a 4×n polygon (n is a natural number). And it is sufficient. In this way, by configuring the cross-sectional shape of the image pickup element 33 to be a 4×n polygon, it is possible to connect the transmission cable 31 by the four electric wires 45 and to further reduce the diameter of the image pickup element and the endoscope. Further, by making the four corners of the 4×n polygonal cross-sectional shape of the image sensor 33 chamfered, the size of the image sensor 33 in the diagonal direction can be made smaller, which can contribute to further reduction in diameter.

As described above, according to the endoscope 11 of the ninth configuration example, it is possible to realize the image pickup element 33 having a small diameter capable of setting the maximum outer diameter Dmax of the distal end portion 15 to 1.0 mm or less.

The endoscope 11 of the present embodiment is provided at the distal end portion 15 of the insertion portion 21, and the image pickup device 33 in which the image pickup surface 41 is covered by the element cover glass 43, and the incident light from the subject is imaged on the image pickup surface 41. The lens 93 and the adhesive resin 37 for fixing the lens 93 and the element cover glass 43 are provided. The lens 93 has a prismatic outer shape, and is configured by a single lens having a first surface on the subject side that is a flat surface and a second surface on the imaging side that has a convex surface. On the imaging side of the lens 93, an optical element portion 201 having a convex curved surface portion 97 which is convex in a substantially spherical shape and which forms a convex lens surface is formed in the central portion, and the peripheral portion has an adhesive surface 203 having a flat end surface. The edge portion 202 that it has is integrally formed. As a result, it is possible to realize the lens 93 having a small diameter that allows the maximum outer diameter Dmax of the tip portion 15 to be 1.0 mm or less.

In addition, in the endoscope 11 of the present embodiment, the bonding surface 203 of the lens 93A has a substantially square shape with a square outer peripheral portion and a rounded square inner peripheral portion.

Further, in the endoscope 11 of the present embodiment, the adhesive surface 203 of the lens 93B has a circular shape that is concentric with the convex curved surface portion 97 having a square outer peripheral portion and a circular dome-shaped inner peripheral portion.

In addition, in the endoscope 11 of the present embodiment, the optical element section 201 of the lens 93C is provided with four optical elements on the circumference corresponding to the four sides of the square of the lens outer shape on the outer circumference of the convex curved surface section 97 having the circular dome shape. It has a barrel shape with a part cut away. As a result, the slope of the inclined surface 204 between the optical element portion 201 and the edge portion 202 can be formed gently, and the releasability at the time of manufacturing the lens can be improved. Further, when the slopes 204 have the same inclination, the adhesive width Wa of the adhesive surface 203 of the edge portion 202 can be made larger, and the adhesive strength can be improved.

Further, in the endoscope 11 of the present embodiment, the lens 93 has the inclined surface 204 that spreads from the lens center to the outer periphery from the outer peripheral portion of the convex curved surface portion 97 to the inner peripheral portion of the adhesive surface 203. When the angle of 204 is the angle θA of the opening viewed from the center of the lens, 60°≦θA≦90°, and the bonding width Wa of the bonding surface 203 is 50 μm or more. As a result, in the lens 93 having a reduced diameter, the lens 93 and the element cover glass 43 can be securely bonded and fixed. Further, by sufficiently ensuring the angle of the inclined surface 204, the releasability at the time of manufacturing the lens can be improved.

In addition, in the endoscope 11 of the present embodiment, the adhesive surface 203 of the lens 93 has the tapered inclined portion 207 that is inclined from the inner peripheral portion of the edge portion 202 to the outer peripheral portion thereof. As a result, the adhesive resin 37 applied to the adhesive surface 203 easily moves to the outer peripheral side and is less likely to enter the edge portion 202, and the adhesive resin 37 interferes with the air layer 95 formed in the optical element portion 201. Can be suppressed.

Further, the endoscope 11 of the present embodiment includes the image pickup element 33, the element cover glass 43, the adhesive resin 37, the lens 93, and the objective cover glass 91 that covers the surface of the lens 93 on the object side. The objective cover glass 91 is made of an optical material having a thickness TGt of 0.1 mm≦TGt≦0.5 mm, a refractive index ndF of 1.3≦ndF, and an Abbe number νdF of 30≦νdF, and the element cover glass 43 has a thickness of SGt is 0.1 mm ≤ SGt ≤ 0.5 mm, refractive index ndR is 1.3 ≤ ndR ≤ 2.0, ndF ≤ ndR, Abbe number νdR is 40 ≤ νdR, νdF ≤ νdR. The lens 93 made of a lens has a focal length f of 0.1 mm≦f≦1.0 mm and an F number FNO of 1.4≦FNO≦8.0. As a result, it is possible to realize the thin lens 93 capable of setting the maximum outer diameter Dmax of the tip portion 15 to 1.0 mm or less.

Further, in the endoscope 11 of the present embodiment, the distance from the imaging point on the imaging side at the focal length of the lens 93 to the end surface of the element cover glass 43 on the object side is x (0≦x≦f), and only air is present. Θair is the maximum angle of the light beam emitted from the lens 93 to the image formation point with respect to the optical axis, and the maximum angle with respect to the optical axis of the light beam emitted from the lens 93 including the element cover glass 43 to the image formation point through the element cover glass 43. Is defined as θgl, the lens 93 and the element cover glass 43 are formed of a combination of a focal length f, an F number FNO, and a refractive index ndR, which satisfies 0.1≦x·(tan θair)/(tan θgl)≦0.5. .. This makes it possible to obtain desired optical performance in the lens 93 having a small diameter.

In addition, in the endoscope 11 of the present embodiment, the image pickup device 33, the element cover glass 43, the adhesive resin 37, the lens 93, and four conductor connections provided on the surface opposite to the image pickup surface 41 of the image pickup device 33. A transmission cable 31 having four electric wires 45 connected to each of the parts 49 is provided. The image sensor 33 has a 4×n polygonal cross section (n is a natural number) perpendicular to the optical axis of the lens 93 or the axial direction passing through the center of the lens. It is connected to the four conductor connecting portions 49 arranged at the four corners of the rear end surface of the xn polygon. As a result, it is possible to realize the image pickup element 33 having a small diameter that can set the maximum outer diameter Dmax of the tip portion 15 to 1.0 mm or less.

Further, in the endoscope 11 of the present embodiment, the four corners of the 4×n polygonal cross-sectional shape of the image sensor 33 are chamfered. As a result, the size of the image sensor 33 in the diagonal direction can be further reduced, which can contribute to further reduction in diameter.

Further, in the endoscope 11 of the present embodiment, the image pickup device 33, the device cover glass 43, and the lens 93 have a 4×n polygonal prism shape having the same outer shape. As a result, the outer diameter from the lens 93 to the image pickup element 33 via the element cover glass 43 can be made smaller.

Further, in the endoscope 11 of the present embodiment, the image pickup device 33 has a length of one side of a 4×n polygon of 0.5 mm or less in a cross section perpendicular to the axial direction passing through the optical axis or the lens center. is there. As a result, the outer dimension of the image pickup element 33 in the diagonal direction can be reduced to about 0.7 mm.

Further, in the endoscope 11 of the present embodiment, the maximum outer diameter of the distal end portion 15 is formed within a range of a finite diameter to 1.0 mm corresponding to the diameter of the circumscribed circle of the substrate of the image sensor 33. Accordingly, by setting the maximum outer diameter Dmax to be less than 1.0 mm, insertion into a blood vessel of a human body can be further facilitated.

<Tenth Configuration Example>
FIG. 23 is a side sectional view in which the sheath 61 of the endoscope 11 of this embodiment extends to the distal end. In the endoscope 11 of the tenth configuration example, the mold portion 65 is formed to have a smaller diameter than the shape shown in FIG. The mold part 65 shown in FIG. 23 does not have the small-diameter extension part 71, and is formed in a cylindrical shape. The sheath 61 covers the outer periphery of the mold portion 65. That is, in the tenth configuration example, the mold portion 65 is made thinner than that shown in FIG. 3, and the thin sheath 61 of the same thickness is extended to the tip. The sheath 61 has a cavity 133 on the plug portion 23 side of the mold rear end surface 131. The optical fiber 59 and the electric wire 45 pass through the cavity 133. Further, the lens 93 and the image pickup element 33 are arranged coaxially. Coaxial refers to a relative positional relationship between the lens 93 and the image sensor 33 in which the optical axis of the lens 93 passes through the center of the imaging surface 41. The structure of the tenth configuration example described above is common to the following eleventh configuration example, twelfth configuration example, and thirteenth configuration example.

Further, in the endoscope 11 of the tenth configuration example, the outer shape in the direction perpendicular to the axial direction passing through the optical axis of the lens 93 or the lens center is formed by a quadrangle having four corners at right angles. The quadrangle at right angles of four corners includes, for example, a square and a rectangle. Further, the square includes a square having the same size as the image pickup element 33 and a square similar to the image pickup element 33 in the outer shape in the direction perpendicular to the optical axis of the lens 93 or the axial direction passing through the lens center. In other words, when the lens 93 has a square outer shape in the direction perpendicular to the optical axis of the lens 93 or the axial direction passing through the lens center, the lens 93 can be smaller in size than the image sensor 33.

The image sensor 33 has a square outer shape in a direction perpendicular to the axial direction passing through the optical axis or the lens center. Further, the image pickup device 33 has a side length longer than or the same as the longest side of the lens 93. Therefore, in the image sensor 33, when the lens 93 is rectangular, the long sides of the rectangle are equal to the four sides. The “longest side” of the lens 93 means one side of the square when the lens 93 is square.

According to the endoscope 11 of the tenth configuration example, in addition to the above-described miniaturization (for example, reducing the outer diameter of the insertion portion on the distal end side) and cost reduction, the sheath 61 and the mold are provided. It is possible to eliminate the connecting portion that connects the end portion 65 with the portion 65. As a result, it is possible to obtain an extremely smooth insertion portion 21 having no connecting portion on the outer peripheral surface. Further, since there is no connecting portion between the end faces of the sheath 61 and the mold portion 65 in the extending direction of the insertion portion 21, there is no risk of the connecting portion peeling off, and the reliability of the endoscope 11 can be improved. ..

<Eleventh configuration example>
FIG. 24 is a perspective view showing an example in which the lens 93D of the endoscope 11 of the present embodiment is quadrangular and the image sensor 33 is square. 25 is a side view of FIG. 24. In the endoscope 11 of the eleventh configuration example, the outer shape in the direction perpendicular to the optical axis of the lens 93D or the lens center is the outer shape in the direction perpendicular to the optical axis of the image sensor 33 or the lens center. It is a smaller analogy. In other words, the outer shape perpendicular to the optical axis of the lens 93 or the axial direction passing through the lens center is a square, and the length of one side of the outer shape of the lens 93 is smaller than the length of one side of the outer shape of the image sensor 33. .. In the eleventh configuration example, the frame-shaped surface 135 that surrounds the lens 93D is exposed outside the lens 93D on the surface of the imaging element 33 to which the lens 93D is joined. That is, a step is formed between the lens 93D and the image sensor 33. The frame-shaped surface 135 is covered by the mold portion 65. The objective cover glass 91D and the diaphragm 51D are formed to have the same outer shape and size as the lens 93D.

According to the endoscope 11 of the eleventh configuration example, in addition to the above-described miniaturization (for example, reduction of the outer diameter of the insertion portion on the distal end side) and cost reduction, the imaging element 33 can be provided. Since the frame-shaped surface 135 is covered with the mold portion 65, the step portion between the lens 93D and the image pickup element 33 is embedded in the mold portion 65, and the length of one side of the outer shape of the lens 93 and the length of the image pickup element 33. As compared with the case where the length of one side of the outer shape is the same, the amount of coverage by the mold portion 65 increases, and thus the fixing strength between the mold portion 65 and the lens 93D and the imaging element 33 can be further increased. ..

<Twelfth configuration example>
FIG. 26 is a perspective view showing an example in which the lens 93E of the endoscope 11 of the present embodiment is rectangular and the image sensor 33 is square. 27 is a perspective view of the rectangular lens 93E shown in FIG. 26 in the endoscope 11 of the present embodiment. FIG. 28 is a front view of the rectangular lens 93E shown in FIG. 26 in the endoscope 11 of the present embodiment.

The endoscope 11 of the twelfth configuration example has a rectangular outer shape in the direction perpendicular to the optical axis of the lens 93E or the axial direction passing through the lens center. The long side 137 of the rectangular lens 93E is the same as one side of the image sensor 33. In the rectangular lens 93E, an optical axis or an axis passing through the lens center passes through the intersection of a pair of diagonal lines. In the rectangular lens 93E, the optical axis or the axis passing through the lens center coincides with the center of the imaging surface 41. In the twelfth configuration example, a pair of long frame surfaces 139 sandwiching the lens 93E protrude from the lens 93E and are exposed on the surface of the imaging element 33 to which the lens 93E is joined. That is, a step is formed between the lens 93E and the image sensor 33. The long frame surface 139 is covered with the mold portion 65. The objective cover glass 91E and the diaphragm 51E are formed in the same outer shape as the lens 93E.

According to the endoscope 11 of the twelfth configuration example, in addition to the above-described miniaturization (for example, thinning of the outer diameter at the insertion portion on the distal end side) and cost reduction, the imaging element 33 can be provided. Since the long frame surface 139 is covered with the mold portion 65, the step portion between the lens 93E and the image pickup element 33 is embedded in the mold portion 65, and the length of one side of the outer shape of the lens 93 and the image pickup element 33. Compared to the case where the length of one side of the outer shape is the same, the amount of coverage by the mold portion 65 is increased, so that the fixing strength between the mold portion 65 and the lens 93E and the imaging element 33 can be further increased. ..

The fixing strength of the mold portion 65 by the endoscope 11 of the twelfth configuration example will be specifically described. In the endoscope 11, particularly when the maximum outer diameter Dmax is a small diameter of less than 1.0 mm, a large effect can be obtained by making the lens 93E rectangular for the square image sensor 33. That is, in the distal end portion 15, the inner peripheral surface of the sheath 61 approaches the corner portion (projection corner) of the imaging element 33 as much as possible because the sheath 61 has a small diameter. With such a structure, when the outer shape of the lens 93 is the same square as that of the image sensor 33, the corners of the lens 93 also approach the inner peripheral surface of the sheath 61. As a result, it becomes difficult for the lens 93 to secure the bonding strength between the corner portion and the sheath 61. On the other hand, according to the twelfth configuration example, with respect to the square image pickup device 33, the lens 93E is formed into a rectangle whose long side is the same length as the side of the image pickup device 33, so that the corner portion of the lens 93E is formed. , Can be separated from the inner peripheral surface of the sheath 61. That is, a space for the sheath adhesive can be secured between the inner peripheral surface of the sheath 61 and the corner of the lens 93E. As a result, the fixing strength between the sheath 61 and the lens 93E can be secured even in the endoscope 11 having a particularly small diameter.

<Thirteenth configuration example>
FIG. 29 is a perspective view showing an example in which the lens 93F of the endoscope of the present embodiment is an octagon and the image sensor 33 is a square. FIG. 30 is a side view of FIG. 29. In the endoscope 11 of the thirteenth configuration example, the outer shape of the lens 93F is an octagon. In other words, the lens 93F has an octagonal prism shape. In this octagon, four short sides 141 having the same length and four long sides 143 having the same length are alternately arranged in parallel, and the short sides 141 facing each other and the long sides 143 facing each other are parallel to each other. .. In other words, the four corners of the quadrangle are chamfered at an angle of 45 degrees. The chamfered portion of the lens 93F becomes the short side 141. In this case, FIG. 29 illustrates the case where the quadrangle is a square. The length of one side of the image sensor 33 is the same as the distance between the pair of long sides of the lens 93F that face each other.

In the thirteenth configuration example, on the surface of the image pickup element 33 to which the lens 93F is joined, four entrance corner surfaces 145 protrude from the short side 141 of the lens 93F. That is, four steps are formed between the lens 93F and the image sensor 33. The inner corner surface 145 is covered with the mold portion 65. The objective cover glass 91F and the diaphragm 51F are formed in the same outer shape as the lens 93F.

According to the endoscope 11 of the thirteenth configuration example, in addition to the above-described miniaturization (for example, thinning of the outer diameter at the insertion portion on the distal end side) and cost reduction, the imaging element 33 can be provided. Since the inner corner surface 145 is covered with the mold portion 65, the step portion between the lens 93F and the image pickup element 33 is embedded in the mold portion 65, and the length of one side of the outer shape of the lens 93 and the image pickup element 33. As compared with the case where the length of one side of the outer shape is the same, the fixing strength between the mold portion 65 and the lens 93F and the image pickup device 33 can be increased in that the amount of coating by the mold portion 65 increases. Further, when the lens 93F has an octagonal shape, it is possible to secure the convex curved surface portion 97 having the same area as in the case of a substantially square shape, and it is not necessary to lower the optical characteristics for securing the fixing strength. That is, the octagonal lens 93F can increase the fixing strength while securing the optical characteristics as in the case of the square shape.

Further, according to the endoscope 11 of the thirteenth configuration example, in the outer shape in the vertical direction of the axial direction passing through the optical axis of the lens 93F or the lens center, the short side is chamfered with respect to the long side of the octagon. Have. As a result, it is possible to further reduce the diameter of the distal end side (for example, the side inserted into the body) of the endoscope 11 as compared with the endoscope 11 (for example, see FIG. 5) of the third configuration example.

Although the embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is obvious to those skilled in the art that various changes or modifications can be conceived within the scope described in the claims, and naturally, these also belong to the technical scope of the present invention. Understood. Further, the respective constituent elements in the above-described embodiments may be arbitrarily combined without departing from the spirit of the invention.

INDUSTRIAL APPLICABILITY The present invention has the effect of reducing the size and cost of an endoscope, and is useful as, for example, an endoscope having a small diameter used in medical surgery and the like.

11... Endoscope 33, 33A, 33B, 33C... Imaging element 37... Adhesive resin 41... Imaging surface 43, 43A, 43B, 43C... Element cover glass 93, 93A, 93B, 93C, 93D, 93E, 93F... Lens (Single lens)
97... Convex curved surface (convex curved surface)
141... Short side 143... Long side 203... Adhesive surface

Claims (4)

A single lens whose outer shape in the direction perpendicular to the optical axis is square,
The external shape of the optical axis and a direction perpendicular is square, and the longest has long than side IMAGING element of said single lens length of one side thereof,
An element cover glass that covers the image pickup surface of the image pickup element and has an outer shape in the direction perpendicular to the optical axis that is the same as the outer shape of the image pickup element;
An outer peripheral surface of the single lens, a mold section for covering and fixing the element cover glass and the image pickup element with a mold resin ,
The single lens in which the optical axis of the single lens is aligned with the center of the imaging surface and the element cover glass are fixed by an adhesive resin,
The single lens is formed in a prismatic shape, and the first surface on the subject side is a flat surface, and the second surface on the imaging side is a convex surface.
The central portion of the single lens has a convex curved surface that is raised in a substantially spherical shape that constitutes the lens surface of the convex surface on the imaging side,
The peripheral edge of the single lens, the end surface is flat, and have a bonding surface between the element cover glass in the entire of the end surfaces,
It said single lens and in contact, and a frame-shaped surface of the element cover glass exposed protrudes from said single lens, Ru covered by the mold portion,
Endoscope. The endoscope according to claim 1,
The outer shape of the single lens in the direction perpendicular to the optical axis is a rectangle,
Endoscope. An octagonal single lens in which long sides and short sides, whose outer shapes in the direction perpendicular to the optical axis face each other, are alternately arranged,
An image pickup device in which the outer shape in the direction perpendicular to the optical axis is a square, and the length of one side is the same as the distance between a pair of long sides facing each other of the single lens,
An element cover glass that covers the image pickup surface of the image pickup element and has an outer shape in the direction perpendicular to the optical axis that is the same as the outer shape of the image pickup element;
An outer peripheral surface of the single lens, a mold section for covering and fixing the element cover glass and the image pickup element with a mold resin ,
The single lens in which the optical axis of the single lens is aligned with the center of the imaging surface and the element cover glass are fixed by an adhesive resin,
The single lens is formed of an octagonal prism, and has a first surface on the subject side that is a flat surface and a second surface on the imaging side that has a convex surface.
The central portion of the single lens has a convex curved surface that is raised in a substantially spherical shape that constitutes the lens surface of the convex surface on the imaging side,
The peripheral edge of the single lens, the end surface is flat, and have a bonding surface between the element cover glass in the entire of the end surfaces,
Contact with the single lens, and, entering the corner surfaces of the element cover glass exposed protrude from the short side of the octagon, Ru covered by the mold portion,
Endoscope. The endoscope according to claim 3 , wherein
The single lens has a structure in which the short side is chamfered with respect to the long side in an outer shape perpendicular to the optical axis.
Endoscope.

Images