JP6529455B2 - Endoscope - Google Patents

Description

  The present invention relates to an endoscope.

  2. Description of the Related Art Endoscopes for imaging the inside of a patient's body, equipment, or structure have been widely used in the medical or industrial fields. In an endoscope of this type, light from an imaging region is imaged on a light receiving surface of an image sensor by an objective lens system in an insertion unit inserted inside the observation target. The endoscope converts the imaging light into an electrical signal, and transmits the electrical signal as an image signal to an external image processing apparatus or the like through a signal cable.

  For example, in an endoscope used in the medical field, in order to reduce the burden on the treated person, it is important to further reduce the outer diameter of the distal end insertion portion inserted into the treated person's body or the like. ing. In the past, oral endoscopy with a normal diameter had a maximum outer diameter of about 8 to 9 mm. For this reason, the tongue base may be easily touched at the time of insertion, and the subject may be accompanied by nausea and shortness of breath. Therefore, in recent years, a narrow diameter transnasal endoscope has rapidly spread. The small diameter transnasal endoscope has a maximum outside diameter of about 5 to 6 mm, which is about half that of a conventional oral endoscope. For this reason, the narrow-diameter transnasal endoscope can be inserted through the nasal passage, and in combination with the thinness of about 5 mm, the vomiting reflex is small and the insertion is often not bothersome.

  For example, the electronic endoscope system 501 of Patent Document 1 shown in FIG. 25 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 elongated 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 treatment subject. The operation unit 513 includes an operation unit main body 523 and a treatment instrument channel insertion unit 525 for inserting various treatment instruments into the insertion unit 511. The operation portion main body 523 is provided with a bending operation knob 527 for bending the bending portion 519. The bending operation knob 527 includes a UD bending operation knob 529 for bending the bending portion 519 in the vertical direction, and an RL bending operation knob 531 for bending the bending portion 519 in the left and right direction.

  Moreover, the endoscope 533 of patent document 2 shown in FIG. 26 is equipped with the outer cylinder 535 in a front-end | tip part. The outer cylinder 535 is provided with an imaging mechanism 539 covered by the filled light shielding material 537. The imaging mechanism 539 is optically coupled to the imaging element 543 having the light receiving portion 541 on one surface, the cover member 545 covering the surface on which the light receiving portion 541 of the imaging element 543 is provided, and the light receiving portion 541 of the imaging element 543 A lens unit 547 and a flexible printed wiring board 549 are provided. The lens unit 547 has an objective cover member 551, an aperture 553, a plano-convex lens 555, and a plano-convex lens 557 from the objective side, and a lens barrel 559 on which these are fixed. An adhesive 561 is fixed between the plano-convex lens 557 and the cover member 545.

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

  By the way, the endoscope is required to further miniaturize the outer diameter (for example, to reduce the outer diameter of the insertion portion which is the tip side of Patent Document 1 or the object side of Patent Document 2). This is not the existing narrow diameter transnasal endoscope described above, but a site (for example, a very thin diameter tube such as a blood vessel) which is difficult to insert into the body of the treated person with the existing thin diameter transnasal endoscope And holes) based on the medical requirement to observe the details inside.

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

  Furthermore, in the endoscope 533 disclosed in Patent Document 2, in the imaging mechanism 539, the imaging element 543 and the flexible printed wiring board 549 are larger in the radial direction than the outer diameter of the lens barrel 559. In addition to this, the endoscope 533 has a configuration in which the imaging mechanism 539 composed of these members is accommodated 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 imaging element 543 and the flexible printed wiring board 549 protruding to the outer side in the radial direction from the lens barrel 559 and the thickness of the outer cylinder 535 have a structure disadvantageous for downsizing. Further, since the outer cylinder 535 is required, the number of parts is increased and the cost is also increased.

  The present invention has been made in view of the above situation, and provides an endoscope that can be miniaturized (for example, reduction in outer diameter at the insertion site on the distal end side) and cost reduction. It is to do.

According to the present invention, an imaging device provided at the tip of the insertion portion, the imaging surface being covered by the device cover glass, a single lens having a substantially square outer shape in a direction perpendicular to the optical axis, and the single lens A bonding resin for fixing the element cover glass, the single lens is formed in a prismatic shape, and a circular hole and the hole are formed with a flat surface on the object side and a central portion on the imaging side The lens unit has a lens having a convex surface in the hole, and the central portion has a convex curved surface that is raised in a substantially spherical shape that forms the convex lens surface on the imaging side. the peripheral unit may have a sloped portion of the tapered shape inclined toward the lens surface of the convex from the end face, the peripheral portion, the end face is plane and of the element cover glass in the entire of the end surfaces an adhesive surface to Yes, provide an endoscope .

  According to the present invention, downsizing and cost reduction can be achieved in an endoscope.

The whole block diagram which shows an example of the endoscope system which used the endoscope of each embodiment The perspective view which shows a mode that the front-end | tip part of the endoscope of 1st Embodiment was seen from the front side. Sectional drawing which shows an example of the front-end | tip part of the endoscope of 1st Embodiment Sectional drawing which shows an example of the structure by which resin for adhesion | attachment was filled in the isolation | separation part of the endoscope of 1st Embodiment. The perspective view which shows a mode that the imaging device with which the transmission cable was connected to the conductor connection part of the endoscope of 1st Embodiment was looked from the back side. Front view showing an example of a tip portion showing an arrangement example of a light guide as an example of illumination means Characteristic chart showing an example of the relationship between the thickness of the mold portion and the transmittance (A) A diagram showing an example of a captured image in the presence of stray light, (B) A diagram showing an example of a captured image in the absence of stray light Characteristic chart showing an example of the relationship between the additive amount of the additive and the tensile strength in the mold part Diagram showing an example of the relationship between the additive amount of the additive in the mold part, the resistance value, and the light blocking ratio Sectional drawing which shows an example of the structure by which the thin sheath was connected to the front-end | tip part The perspective view which shows a mode that the front-end | tip part of the endoscope of 2nd Embodiment was seen from the front side. Sectional drawing which shows the structural example of the front-end | tip part of the endoscope of 2nd Embodiment Sectional drawing which shows the structural example of the state by which the lens in the endoscope of 2nd Embodiment and the image pick-up element were directly attached via adhesive resin. The perspective view which shows a mode that the imaging device with which the transmission cable was connected to the conductor connection part of the endoscope of 2nd Embodiment was seen from the back side. Side view showing an example of dimensions of objective cover glass, lens, and element cover glass The figure which shows the 1st example of the lens shape in the endoscope of 2nd Embodiment The figure which shows the 1st example of the lens shape in the endoscope of 2nd Embodiment The figure which shows the 1st example of the lens shape in the endoscope of 2nd Embodiment The figure which shows the 2nd example of the lens shape in the endoscope of 2nd Embodiment The figure which shows the 2nd example of the lens shape in the endoscope of 2nd Embodiment The figure which shows the 2nd example of the lens shape in the endoscope of 2nd Embodiment The figure which shows the 3rd example of the lens shape in the endoscope of 2nd Embodiment The figure which shows the 3rd example of the lens shape in the endoscope of 2nd Embodiment The figure which shows the 3rd example of the lens shape in the endoscope of 2nd Embodiment The figure which shows the 3rd example of the lens shape in the endoscope of 2nd Embodiment The figure which shows the structural example of the adhesion surface with element cover glass in the lens of the endoscope of 2nd Embodiment The figure explaining the relationship between the focal distance of the lens in the endoscope of 2nd Embodiment, and the thickness of an element cover glass The figure which shows the 1st example of the image pick-up element in the endoscope of 2nd Embodiment The figure which shows the 1st example of the image pick-up element in the endoscope of 2nd Embodiment The figure which shows the 2nd example of the image pick-up element in the endoscope of 2nd Embodiment The figure which shows the 2nd example of the image pick-up element in the endoscope of 2nd Embodiment The figure which shows the 3rd example of the image pick-up element in the endoscope of 2nd Embodiment The figure which shows the 3rd example of the image pick-up element in the endoscope of 2nd Embodiment The whole block diagram of the electronic endoscope system provided with the endoscope of a prior art example Partial cross-sectional view showing an example of a conventional endoscope end structure

  Hereinafter, each embodiment which specifically disclosed the endoscope concerning the present invention is described in detail, referring to drawings suitably. However, the detailed description may be omitted if necessary. For example, detailed description of already well-known matters and redundant description of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. It is to be understood that the attached drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and they are not intended to limit the claimed subject matter.

  First, a basic configuration example common to the endoscope of each embodiment will be described first. The configuration example is a component that can be included in the endoscope according to the present invention. The endoscope according to the present invention does not exclude the provision of the following configuration examples in an overlapping manner.

First Embodiment
<Example of basic configuration>
FIG. 1 is an overall configuration diagram showing an example of an endoscope system using the endoscope of each embodiment. In FIG. 1, the entire configuration of an endoscope system 13 including an endoscope 11 and a video processor 19 is shown in a perspective view.

  In addition, about the direction used for description in this specification, suppose that the description of the direction in each figure is followed. Here, “upper” and “lower” correspond to the upper and lower sides of the video processor 19 placed in the horizontal plane, and “front (front)” and “rear” represent the endoscope main body (hereinafter referred to as “the endoscope 11 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 includes, for example, an endoscope 11 which is a soft mirror for medical use, and a still image or a moving image obtained by imaging the inside of an observation target (for example, a blood vessel of a human body) The configuration includes a video processor 19 that performs known image processing and the like. The endoscope 11 includes an insertion portion 21 extending substantially in the front-rear direction and inserted into the 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 27 which opens in the front wall 25. The rear portion of the plug portion 23 of the endoscope 11 is inserted into the socket portion 27 so that the endoscope 11 can transmit / receive power and various signals (video signal, control signal, etc.) to / from the video processor 19 It is.

  The power and various signals described above are led from the plug portion 23 to the flexible portion 29 via the transmission cable 31 (see FIG. 3 or 4) inserted into the flexible portion 29. The image data output from the imaging device 33 provided at the distal end portion 15 is transmitted from the plug unit 23 to the video processor 19 via the transmission cable 31. The video processor 19 performs known image processing such as color correction and tone 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 a monitor device having a display device such as a liquid crystal display panel, for example, and displays an image of a subject imaged by the endoscope 11 (for example, image data showing a state in 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 connected to the distal end of the flexible portion 29. The flexible section 29 has an appropriate length corresponding to various types of endoscopic examination, endoscopic surgery, and the like. The flexible portion 29 is formed, for example, by covering a net on the outer periphery of a spirally wound metal thin plate and further covering the outer periphery with a coating, and is formed to have sufficient flexibility. The flexible portion 29 connects the tip portion 15 and the plug portion 23.

  The endoscopes 11 and 111 of each embodiment described below can be inserted into a small diameter body cavity by being formed with a small diameter. The small diameter body cavity is not limited to the blood vessels of the human body, and includes, for example, ureter, pancreatic duct, bile duct, bronchioles and the like. That is, the endoscopes 11 and 111 can be inserted into blood vessels, ureter, pancreatic duct, bile duct, bronchioles and the like of the human body. In other words, the endoscope 11, 111 can be used to observe a lesion in a blood vessel. The endoscopes 11, 111 are effective in identifying atherosclerotic plaques. Moreover, it becomes applicable also to the observation by the endoscope at the time of cardiac catheter test | inspection. Furthermore, the endoscopes 11 and 111 are also effective in detecting thrombi and arteriosclerotic yellow plaques. In the arteriosclerotic lesion, color tone (white, pale yellow, yellow) or surface (smooth, irregular) is observed. In thrombi, color tones (red, white, dark red, yellow, brown, mixed color) are observed.

  The endoscopes 11 and 111 can be used for diagnosis and treatment of renal pelvis and ureteral cancer and idiopathic renal hemorrhage. In this case, the endoscopes 11 and 111 can be inserted from the urethra into the bladder and further advanced into the ureter to observe the ureter and the renal pelvis.

  In addition, the endoscopes 11 and 111 can be inserted into the Vater papilla opening in the duodenum. Bile is made from the liver and through the bile ducts, and pancreatic fluid is made from the pancreas and drained from the Vater papilla in the duodenum through the pancreatic ducts. The endoscopes 11, 111 can be inserted from the Vater papilla, which is the opening of the bile duct and pancreatic duct, to enable observation of the bile duct or pancreatic duct.

  Furthermore, the endoscopes 11 and 111 can be inserted into the bronchus. The endoscopes 11 and 111 are inserted from the oral cavity or the nasal cavity of a sample in a supine position (that is, a person to be treated). The endoscopes 11 and 111 pass the pharynx and the larynx, and are inserted into the trachea while visually recognizing the vocal cords. The bronchus becomes thinner each time it branches. For example, according to the endoscope 11 or 111 having the maximum outer diameter Dmax of less than 2 mm, it is possible to confirm the lumen up to the subsegment bronchus.

  Next, various configuration examples of the endoscope of the first embodiment will be described. The endoscope 11 of the first embodiment can have the respective configurations of the first configuration example to the seventeenth configuration example.

  FIG. 2 is a perspective view showing the distal end portion 15 of the endoscope 11 of the first embodiment as viewed from the front side. FIG. 3 is a cross-sectional view showing an example of the distal end portion 15 of the endoscope 11 according to the first embodiment. FIG. 4 is a cross-sectional view showing an example of a configuration in which the bonding resin 37 is filled in the separation portion 47 of the endoscope 11 of the first embodiment. FIG. 5 is a perspective view showing the image pickup device 33 in which the transmission cable 31 is connected to the conductor connection portion 49 of the endoscope 11 according to the first embodiment as viewed from the rear side.

  In FIG. 2, the configuration of the distal end portion 15 of the endoscope 11 shown in FIG. 1 is shown in a perspective view. In FIG. 3, the configuration of the tip portion 15 shown in FIG. 2 is shown in a cross-sectional view. FIG. 4 is a cross-sectional view showing a configuration in which the mold resin 17 is removed at the tip end portion 15 shown in FIG. FIG. 5 is a perspective view showing a configuration in which the imaging device 33 shown in FIG. 4 is viewed from the side opposite to the lens unit 35.

<First Configuration Example>
The endoscope 11 according to the first configuration example includes a lens unit 35 housing a lens in a lens support member 39, an imaging element 33 whose imaging surface is covered by an element cover glass 43, and an optical axis of the lens at the center of the imaging surface. An adhesive resin 37 for fixing the matched lens unit 35 and the element cover glass 43, and four conductor connection portions 49 provided on the side opposite to the imaging surface of the imaging element 33 (that is, the rear side) And a transmission cable 31 having four electric wires 45 connected to each other.

  The lens support member 39 is formed so as to be sandwiched between a plurality of (three in the illustrated example) lenses L1 to L3 formed of an optical material (for example, glass, resin, etc.), the lens L1 and the lens L2. The diaphragm 51 and the diaphragm 51 are incorporated close to each other in the direction of the optical axis. The diaphragm 51 is provided to adjust the amount of light incident on the lens L2 or the lens 93, and only light passing through the diaphragm 51 can be incident on the lens L2 or the lens 93. Here, the term “proximity” means that the lenses are slightly separated in order to avoid damage due to contact between lenses. The lenses L1 to L3 are fixed to the inner peripheral surface of the lens support member 39 by an adhesive over the entire circumference.

  In the following description, the term "adhesive" is not a strict meaning of a substance used to bond the surface of a solid, but a substance that can be used to bond two substances, or cured. When the adhesive has high barrier properties against gas and liquid, it is used in the broad sense of a substance having a function as a sealing material.

  The front end of the lens support member 39 is sealed (sealed) by the lens L1 and the rear end of the lens support member 39 by the lens L3 so that air or moisture does not enter the inside of the lens support member 39. . Therefore, air or the like can not escape from one end of the lens support member 39 to the other end. In the following description, the lenses L1 to L3 are collectively referred to as an optical lens group LNZ.

  As a metal material which comprises the lens support member 39, nickel is used, for example. Nickel has a relatively high rigidity and high corrosion resistance, and is suitable as a material for forming the tip portion 15. In addition, the circumference of the lens support member 39 before the examination or before the surgery so that the nickel constituting the lens support member 39 is not directly exposed from the tip portion 15 at the time of the examination using the endoscope 11 or at the time of surgery. Is preferably uniformly coated with a mold resin 17 and the tip 15 is provided with a biocompatible coating. For example, a copper-nickel alloy may be used instead of nickel. The copper-nickel alloy also has high corrosion resistance, and is suitable as a material for forming the tip portion 15. Moreover, as a metal material which comprises the lens support member 39, Preferably, the material which can be manufactured by electroforming (electroplating) is selected. Here, the reason why electroforming is used is that the dimensional accuracy of members manufactured by electroforming is extremely high, less than 1 μm (so-called submicron accuracy), and the variation when manufacturing a large number of members is also small. Further, stainless steel (for example, SUS316) may be used as a metal material for forming the lens support member 39. Stainless steel (also referred to as a SUS tube) has high biocompatibility, and is considered to be suitable, for example, as an endoscope to be inserted into a small diameter portion such as a blood vessel of a human body. The lens support member 39 is a very small member, and the error in the inner and outer diameter dimensions affects the optical performance of the endoscope 11 (that is, the image quality of the captured image). By forming the lens supporting member 39 by, for example, a nickel electroformed tube, the endoscope 11 capable of capturing a high quality image while securing high dimensional accuracy despite the small diameter can be obtained.

  The lens support member 39 may be a sheet material or the like other than metal, as long as the lens support member 39 can achieve positioning when aligning the optical axes of the respective lenses of the lens unit 35. When the lens unit 35 is covered by the mold resin 17, the relative positions of the respective lenses are fixed. For this reason, the lens supporting member 39 can be made of a material having a small strength, a small thickness, and a light weight, as compared with a conventional lens barrel used to support a plurality of lenses. As a result, it becomes possible to contribute to the diameter reduction of the distal end portion 15 in the endoscope 11. The lens support member 39 does not exclude the use of the same metal lens barrel as that in the prior art.

  As shown in FIG. 5, the imaging device 33 is configured by, for example, a small charge coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) imaging device having a square shape when viewed from the front-rear direction. In the imaging element 33, light incident from the outside is imaged on the imaging surface 41 by the optical lens group LNZ in the lens support member 39. Further, in the imaging element 33, the imaging surface 41 is covered by the element cover glass 43.

  The adhesive resin 37 is made of, for example, a UV / thermosetting resin. The bonding resin 37 preferably has a light transmitting property and 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 filling adhesive which can not be irradiated with ultraviolet rays can be cured by heat treatment. The adhesive resin 37 fixes the lens unit 35 whose optical axis of the lens is aligned with the center of the imaging surface 41 to the element cover glass 43. Thereby, the lens unit 35 and the imaging device 33 are directly adhered and fixed by the adhesive resin 37, that is, the lens unit 35 and the imaging device 33 are directly attached via the adhesive resin 37. The adhesive resin 37 is, for example, a type of adhesive that requires heat treatment to obtain the final hardness, but curing proceeds to a certain degree of hardness even by ultraviolet irradiation.

  In the endoscope 11, when the light emission surface of the lens facing the element cover glass 43 is concave, the edge portion 55 which is the annular end face around the lens is bonded to the element cover glass 43. At this time, the outer periphery of the lens and the outer periphery of the lens support member 39 may be simultaneously fixed by the bonding resin 37. By bonding the edge portion 55 of the lens to the element cover glass 43, an air layer is provided between the lens and the imaging element 33. By providing an air layer between the lens and the imaging device 33, the optical performance of the lens can be enhanced. For example, the refractive index difference of the light emitted from the lens to the air layer can be increased, and the power for refracting the light can be obtained. This facilitates optical design such as increasing the resolution and increasing the angle of view. As a result, the image quality of the image captured by the endoscope 11 is improved.

  At the rear on the back side of the imaging device 33, four conductor connection portions 49 are provided. The conductor connection portion 49 can be formed by, for example, a land grid array (LGA). The four conductor connection portions 49 include a pair of power connection portions and a pair of signal connection portions. The four conductor connection portions 49 are electrically connected to the four electric wires 45 of the transmission cable 31. The transmission cable 31 is composed of a pair of power lines which are electric wires 45 and a pair of signal lines which are electric wires 45. That is, a pair of power lines of the transmission cable 31 are connected to the pair of power connection portions of the conductor connection portion 49. A pair of signal lines of the transmission cable 31 are connected to the pair of signal connection portions of the conductor connection portion 49.

  As described above, according to the endoscope 11 of the first configuration example, the lens unit 35 and the imaging device 33 are fixed in a state of being held by the bonding resin 37 for a predetermined distance. The fixed lens unit 35 and the imaging device 33 are aligned with the optical axis of the lens unit 35 and the center of the imaging surface 41. Further, the distance between the lens unit 35 and the imaging device 33 is aligned at a distance at which incident light from an object passing through the lens unit 35 is focused on the imaging surface 41 of the imaging device 33. The lens unit 35 and the imaging device 33 are fixed after being aligned.

  A separation portion 47 (see FIG. 4) is formed between the fixed lens unit 35 and the imaging element 33. The shape of the separating portion 47 is determined by the relative alignment between the lens unit 35 and the imaging device 33 and the mutual fixing by the adhesive resin 37. That is, the separation portion 47 is an adjustment gap for aligning the lens unit 35 and the imaging device 33. The adjustment gap is not lost even when the bonding resin 37 is filled. In the specific example of the dimension mentioned above, adjustment is performed between at least about 30 μm and about 100 μm. The tolerance in this case is ± 20 μm. Therefore, the minimum adjustment gap in this case will remain at 10 μm.

  In the endoscope 11, after the separation portion 47 becomes an adjustment gap and alignment between the lens unit 35 and the imaging device 33 is completed, the separation portion 47 is used as a fixing space for the adhesive resin 37. Thereby, the lens unit 35 and the imaging element 33 can be fixed directly. As a result, an intervening member such as a frame or a holder for fixing the lens unit 35 to the imaging device 33, which has been conventionally required, is not necessary. Further, since the frame or the holder can be omitted, the number of parts is reduced and the fixing structure is simplified. As a result, the diameter of the distal end portion 15 of the endoscope 11 can be reduced, and even in the case of further downsizing (for example, reduction of the outer diameter at the insertion portion on the distal end side), the minimum dimension Can be configured with In addition, the cost of parts can be reduced. Furthermore, since there are few intervening parts when fixing the lens unit 35 and the imaging device 33, the number of operation steps required for the operation for alignment and fixation can be reduced, and highly accurate alignment can be easily performed. Further, the manufacturing cost can be reduced, and the productivity can be improved.

  Further, according to the endoscope 11, the transmission cable 31 including the four electric wires 45 is connected to the imaging element 33. The endoscope 11 can achieve both size reduction and cost reduction by forming the transmission cable 31 with the four electric wires 45. For example, although it is possible to set the number of electric wires 45 of the transmission cable 31 to four or less (for example, three) because of the arrangement space of the conductor connection portion 49 with respect to the rear of the back side of the imaging device 33 If the signal line of the book is abolished, it is necessary to superimpose the signal of the captured image or the control signal sent from the video processor 19 on the waveform of the power passing through the power line. Then, a modulation circuit, a demodulation circuit, and the like are necessary for signal superposition, and the number of parts increases, and the total cost increases. In addition, if a dedicated signal line is used to transmit and receive various signals (signals of captured image, signals for control, etc.), the circuit configuration becomes easy, but it is disadvantageous for the diameter reduction of the endoscope. . On the other hand, if the number of electric wires 45 of the transmission cable 31 is more than four (for example, five), the arrangement space of the individual conductor connection parts 49 with respect to the rear of the image sensor 33 becomes narrow. When manufacturing the endoscope 11 which makes the maximum outside diameter 1.8 mm or less, the connection work by soldering becomes difficult, and the manufacture of the endoscope 11 becomes difficult. As described above, in the endoscope 11, when the transmission cable 31 is the four electric wires 45, remarkable effects can be achieved in achieving both size reduction and cost reduction.

Second Configuration Example
In the endoscope 11 of the second configuration example, in the endoscope 11 of the present embodiment, the maximum outer diameter Dmax of the distal end portion 15 is a finite diameter equivalent to the diameter of the circumscribed circle of the substrate of the imaging element 33 capable of dicing. It can be formed in the range of 1.8 mm.

  In the endoscope 11 of the present embodiment, as the imaging device 33 having a square cross section in the direction perpendicular to the optical axis, one having a dimension of 1.0 mm is used. Thereby, the endoscope 11 has a diagonal dimension of the imaging device 33 of about 1.4 mm, and including the light guide 57 (for example, φ 150 μm) as the illumination means, the one having the maximum outer diameter Dmax of 1.8 mm or less It becomes possible.

  As described above, according to the endoscope 11 of the second configuration example, by setting the maximum outer diameter Dmax to less than 1.8 mm, for example, insertion into a blood vessel of a human body can be easily enabled.

<Third configuration example>
In the endoscope 11 of the third configuration example, in the endoscope 11 of the present embodiment, as shown in FIG. 5, the substrate of the imaging device 33 is formed in a square, and the four conductor connection portions 49 are the imaging device They are arranged side by side along one side of the 33 substrates. One conductor connection portion 49 is formed in a rectangular shape. The four conductor connection portions 49 are arranged with their long sides in parallel and separated from each other. The four conductor connection portions 49 are disposed at the central portion of the substrate of the imaging device 33. Therefore, each conductor connection portion 49 is separated from the peripheral edge of the substrate of the imaging device 33.

  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, right and left, and two upper and lower stages, and the outer periphery of the insulation coating is further bundled by the outer sheath to form one transmission cable 31. Each conductor has a bend 53 bent in a U-shape along the longitudinal direction of the conductor connection 49. The bent portion 53 of the electric wire 45 is formed in advance and is abutted against the conductor connection portion 49. The end of the bent portion 53 of the electric wire 45 is connected to the conductor connection portion 49 by solder. The imaging element 33 and the transmission cable 31 are covered with the mold resin 17. Accordingly, the sheath of the conductor connection portion 49, the bending portion 53, the electric wire 45, and the transmission cable 31 is embedded in the mold resin 17.

  As described above, according to the endoscope 11 of the third configuration example, the four conductor connection portions 49 can be disposed in parallel with the central portion of the substrate of the imaging device 33, so that the conductor connection portion 49 can be easily formed. Since the conductor of the electric wire 45 is connected to each of the four conductor connection portions 49 separated in one direction by soldering, the connection operation can be facilitated. Since the conductor connection portion 49 is disposed at the central portion of the substrate of the imaging device 33, the bent portion 53 can be formed in the conductor. The bent portion 53 is embedded and fixed by the mold portion 65, so that the tension acting on the transmission cable 31 can be reduced to act on the joint portion between the conductor and the conductor connection portion 49 (function as strain relief). Thereby, the connection reliability of the electric wire 45 and the conductor connection part 49 can be improved.

Fourth Configuration Example
In the endoscope 11 of the fourth configuration example, in the endoscope 11 of the present embodiment, illumination means is provided along the lens unit. That is, the endoscope 11 of the fourth configuration example has the light guide 57 as an example of the illumination unit. Hereinafter, the illumination means will be described by way of example in the case of the light guide 57, but in addition to this, the illumination means may be an LED directly attached to the insertion tip surface of the distal end portion 15. In this case, the light guide 57 is unnecessary.

  The light guide 57 consists of one optical fiber 59. For the optical fiber 59, for example, a plastic optical fiber (POF) is preferably used. The plastic optical fiber is made of a silicone resin or an acrylic resin, and the core and the cladding are formed of plastic. The optical fiber 59 may be, for example, a bundle fiber or the like 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 is an exit end face at the tip end 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 27 or the like. The endoscope 11 connects the plug 23 to the socket 27 so that 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 one optical fiber from the light source to the emission end of the illumination light, and to reduce the light loss.

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

<Fifth Configuration Example>
FIG. 6 is a front view showing an example of a tip portion showing an arrangement example of the light guide 57 as an example of the illumination means. In the endoscope 11 of the fifth configuration example, in the endoscope 11 of the present embodiment, a plurality of light guides 57 as an example of illumination means are provided in the circumferential direction of the lens unit 35. The four light guides 57 can be provided at equal intervals in the circumferential direction of the lens unit 35.

  As described above, according to the endoscope 11 of the fifth configuration example, four light guides 57 are provided at equal intervals in the circumferential direction of the lens unit 35, so shadows are less likely to occur on the top, bottom, left, and right of the subject. Thereby, the endoscope 11 can obtain a clear captured image as compared with the configuration with one light guide 57 or the configuration with two light guides.

<Sixth configuration example>
In the endoscope 11 of the sixth configuration example, in the endoscope 11 of the present embodiment, the imaging element 33 is formed in a square shape. The optical fibers 59 of the four light guides 57 are disposed substantially in the center of each side of the substrate of the imaging device 33 in a space sandwiched by the substrate of the imaging device 33 and the circumscribed circle of the substrate of the imaging device 33 There is.

  As described above, according to the endoscope 11 of the sixth configuration example, the space sandwiched between the square image pickup device 33 and the circular mold portion 65 substantially circumscribed to the image pickup device 33 can be effectively used. A plurality of (in particular, four) optical fibers 59 can be easily disposed without increasing the outer diameter. Thereby, the endoscope 11 can obtain a clear image while facilitating manufacture without increasing the outer diameter of the distal end portion 15.

<Seventh configuration example>
In the endoscope 11 of the seventh configuration example, in the endoscope 11 of the present embodiment, at least a part of the lens unit, an imaging element, a part of the transmission cable, and a part of the illumination means are covered with mold resin and fixed The mold portion 65 made of a mold resin is made of a resin material containing an additive, and the light transmittance can be 10% or less.

  FIG. 7 is a characteristic diagram showing an example of the relationship between the thickness of the mold portion 65 and the transmittance. FIG. 7 shows an example of measurement of transmittance when carbon black as an additive is added to a mold resin material (epoxy resin). In FIG. 7, black circles and broken lines show the case where 5% by weight (wt%) of carbon black is added, and black rhombuses and dashed dotted lines show the case where 1% by weight (wt%) of carbon black is added.

  When 5% by weight of carbon black is added, the light transmittance is about 0.5% (light blocking ratio 99.5%) even if the thickness is 30 μm or less, almost independently of the thickness of the mold portion 65. High light blocking performance. When 1% by weight of carbon black is added, the transmittance increases as the thickness of the mold portion 65 decreases. In the case of 1 wt% addition, if the thickness of the mold portion 65 is 30 μm or more, the transmittance can be suppressed to 8.0% or less. Therefore, the mold part 65 can fully satisfy the conditions of 10% or less of the transmittance | permeability by setting thickness T to 30 micrometers or more. For example, when the thickness of the mold portion 65 is 50 μm or more, the transmittance is 4.5% or less at 1% by weight addition, the transmittance is 0.5% or less at 5% by weight addition, and light can be blocked more reliably.

  If the transmittance of the mold unit 65 is 10% or less, a good captured image with less influence of stray light can be obtained in the imaging unit including the lens unit 35 and the imaging device 33. If the transmittance of the mold portion 65 is 6% or less, the influence of stray light can be sufficiently suppressed even if the sensitivity of the imaging device 33 is high. When the transmittance is greater than 10%, the influence of stray light is generated, which causes a defect as a captured image.

  FIG. 8A is a view showing an example of a captured image in the case where there is stray light. FIG. 8B is a view showing an example of a captured image when there is no stray light. When stray light occurs as shown in FIG. 8A, overexposure due to stray light occurs, for example, in a ring shape in a captured image, and a clear image can not be obtained. In the imaging unit in which the endoscope 11 is in use, it is necessary to make a state in which stray light does not occur as shown in FIG. 8 (B).

  When an additive is added to the mold portion 65, as shown in FIG. 7, the light shielding performance is improved as the additive amount (content) of the additive is increased, but the adhesive strength of the mold portion 65 is decreased. There is a nature. Therefore, it is necessary to add an appropriate amount to the mold resin material according to the adhesive strength characteristics of the additive.

FIG. 9 is a characteristic diagram showing an example of the relationship between the additive amount of the additive in the mold portion 65 and the tensile strength. FIG. 9 shows an example of measurement of tensile strength when carbon black as an additive is added to a mold resin material (epoxy resin). Here, the tensile strength corresponds to the adhesive strength of the mold portion 65. As shown in FIG. 9, when the addition amount is 1% by weight, the tensile strength decreases only by about 2.5%. When the addition amount is 5% by weight, the tensile strength decreases by about 12%. When the tensile strength decreases by about 20%, the adhesive strength as a mold member may not be obtained sufficiently. Therefore, when carbon black is added, the addition amount is preferably 5% by weight or less.

  When a conductive material such as carbon black is used as an additive, the electrical resistance decreases and the conductivity is added as the amount of addition increases.

FIG. 10 is a view showing an example of the relationship between the additive amount of the additive in the mold portion 65, the resistance value, and the light blocking ratio. FIG. 10 shows a measurement example of the resistance value and the light blocking ratio when carbon black as an additive is added to the mold resin material (epoxy resin). As the addition amount of carbon black, three cases of no addition (0% by weight addition), 1% by weight addition, and 5% by weight addition were measured. The light blocking ratio is an example in the case where the thickness of the mold portion 65 is 50 μm. When no additive is added, the resistance value is 1.8 to 5.0 × 10 ¹³ . In the case of 1% by weight addition, the resistance value is 2.5 to 3.0 × 10 ¹³ , the light blocking ratio is 95% or more, and in the case of 5% by weight addition, the resistance value is 3.5 to 5.0 × 10 ¹⁰ And the light blocking rate is 99% or more. In the case of 5% by weight addition, the value of the electrical resistance decreases by 1000 times or more compared to the case of 1% by weight addition. For this reason, it is necessary to add an appropriate amount to the mold resin material according to the conductive property of the additive and the insulating property required for the internal component (electronic circuit etc.) to be sealed.

  When the electrical resistance in the mold portion 65 is small, a leakage current or the like may occur in the conductor connection portion 49 connected to the imaging element 33 and the transmission cable 31, and the electrical characteristics around the signal processing portion of the imaging unit may deteriorate. On the other hand, by giving moderate conductivity in the mold portion 65, when static electricity is generated in the imaging unit, the impact of electrostatic discharge can be reduced, and an excessive current to the imaging element 33 can be suppressed. It is possible to suppress electric breakdown. That is, it is possible to cope with the surge of the imaging unit.

  As described above, according to the endoscope 11 of the seventh configuration example, the resin material (mold resin 17) of the mold section 65 contains an additive, whereby the light transmittance of the mold section 65 is reduced to 10% or less. And the thickness of the mold portion 65 can be reduced. As a result, the imaging unit of the endoscope 11 can be miniaturized while having sufficient light blocking characteristics.

Eighth Configuration Example
In the endoscope 11 of the eighth configuration example, as shown in FIG. 3, in the endoscope 11 of the present embodiment, a lens unit 35 for housing a lens in a lens support member 39 and an element cover glass 43 having an imaging surface 41. And an adhesive resin 37 for fixing an element cover glass 43 and a lens unit 35 whose optical axis of the lens is aligned with the center of the imaging surface 41, and an imaging element capable of dicing the maximum outer diameter Dmax. A mold for covering and fixing at least a part of the lens unit 35 and the imaging device 33 with the tip portion 15 formed in a range of a finite diameter-1.8 mm corresponding to the diameter of the circumscribed circle of 33 substrates And a tubular sheath 61 formed to have the same outer diameter as the distal end portion 15 and connected to cover at least a part of the mold portion 65.

  In the following description, the same reference numerals are given to the same members or configurations to simplify or omit the description. Further, in the description of the endoscope 11 (see FIG. 3) of the eighth configuration example, the description will be made while appropriately comparing with the endoscope 11 (see FIG. 11) of the tenth configuration example.

  The sheath 61 is made of a flexible resin material. The sheath 61 can be provided with a single wire, a plurality of wires, and a braided tensile strength wire on the inner circumferential side for the purpose of imparting strength. The tensile strength line includes aramid fibers such as poly-p-phenylene terephthalamide fibers, polyarylate fibers, polyparaphenylene benzbisoxazole fibers, polyester fibers such as polyethylene terephthalate fibers, nylon fibers, thin wires of tungsten, or stainless steel A thin line can be mentioned as an example.

  In the endoscope 11 of the eighth configuration example, as in the endoscope 11 (see FIG. 11) of the tenth configuration example described later, the entire imaging element 33 and at least a part of the lens unit 35 on the imaging element 33 side A portion of the transmission cable 31 and a portion of the light guide 57 are covered with the mold resin 17 and fixed. “At least” is a concept also including that the mold resin 17 covers the entire outer periphery of the lens support member 39. The mold resin 17 covers the imaging element 33 and the lens unit 35 to continuously cover the separation portion 47 therebetween. An X-ray opaque marker may be included in the distal end portion 15 of the endoscope 11 of the eighth configuration example. As a result, in the endoscope 11 of the eighth configuration example, confirmation of the tip position under X-ray fluoroscopy becomes easy.

  Further, the endoscope 11 of the eighth configuration example is provided with a tip flange portion 63 at the tip portion 15 in the same manner as the endoscope 11 (see FIG. 11) of the tenth configuration example described later. The front end flange portion 63 can be formed of, for example, stainless steel. The distal end flange portion 63 is formed in a cylindrical shape in which a large diameter portion and a small diameter portion are connected from the distal end side. The outer diameter of the large diameter portion of the tip flange portion 63 is formed with the maximum outer diameter Dmax (1.8 mm), and the large diameter portion has an insertion hole (not shown) for inserting four optical fibers 59. The respective optical fibers 59 are inserted from the insertion holes. The small diameter portion is provided with an insertion hole (not shown) for inserting the lens unit 35, and the lens unit 35 is inserted from the insertion hole. The tip flange portion 63 holds the lens unit 35 coaxially. A fiber holding hole 67 for holding the tip side of the optical fiber 59 is bored in the large diameter portion of the tip flange portion 63 outside the small diameter portion. The four fiber holding holes 67 are provided at equal intervals in the circumferential direction. The optical fiber 59 whose distal end is inserted into the fiber holding hole 67 is led backward along the small diameter portion.

  In the endoscope 11 of the eighth configuration example, the optical fiber 59 behind the distal end flange portion 63 is disposed inside the cover tube 69 (see FIG. 3). The cover tube 69 is formed to have the same outer diameter as the distal end flange portion 63. The cover tube 69 is formed of metal, resin or the like. The front end of the cover tube 69 abuts on the large diameter portion of the front end flange portion 63, and at least the rear end has a total length reaching the transmission cable 31. The mold resin 17 is filled inside the cover tube 69. That is, in the endoscope 11 of the eighth configuration example, the mold portion 65 is covered by the cover tube 69. In the endoscope 11 of the tenth configuration example to be described later, the cover tube 69 is omitted, and the distal end of the sheath 61 abuts on the rear end of the distal end flange portion 63 and is bonded with an adhesive or the like (FIG. 11) Except for reference), it is the structure equivalent to the endoscope 11 of a 1st structural example.

  The mold portion 65 filled in the cover tube 69 has a small diameter extension portion 71 (see FIG. 3) extending rearward from the rear end of the cover tube 69. The small-diameter extension portion 71 is formed in a cylindrical shape and has four optical fibers 59 embedded therein. The small diameter extension 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 by an adhesive or the like. That is, in the endoscope 11 of the eighth configuration example shown in FIG. 3, the distal end flange portion 63, the cover tube 69, and the sheath 61 are continuous at the coaxial maximum outer diameter Dmax of 1.8 mm. In the endoscope 11 of the tenth configuration example shown in FIG. 11, the distal end flange portion 63 and the sheath 61 are connected at a coaxial maximum outer diameter Dmax of 1.8 mm.

  As described above, according to the endoscope 11 of the eighth configuration example and the tenth configuration example, at least a part of the lens unit 35, a part of the imaging device 33 and the transmission cable 31 are covered with the mold resin 17 and fixed. Therefore, there are few intervening parts when fixing the lens unit 35 and the imaging device 33. As a result, the diameter of the distal end portion 15 of the endoscope 11 can be reduced, and even in the case of achieving further reduction in diameter, it can be configured with the minimum size. In addition, 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 an affected part having a very small diameter such as a blood vessel of a human body. As a result, downsizing and cost reduction can be achieved in the endoscope 11.

  In addition, the mold resin 17 contributes to an increase in the fixing strength between the imaging element 33 and the lens unit 35 by being continuously formed across the imaging element 33 and the lens unit 35. Further, the mold resin 17 also improves the airtightness (that is, the small gap is small), the water tightness, and the light shielding property of the separated portion 47. Furthermore, the mold resin 17 also enhances the light shielding property when the optical fiber 59 for the light guide 57 is embedded.

  In addition, since the light guide 57 is molded with the mold resin 17 on the tip end portion 15 of the endoscope 11, the light guide 57 acts as a structural material, and the flexible portion 29 and the tip of the small diameter endoscope 11 are also used. The connection strength with the unit 15 can be improved. Furthermore, in the endoscope 11, when the distal end portion 15 is viewed from the outermost surface on the insertion side of the distal end flange portion 63 (see FIG. 6), an insertion hole for lens unit 35 provided in advance in the distal end flange portion 63 Between the lens unit 35 and the lens unit 35, and between the four fiber holding holes 67 and the respective optical fibers 59 previously provided in the tip flange 63 in correspondence with the respective optical fibers 59, respectively. Filled by For this reason, in the endoscope 11, the gap between each of the insertion holes and the fiber holding hole 67 described above and each member (that is, the lens support member 39 and the optical fiber 59) is eliminated. Further, in the endoscope 11, the tip flange portion 63 and the cover tube 69 and the tip end of the cover tube 69 and the sheath 61 or the tip flange portion 63 and the sheath 61 are bonded by the bonding resin 37. There is no gap between them. Therefore, when the endoscope 11 is subjected to a sterilizing action (that is, it is cleaned) after being used at the time of an inspection or surgery, the cleaning residue such as unnecessary liquid may adhere to the endoscope 11 It is alleviated and can have a high degree of convenience in terms of hygiene when 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. For this reason, the distance to the subject is likely to change depending on the rotation angle of the tip, and it is difficult to stably obtain a good image. Furthermore, when the axis of the tip 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 changes depending on the rotation angle of the tip, especially when entering a hole with a narrow diameter Sex is reduced. On the other hand, according to the endoscope 11 of the eighth configuration example, the tip flange portion 63, the cover tube 69, and the sheath 61 are coaxially connected, and according to the endoscope 11 of the tenth configuration example, the tip flange Since the portion 63 and the sheath 61 are coaxially connected, it is easy to reduce the diameter of both, a stable image can be stably obtained, and the insertion operability can be enhanced.

<The ninth configuration example>
The endoscope 11 of the 9th structural example can make thickness of the sheath 61 the range of 0.1-0.3 mm in the endoscope 11 of this embodiment. The thickness of the sheath 61 matches the step size at the step between the cover tube 69 and the small diameter extension 71. The small-diameter extension portion 71 is a portion protruding to the opposite side of the lens unit 35 with the imaging element 33 interposed therebetween. That is, in the small-diameter extension portion 71, one transmission cable 31 is disposed at the center, and four optical fibers 59 are disposed outside the transmission cable 31. Therefore, the small-diameter extension portion 71 can be easily reduced in diameter as compared with the mold portion 65 in the portion in which the imaging device 33 is embedded. That is, since the sheath 61 has the same outer diameter as the cover tube 69, the design freedom of the wall thickness is improved.

  As described above, according to the endoscope 11 of the ninth configuration example, since the thickness of the sheath 61 can be increased to 0.3 mm, it is easy to increase the tensile strength of the sheath 61.

<10th configuration example>
FIG. 11 is a cross-sectional view showing an example of a configuration in which a thin-walled sheath is connected to the distal end.

  In the endoscope 11 of the tenth configuration example, the thickness of the sheath 61 can be 0.1 mm in the endoscope 11 of the present embodiment. When the thickness of the sheath 61 is 0.1 mm, the endoscope 11 can dispense with the cover tube 69 described in the endoscope 11 of the eighth configuration example. That is, in the endoscope 11 of the tenth configuration example, the imaging element 33 and the lens unit 35 are embedded by making the sheath 61 a thickness (0.1 mm) substantially equal to the thickness of the cover tube 69. It is possible to cover the mold portion 65 of the portion where it is located. In the endoscope 11 of the tenth configuration example, the distal end of the sheath 61 abuts on the rear end surface of the distal end flange portion 63 and is fixed by an adhesive or the like. The sheath 61 can compensate for the reduction in tensile strength caused by the thinning by the above-described tensile strength line or the like.

  As described above, according to the endoscope 11 of the tenth configuration example, since the cover tube 69 can be omitted and the sheath 61 can be directly connected to the distal end flange portion 63, the number of parts can be reduced.

Second Embodiment
Next, an endoscope 111 of the second embodiment will be described.

  FIG. 12 is a perspective view showing the distal end portion of the endoscope 111 of the second embodiment as viewed from the front side. FIG. 13 is a cross-sectional view showing a configuration example of the distal end portion of the endoscope 111 of the second embodiment. FIG. 14 is a cross-sectional view showing a configuration example of a state in which the lens and the imaging device in the endoscope 111 of the second embodiment are directly attached via an adhesive resin. FIG. 15 is a perspective view of an imaging device in which a transmission cable is connected to the conductor connection portion of the endoscope according to the second embodiment as viewed from the side opposite to the lens unit. In the second embodiment, the same members as the members described in the first embodiment are denoted by the same reference numerals, and redundant descriptions will be omitted.

<Eleventh configuration example>
The endoscope 111 shown in FIG. 12 forms the maximum outer diameter Dmax of the tip 15 shown in FIG. 13 in a range of a finite diameter ̃1.0 mm corresponding to the diameter of the circumscribed circle of the substrate of the imaging element 33 capable of dicing. can do.

  In the endoscope 111 of the present embodiment, as the imaging device 33 having a square cross section in the direction perpendicular to the direction of the optical axis, one having a dimension of 0.5 mm or less is used. Thereby, the endoscope 111 has a diagonal dimension of the imaging device 33 of about 0.7 mm, and including the light guide 57 (for example, φ 50 μm) as the illumination means, the one having the maximum outer diameter Dmax of 1.0 mm or less It becomes possible.

  As described above, according to the endoscope 111 of the eleventh configuration example, by setting the maximum outer diameter Dmax to less than 1.0 mm, for example, insertion into a blood vessel of a human body can be further easily enabled.

<12th configuration example>
In the endoscope 111 of the twelfth configuration example, in the endoscope 111 of the present embodiment, as shown in FIG. 15, the substrate of the imaging device 33 is formed in a square shape, and the conductor connection portion 49 is of the imaging device 33. Located at the four corners of the substrate. One conductor connection portion 49 is formed, for example, in a circular shape. The four conductor connection portions 49 are arranged at the four corners of the square, which allows the arrangement at a 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, right and left, and two upper and lower stages, and the outer periphery of the insulation coating is further bundled by the outer sheath to form one transmission cable 31. Each conductor is formed into four parallel straight lines with the insulation coating peeled off. The end of the conductor 45 is connected to the conductor connection 49 by solder. The imaging device 33 and the transmission cable 31 are covered with a mold resin 17 as shown in FIG. Accordingly, the conductor connection portion 49, the conductor, the insulating coating of the electric wire 45, and the outer cover of the transmission cable 31 are embedded in the mold resin 17.

  As described above, according to the endoscope 111 of the twelfth configuration example, the four conductor connection portions 49 can be disposed at the four corners of the substrate of the imaging element 33. In the substrate, as shown in FIG. 15, they can be equally spaced from each other at the maximum distance. As a result, the two adjacent conductor connection parts 49 are not connected by solder in the process of soldering, and the insulation distance can be easily secured, and the diameter reduction of the tip 15 can be facilitated. . In the endoscope 11 of the first embodiment, as shown in FIG. 15, four conductor connection portions 49 may be arranged at the four corners of the substrate of the imaging device 33.

<13th Configuration Example>
The endoscope 111 according to the thirteenth configuration example includes, as shown in FIG. 14, an objective cover glass 91, an element cover glass 43, an imaging element 33 whose imaging surface 41 is covered by the element cover glass 43, and an objective cover glass 91. And the element cover glass 43, and the lens 93 whose optical axis is aligned 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 And an air layer 95 provided between the lens 93 and the element cover glass 43.

  In the endoscope 11 of the first embodiment, the adhesive resin 37 is applied to the separation portion 47 having a finite width between the final lens L3 and the element cover glass 43 among the three lenses, The lens L3 and the element cover glass 43 are directly attached. On the other hand, in the endoscope 111 of the second embodiment, the lens 93 and the element cover glass 43 are directly attached via the adhesive resin 37. As a result, in the endoscope 111, the bonding resin 37 is substantially linear in side view (see FIG. 15). Further, in the endoscope 111 of the second embodiment, the lens 93 and the element cover glass 43 are directly attached by the adhesive resin 37 at the edge portions on both ends of the lens 93, and the adhesive resin 37 is It is applied only to the part.

  The lens 93 is, for example, a single lens, has an outer shape formed in the same prism as the imaging device 33, and has a square cross section in the direction perpendicular to the direction of the optical axis. The lens 93 focuses incident light from a subject that has passed through the objective cover glass 91 on the imaging surface 41 of the imaging element 33 via the element cover glass 43. A recess is formed on the surface of the lens 93 on the element cover glass 43 side. A convex curved surface portion 97 raised in a substantially spherical shape is formed on the bottom surface of the recess. The lens 93 has a function as an optical element for focusing light by the convex curved surface portion 97. The raised 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, the quadrangular ring-shaped end face surrounding the recess is bonded to the element cover glass 43 via the bonding resin 37. Thus, air is sealed in the recess between the lens 93 and the element cover glass 43. It is preferable that the air sealed in the recessed part which became this sealed space is dry air. In addition, nitrogen may be sealed in the recess. Thus, between the lens 93 and the element cover glass 43, an air layer 95 having an inner volume of the recess is formed. A convex curved surface portion 97 is disposed 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 111 with the maximum outer diameter Dmax of 1.0 mm, whether the number of lenses can be reduced or not is an important requirement of the diameter reduction. Therefore, when the lens 93 which is a single lens is provided in the endoscope 111, it is important how to make the refractive index difference with the lens 93 in a minute area in the width direction parallel to the optical axis direction. The endoscope 111 according to the thirteenth configuration example is characterized in that an air layer capable of obtaining a large difference in refractive index with the lens 93 is provided on the optical element surface.

  As described above, according to the endoscope 111 of the thirteenth 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 end face of the square ring is bonded to the element cover glass 43. In the above region, an air layer 95 for increasing the difference in refractive index with the lens 93 can be secured. At the same time, the lens 93 can be easily aligned with the imaging surface 41. The lens 93 can obtain a large lens power with the lens 93 by securing the air layer 95. Thereby, the number of lenses in the endoscope 111 can be reduced to one. As a result, downsizing and cost reduction of the endoscope 111 can be achieved.

<Fourteenth configuration example>
FIG. 16 is a side view showing an example of dimensions of an objective cover glass, a lens, and an element cover glass. In the endoscope 111 of the fourteenth configuration example, in the endoscope 111 of the present embodiment, the thickness TGt in the direction along the optical axis of the objective cover glass 91, the thickness SRt of the lens 93, and the thickness SGt of the element cover glass 43 , Both are formed in the range of 0.1 to 0.5 mm. In addition, the objective cover glass 91, the lens 93, the element cover glass 43, and the imaging element 33 have a square with one side of a square of a cross section perpendicular to the optical axis direction being 0.5 mm. In the image pickup device 33 shown in FIGS. 13 to 16, the electric circuit 99 is drawn with a thickness. Further, a bonding resin 37 for bonding the element cover glass 43 and the imaging element 33 is drawn with a thickness.

  The element cover glass 43 has a function of holding the distance between the lens 93 and the imaging surface 41 in accordance with the focal length and the optical characteristics of the lens 93. The element cover glass 43 facilitates this adjustment by setting the thickness SGt in the range of 0.1 to 0.5 mm.

  The lens 93 can function as an optical element and secure the air layer 95 by setting the thickness SRt in the range of 0.1 to 0.5 mm.

  The objective cover glass 91 can be used singly without using any other reinforcing member by setting the thickness TGt in the range of 0.1 to 0.5 mm. In addition, it is possible to suppress the decrease in the angle of view due to the kicking of the light beam due to the increase in thickness more than necessary.

  As described above, according to the endoscope 111 of the fourteenth configuration example, the lens 93 and the imaging device 33 are maintained at an appropriate distance, and the reduction of the angle of view is suppressed while securing the air layer 95 is facilitated. The enlargement of the dimension in the direction along the optical axis from the cover glass 91 to the imaging device 33 can be suppressed.

<Fifteenth Configuration Example>
In the endoscope 111 of the fifteenth configuration example, as shown in FIG. 13, in the endoscope 111 of the present embodiment, 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 device 33 A mold 65 covering and fixing with the mold resin 17 and forming an outer shell of the tip 15 and having the same outer diameter as the tip 15 and covering at least a part of the mold 65 And a tubular sheath 61 to be connected.

  The sheath 61 is made of a flexible resin material as described above. Further, the sheath 61 can be provided with single-wire, multi-wire, and braided tensile strength wire on the inner peripheral side for the purpose of imparting strength as described above. The material of the tensile wire is the same as described above.

  In the endoscope 111, the objective cover glass 91, the lens 93, the element cover glass 43, the entire imaging device 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. And the mold resin 17 is exposed to the outside. The distal end portion 15 of the endoscope 111 may include an X-ray opaque marker. Thereby, the endoscope 111 can easily confirm the tip position under radioscopy.

  In the endoscope 111, the objective cover glass 91, the lens 93, the element cover glass 43, the imaging device 33, a part of the transmission cable 31, and a part of the light guide 57 (imaging unit) are covered with the mold resin 17 and fixed. Therefore, there are few intervening parts when fixing these respective members. As a result, the diameter of the distal end portion 15 of the endoscope 111 can be reduced, and even if the diameter is further reduced, the diameter can be reduced to the minimum size. In addition, the cost of parts can be reduced. For example, it is possible to realize the endoscope 111 which can be applied so as to be able to image an affected part having a very small diameter such as a blood vessel of a human body. As a result, downsizing and cost reduction can be achieved in the endoscope 11.

  Further, since the mold resin 17 is formed so as to cover the imaging element 33 to the objective cover glass 91, the molding resin 17 contributes to an increase in the fixing strength of these imaging units. In addition, the mold resin 17 also enhances the air tightness (that is, no fine gap) of the air layer 95, the water tightness, and the light shielding property. Furthermore, the mold resin 17 also enhances the light shielding property when the optical fiber 59 for the light guide 57 is embedded.

  In addition, since the light guide 57 is molded with the mold resin 17 at the tip end portion 15 of the endoscope 111, the light guide 57 acts as a structural material, and the flexible portion 29 and the tip of the small diameter endoscope 111 are also made. The connection strength with the unit 15 can be improved. Further, in the endoscope 111, when the distal end portion 15 is viewed from the outermost surface on the insertion side (for example, see FIG. 12), the mold resin 17 covers the objective cover glass 91 of the distal end portion 15 and 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 111 is sterilized (that is, it is cleaned) after being used at the time of examination or surgery, the cleaning residue such as unnecessary liquid may adhere to the endoscope 111. This can be alleviated, and can have a higher degree of convenience in terms of hygiene when used for the next examination or surgery as compared with the endoscope 11 of the first embodiment.

  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. For this reason, the distance to the subject is likely to change depending on the rotation angle of the tip, and it is difficult to stably obtain a good image. Furthermore, when the axis of the tip 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 changes depending on the rotation angle of the tip, especially when entering a hole with a narrow diameter Sex is reduced. On the other hand, according to the endoscope 111, 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 disposed concentrically with the tip portion 15. As a result, in the endoscope 111 of the fifteenth configuration example, the diameter can be easily reduced, a good image can be stably obtained, and the insertion operability can be enhanced.

<Sixteenth Configuration Example>
As for the endoscope 111 of the 16th structural example, it is preferable to make thickness of the sheath 61 into the range of 0.1-0.3 mm.

  The mold portion 65 of the endoscope 111 has a small-diameter extension portion 71 shown in FIG. 13 which extends rearward from the rear end covering the imaging element 33. The small-diameter extension portion 71 is formed in a cylindrical shape and has four optical fibers 59 embedded therein. The small diameter extension 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 71 by an adhesive or the like. That is, the mold portion 65 and the sheath 61 are continuous at the coaxial maximum outer diameter Dmax of 1.0 mm.

  As described above, according to the endoscope 111 of the sixteenth configuration example, since the thickness of the sheath 61 can be increased to 0.3 mm, it is 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 distal end portion 15 is 1.0 mm, the thickness of the sheath 61 is 0.23 mm. Thereby, the endoscope 111 can make the maximum outer diameter Dmax of the distal end portion 15 be 1.0 mm by setting the thickness of the sheath 61 in the range of 0.1 to 0.3 mm described above. be able to.

<Seventeenth configuration example>
The seventeenth configuration example shows a configuration example of a lens shape as a specific example of the configuration of the lens 93 in the endoscope 111. FIG. 17A, FIG. 17B and FIG. 17C are diagrams showing a first example of the lens shape.

  The lens 93A of the first example is configured of 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, the central portion is formed with an optical element portion 201 having a circular dome-shaped convex curved surface portion 97 that bulges in a substantially spherical shape that forms the lens surface of the convex second surface LR2. An edge portion 202 is integrally formed as a frame body having an adhesive surface 203 having a flat end surface. The edge portion 202 has a dimension in the thickness direction (optical axis direction) larger than that of 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 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 outer peripheral portion and a square inner peripheral portion, and the four sides excluding the corner portion have substantially equal widths. In the bonding surface 203 of the edge portion 202, the bonding width Wa of equal-width portions on four sides is, for example, 50 μm or more. An air layer 95 is formed on the inner side of the edge portion 202 between the convex curved surface portion 97 which is a lens surface of the second surface LR 2 and the element cover glass 43.

  The dimension in the thickness direction of the lens 93 (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 bonding surface 203 of the edge portion 202, there is an inclined surface 204 which spreads from the lens center toward the outer periphery. The angle θA of the inclined surface 204 is, for example, θA = 60 ° when it is the angle θA of the opening viewed from the lens center.

  FIG. 18A, FIG. 18B and FIG. 18C are diagrams showing a second example of the lens shape. The lens 93B of the second example is an optical element having a circular dome-shaped convex curved surface portion 97 that bulges in a substantially spherical shape that forms the lens surface of the convex second surface LR2 on the imaging side of the lens 93B. A portion 201 is formed, and a peripheral edge portion is integrally formed with an edge portion 202 which is a frame having an adhesive surface 203 having a flat end surface. Here, the configuration of the part different from the first example will be mainly described, and the description of the same part as the first example will be omitted. The bonding surface 203 of the edge portion 202 is a circle whose outer peripheral portion is square and whose inner peripheral portion is concentric with the convex curved surface portion 97 having a circular dome shape, and the bonding width Wa of the minimum portion is 50 μm, for example. There is. The width Wc of the flat 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 which spreads from the lens center toward the outer periphery. The angle θA of the inclined surface 204 is, for example, θA = 60 ° when it is the angle θA of the opening viewed from the lens center.

  19A, 19B, 19C and 19D are diagrams showing a third example of the lens shape. The lens 93C of the third example is an optical element having a circular dome-shaped convex curved surface portion 97 that bulges in a substantially spherical shape that forms the lens surface of the convex second surface LR2 on the imaging side of the lens 93C. A portion 201 is formed, and a peripheral edge portion is integrally formed with an edge portion 202 which is a frame having an adhesive surface 203 having a flat end surface. Here, the configuration of the part different from the first example will be mainly described, and the description of the same part as the first example will be omitted. The optical element portion 201 at the center 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 off at the outer peripheral portion of the circular dome shaped convex curved surface portion 97 It has become. An inclined surface 204 is formed from the inner peripheral portion of the bonding surface 203 to the outer peripheral portion of the barrel-shaped optical element portion 201 in the peripheral portion 202. As shown in FIG. 19D, the lens 93C of the third example is an unnecessary portion of the image circle 212 of the circular lens 93C with respect to the imaging surface 211 of the square imaging device 33, that is, outside the four sides of the imaging surface 211. It has a shape obtained by cutting four outer peripheral regions 214 on which light rays forming an image in the region 213 are incident. The angle θA of the inclined surface 204 on the inner peripheral portion of the edge portion 202 is, for example, θA = 90 ° when the opening angle θA viewed from the lens center is, and the inclination is made smaller than 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 is larger. It can be taken.

  The lens 93 is manufactured, for example, by nanoimprinting, injection molding, or the like. The lens 93 forms a lens group in which a plurality of minute lenses of the same shape are arrayed by using a mold made of a nanoimprint master or the like, and after releasing the lens group of a molded product, dicing is performed to individual lenses. Produced 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. If the draft of the molded product is as large as possible, the releasability will be better. From the viewpoint of releasability, the sloped surface 204 of the lens 93 should be smooth with respect to the plane perpendicular to the optical axis of the lens 93. desirable. On the other hand, in order to reduce the external dimension of the lens 93, it is better to make the inclined surface 204 of the lens 93 as upright as possible. When the lens 93 is bonded to the element cover glass 43 by the bonding resin 37, the bonding surface 203 of the edge portion 202 to which the bonding resin 37 is attached is preferably as large as possible in terms of bonding strength.

  Therefore, in consideration of each factor of the diameter reduction, releasability and adhesion strength of the lens 93 comprehensively, in order to securely bond the lens 93 and the element cover glass 43 at the edge portion 202, the edge portion 202 The dimensions of the adhesive surface 203 of the For example, as an example of the size of the lens 93 whose outer shape is a quadrangular prism, when the dimension of one side of the square of the cross section perpendicular to the optical axis direction is 0.5 mm, the bonding surface 203 of the edge portion 202 has the bonding width Wa For example, 50 μm or more. In this case, in the endoscope 111 in which the maximum outer diameter Dmax of the distal end 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 in the edge portion 202 Of 50 μm or more. Further, in order to achieve both the miniaturization and the releasability of the lens 93, the angle θA of the inclined surface 204 is, for example, 60 ° ≦ θA ≦ 90 °, where the angle θA of the opening viewed from the lens center. 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 with respect to a plane perpendicular to the optical axis of the lens 93 60 degrees or less, 45 degrees or more.

  As described above, according to the endoscope 111 of the seventeenth configuration example, it is possible to realize the small diameter lens 93 capable of setting the maximum outer diameter Dmax of the distal end portion 15 to 1.0 mm or less. In addition, in the lens 93 whose diameter is reduced, by setting the bonding width Wa of the bonding surface 203 of the edge portion 202 to 50 μm or more, the lens 93 and the element cover glass 43 can be securely bonded and fixed. . Further, as the angle of the inclined surface 204 between the optical element portion 201 at the central portion of the lens 93 and the edge portion 202 at the peripheral portion, the angle θA of the opening viewed from the lens center is 60 ° ≦ θA ≦ 90 °. Thereby, the releasability at the time of lens preparation can be improved.

<18th Configuration Example>
The eighteenth configuration example shows a configuration example of the bonding surface of the lens 93 and the element cover glass 43 in the endoscope 111.

  FIG. 20 is a view showing a configuration example of the bonding surface of the lens 93 with the element cover glass 43. As shown in FIG. The lens 93 makes the optical axis alignment with the image pickup surface 41 of the image pickup device 33 easy by fixing the outer shape of the square column to the element cover glass 43 of the image pickup device 33 and bonding with the adhesive resin 37. can do. The adhesion surface 203 of the edge portion 202 of the lens 93 is inclined not to be a plane parallel to the end face of the element cover glass 43 but inclined so as to have a predetermined angle in a state of facing the element cover glass 43 for adhesion fixing. It may have the part 207. The inclined portion 207 of the adhesive surface 203 has a tapered shape which is inclined from the inner peripheral portion to the outer peripheral portion of the edge portion 202, and the thickness dimension of the outer peripheral portion is extremely small. 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 minutely 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 adhesive resin 37 on the adhesive surface is outer periphery by the inclined portion 207 of the adhesive surface 203. It is easy to move to the side, and it becomes difficult to enter inside the edge portion 202, and interference of the adhesive resin 37 with the air layer 95 formed in the optical element portion 201 can be suppressed.

  As described above, according to the endoscope 111 of the eighteenth configuration example, intrusion of the adhesive resin 37 into the air layer 95 between the lens 93 and the element cover glass 43 can be suppressed, and the air layer 95 is secured. The lens 93 and the element cover glass 43 can be securely adhered and fixed.

<The nineteenth configuration example>
The nineteenth configuration example shows a specific example of the configuration of the optical system in the endoscope 111.

Hereinafter, 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.
・ Objective cover glass 91
Thickness TGt of objective cover glass 91: TGt = 0.1 to 0.5 mm
One 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 d dF of the objective cover glass 91: 30 ν d dF
. Element cover glass 43
Thickness SGt of element cover glass 43: SGt = 0.1 to 0.5 mm
One 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 d dR of element cover glass 43: 40 ν d d R, d d F ν d d R
・ Lens 93
Focal length f of lens 93: 0.1 mm ≦ f ≦ 1.0 mm
F-number FNO of lens 93: 1.4 ≦ FNO ≦ 8.0

  FIG. 21 is a view for explaining the relationship between the focal length f of the lens 93 and the thickness tg (= SGt) of the element cover glass 43. As shown in FIG. In FIG. 21, f is the focal length of the lens 93, x is the distance from the imaging point on the imaging side to the subject end face of the element cover glass 43 at the focal length of the lens 93, tg is the thickness SGt of the element cover glass 43 Show. Further, θair is the maximum angle of the light beam emitted from the lens 93 to the imaging point in the air only state (in the case of a single lens) (the light ray connecting the imaging point in the air from the exit pupil of the lens Angle, θgl is the maximum angle to the optical axis of the light beam emitted from the lens 93 through the element cover glass 43 to the image forming point (in the case of lens + element cover glass) including the element cover glass 43 An angle between a light ray connecting an imaging point in a state including air and an element cover glass from the pupil and the optical axis). Here, x is 0 ≦ x ≦ f, and the distance from the exit pupil of the lens 93 to the object-side end face of the element cover glass 43 is f−x.

The relationship between the F-number FNO of the lens 93 and the numerical aperture NA is
FNO = 1 / (2 · NA)
Because
FNO = 1 / (2 · sin θ air)
It becomes. Therefore, the relationship of the following equation (1) can be derived.
sinθair = 1 / (2 · FNO) (1)
θair = sin ⁻¹ {1 / (2 · FNO)}
Also, according to Snell's law,
1 · sin θ air = ngl · sin θ gl
It becomes. Therefore, the relationship of the following equation (2) can be derived.
sinθgl = (sinθair) / ngl
= 1 / (2 · FNO · ngl) ... (2)
θgl = sin ⁻¹ {1 / (2 · FNO · ngl)}

In FIG. 21, the radius of the exit pupil of the lens 93 is f · tanθair, and in the state of air alone with the lens alone, the light from the exit pupil of the lens 93 to the imaging point in the air is the subject of the element cover glass 43 The distance to the optical axis at the position of the side end face is x · tan θair. Further, in a state including the lens 93 and the element cover glass 43, a light ray connecting an imaging point in a state where air and the element cover glass 43 are combined from the exit pupil of the lens 93 The distance to the end is tg · tan θgl. Here, since x tan θair = tg tan θgl, the thickness tg of the element cover glass 43 can be obtained by the following equation (3).
tg = xtan θair × (1 / tan θgl)
= X · (tan θ air) / (tan θ gl) (3)

Therefore, assuming that the thickness tg (= SGt) of the element cover glass 43 is 0.1 mm ≦ tg ≦ 0.5 mm, f, FNO, ngl (where x is a parameter) satisfying the relationship of the following formula (4) The combination of ndnd R) may be obtained from the expressions (1) and (2) and set as the numerical value of the optical characteristics of the lens 93 and the element cover glass 43.
0.1 ≦ x · (tan θ air) / (tan θ gl) ≦ 0.5 (4)
Here, tanθair and tanθgl can be expressed by FNO and ngl because they are obtained from sinθair and sinθgl.

  Next, as an optical characteristic of the lens 93 and the element cover glass 43, a specific combination of f, FNO, ngl (= ndR) when the thickness tg (= SGt) of the element cover glass 43 is tg = 0.40 mm. An example is shown. In the following example, BF indicates back focus (the distance from the center of the lens (the position of the exit pupil) to the imaging point (the imaging surface of the imaging device)), and BF is between the lens 93 and the element cover glass 43 Adjusted by distance.

(1) Long distance in the air (f, FNO, ndR) = (0.306, 4.01, 1.5168), BF = 0.1025
A distance in the air corresponds to, for example, observation of a trachea or larynx in a human body in an endoscope. It is used to diagnose the lungs of the human body and the upper airway of the respiratory system.

(2) Aerial short distance (f, FNO, ndR) = (0.306, 4.50, 1.5168), BF = 0.0375
The short distance in the air corresponds to observation of, for example, an area bronchus or bronchiole in a human body in an endoscope. It is used to diagnose the lungs of the human body and the lower airways of the respiratory system.

(3) Underwater distance (f, FNO, ndR) = (0.306, 4.02, 1.5168), BF = 0.1025
The underwater distance corresponds to observation of, for example, the uterus in the human body, the stomach, etc. in an endoscope.

(4) Underwater short distance (f, FNO, ndR) = (0.306, 4.47, 1.5168), BF = 0.0375
The underwater short distance corresponds to observation of, for example, a bladder in a human body, a coronary artery, a knee joint, a hip joint or the like in an endoscope. It is used for the diagnosis of blood vessels etc. of the human body.

  As described above, according to the endoscope 111 of the nineteenth configuration example, it is possible to realize the small diameter lens 93 capable of setting the maximum outer diameter Dmax of the distal end portion 15 to 1.0 mm or less. In addition, it is possible to obtain desired optical performance in the lens 93 with a small diameter.

<Twentieth Configuration Example>
The twentieth configuration example shows a specific example of the configuration of the imaging element 33 in the endoscope 111. 22A and 22B are diagrams showing a first example of the imaging device.

  The imaging element 33A of the first example has a rectangular cross section cut by a plane perpendicular to the optical axis of the lens 93. In this case, the external shape of the imaging surface on the element cover glass 43A side and the terminal surface on the transmission cable 31 side is a tetragonal shape, and the external shape of the imaging element 33A and the element cover glass 43A is formed in a square prism. . In addition, the imaging element 33A, the element cover glass 43A, and the lens 93 (not shown) are formed in a quadrangular prism shape having the same outer shape.

  An electric circuit 99A with a circuit pattern is provided on a substrate (terminal surface) provided on the rear end side of the imaging element 33A, and conductor connection portions (connection lands) 49 are provided on four corner portions, 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 imaging element 33A. The four electric wires 45 are positioned and connected to the four corner portions of the terminal surface of the imaging device 33A in a state where the end portions are respectively formed in a crank shape. Here, the width (length of one side of the rectangular cross section) SQL of the outer shape of the imaging element 33A is, for example, 0.5 mm or less, and the pitch PC between adjacent wires of the four wires 45 is, for example, 0. It is 3 mm or more.

  23A and 23B illustrate a second example of the imaging device. The image pickup device 33B of the second example is formed to have an octagonal shape in a cross section taken along a plane perpendicular to the optical axis of the lens 93, and the outer shapes of the image pickup device 33B and the element cover glass 43B are formed in an octagonal column. It is done. In addition, the imaging element 33B, the element cover glass 43B, the electric circuit 99B, and the lens 93 (not shown) are formed in the same octagonal columnar shape. Here, the configuration of the part different from the first example will be mainly described, and the description of the same part as the first example will be omitted.

  The second example is an example having an octagonal shape in which four corner portions (four corners) of a square are cut off (chamfered) by one cutting surface 221B in the cross-sectional shape of the imaging device 33B. The size of the cutout portion of the outer shape of the imaging element 33B is, for example, 20 to 50 μm from the apex of the quadrangle to the end of the cutout surface 221B. As described above, the four corners of the outer shape of the imaging device 33B are cut off by the cutting surface 221B, thereby separating the wire pitch PC between the four electric wires 45 as much as possible, and the outer dimensions of the imaging device 33B in the diagonal direction. It can be made smaller and can contribute to the further reduction in diameter of the endoscope. For example, when the dimension CS of the cutout portion is 21.2 μm, the outer dimensions of the imaging element 33B in the diagonal direction decrease by 15 μm at one location, and become 30 μm smaller at both ends in the diagonal direction. If the configuration of this cutting surface 221B is applied to an imaging element whose external dimension SQL is 0.5 mm on one side and the external dimension in the diagonal direction is 0.705 mm in a state where the external shape is a square, the external dimension in the diagonal direction is chamfered. Becomes as small as 0.675 mm, making it possible to realize a narrow-diameter endoscope having a diameter of 0.7 mm or less.

  24A and 24B are diagrams showing a third example of the imaging device. The imaging device 33C of the third example is formed to have a 12-angular shape in cross section taken along a plane perpendicular to the optical axis of the lens 93, and the external shapes of the imaging device 33C and the element cover glass 43C are formed in 12 prismatic shapes. It is done. In addition, the imaging element 33C, the element cover glass 43C, the electric circuit 99C, and the lens 93 (not shown) are formed in an octagonal prism shape having the same outer shape. Here, the configuration of the part different from the first example will be mainly described, and the description of the same part as the first example will be omitted. The third example is an example having a dodecagonal shape in which four corner portions of a tetragon are cut off by two cut surfaces 221C in the cross-sectional shape of the imaging device 33C. The size of the cutout portion of the outer shape of the imaging element 33C can be increased by cutting off in two planes, so that the dimension CS to the end of the cutout surface with respect to the apex of the quadrilateral can be increased as compared with the second example. Therefore, the diameter of the imaging device can be further reduced.

  The sectional shape in the direction perpendicular to the lens optical axis of the imaging device 33 is not limited to a quadrilateral, an octagon, or a dodecagon, and may be a 4 × n prism (n is a natural number) such as a hexagon. As described above, by forming the cross-sectional shape of the imaging element 33 into a 4 × n square, the diameter of the imaging element and the endoscope can be further reduced while enabling the connection of the transmission cable 31 by the four electric wires 45. Further, by setting the four corners of the 4 × n square cross-sectional shape of the imaging device 33 to be chamfered, the size in the diagonal direction of the imaging device 33 can be further reduced, which can contribute to further reduction in diameter.

  As described above, according to the endoscope 111 of the twentieth configuration example, it is possible to realize the small diameter imaging element 33 capable of setting the maximum outer diameter Dmax of the distal end portion 15 to 1.0 mm or less.

  In the endoscope 111 of the present embodiment, the imaging element 33 is provided at the distal end portion 15 of the insertion portion 21 and the imaging surface 41 is covered by the element cover glass 43, and focuses incident light from a subject on the imaging surface 41 A lens 93 and a bonding resin 37 for fixing the lens 93 and the element cover glass 43 are provided. The lens 93 is formed of a single lens whose outer shape is formed in a prismatic shape, the first surface on the subject side is flat, and the second surface on the imaging side is convex. On the imaging side of the lens 93, the central portion is formed with an optical element portion 201 having a convex curved surface portion 97 which is raised in a substantially spherical shape constituting a convex lens surface, and the peripheral portion is a bonding surface 203 having a flat end surface. The edge part 202 which has is integrally formed. As a result, it is possible to realize a lens 93 with a small diameter which can make the maximum outside diameter Dmax of the tip end portion 15 be 1.0 mm or less.

  Further, in the endoscope 111 of the present embodiment, the bonding surface 203 of the lens 93A has a substantially square shape whose outer peripheral portion is a square shape and whose inner peripheral portion is a rounded square shape.

  Further, in the endoscope 111 of the present embodiment, the bonding surface 203 of the lens 93B is a circular shape concentric with the convex curved surface portion 97 having a square outer peripheral portion and a circular dome shaped inner peripheral portion.

  Further, in the endoscope 111 of the present embodiment, the optical element portion 201 of the lens 93C has four on the circumference corresponding to the four sides of the square of the lens outer shape at the outer peripheral portion of the convex curved surface portion 97 having a circular dome shape. It has a barrel shape with a part cut out. Thereby, the inclination of the inclined surface 204 between the optical element portion 201 and the edge portion 202 can be gently formed, and the releasability at the time of lens production can be improved. Further, when the inclination of the inclined surface 204 is the same, the bonding width Wa of the bonding surface 203 of the edge portion 202 can be made larger, and the bonding strength can be improved.

  Further, in the endoscope 111 of the present embodiment, the lens 93 has an inclined surface 204 which 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 Assuming that the angle 204 is the angle θA of the opening viewed from the lens center, 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 whose diameter is reduced, the lens 93 and the element cover glass 43 can be securely adhered and fixed. Further, by securing a sufficient angle of the inclined surface 204, it is possible to improve the releasability at the time of lens production.

  Further, in the endoscope 111 of the present embodiment, the bonding surface 203 of the lens 93 has a tapered inclined portion 207 which is inclined from the inner peripheral portion of the edge portion 202 toward the outer peripheral portion. As a result, the adhesive resin 37 applied to the adhesive surface 203 is likely to move to the outer peripheral side, is less likely to enter the inner side than the edge portion 202, and the adhesive resin 37 interferes with the air layer 95 formed in the optical element portion 201. You can suppress that.

  Further, the endoscope 111 of the present embodiment is provided with an objective cover glass 91 which covers the object side surface of the lens 93 together with the imaging element 33, the element cover glass 43, the adhesive resin 37 and the lens 93. 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 ddF of 30 ≦ νdF, and the element cover glass 43 has a thickness SGt is 0.1 mm ≦ SGt ≦ 0.5 mm, refractive index ndR is 1.3 ≦ ndR ≦ 2.0, ndF ≦ ndR, Abbe number d dR is 40 ≦ d d R, d d F ≦ d d R A lens 93 with 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 a lens 93 with a small diameter which can make the maximum outside diameter Dmax of the tip end portion 15 be 1.0 mm or less.

  Further, in the endoscope 111 of the present embodiment, the distance from the imaging point on the imaging side at the focal distance of the lens 93 to the end face on the subject side of the element cover glass 43 is x (0 ≦ x ≦ f), the state of air only Maximum angle of the light beam emitted from the lens 93 to the imaging point by .theta.air, the maximum angle of the light beam emitted from the lens 93 including the element cover glass 43 to the imaging point through the element cover glass 43 When the lens 93 and the element cover glass 43 satisfy 0.1 ≦ x · (tan θair) / (tan θgl) ≦ 0.5, the combination of the focal length f, the F number FNO, and the refractive index ndR is . As a result, it is possible to obtain desired optical performance in the lens 93 of small diameter.

  Further, in the endoscope 111 of the present embodiment, four conductor connections provided on the surface opposite to the imaging surface 41 of the imaging device 33 together with the imaging device 33, the device cover glass 43, the adhesive resin 37, and the lens 93. A transmission cable 31 having four wires 45 connected to each of the parts 49 is provided. The image sensor 33 has a 4 × n square (n is a natural number) cross-sectional shape in the direction perpendicular to the optical axis of the lens 93, and the four electric wires 45 have a 4 × n square rear end face of the image sensor 33. The four conductor connections 49 disposed at the four corners are respectively connected. As a result, it is possible to realize an imaging element 33 with a small diameter that can make the maximum outside diameter Dmax of the tip end portion 15 be 1.0 mm or less.

  Further, in the endoscope 111 of the present embodiment, four corners of the 4 × n square cross-sectional shape of the imaging element 33 are chamfered. As a result, the size in the diagonal direction of the imaging device 33 can be made smaller, which can contribute to further reduction in diameter.

  Further, in the endoscope 111 of the present embodiment, the imaging element 33, the element cover glass 43, and the lens 93 are 4 × n square prisms having the same outer shape. As a result, the outer diameter from the lens 93 through the element cover glass 43 to the imaging element 33 can be further reduced.

  Moreover, in the endoscope 111 of the present embodiment, the length of one side of the 4 × n square of the cross section in the direction perpendicular to the optical axis of the imaging device 33 is 0.5 mm or less. As a result, it is possible to reduce the outer dimension of the imaging device 33 in the diagonal direction to about 0.7 mm.

  Further, in the endoscope 111 of the present embodiment, the maximum outer diameter of the distal end portion 15 is formed in a range of a finite diameter ̃1.0 mm corresponding to the diameter of the circumscribed circle of the substrate of the imaging device 33. Thus, by setting the maximum outer diameter Dmax to less than 1.0 mm, for example, insertion into a blood vessel of a human body can be further easily enabled.

  Although various 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 will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the appended claims, and of course these also fall within the technical scope of the present invention. It is understood. In addition, the components in the above embodiment may be arbitrarily combined without departing from the spirit of the invention.

  The present invention has the effect of achieving downsizing and cost reduction in an endoscope, and is useful as, for example, a narrow-diameter endoscope used for medical surgery and the like.

11, 111 ... Endoscope 15 ... Tip part 17 ... Mold resin 31 ... Transmission cable 33, 33A, 33B, 33C ... Image sensor 35 ... Lens unit 37 ... Resin for adhesion 41 ... Imaging surface 43, 43A, 43B, 43C ... Element cover glass 45 Electric wire 49 Conductor connection portion 57 Light guide 59 Optical fiber 65 Mold portion 91 Objective cover glass 93, 93A, 93B, 93C Lens 95 Air layer 97 Convex curved surface portion 99 99A 99B, 99C ... electric circuit 201 ... optical element section 202 ... edge section 203 ... bonding surface 204 ... inclined surface Dmax ... maximum outer diameter

Claims (7)

An imaging element provided at the tip of the insertion section, the imaging surface being covered by an element cover glass;
A single lens whose outer shape in the direction perpendicular to the optical axis is substantially square,
An adhesive resin for fixing the single lens and the element cover glass;
The single lens is formed in a prismatic shape, has a flat surface on the subject side, a circular hole with an imaging side on the center and a peripheral edge surrounding the hole, and the lens has a convex surface in the hole. Have
The central portion has a convex curved surface that bulges in a substantially spherical shape that constitutes the convex lens surface on the imaging side,
The peripheral unit may have a sloped portion of the tapered shape inclined toward the lens surface of the convex from the end face,
The peripheral portion, the end surface is flat, and to have a bonding surface between the element cover glass in the entire of the end surfaces,
Endoscope. A single lens whose outer shape in the direction perpendicular to the optical axis is substantially square,
An element cover glass which covers the imaging surface of the imaging element and whose outer shape in the direction perpendicular to the optical axis is substantially the same as the outer shape of the single lens;
It has an adhesive resin for fixing the single lens whose optical axis of the single lens is aligned to the center of the imaging surface and the element cover glass,
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 which is convex in a substantially spherical shape which constitutes the convex lens surface on the imaging side,
The peripheral portion of the single lens has a flat end surface and has an adhesive surface with the element cover glass over the entire end surface,
The bonding surface has a substantially square outer peripheral portion and a square inner peripheral portion.
Endoscope. An outer peripheral portion of the convex surface having a circular dome shape has a barrel shape in which four portions on the circumference corresponding to four sides of the square of the outer shape of the single lens are partially cut away.
The endoscope according to claim 2. The bonding surface has a tapered inclined portion which is inclined from the inner peripheral portion to the outer peripheral portion of the peripheral portion.
The endoscope according to claim 2 or 3. Before SL single lens, toward the inner peripheral portion of the adhesive surface from an outer peripheral portion of the convex surface, an inclined surface extending toward the outer periphery from the center of the lens, the angle of the inclined surface, the center of said single lens Assuming that the opening angle θA viewed from the point of view, 60 ° ≦ θA ≦ 90 °
The endoscope as described in any one of Claims 1-4 . Before SL adhesive surface has an adhesive width of more than 50 [mu] m,
The endoscope as described in any one of Claims 1-5. In the bonding surface, four sides from the outer peripheral portion to the inner peripheral portion excluding the corner portion of the bonding surface have substantially equal widths.
The endoscope as described in any one of Claims 2-4.