JP6765213B2 - Endoscope - Google Patents

Description

The present invention relates to an endoscope.

Conventionally, as shown in FIGS. 46 and 47, a small-diameter endoscope having a diameter of less than 3 mm is known (see, for example, Patent Document 1). FIG. 46 is a front view of the tip of a conventional small-diameter electronic endoscope. FIG. 47 is a perspective view of the light guide fiber bundle alone at the tip of the small-diameter electronic endoscope. In the small-diameter endoscope of Patent Document 1, an insulating cylinder 503 is fitted on the outer circumference of the observation window 501, and the tip main body inner cylinder 505 is arranged on the outer circumference of the insulating cylinder 503. The outer edge of the tip body inner cylinder 505 is scraped off according to the shape of the string of the injection end surface 507, and the injection end of the light guide fiber bundle 509 shown in FIG. 47 is the tip body outer cylinder 511 and the inside of the tip body. It is inserted in a state of being filled in the space between the cylinder 505 and the cylinder 505. This light guide fiber bundle 509 is in a state of being individually filled in the space inside the outer cylinder 511 of the tip body and covered with a hard molded portion 513 and a flexible protective tube 515 that is fixed to the space shape with an adhesive. Three regions are formed: a flexible portion 517 inserted and arranged in the insertion portion, and a transition portion 519 between the rigid molded portion 513 and the flexible portion 517.

Japanese Unexamined Patent Publication No. 2008-212309

The small-diameter endoscope of Patent Document 1 includes a tip body inner cylinder 505 as a holder for holding an objective optical system composed of a plurality of lenses and a solid-state image sensor. Therefore, a space for providing this holder is required. Further, since the illumination means such as the light guide fiber bundle 509 is arranged around the observation window 501 formed in a circle and the objective optical system, the outer diameter is increased by that amount. In the configuration in which the illumination means is arranged around the circular lens, a wasted space is generated on the insertion tip surface, and it is difficult to increase the member arrangement density on the insertion tip surface. Therefore, it is disadvantageous for miniaturization of the small-diameter endoscope.

Further, if a plurality of optical fibers included in the light guide fiber bundle 509 are arbitrarily arranged, the number of optical fibers that can be accommodated in the limited space may decrease, and the brightness due to illumination may decrease.

The present invention has been devised in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide an endoscope capable of achieving both miniaturization of the endoscope and improvement of lighting efficiency.

In the present invention, a single lens having a substantially quadrangular outer shape in the direction perpendicular to the center of the lens and a single lens having a substantially quadrangular outer shape in the direction perpendicular to the center of the lens, the length of which side is one side of the single lens. An image pickup element having the same length as the lens, an element cover glass that covers the image pickup surface of the image pickup element and has an outer shape in the direction perpendicular to the lens center that is the same as the outer shape of the image pickup element, and is arranged coaxially with the lens center. A single lens, an element cover glass, and a sheath that surrounds each outer surface of the image pickup element and is substantially in contact with the image pickup element, and has a circular outer shape, and is arranged along the center of the lens to form a single lens and image pickup. The lighting means inserted between each outer surface of the element and the inner peripheral surface of the sheath, and the outer shape of the single lens arranged on the objective side of the single lens and perpendicular to the center of the lens. The same objective cover glass and a plurality of illumination means are provided, and the plurality of illumination means are arranged in parallel along at least one side of a single lens or an imaging element to provide an objective cover glass and a single lens. Provided is an endoscope in which an objective cover glass and a sheath are provided on substantially the same plane on an insertion tip surface at a tip including the lens.

According to the present invention, it is possible to achieve both miniaturization of the endoscope and improvement of lighting efficiency.

Overall configuration diagram showing an example of an endoscope system using the endoscope of this embodiment A perspective view showing a state in which the tip of the endoscope of the present embodiment is viewed from the front side. Sectional drawing which shows the structural example of the tip part of the endoscope of this embodiment Cross-sectional view showing a configuration example of a state in which a lens and an image sensor in the endoscope of the present embodiment are directly attached via an adhesive resin. A perspective view showing a state in which an image sensor in which a transmission cable is connected to a conductor connection portion of the endoscope of the present embodiment is viewed from the rear side. The figure which shows the 1st example of the lens shape in the endoscope of this embodiment The figure which shows the 1st example of the lens shape in the endoscope of this embodiment The figure which shows the 1st example of the lens shape in the endoscope of this embodiment The figure which shows the 2nd example of the lens shape in the endoscope of this embodiment The figure which shows the 2nd example of the lens shape in the endoscope of this embodiment The figure which shows the 2nd example of the lens shape in the endoscope of this embodiment The figure which shows the 3rd example of the lens shape in the endoscope of this embodiment The figure which shows the 3rd example of the lens shape in the endoscope of this embodiment The figure which shows the 3rd example of the lens shape in the endoscope of this embodiment The figure which shows the 3rd example of the lens shape in the endoscope of this embodiment The figure which shows the structural example of the adhesive surface with the element cover glass in the lens of the endoscope of this embodiment. The figure which shows the 1st example of the image pickup element in the endoscope of this embodiment The figure which shows the 1st example of the image pickup element in the endoscope of this embodiment The figure which shows the 2nd example of the image pickup element in the endoscope of this embodiment The figure which shows the 2nd example of the image pickup element in the endoscope of this embodiment The figure which shows the 3rd example of the image pickup element in the endoscope of this embodiment The figure which shows the 3rd example of the image pickup element in the endoscope of this embodiment An enlarged perspective view of a main part of a holder with a notch as a light-shielding member in the endoscope of the present embodiment. A plan sectional view of the endoscope shown in FIG. 23. An exploded perspective view of the endoscope shown in FIG. 23. An enlarged perspective view of a main part of a holder with a through hole for a light-shielding member in the endoscope of the present embodiment. An exploded perspective view of the endoscope shown in FIG. 26. The light-shielding member in the endoscope of this embodiment is an enlarged perspective view of a main part of a resin mold. A plan sectional view of the endoscope shown in FIG. 28. An exploded perspective view of the endoscope shown in FIG. 28. Enlarged perspective view of the main part of the pipe where the light-shielding member in the endoscope of this embodiment A plan sectional view of the endoscope shown in FIG. 31. An exploded perspective view of the endoscope shown in FIG. 31. The light-shielding member in the endoscope of the present embodiment is an enlarged perspective view of a main part of the jacket. An enlarged perspective view of the optical fiber covered with the jacket of FIG. 34. A perspective view of the tip of the endoscope in the present embodiment in which the image sensor and the sheath are substantially in contact with each other and the four corners of the image sensor are not chamfered. A perspective view of the sheath of the endoscope shown in FIG. 36. Front sectional view including the image sensor of the endoscope shown in FIG. A perspective view of a tip portion in which the image sensor and the sheath of the endoscope of the present embodiment are substantially in contact with each other and the four corners of the image sensor are chamfered. A perspective view of the sheath of the endoscope shown in FIG. 39. Front sectional view including the sensor of the endoscope shown in FIG. 39. A plan sectional view of the endoscope shown in FIG. 39. Front sectional view in which a plurality of optical fibers are arranged along four sides of the image sensor in the endoscope of the present embodiment. Front sectional view in which a plurality of optical fibers are arranged along two sides of an image sensor in the endoscope of the present embodiment. The figure for demonstrating the length of the diameter of the optical fiber in the endoscope of this embodiment. Front view of the tip of a conventional small-diameter electronic endoscope Perspective view of the light guide fiber bundle unit at the tip of a small-diameter electronic endoscope

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

First, a basic configuration example common to the endoscopes of the present embodiment will be described. The configuration example is a configuration requirement that the endoscope according to the present invention can have. The endoscope according to the present invention does not exclude the following configuration examples from being duplicated with each other.

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

In addition, about the direction used for explanation in this specification, it is assumed that the description of the direction in each figure is followed. Here, "top" and "bottom" correspond to the top and bottom of the video processor 19 placed on a horizontal plane, respectively, and "front (front)" and "rear" correspond to the endoscope main body (hereinafter, "endoscope 11"). The tip side of the insertion portion 21 and the base end side of the plug portion 23 (in other words, the video processor 19 side) correspond to each other.

As shown in FIG. 1, the endoscope system 13 is, for example, a still image or a moving image obtained by photographing the inside of an observation target (for example, a blood vessel of a human body) with an endoscope 11 which is a flexible mirror for medical use. On the other hand, the configuration includes a video processor 19 that performs well-known image processing and the like. The endoscope 11 includes an insertion portion 21 extending substantially in the front-rear direction and being inserted into the inside of 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 portion 27 that opens into the front wall 25. The rear portion of the plug portion 23 of the endoscope 11 is inserted into the socket portion 27, whereby the endoscope 11 can send and receive electric power and various signals (video signals, control signals, etc.) to and from the video processor 19. Is.

The power and various signals described above are guided from the plug portion 23 to the flexible portion 29 via a transmission cable 31 (see FIG. 3 or FIG. 4) inserted inside the flexible portion 29. The image data output by the image sensor 33 provided at the tip portion 15 is transmitted from the plug portion 23 to the video processor 19 via the transmission cable 31. The video processor 19 performs well-known image processing such as color correction and gradation correction on the image data transmitted from the plug unit 23, and outputs the image data after the image processing to a display device (not shown). The display device is a monitor device having a display device such as a liquid crystal display panel, and displays an image of a subject captured 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 soft portion 29 whose rear end is connected to the plug portion 23, and a tip portion 15 connected to the tip of the soft portion 29. The flexible portion 29 has an appropriate length corresponding to various methods such as endoscopy and endoscopic surgery. The flexible portion 29 is formed by, for example, covering the outer periphery of a spirally wound metal thin plate with a net, and further covering the outer periphery with a coating, and is formed so as to have sufficient flexibility. The flexible portion 29 connects between the tip portion 15 and the plug portion 23.

The endoscope 11 of the embodiment described below can be inserted into a body cavity having a small diameter by forming the insertion portion 21 with a small diameter. The small-diameter body cavity is not limited to blood vessels of the human body, and includes, for example, ureters, pancreatic ducts, bile ducts, bronchioles, and the like. That is, the endoscope 11 can be inserted into a blood vessel, a ureter, a pancreatic duct, a bile duct, a bronchiole, or the like of the human body. In other words, the endoscope 11 can be used for observing lesions in blood vessels. The endoscope 11 is effective in identifying atherosclerotic plaques. It can also be applied to endoscopic observation during cardiac catheterization. Furthermore, the endoscope 11 is also effective in detecting thrombi and arteriosclerotic yellow plaques. In atherosclerotic lesions, color tone (white, pale yellow, yellow) and surface (smoothness, irregularity) are observed. In the thrombus, color tones (red, white, dark red, yellow, brown, mixed) are observed.

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

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

Further, the endoscope 11 can be inserted into the bronchus. The endoscope 11 is inserted through the oral cavity or nasal cavity of the supine specimen (that is, the subject). The endoscope 11 passes through the pharynx and larynx and is inserted into the trachea while visually recognizing the vocal cords. The bronchi become thinner with each branch. For example, according to the endoscope 11 having a maximum outer diameter Dmax of less than 2 mm, it is possible to confirm the lumen up to the subtertiary bronchus.

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

In the following description, the term "adhesive" is not only a strict meaning of a substance used for adhering a surface to a surface of a solid object, but also a substance that can be used for bonding two objects, or curing. When the adhesive has a high barrier property against gas and liquid, it is used in a broad sense as a substance having a function as a sealing agent.

<First configuration example>
FIG. 2 is a perspective view showing a state in which the tip portion 15 of the endoscope 11 of the present embodiment is viewed from the front side. FIG. 3 is a cross-sectional view showing a configuration example of the tip portion 15 of the endoscope 11 of the present embodiment. The endoscope 11 shown in FIG. 2 has a maximum outer diameter Dmax of the tip portion 15 shown in FIG. 3 formed in a range of a finite diameter to 1.0 mm corresponding to the diameter of the circumscribed circle of the substrate of the dicing image sensor 33. can do.

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

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

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

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 stages on the left and right and two on the upper and lower sides, and the outer periphery of the insulating coating is further bundled by a jacket to form one transmission cable 31. Each conductor is formed in a straight line in which four conductors are parallel to each other with the insulating coating stripped off. The tip of the conductor of the electric wire 45 is connected to the conductor connecting portion 49 by soldering. As shown in FIG. 3, the image sensor 33 and the transmission cable 31 are covered with the mold resin 17. Therefore, the conductor connecting 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 11 of the second configuration example, the four conductor connection portions 49 can be arranged at the four corners of the substrate of the image pickup element 33, so that the four conductor connection portions 49 can be arranged on the square image pickup element 33. As shown in FIG. 5, the substrates can be arranged evenly spaced from each other at the maximum distance. As a result, the two adjacent conductor connecting portions 49 are not connected by soldering in the soldering process, the insulation distance can be easily secured, and the diameter of the tip portion 15 can be easily reduced. ..

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

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

The adhesive resin 37 is made of, for example, a UV / thermosetting resin. The adhesive resin 37 preferably has translucency 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 that cannot be irradiated with ultraviolet rays can be cured by heat treatment. The adhesive resin 37 fixes the lens 93 whose optical axis is aligned with the center of the imaging surface 41 to the element cover glass 43. As a result, the lens 93 and the image sensor 33 are directly bonded and fixed by the adhesive resin 37, that is, the lens 93 and the image sensor 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 is cured to a certain hardness even by irradiation with ultraviolet rays.

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

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

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

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

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

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

In the endoscope 11, the objective cover glass 91, the lens 93, the element cover glass 43, the entire image sensor 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. An X-ray opaque marker may be included in the tip portion 15 of the endoscope 11. This makes it easy for the endoscope 11 to confirm the tip position under fluoroscopy.

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

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

As described above, according to the endoscope 11 of the fourth configuration example, by providing the light guide 57, it is possible to take a picture in a dark part by using the endoscope 11 alone.

Further, as shown in FIG. 2, in the endoscope 11 of the fourth configuration example, the light guide 57 as an example of the lighting means is the objective cover glass 91, the lens 93, the element cover glass 43, and the image sensor 33, respectively. It is a configuration provided in a plurality of surroundings. For example, four light guides 57 can be evenly provided at equal intervals. As a result, according to the endoscope 11 of the fourth configuration example, four light guides 57 are evenly spaced around each of the objective cover glass 91, the lens 93, the element cover glass 43, and the image sensor 33 at equal intervals. Since it is provided, shadows are less likely to occur on the top, bottom, left, and right of the subject. As a result, the endoscope 11 can obtain a clear captured image as compared with the configuration in which the light guide 57 is one or two.

Further, in the endoscope 11 of the present embodiment, the image pickup element 33 is formed in a square shape. The optical fibers 59 of the four light guides 57 are arranged at substantially the center of each side of the substrate of the image sensor 33 in a space sandwiched between the substrate of the image sensor 33 and the circumscribed circle of the substrate of the image sensor 33. There is.

As described above, according to the endoscope 11 of the fourth configuration example, the space sandwiched between the square image sensor 33 and the circular mold portion 65 substantially circumscribing the image sensor 33 can be effectively used, and the tip portion 15 can be effectively used. A plurality of (particularly four) optical fibers 59 can be easily arranged without increasing the outer diameter. As a result, the endoscope 11 can obtain a clear image while facilitating the manufacture without increasing the outer diameter of the tip portion 15.

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

Further, since the mold resin 17 is molded by covering the image sensor 33 to the objective cover glass 91, it contributes to an increase in the fixing strength of these image pickup units. Further, the mold resin 17 also enhances the airtightness (that is, no fine gaps), watertightness, and light-shielding property of the air layer 95. Further, the mold resin 17 also enhances the light-shielding property when the optical fiber 59 for the light guide 57 is embedded.

Further, since the light guide 57 is molded on the tip portion 15 of the endoscope 11 by the molding resin 17, the light guide 57 acts as a structural material, and even in the small-diameter endoscope 11, the soft portion 29 and the tip end. The connection strength with the portion 15 can be improved. Further, in the endoscope 11, when the tip portion 15 is viewed from the outermost surface on the insertion side (see, for example, FIG. 2), the mold resin 17 covers the tip portion 15 including the objective cover glass 91 and the four optical fibers 59. Therefore, there is no clearance around each of the objective cover glass 91 and the four optical fibers 59 (that is, a gap around each). Therefore, when the endoscope 11 is sterilized (that is, washed) after being used during an examination or surgery, cleaning residue such as unnecessary liquid may adhere to the endoscope 11. It can be alleviated and have even higher convenience in terms of hygiene when used for the next examination or surgery.

Further, in some conventional endoscopes, the axis of the tip and the optical axis of the lens unit are eccentric. With such a configuration, the distance to the subject is likely to change depending on the rotation angle of the tip portion, and it is difficult to stably obtain a good image. Furthermore, if the axis of the tip and the optical axis of the lens unit 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, and operability is particularly high when entering a hole with a small diameter. Decreases. On the other hand, according to the endoscope 11, the objective cover glass 91, the lens 93, the element cover glass 43, and the image pickup element 33 are coaxially connected. That is, the objective cover glass 91 is arranged concentrically with the tip portion 15. As a result, the endoscope 11 of the fourth configuration example can be easily reduced in diameter, a good image can be stably obtained, and the insertion operability can be improved.

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

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

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

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

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

The thickness direction dimension (thickness SRt) of the lens 93 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 up to the first surface LR1 on the outer peripheral portion of the convex curved surface portion 97 (second surface LR2) of the optical element portion 201 is 110 μm to 120 μm. Further, from the outer peripheral portion of the convex curved surface portion 97 of the optical element portion 201 to the inner peripheral portion of the adhesive surface 203 of the edge portion 202, there is an inclined surface 204 extending from the center of the lens toward the outer circumference. Assuming that the angle θA of the inclined surface 204 is the angle θA of the aperture seen from the center of the lens, for example, θA = 60 °.

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

12, FIG. 13, FIG. 14, and FIG. 15 are views showing a third example of the lens shape in the endoscope 11 of the present embodiment. The lens 93C of the third example is an optical element having a substantially spherical dome-shaped convex curved surface portion 97 whose central portion constitutes the lens surface of the convex second surface LR2 on the imaging side of the lens 93C. The portion 201 is formed, and the peripheral portion is integrally formed with an edge portion 202 which is a frame body having an adhesive surface 203 whose end surface is flat. Here, the configuration of the portion different from that of the first example will be mainly described, and the description of the same portion as that of the first example will be omitted. The optical element portion 201 at the center has a shape in which four portions 206 on the circumference corresponding to the four sides of the square of the lens outer shape are partially cut out at the outer peripheral portion of the convex curved surface portion 97 having a circular dome shape. ing. The edge portion 202 of the peripheral edge portion has an inclined surface 204 formed from the inner peripheral portion of the adhesive surface 203 to the outer peripheral portion of the barrel-shaped optical element portion 201. As shown in FIG. 15, the lens 93C of the third example has an unnecessary portion of the image circle 212 of the circular lens 93C, that is, outside the four sides of the image pickup surface 211 with respect to the image pickup surface 211 of the square image sensor 33. The shape is such that the four outer peripheral regions 214 in which the light rays to be imaged in the region 213 are incident are cut. The angle θA of the inclined surface 204 of the inner peripheral portion of the edge portion 202 is, for example, θA = 90 ° when the angle θA of the aperture seen from the center of the lens is set. It can be formed gently. On the other hand, as in the first and second examples, 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 made larger. Can be taken.

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

Therefore, in order to ensure that the lens 93, the element cover glass, and 43 can be reliably adhered to each other at the edge portion 202 by comprehensively considering each element of the lens 93 having a smaller diameter, releasability, and adhesive strength, the edge portion 202 Set the dimensions of the adhesive surface 203 of. For example, as an example of the size of a lens 93 having a square columnar outer shape, when the dimension of one side of a square having a cross section perpendicular to the optical axis direction or the axial direction passing through the lens center is 0.5 mm, the adhesive surface of the edge portion 202 In 203, the adhesive width Wa is set to, for example, 50 μm or more. In this case, in the endoscope 11 in which the maximum outer diameter Dmax of the tip portion 15 is 1.0 mm or less, the dimension of one side of the outer shape of the lens 93 is set to 0.5 mm or less, and the adhesive width Wa of the adhesive surface 203 in the edge portion 202. Is secured at 50 μm or more. Further, in order to achieve both miniaturization and releasability of the lens 93, the angle θA of the inclined surface 204 is set to, for example, 60 ° ≤ θA ≤ 90 °, where the angle θA of the opening seen from the center of the lens is set. In this case, the angle of the inclined surface 204 is 30 ° or more and 45 ° or less with respect to the optical axis direction (direction parallel to the mold release direction) of the lens 93, and the axial direction passing through the optical axis of the lens 93 or the lens center. It is 60 ° or less and 45 ° or more with respect to the plane perpendicular to.

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

<7th configuration example>
The seventh configuration example shows a configuration example of the adhesive surface between the lens 93 and the element cover glass 43 in the endoscope 11.

FIG. 16 is a diagram showing a configuration example of an adhesive surface of the lens 93 of the endoscope 11 of the present embodiment with the element cover glass 43. The lens 93 is fixed by easily aligning the optical axis with the image pickup surface 41 of the image pickup element 33 by aligning the outer shape of the square columnar shape with the element cover glass 43 of the image pickup element 33 and adhering the lens 93 with the adhesive resin 37. can do. The adhesive surface 203 of the edge portion 202 of the lens 93 is not a flat surface parallel to the end surface of the element cover glass 43 but is inclined so as to have a predetermined angle in a state where the adhesive surface 203 is opposed to the element cover glass 43 for adhesive fixing. It may have a part 207. The inclined portion 207 of the adhesive surface 203 has a tapered shape inclined from the inner peripheral portion of the edge portion 202 toward the outer peripheral portion, and the thickness dimension of the outer peripheral portion is slightly reduced. The inclination angle of the inclined portion 207 of the adhesive surface 203 is, for example, 0.5 ° or more. When a small amount of the adhesive resin 37 is applied to the adhesive surface 203 of the edge portion 202 in order to bond the lens 93 to the element cover glass 43, the adhesive resin 37 on the adhesive surface is covered by the inclined portion 207 of the adhesive surface 203. It is easy to move to the side, it is difficult to enter inside the edge portion 202, and it is possible to prevent the adhesive resin 37 from interfering with the air layer 95 formed in the optical element portion 201.

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

<8th configuration example>
The eighth configuration example shows a specific example of the configuration of the optical system in the endoscope 11.

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

<9th configuration example>
The ninth configuration example shows a specific example of the configuration of the image pickup device 33 in the endoscope 11. 17 and 18 are views showing a first example of the image pickup device 33 in the endoscope 11 of the present embodiment.

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

An electric circuit 99A based on a circuit pattern is provided on the substrate (terminal surface) provided on the rear end side of the image pickup element 33A, and conductor connection portions (connection lands) 49 are provided at each of the four corners, respectively. The transmission cable 31 by the electric wire 45 is connected by soldering or the like. That is, four electric wires 45 are connected at the four corners of the terminal surface of the image sensor 33A. The four electric wires 45 are connected at four corners of the terminal surface of the image sensor 33A with their ends molded into a crank shape. Here, the width of the outer shape of the image sensor 33A (the length of one side of the quadrangular cross section) SQL is, for example, 0.5 mm or less, and the pitch PC between the wires adjacent to the four wires 45 is, for example, 0.3 mm. That is all.

19 and 20 are views showing a second example of the image pickup device 33 in the endoscope 11 of the present embodiment. In the image sensor 33B of the second example, the shape of the cross section cut by a plane perpendicular to the optical axis of the lens 93 or the axial direction passing through the lens center is formed into an octagonal shape, and the external shapes of the image sensor 33B and the element cover glass 43B. Is formed in an octagonal columnar shape. Further, the image sensor 33B, the element cover glass 43B, the electric circuit 99B, and the lens 93 (not shown) are formed in an octagonal columnar shape having the same outer shape. Here, the configuration of the portion different from that of the first example will be mainly described, and the description of the same portion as that of the first example will be omitted.

The second example is an example in which the cross-sectional shape of the image sensor 33B has an octagonal shape in which four quadrangular corners (four corners) are cut out (chamfered) by one cut surface 221B. As for the dimension of the cut-out portion of the outer shape of the image sensor 33B, the dimension CS to the end of the cut-out surface 221B with respect to the apex of the quadrangle is, for example, 20 to 50 μm. In this way, by cutting out the four corners of the outer shape of the image sensor 33B on the cut surface 221B, the pitch PCs between the four wires 45 are separated as much as possible, and the outer dimensions of the image sensor 33B in the diagonal direction are adjusted. It can be made smaller and can contribute to further reducing the diameter of the endoscope. For example, if the dimension CS of the cut-out portion is 21.2 μm, the external dimension of the image sensor 33B in the diagonal direction is reduced by 15 μm in one place, and the diameter is reduced by 30 μm at both ends in the diagonal direction. When the configuration of the cut surface 221B is applied to an image sensor having a square outer shape, an outer dimension SQL on one side of 0.5 mm, and an outer dimension of 0.705 mm in the diagonal direction, the outer dimensions in the diagonal direction are chamfered. Is as small as 0.675 mm, making it possible to realize a small-diameter endoscope with a diameter of 0.7 mm or less.

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

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

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

The endoscope 11 of the present embodiment is provided at the tip end portion 15 of the insertion portion 21, and the image pickup surface 41 is covered with the element cover glass 43, and the incident light from the subject is imaged on the image pickup surface 41. It includes a lens 93, and an adhesive resin 37 for fixing the lens 93 and the element cover glass 43. The lens 93 is composed of a single lens having a prismatic outer shape, a first surface on the subject side having a flat surface, and a second surface on the imaging side having a convex surface. On the imaging side of the lens 93, an optical element portion 201 having a substantially spherically raised convex curved surface portion 97 forming a convex lens surface is formed in the central portion, and an adhesive surface 203 having a flat end surface is formed in the peripheral portion. The edge portion 202 to be held is integrally formed. As a result, it is possible to realize a lens 93 having a small diameter capable of setting the maximum outer diameter Dmax of the tip portion 15 to 1.0 mm or less.

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

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

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

Further, in the endoscope 11 of the present embodiment, the lens 93 has an inclined surface 204 extending from the center of the lens toward 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, and the inclined surface. Assuming that the angle of 204 is the angle θA of the opening seen from the center of the lens, 60 ° ≦ θA ≦ 90 °, and the bonding width Wa of the bonding surface 203 is 50 μm or more. As a result, in the lens 93 having a reduced diameter, the lens 93 and the element cover glass 43 can be reliably adhered and fixed. Further, by ensuring a sufficient angle of the inclined surface 204, it is possible to improve the releasability at the time of manufacturing the lens.

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

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

Further, in the endoscope 11 of the present embodiment, the distance from the imaging point on the imaging side to the end face on the subject side of the element cover glass 43 at the focal length of the lens 93 is x (0 ≦ x ≦ f), and only air is used. The maximum angle of the light beam emitted from the lens 93 to the imaging point with respect to the optical axis is θair, and the maximum angle of the light beam emitted from the lens 93 including the element cover glass 43 to the imaging point via the element cover glass 43 with respect to the optical axis. Is θgl, the lens 93 and the element cover glass 43 are made of a combination of a focal length f, an F number FNO, and a refractive index ndR that satisfy 0.1 ≦ x · (tan θair) / (tan θgl) ≦ 0.5. .. This makes it possible to obtain desired optical performance in the lens 93 having a small diameter.

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

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

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

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

Further, in the endoscope 11 of the present embodiment, the maximum outer diameter of the tip portion 15 is formed in a range of a finite diameter to 1.0 mm corresponding to the diameter of the circumscribed circle of the substrate of the image sensor 33. As a result, by setting the maximum outer diameter Dmax to less than 1.0 mm, for example, insertion into a blood vessel of the human body can be made more easily.

<10th configuration example>
FIG. 23 is an enlarged perspective view of a main part of a holder with a notch as a light-shielding member in the endoscope 11 of the present embodiment. FIG. 24 is a plan sectional view of the endoscope 11 shown in FIG. 23. FIG. 25 is an exploded perspective view of the endoscope 11 shown in FIG. 23.

The endoscope 11 of the tenth configuration example has a single lens (for example, a lens 93) having a quadrangular outer shape (for example, a square or a rectangular shape) in the direction perpendicular to the optical axis or the lens center, and is coaxial with the optical axis or the lens center. The lens 93 is surrounded by the lens 93, and the outer circumference of the sheath 61 is arranged between the outer circumference of the sheath 61 and at least one side of the lens 93, and is arranged along the optical axis or the center of the lens. A light-shielding member (for example, a cylindrical holder 131) provided between the lens 93 and the light guide 57 is provided with an extending illumination means (for example, a light guide 57). Further, the endoscope 11 has an outer shape of a quadrangle (for example, a square or a rectangle) in the direction perpendicular to the optical axis or the center of the lens, and the length of one side thereof is the same as the length of one side of the lens 93. 33 and an element cover glass 43 that covers the image pickup surface 41 of the image pickup element 33 and has the same outer shape as the outer shape of the image pickup element 33 in the direction perpendicular to the optical axis or the lens center are further included.

The endoscope 11 is assembled as follows. Specifically, the lens 93 shown in FIG. 25, the image sensor 33, and the transmission cable 31 are assembled to complete the camera assembly (that is, a unit composed of a plurality of components related to the camera; the same applies hereinafter). Next, a fiber assembly (that is, a unit composed of a plurality of components relating to the optical fiber 59; the same applies hereinafter) is assembled. The fiber assembly includes, for example, a plurality of light guides 57 and a cylindrical holder 131 as an example of a light-shielding member. Next, the camera assembly and the fiber assembly are fixed so as to be inserted into the opening in the center of the housing of the cylindrical holder 131 which is the fiber assembly. A distance of at least about 50 (μm) is secured between one side of the objective cover glass 91 and the notch 133. Finally, the sheath 61 is covered up to the cylindrical holder 131 and fixed by the adhesive resin 37 without any gap.

According to the endoscope 11 of the tenth configuration example, the light guide 57 is arranged between the sheath 61 having a circular outer circumference and at least one side of the quadrangular lens 93. As a result, the space generated by the shape difference between the circular portion of the sheath 61 and the quadrangular portion of the lens 93 can be used for the arrangement of the light guide 57, and the member arrangement density at the tip portion 15 can be increased. That is, the space efficiency can be improved as compared with the conventional configuration in which the light guide 57 is arranged on the outer circumference of the circular lens. As a result, wasted space can be suppressed and miniaturization can be easily achieved. Further, in the endoscope 11, since the lens 93 and the image pickup element 33 are formed in a quadrangular shape, the alignment between the lens center and the image pickup center can be easily performed. In addition to this, since the four sides of the lens 93 and the image sensor 33 and the four corners of the lens 93 and the image sensor 33 can be fixed by the adhesive resin 37, the fixed area can be increased. As a result, the lens 93 and the image sensor 33 can be fixed with high strength.

Further, in the endoscope 11 of the tenth configuration example, the outer shape of the image pickup element 33 is a quadrangle. The outer shape of the sheath 61 is circular. Here, when the inner diameter of the sheath 61 is brought close to the corner portion of the rectangular image sensor 33 to the extent permitted by the strength, the area available in the sheath 61 excludes the space for arranging the square image sensor 33 located at the center. It will be the remaining space. The remaining space is a half-moon columnar portion connecting four arcs and both ends of the arcs with one side of a quadrangle (more precisely, a straight line slightly longer than one side). In the endoscope 11, a light-shielding member (cylindrical holder 131) is formed by a square hole cylinder in which these four half-moon columnar portions are connected by thin-walled portions outside the corner portion of the image sensor 33. That is, in the endoscope 11, the cylindrical holder 131 is formed by making maximum use of the remaining space excluding the essential space. As a result, it is possible to reliably prevent the light leaking from the outer surface of the optical fiber 59 in the extending direction while realizing miniaturization. The cylindrical holder 131 can be a metal (for example, SUS material) holder.

Here, with reference to FIG. 23, the maximum outer diameter of the endoscope 11 shown in FIG. 23 will be specifically described as 1.0 mm or less. In FIG. 23, the shortest distance between the four corners (corners) of the objective cover glass 91 whose outer shape in the direction perpendicular to the center of the lens is quadrangular (for example, square) and the inner peripheral surface of the sheath 61 is the mass productivity of the endoscope 11. In consideration of (including workability) and handleability (that is, it is not easily damaged during assembly), it is set to about 50 μm. Further, since the length of each side of the objective cover glass 91, the lens 93, the element cover glass 43, and the image sensor 33 whose outer shape in the direction perpendicular to the center of the lens is a quadrangle (for example, a square) is 500 μm, they are diagonal to each other. The dimensions are about 705 μm. The thickness of the sheath 61 used this time is 97 (μm), and the maximum outer diameter Dmax of the endoscope 11 is 705 (μm) +50 (μm) +50 (μm) +97 (μm) ≈1000 (μm). = 1.0 (mm), which is 1.0 (mm) or less.

Further, the cylindrical holder 131 is provided with a notch 133 or a through hole in the thick half-moon columnar portion to provide an insertion space for the light guide 57 without reducing the strength of the holder. It can be easily secured. In other words, it can be said that the shape is extremely space efficient. In this case, if the notch 133 is formed as a rectangle having a long side along one side, the light guide 57 can be efficiently arranged and the assembling property becomes easy.

In the endoscope 11 of the tenth configuration example, the cylindrical holder 131 is longer than the length from the insertion tip surface 135 at the tip portion 15 of the endoscope 11 to the image pickup surface 41 of the image pickup element 33.

According to the endoscope 11 of the tenth configuration example, the cylindrical holder 131 extends to the rear of the imaging surface 41 to shield the lens side surface of the lens 93, so that the optical fiber 59 extends from the outer surface in the extending direction. It is possible to reliably prevent the leaked light from entering the medium from the side surface of the lens.

Further, in the endoscope 11 of the tenth configuration example, a notch 133 is formed in the cylindrical holder 131. When the notch 133 is formed as a rectangle having a long side along one side of the image pickup device 33, a plurality of optical fibers 59 can be efficiently arranged and processing can be facilitated. For example, in the endoscope 11 of the tenth configuration example, when the outer diameter of the optical fiber 59 is 0.052 mm, at least 6 fibers on one side and 12 fibers on both sides can be accommodated in the direction along the chord of the half-moon columnar portion. The required number may differ depending on the observation target, the distance to the observation target, and the light source used.

Further, in the endoscope 11 of the tenth configuration example, a plurality of light guides 57 are arranged point-symmetrically with respect to the center of the lens.

According to the endoscope 11, since the light guide 57 is arranged point-symmetrically at the center of the lens 93, the illumination light is evenly distributed to the left and right and up and down, especially when the illumination light is applied to the circular inner peripheral surface. Can shine. As a result, shadows are less likely to be generated on the subject, and the captured image can be easily seen. Further, since the light guide 57 is point-symmetrical with respect to the axis of the tip portion 15, the light distribution of the illumination light is unlikely to change depending on the rotation angle of the tip portion 15, and the operation is particularly performed when entering a blood vessel having a small diameter. Improves sex.

Further, in the endoscope 11 of the tenth configuration example, a plurality of optical fibers 59 are arranged in parallel with the side surface of the lens along the lens center of the lens 93, and are arranged in a row along one side of the lens 93.

According to the endoscope 11, the optical fiber 59 is arranged vertically along one side of the lens 93. With such a configuration, the space can be effectively used as compared with the case where the optical fiber 59 is arranged only in the center of one side. In addition to this, the endoscope 11 arranges a plurality of optical fibers 59 in a line along one side, so that a wide range of illumination light can be evenly distributed.

The cylindrical holder 131 may extend a square cylinder continuous portion 137 for ensuring the thickness of the sheath 61 at the rear portion on the side opposite to the insertion tip surface 135. The cylindrical holder 131 can be provided with a square cylinder continuous portion 137 to increase the connection strength with the sheath 61. That is, the sheath 61 can be made thicker at the extrapolated portion of the square tube continuous portion 137. Further, it is preferable to form the square hole 139 for accommodating the objective cover glass 91 formed inside the cylindrical holder 131 so as to be close to the outer peripheral circle of the cylinder within the range allowed by the strength, from the viewpoint of improving space efficiency. ..

Therefore, according to the endoscope 11 of the tenth configuration example, the space efficiency (member placement density) on the insertion tip surface 135 can be increased (wasted space can be suppressed), so that the size can be reduced and the lens 93 and the image pickup can be performed. The element 33 can be easily fixed with high strength, and stray light from the light guide 57 can be prevented.

Further, on the insertion tip surface 135 of the endoscope 11, the sheath 61 and the camera assembly and the fiber assembly are filled with the adhesive resin 37 without a gap, so that it is possible to prevent the liquid from entering the tip portion 15. It can be done and it becomes easy to wash.

<11th configuration example>
FIG. 26 is an enlarged perspective view of a main part of a holder with a through hole for a light-shielding member in the endoscope 11 of the present embodiment. FIG. 27 is an exploded perspective view of the endoscope 11 shown in FIG. 26.

In the endoscope 11 of the eleventh configuration example, the light-shielding member is a cylindrical holder 141 that coaxially accommodates the lens 93, and is located along the center of the lens between the outer peripheral surface of the holder of the cylindrical holder 141 and one side of the lens 93. A directional through hole 143 is formed. A plurality of optical fibers 59 are inserted through the through hole 143. In the endoscope 11 of the eleventh configuration example, when the outer diameter of the optical fiber 59 is, for example, 0.052 mm, at least 6 fibers on one side and 12 fibers on both sides can be accommodated in the direction along the chord of the through hole 143. The required number may differ depending on the observation target, the distance to the observation target, and the light source used.

The endoscope 11 is assembled as follows. Specifically, the lens 93 shown in FIG. 27, the image sensor 33, and the transmission cable 31 are assembled to complete the camera assembly. The fiber assembly is then assembled by attaching the plurality of ride guides 57 to the cylindrical holder 141. The fiber assembly includes, for example, a plurality of light guides 57 and a cylindrical holder 141 as an example of a light-shielding member, and the plurality of light guides 57 are inserted into and fixed through holes 143 of the cylindrical holder 141. The camera Assy is then mounted on the Fiber Assy cylindrical holder 141. Similarly, a distance of at least about 50 (μm) is secured between one side of the objective cover glass 91 and the through hole 143. Finally, the sheath 61 is covered up to the cylindrical holder 141, and the gap between the sheath 61 and the camera assembly and the fiber assembly is filled with the adhesive resin 37 and fixed.

According to the endoscope 11 of the eleventh configuration example, a through hole 143 in the direction along the center of the lens is formed in the half-moon columnar portion of the cylindrical holder 141 of the square hole cylinder. The light guide 57 can be efficiently arranged by forming the through hole 143 into a substantially half-moon-shaped hole in the direction in which the strings are along one side.

Further, on the insertion tip surface of the endoscope 11, the gap (including the through hole 143) created by fixing the camera assembly and the fiber assembly is filled with the adhesive resin 37, so that the liquid does not enter the tip portion 15. It can be prevented and it becomes easy to clean.

<12th configuration example>
FIG. 28 is an enlarged perspective view of a main part of the mold resin as the light-shielding member in the endoscope 11 of the present embodiment. FIG. 29 is a plan sectional view of the endoscope 11 shown in FIG. 28. FIG. 30 is an exploded perspective view of the endoscope 11 shown in FIG. 28.

In the endoscope 11 of the twelfth configuration example, the light-shielding member is a mold resin 145 that covers the outer surface of the light guide 57 in the extending direction.

The endoscope 11 is assembled as follows. Specifically, the lens 93 shown in FIG. 30, the image sensor 33, and the transmission cable 31 are assembled to complete the camera assembly. Next, the fiber assembly is molded with resin to complete the process. Next, the fiber assembly is fixed to the camera assembly (see the dotted line). Finally, the sheath 61 is covered from the outside of the fiber assembly to which the camera assembly is fixed, and the mold resin 146 is filled in the gap formed between the fiber assembly and the camera assembly and the sheath 61 and fixed without a gap.

According to the endoscope 11 of the twelfth configuration example, a plurality of optical fibers 59 constituting the light guide 57 are fiber bundled by the mold resin 145. The plurality of optical fibers 59 are arranged in a row along one side of the lens 93. In the endoscope 11 of the twelfth configuration example, when the outer diameter of the optical fiber 59 is, for example, 0.052 mm, at least 8 fibers on one side and 16 fibers on both sides can be accommodated in the direction along the chord. The mold resin 145 is molded at any of the above-mentioned four half-moon columnar portions in the same shape as the half-moon columnar portion. In the mold resin 145, the optical fiber 59 is arranged in advance in the cavity filled with the molten resin by using a resin mold, and the molten resin is filled. As a result, a plurality of optical fibers 59 are integrally formed in the half-moon columnar portion in a state of being inserted in a row.

In addition, in the mold resin 145, when there is a concern about light leakage from the outer surface of the optical fiber 59 in the extending direction due to the thin wall, a resin containing carbon (for example, carbon black) is used. be able to. Further, a thin-film film such as metal or a light-shielding film by screen printing may be formed on the side surface of the lens. As a result, even if the light-shielding member is the mold resin 145, the light-shielding performance can be further improved. Further, on the insertion tip surface of the endoscope 11, the sheath 61 and the camera assembly and the fiber assembly are filled with the mold resin 146 without a gap, so that it is possible to prevent the liquid from entering the tip portion 15. It also becomes easier to clean.

<13th configuration example>
FIG. 31 is an enlarged perspective view of a main part of the pipe 147 as a light-shielding member in the endoscope 11 of the present embodiment. FIG. 32 is a plan sectional view of the endoscope 11 shown in FIG. 31. FIG. 33 is an exploded perspective view of the endoscope 11 shown in FIG. 31.

In the endoscope 11 of the thirteenth configuration example, the light-shielding member is a pipe 147 through which the light guide 57 is inserted inward.

The endoscope 11 is assembled as follows. Specifically, the lens 93 shown in FIG. 33, the image sensor 33, and the transmission cable 31 are assembled to complete the camera assembly. Next, the optical fiber 59 is inserted into the pipe 147 and fixed tightly by the adhesive resin 37 to assemble the fiber assembly. Next, the fiber assembly is fixed to the opposite side surface of the camera assembly by the adhesive resin 37 without any gap. Finally, the sheath 61 inserted through the transmission cable 31 is covered to the outside of the fiber assembly fixed to the camera assembly, and the gap between the sheath 61 and the camera assembly and the fiber assembly is filled with the adhesive resin 37. Is fixed. Although the adhesive resin 37 is not shown in FIG. 31, the gap formed between the sheath 61 and the camera assembly and the fiber assembly is filled with the adhesive resin 37. Further, in FIG. 32, the adhesive resin 37 is shown so as to be adhered to at least the end surface of the image sensor 33 (in other words, the end surface of the pipe 147), but the adhesion range of the adhesive resin 37 is It is not limited to the terminal surface of the image sensor 33. For example, the adhesive resin 37 includes a conductor connecting portion 49, an electric wire 45, and a part of a transmission cable 31 on the rear end side (that is, the side opposite to the objective side) of the image sensor 33 in the sheath 61. It may be adhered to.

According to the endoscope 11 of the thirteenth configuration example, a plurality of optical fibers 59 constituting the light guide 57 can be shielded from light by inserting them into the oval holes 149 of the pipe 147. In the endoscope 11 of the thirteenth configuration example, when the outer diameter of the optical fiber 59 is, for example, 0.052 mm, at least eight optical fibers on one side and 16 optical fibers on both sides can be accommodated in the direction along the oval hole 149. The pipe 147 is formed in a long cylinder. As the material of the pipe 147, for example, a Ni electroformed material can be used. The minor axis of the long cylinder substantially matches the outer diameter of the optical fiber 59. As a result, the pipe 147 can bundle a plurality of optical fibers 59 in a line in the major axis direction. The optical fiber 59 inserted in the pipe 147 is preferably fixed by the above-mentioned adhesive resin 37. The pipe 147 can fix the surface in the direction along the long axis to the side surface of the lens. By using the long cylindrical pipe 147 as the light-shielding member, a plurality of optical fibers 59 can be reliably shielded from light and bundled easily and with high strength. Further, on the tip surface of the endoscope 11, the sheath 61 and the camera assembly and the fiber assembly are filled with the adhesive resin 37 without a gap, so that it is possible to prevent the liquid from entering the tip portion 15. It also becomes easier to clean.

<14th configuration example>
FIG. 34 is an enlarged perspective view of a main part of the jacket 151 as a light-shielding member in the endoscope of the present embodiment. FIG. 35 is an enlarged perspective view of the optical fiber 59 covered with the jacket 151 of FIG. 34.

The endoscope 11 of the 14th configuration example has a single lens (for example, a lens 93) having a quadrangular outer shape (for example, a square or a rectangular shape) in the direction perpendicular to the optical axis or the center of the lens, and is coaxial with the optical axis or the center of the lens. The lens 93 is surrounded by the lens 93, and the outer circumference of the sheath 61 is arranged between the outer circumference of the sheath 61 and at least one side of the lens 93, and is arranged along the optical axis or the center of the lens. It is provided with an extending lighting means (for example, a light guide 57) and a light-shielding member provided between the lens 93 and the light guide 57. Further, the light-shielding member referred to here is a jacket 151 that covers the outer surface of the light guide 57 in the extending direction. The jacket 151 is provided on each optical fiber 59 constituting the light guide 57. Further, the endoscope 11 of the 14th configuration example has a quadrangular outer shape (for example, a square or a rectangle) in the direction perpendicular to the optical axis or the center of the lens, and the length of one side thereof is the length of one side of the lens 93. It further includes an imaging element 33 that is the same, and an element cover glass 43 that covers the imaging surface 41 of the imaging element 33 and whose outer shape in the direction perpendicular to the optical axis or the lens center is the same as the outer shape of the imaging element 33.

The endoscope 11 is assembled as follows. Specifically, the lens 93 shown in FIG. 30, the image sensor 33, and the transmission cable 31 are assembled to complete the camera assembly. Next, the fiber assembly including the plurality of optical fibers 59 provided with the jacket 151 is molded with resin to complete the process. Next, the fiber assembly is fixed to the camera assembly (see the dotted line). Finally, the sheath 61 is covered from the outside of the fiber assembly to which the camera assembly is fixed, and the mold resin 146 is filled in the gap formed between the fiber assembly and the camera assembly and the sheath 61 and fixed without a gap. In FIG. 34, the mold resin 146 is not shown in the gap formed between the sheath 61 and the camera Assy and the fiber Assy, but it occurs between the sheath 61 and the camera Assy and the fiber Assy. The gap is filled with the mold resin 146. Further, in FIG. 34, the mold resins 145 and 146 are shown so as to cover at least the end surface of the image sensor 33, but the coverage range of the mold resins 145 and 146 is not limited to the end surface of the image sensor 33. .. For example, the mold resins 145 and 146 include a conductor connecting portion 49, an electric wire 45, and a part of a transmission cable 31 on the rear end side (that is, the side opposite to the objective side) of the end surface of the image sensor 33 in the sheath 61. You may cover and fix it as such.

According to the endoscope 11 of the 14th configuration example, the outer surface of each optical fiber 59 in the extending direction is covered with the cylindrical jacket 151. The jacket 151 uses a material having a high light-shielding property. As a material having a high light-shielding property, for example, a resin containing carbon can be used.

In the optical fiber 59, quartz glass or resin is generally used for the core 153 and the clad 155. The larger the maximum light receiving angle NA (Numerical Aperture: numerical aperture) of the optical fiber 59, the larger the light collecting ability and the easier the coupling with the light source. However, the larger the NA, the larger the light loss and light dispersion between the core 153 and the clad 155. Therefore, it is necessary to optimally obtain the NA value. By providing the jacket 151, the optical fiber 59 can reliably block the leaked light generated when the optimum NA value is set with a simple structure.

<15th configuration example>
Although not shown, the endoscope of the fifteenth configuration example includes a single lens (for example, lens 93) having a quadrangular outer shape (for example, square or rectangular) in the direction perpendicular to the optical axis or the center of the lens, and an optical axis. Alternatively, the lens is arranged coaxially with the center of the lens and surrounds the lens, and the outer circumference thereof is arranged between a circular sheath (for example, sheath 61) and the outer circumference of the sheath and at least one side of the lens. It includes a lighting means (for example, a light guide 57) extending along a shaft or a center of a lens, and a light-shielding member provided between the lens and the light guide. Further, the light-shielding member referred to here is a light-shielding film (not shown) formed on the side surface of the lens along the lens center of the lens. Further, the endoscope 11 of the 15th configuration example has a quadrangular outer shape (for example, a square or a rectangle) in the direction perpendicular to the optical axis or the center of the lens, and the length of one side thereof is the length of one side of the lens 93. The image pickup element 33 which is the same and the element cover glass 43 which covers the image pickup surface 41 of the image pickup element 33 and whose outer shape in the direction perpendicular to the optical axis or the lens center is the same as the outer shape of the image pickup element 33 are further included. Further, in the endoscope 11 of the 15th configuration example, the space between the sheath 61 and the light guide 57 and the space between the sheath 61 and the objective cover glass 91, the lens 93, the element cover glass 43 and the image sensor 33 are tenth. Leakage light from the light guide 57 may be shielded by appropriately combining with the configurations of the endoscopes of the configuration examples to the 14th configuration example.

According to the endoscope 11 of the fifteenth configuration example, by forming a light-shielding film on the side surface of the lens, light leaking from the outer surface in the extending direction of the optical fiber arranged in the vicinity thereof is incident on the side surface of the lens. Be prevented. The light-shielding film can be formed by vacuum deposition. Vacuum deposition evaporates and sublimates the film-forming material in a vacuum, and attaches and deposits the particles. As the film forming material, for example, aluminum, chromium, gold or the like can be used.

In the tenth configuration example, the eleventh configuration example, the twelfth configuration example, the thirteenth configuration example, and the fourteenth configuration example described above, the maximum outer diameter Dmax is 1 mm or less. The maximum outer diameter Dmax of the endoscope 11 may be less than 2 mm (for example, 1.8 mm). The image sensor 33 has a maximum side length of 0.51 mm and a thickness of 0.51 mm. The maximum outer diameter of the optical fiber 59 is 0.052 mm. Further, the light guides 57, which are lighting means, are arranged at two points symmetrically with each other, for example.

<16th configuration example>
FIG. 36 is a perspective view of a tip portion 15 in which the image pickup element 33 and the sheath 61 of the endoscope 11 of the present embodiment are substantially in contact with each other and the four corners of the image pickup element 33 are not chamfered. FIG. 37 is a perspective view of the sheath 61 of the endoscope 11 shown in FIG. 36. FIG. 38 is a front sectional view including the image pickup element 33 of the endoscope 11 shown in FIG. The front sectional view shows a cross section perpendicular to the optical axis or the center of the lens.

Further, FIG. 29 described above can also be used as a plan sectional view of the endoscope 11 shown in FIG. 36. When FIG. 29 is applied to this configuration example, the gap between the image sensor 33 and the sheath 61 is reduced by the amount that the image sensor 33 and the sheath 61 are substantially in contact with each other, so that the thickness of the mold resin filled in this gap is reduced. ..

In this configuration example, the description of the same configuration as the above-described configuration example may be simplified or omitted.

The endoscope 11 of the 16th configuration example includes a single lens (for example, a lens 93) having a substantially quadrangular outer shape (for example, a square or a rectangle) in the direction perpendicular to the optical axis or the center of the lens. The endoscope 11 includes an image sensor 33 having a substantially quadrangular outer shape (for example, a square or a rectangle) in the direction perpendicular to the center of the lens, and the length of one side thereof is the same as the length of one side of a single lens. .. The endoscope 11 covers the image pickup surface 41 of the image pickup element 33, and includes an element cover glass 43 whose outer shape in the direction perpendicular to the lens center is the same as the outer shape of the image pickup element 33. The endoscope 11 is arranged coaxially with the center of the lens, surrounds each outer surface of the single lens, the element cover glass 43, and the image pickup element 33, and includes a sheath 61 having a circular outer shape. Further, the sheath 61 is substantially in contact with the image sensor 33.

The endoscope 11 is assembled as follows, for example. Specifically, the lens 93, the image sensor 33, and the transmission cable 31 are assembled to complete the camera assembly. Next, a light guide 57 including a plurality of optical fibers 59 is arranged along at least one side of a member such as an image sensor 33, an element cover glass 43, a lens 93, and an objective cover glass 91, and is attached to this side. Is fixed by. Next, the sheath 61 is covered from the outside of the light guide 57 fixed to the camera assembly. Finally, the mold resins 145 and 146 are filled in the gaps formed between the fiber assembly and the light guide 57 and the sheath 61 and fixed without gaps.

Here, "substantially contacting" means having a position where the image sensor 33 and the sheath 61 are the shortest distance, that is, having a minute gap (gap) between the four corners (corners) of the image sensor 33 and the sheath 61. It may or may not have.

When it has a minute gap, the assembly performance when assembling the endoscope can be improved. That is, when the sheath 61 is covered from the outside of the camera assembly and the fiber assembly when the endoscope 11 is assembled, the sheath 61 is caught by the image sensor 33 of the camera assembly or the fiber assembly, which hinders the smooth assembly of the sheath 61. Can be suppressed.

When there is no minute gap, the four corners of the image sensor 33 and the sheath 61 come into contact with each other. In this case, a heat shrink tube is used as the sheath 61. For example, in the above assembly step, there are gaps between the four corners of the image sensor 33 and the sheath 61 before heating. When the sheath 61 is heated after the sheath 61 is covered or the mold resin 146 is filled, the sheath 61 contracts, and the four corners of the image sensor 33 come into contact with the inner peripheral surface of the sheath 61. For example, the contact state (whether the image sensor 33 and the sheath 61 are in slight contact with each other, or in complete contact with each other, etc.) may be adjusted depending on the degree of heating of the sheath 61.

In this way, by using the heat-shrinkable tube, the diagonal length of the image sensor 33 and the diameter length of the sheath 61 can be made substantially the same, and the diameter of the tip portion 15 of the endoscope 11 can be further reduced. it can.

Further, since the number of outer surfaces of the image sensor 33 is the same as the number of one side of the image sensor 33, there are four when the outer shape of the image sensor 33 is quadrangular.

According to the endoscope 11 of the 16th configuration example, the space corresponding to the holder can be reduced by omitting the holder for holding the lens 93 and the image pickup element 33. Further, when the image sensor 33 and the sheath 61 are substantially in contact with each other, the diagonal length of the quadrangular cross section in the front view of the image sensor 33 and the diameter length of the circular cross section in the front view of the sheath 61 become substantially the same. It contributes to reducing the diameter of the tip portion 15 of the mirror 11.

Further, in the endoscope 11, even if the holder is absent, the sheath 61 is substantially in contact with the four corners of the image sensor 33, so that the endoscope 11 is in a plane direction perpendicular to the optical axis of the lens 93 or the axial direction passing through the lens center. The position of the image sensor 33 is fixed and held at a predetermined position. Further, by surrounding the sheath 61 including the outer surfaces of the image sensor 33, the element cover glass 43, and the lens 93, the strength of the outer periphery of the image sensor 33, the element cover glass 43, and the lens 93 is improved. Therefore, even if an external force is generated on the tip portion 15 of the endoscope 11, unintended deformation of the tip portion 15 can be suppressed.

As described above, according to the endoscope 11, it is possible to achieve both miniaturization of the endoscope 11 and improvement of robustness at the tip portion 15.

Further, in the endoscope 11, the sheath 61 may be substantially in contact with the image sensor 33, and the sheath 61 may be substantially in contact with the lens 93. As a result, the position of the image sensor 33 and the sheath 61 are fixed at a predetermined position in the plane direction perpendicular to the optical axis of the lens 93 or the axial direction passing through the lens center. Alternatively, the sheath 61 may be substantially in contact with the lens 93 instead of the sheath 61 being substantially in contact with the image sensor 33. Further, at least one of the element cover glass 43 and the objective cover glass 91 may be substantially in contact with the sheath 61.

Further, in the endoscope 11, the objective cover glass 91 is arranged on the objective side of the lens 93, and the outer shape in the direction perpendicular to the lens center is the same as the outer shape of the lens 93. The objective cover glass 91 and the sheath 61 are provided on substantially the same plane on the insertion tip surface 135 of the tip portion 15 including the objective cover glass 91 and the lens 93.

That is, the sheath 61 extends to the tip of the tip 15 on the outside of the lens 93, the element cover glass 43, and the image sensor 33. As a result, the sheath 61 surrounds the image sensor 33 on the rear surface side to the objective cover glass 91 at the tip of the tip 15, so that the robustness is improved up to the tip of the tip 15.

Further, the endoscope 11 is arranged along the center of the lens, and includes a lighting means (for example, a light guide 57) inserted between each outer surface of the lens 93 and the image sensor 33 and the inner peripheral surface of the sheath. May be good.

As a result, the endoscope 11 can use the space generated by the shape difference between the circular cross-section portion in the front view of the sheath 61 and the quadrangular cross-section portion in the front view of the lens 93 and the image sensor 33 for the arrangement of the light guide 57. The member arrangement density at the tip portion 15 can be improved. Therefore, it is possible to illuminate the subject while suppressing wasted space.

Further, the endoscope 11 may be filled with a mold portion (for example, mold resin 145, 146) between each outer surface of the lens 93 and the image sensor 33 and the inner peripheral surface of the sheath 61. Although the mold resins 145 and 146 of the twelfth configuration example are omitted in FIGS. 36 and 37, the mold resins 145 and 146 are filled in the same manner as in FIG. 28.

As a result, the endoscope 11 is made more robust by the mold resin 145, 146 filled between the image sensor 33 and the sheath 61 while the image sensor 33 and the sheath 61 are substantially in contact with each other to reduce the diameter. Can be maintained. Further, the endoscope 11 can be improved in waterproofness and dustproofness by filling the mold resin between the image pickup element 33 and the sheath 61 without a gap.

<17th configuration example>
FIG. 39 is a perspective view of a tip portion 15 in which the image pickup element 33 and the sheath 61 of the endoscope 11 of the present embodiment are substantially in contact with each other and the four corners of the image pickup element 33 are chamfered. FIG. 40 is a perspective view of the sheath 61 of the endoscope 11 shown in FIG. 39. FIG. 41 is a front sectional view including the image pickup element 33 of the endoscope 11 shown in FIG. 39. FIG. 42 is a plan sectional view of the endoscope 11 shown in FIG. 39.

In this configuration example, the description of the same configuration as the above-described configuration example may be simplified or omitted.

In FIGS. 39 to 42, the four corners of the image sensor 33 are chamfered and shown by the cut surface 221. The cut surfaces at the four corners of the element cover glass 43 are shown by the cut surfaces 222. The cut surfaces at the four corners of the lens 93 are shown by the cut surface 223. The cut surfaces at the four corners of the objective cover glass 91 are shown by the cut surfaces 224.

In the endoscope 11 of the 17th configuration example, at least the image sensor 33 has a shape in which at least a part of the four corners of the quadrangle is cut off as compared with the 16th configuration example. At least a part of the four corners indicates that all four corners of the quadrangle may be chamfered or three or less corners may be chamfered. Further, as a method of chamfering, for example, the method shown in the ninth configuration example can be mentioned. That is, the outer shape of the image sensor 33 may be octagonal, dodecagonal, or polygonal 13 or more.

According to the endoscope 11 of the 17th configuration example, the diagonal length of the image sensor 33 can be shortened by cutting off at least a part of the four corners of the image sensor 33 having a quadrangular cross section in the front view. Since the image sensor 33 and the sheath 61 are substantially in contact with each other, the diagonal length of the quadrangular cross section in the front view of the image sensor 33 and the diameter length of the circular cross section in the front view of the sheath 61 are substantially the same. Therefore, since the length of the diameter of the sheath 61 arranged on the outermost side of the endoscope 11 can be shortened, the diameter of the endoscope 11 can be further reduced as compared with the case where the four corners of the image pickup element 33 are not chamfered.

Further, in the endoscope 11, the lens 93 may have a shape in which at least a part of four corners having a quadrangular cross section is cut off in a front view. At least a part of the four corners indicates that all four corners of the quadrangle may be chamfered or three or less corners may be chamfered. Moreover, as a method of chamfering, the same method as the method of chamfering the image pickup device 33 can be mentioned. That is, the outer shape of the lens 93 may be an octagonal shape, a dodecagonal shape, or a polygonal shape of 13-sided or more.

The lens 93 may be chamfered by a method different from the chamfering method of the image sensor 33. Therefore, the outer shape of the image sensor 33 and the outer shape of the lens 93 may be different.

The endoscope 11 can shorten the diagonal length of the lens 93 by cutting off at least a part of the four corners of the lens 93 having a quadrangular cross section in the front view. When the lens 93 and the sheath 61 are substantially in contact with each other, the diagonal length of the quadrangular cross section in the front view of the lens 93 and the diameter length of the circular cross section in the front view of the sheath 61 are substantially the same. Therefore, since the length of the diameter of the sheath 61 arranged on the outermost side of the endoscope 11 can be shortened, the diameter of the endoscope 11 can be further reduced as compared with the case where the four corners of the lens 93 are not chamfered.

In general, it is more difficult to reduce the size of the image sensor 33 than to reduce the size of the lens 93. Therefore, when the diameter of the endoscope 11 is reduced to the maximum, the image sensor 33 is diagonally reduced in diameter. It is presumed that the length becomes a bottleneck for reducing the diameter of the tip portion 15 of the endoscope 11. Therefore, when the area of the quadrangle cross section (the area not chamfered) in the front view of the image pickup element 33 is larger than the area of the quadrangle cross section in the front view of the lens 93, the image pickup element 33 is chamfered and the lens 93 is not chamfered. May be good. In this case, the diameter of the tip portion 15 of the endoscope 11 can be reduced by making the diagonal length of the quadrangular cross section and the diameter length of the sheath 61 substantially the same in the front view of the lens 93. When the area of the quadrangle cross section in the front view of the image sensor 33 is larger than the area of the quadrangle cross section in the front view of the lens 93, the image sensor 33 and the lens 93 may be chamfered. As a result, the diameter of the tip portion 15 of the endoscope 11 can be reduced as compared with the case where the image sensor 33 is chamfered and the lens 93 is not chamfered.

On the other hand, the area of the quadrangle cross section in the front view of the image pickup element 33 may be smaller than the area of the quadrangle cross section in the front view of the lens 93. In this case, the image pickup element 33 may not be chamfered and the lens 93 may be chamfered. .. In this case, the diameter of the tip portion 15 of the endoscope 11 can be reduced by making the diagonal length of the quadrangular cross section and the diameter length of the sheath 61 substantially the same in the front view of the image sensor 33. When the area of the image sensor 33 is smaller than the area of the lens 93, chamfering may be performed on both the image sensor 33 and the lens 93. As a result, the diameter of the tip portion 15 of the endoscope 11 can be reduced as compared with the case where the lens 93 is chamfered without chamfering the image sensor 33.

As with the image sensor 33 and the lens 93, the element cover glass 43 and the objective cover glass 44 may be chamfered. FIG. 42 illustrates a state in which the four corners of the image sensor 33, the element cover glass 43, the lens 93, and the objective cover glass 91 are cut and chamfered by the cut surfaces 221, 222, 223, and 224, respectively.

In FIG. 40, six optical fibers 59 are arranged in parallel (here, one row) along each of the two parallel sides of the image sensor 33, and in FIG. 41, along each of the four sides of the image sensor 33. Three optical fibers 59 are arranged in parallel (here, one row). In this configuration example, the number of sides on which the optical fibers 59 are arranged and the number of optical fibers 59 arranged per side are arbitrary.

Although the shape of the transmission cable 31 is different between the plan sectional view shown in FIG. 42 including the chamfered image sensor 33 and the plan sectional view shown in FIG. 29 including the non-chamfered image sensor 33. , Both configurations can be adopted. That is, in FIG. 42, the transmission cable 31 shown in FIG. 29 may be described, or in FIG. 29, the transmission cable 31 shown in FIG. 42 may be described.

Further, in FIG. 29, the mold resin 145 extends from the tip of the tip portion 15 to the cross-sectional position of the image sensor 33, and in FIG. 42, the mold resin 145 extends from the tip of the tip portion 15 beyond the image sensor 33 to the electric wire 45. Although it extends to the cross-sectional position, either configuration can be adopted. That is, in FIG. 42, the mold resin 145 shown in FIG. 29 may be described, or in FIG. 29, the mold resin 145 shown in FIG. 42 may be described.

<18th configuration example>
As shown in FIGS. 37 and 40, for example, the endoscope 11 of the 18th configuration example has a substantially quadrangular outer shape (for example, a square, a rectangle, a chamfered quadrangle) in the direction perpendicular to the optical axis or the center of the lens. It comprises a single lens (eg, lens 93). The endoscope 11 includes an image sensor 33 having a substantially quadrangular outer shape (for example, a square or a rectangle) in the direction perpendicular to the center of the lens, and the length of one side thereof is the same as the length of one side of a single lens. .. The endoscope 11 covers the image pickup surface 41 of the image pickup element 33, and includes an element cover glass 43 whose outer shape in the direction perpendicular to the lens center is the same as the outer shape of the image pickup element 33. The endoscope 11 is arranged coaxially with the center of the lens, surrounds the outer surface of the single lens, the element cover glass 43, and the image pickup element 33, and includes a sheath 61 having a circular outer shape. Further, the sheath 61 is substantially in contact with the image sensor 33. Further, the endoscope 11 is arranged along the center of the lens, and is provided with an illumination means (for example, an optical fiber 59) inserted between each outer surface of the single lens and the image sensor 33 and the inner peripheral surface of the sheath 61. , Equipped with. A plurality of lighting means are provided. The plurality of illumination means are arranged in parallel (for example, one row) along at least one side (for example, sides H1 to H4) of the single lens or the image sensor 33.

According to the endoscope 11 of the eighteenth configuration example, the space corresponding to the holder can be reduced by omitting the holder for holding the lens 93 and the image pickup element 33. Further, since the image sensor 33 whose four corners are chamfered or not chamfered and the sheath 61 are substantially in contact with each other, the diagonal length of the substantially quadrangular cross section and the diameter length of the sheath 61 are substantially reduced in the front view of the image sensor 33. It becomes the same and contributes to reducing the diameter of the tip portion 15 of the endoscope 11.

Further, the endoscope 11 creates a space created by a shape difference between a circular cross-section portion in the front view of the sheath 61 and a quadrangular cross-section portion in the front view of the lens 93 and the image sensor 33 (here, a plurality of optical fibers). It can be used for the arrangement of 59), and the member arrangement density at the tip portion 15 can be improved. Therefore, the endoscope 11 can suppress wasted space at the tip portion 15.

Further, in the endoscope 11, a plurality of optical fibers 59 are not arbitrarily arranged in the space generated above, but are arranged in parallel along at least one side of the lens 93 or the image pickup element 33. Therefore, as compared with the case where a plurality of optical fibers 59 are arbitrarily arranged, the number of optical fibers 59 can be increased and arranged in a space of the same size. Therefore, as the number of lights increases, the brightness of the lights can be increased.

As described above, according to the endoscope 11, it is possible to achieve both miniaturization of the endoscope 11 and improvement of lighting efficiency.

<19th configuration example>
In the endoscope 11 of the 19th configuration example, a plurality of illumination means (for example, an optical fiber 59) are arranged in parallel along at least two sides of a single lens (for example, a lens 93) or an image pickup element 33, and the lens center. Are arranged point-symmetrically with respect to.

In FIGS. 38 and 41, three optical fibers 59 are arranged in parallel (here, one row) along the four sides H1 to H4 of the quadrangular cross section in the front view of the image sensor 33. With reference to FIGS. 38 and 41, it can be understood that the optical fibers 59 are arranged at point-symmetrical positions with respect to the center of the image sensor 33. The center of the image sensor 33 coincides with the center of the lens and the center of the image sensor 33 in a cross section in the direction perpendicular to the optical axis or the center of the lens.

According to the endoscope 11 of the 19th configuration example, since the optical fibers 59 are arranged at equal distances with the center of the image pickup element 33 interposed therebetween, the observation target can be evenly illuminated. Therefore, the endoscope 11 can reduce illumination unevenness, equalize the amount of light obtained from the subject in each pixel of the image pickup device 33, and make the image quality uniform in each pixel. Therefore, the image quality of the image of the subject obtained by the endoscope 11 is improved.

In this configuration example, the number of optical fibers 59 is arbitrary. Further, which side of the quadrangle the optical fibers are arranged in parallel is also arbitrary. Further, in the parallel arrangement, they may be arranged in one row with respect to at least one side of the image sensor 33, or may be arranged in two or more rows if the arrangement space is acceptable.

FIG. 43 is a diagram showing a first modification of the arrangement of the plurality of optical fibers 59. In FIG. 43, five optical fibers 59 are arranged in parallel (here, one row) along the four sides H1 to H4 having a quadrangular cross section in the front view of the image sensor 33.

FIG. 44 is a diagram showing a second modification of the arrangement of the plurality of optical fibers 59. In FIG. 44, five optical fibers 59 are arranged in parallel (here, one row) along two sides H1 and H2 having a quadrangular cross section when viewed from the front of the image sensor 33. In FIG. 44, the two sides H1 and H2 are sides that are point-symmetrical with respect to the center of the image sensor 33, and the optical fibers 59 are arranged point-symmetrically with respect to the center of the image sensor 33. There is.

<20th configuration example>
FIG. 45 is a diagram for explaining an example of the length of the diameter of the optical fiber 59 in the endoscope 11 of the present embodiment.

In the endoscope 11 of the 20th configuration example, the image sensor 33 has a square outer shape in the direction perpendicular to the center of the lens. Further, the length of the diameter of the lighting means (for example, the optical fiber 59) is 0.2 times or less the length of one side of the image pickup device 33.

According to the endoscope 11 of the 20th configuration example, the diameter of the optical fiber 59 is contained in the space sp generated by the shape difference between the circular cross section in the front view of the sheath 61 and the substantially quadrangular cross section in the front view of the lens 93. It can be accommodated in consideration of the length of.

In FIG. 45, assuming that the length of one side of the image sensor 33 is “a”, the diagonal length of the image sensor 33 is “√2a”. √A indicates the square root of the value A. Therefore, √2 indicates the square root of the value 2. In FIG. 45, the four corners having a square cross section are substantially in contact with the inner peripheral surface 61a of the sheath 61 when viewed from the front of the image sensor 33. Since the outer shape of the sheath 61 is circular, the length of the diameter of the sheath 61 is “√2a”.

In the cross section of FIG. 45, a space sp is formed between the sheath 61 having a substantially circular cross section in front view and the image sensor 33 having a square cross section in front view. In the space sp, the distance d1 from the inner peripheral surface 61a of the sheath 61 to the side H1 of the image sensor 33 orthogonal to the radial direction of the circular cross section in the front view of the sheath 61 corresponds to the maximum length of the diameter of the optical fiber 59. To do. This distance d1 is represented by the following (Equation 1).
d1 = (√2a-a) / 2≈0.2a ... (Equation 1)

That is, the diameter of the optical fiber 59 that can be inserted into the space sp is 0.2 times or less the length a of one side of the image sensor 33.

The length a of one side of the image sensor 33 is, for example, 500 μm, and the length of the diameter of the optical fiber 59 is, for example, 50 μm. In this case, the diameter of the optical fiber 59 is 0.1 times one side of the image pickup device 33, and satisfies (Equation 1) relating to the maximum length d1 of the diameter of the optical fiber 59.

Although the embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, which naturally belong to the technical scope of the present invention. Understood. In addition, each component in the above embodiment may be arbitrarily combined as long as the gist of the invention is not deviated.

The present invention is useful as an endoscope or the like that can achieve both miniaturization of the endoscope and improvement of lighting efficiency.

11 Endoscope 15 Tip 33, 33A, 33B, 33C Image sensor 37 Adhesive resin 41 Image sensor 43 Element cover glass 57 Light guide 59 Optical fiber (illumination means)
61 Sheath 61a Inner peripheral surface 91 Objective cover glass 93, 93A, 93B, 93C Lens (single lens)
135 Insertion tip surface 145,146 Molded resin

Claims (5)

A single lens with a substantially quadrangular outer shape in the direction perpendicular to the center of the lens,
An image sensor whose outer shape in the direction perpendicular to the center of the lens is substantially quadrangular and whose side length is the same as the length of one side of the single lens.
An element cover glass that covers the imaging surface of the image sensor and has the same outer shape in the direction perpendicular to the center of the lens as the outer shape of the image sensor.
A sheath that is arranged coaxially with the center of the lens, surrounds each outer surface of the single lens, the element cover glass, and the image sensor, and is substantially in contact with the image sensor, and the surrounding outer shape is circular. ,
Illumination means arranged along the center of the lens and inserted between each outer surface of the single lens and the image sensor and the inner peripheral surface of the sheath.
An objective cover glass which is arranged on the objective side of the single lens and whose outer shape in the direction perpendicular to the center of the lens is the same as the outer shape of the single lens is provided.
A plurality of the lighting means are provided.
The plurality of illumination means are arranged in parallel along at least one side of the single lens or the image sensor .
The objective cover glass and the sheath are provided on substantially the same plane on the insertion tip surface at the tip portion including the objective cover glass and the single lens.
Endoscope. The endoscope according to claim 1 .
The plurality of illumination means are arranged in parallel along at least two sides of the single lens or the image sensor, and are arranged point-symmetrically with respect to the center of the lens.
Endoscope. The endoscope according to claim 1 or 2 .
The image sensor has a square outer shape in the direction perpendicular to the center of the lens.
The length of the diameter of the lighting means is 0.2 times or less the length of one side of the image pickup device.
Endoscope. The endoscope according to any one of claims 1 to 3 , further
The maximum outer diameter of the tip including the single lens is 1.0 mm or less.
Endoscope. The endoscope according to any one of claims 1 to 4 .
An endoscope in which the single lens and the element cover glass are directly attached via an adhesive resin.