JP2017023210A - Endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endoscope capable of achieving miniaturization and cost reduction, and a method of manufacturing the endoscope.SOLUTION: An endoscope includes: a lens unit 35 for accommodating a lens in a lens support member 39; an image pick-up device 33 whose imaging surface 41 is covered by a device cover glass 43; a transmission cable 31 electrically connected to the image pick-up device 33; and a light guide 57 provided along the lens unit. The lens unit 35 in which an optical axis LC of the lens coincides with a center of the imaging surface 41, and the device cover glass 43 are fixed by an adhesion resin 37. At least a part of the lens unit 35, the image pick-up device 33, a part of the transmission cable 31, and a part of the light guide 57 are covered by a mold resin 17, and fixed. The mold resin 17 is exposed to the outside.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an endoscope.

  2. Description of the Related Art Conventionally, endoscopes for imaging the inside of a patient's body, equipment, or structure are widely used in the medical field or the industrial field. As an endoscope of this type, at the insertion part inserted into the observation object, the light from the imaging part is imaged on the light receiving surface of the image sensor by the objective lens system, and the imaged light is converted into an electrical signal. Then, it is transmitted as a video signal to an external image processing apparatus or the like via a signal cable. In a rigid portion provided at the distal end of this type of endoscope, a large number of components such as an imaging element and an optical element such as a lens that forms an optical image on an imaging surface of the imaging element are arranged. In recent years, in an endoscope having such a complicated configuration, it is important to further reduce the outer diameter in order to manufacture the endoscope more easily and reduce the burden on the patient.

  For example, in an electronic endoscope 501 shown in FIGS. 17A and 17B of Patent Document 1, a recess 505 is formed in a substrate 503, and a solid-state imaging device 507 is disposed in the recess. A conductive wire 509 is installed between the solid-state imaging device 507 and the upper surface side of the stepped portion of the substrate 503. The conductive wire portion is sealed with resin, and a glass plate 513 is bonded to the light receiving surface 511 of the solid-state imaging element 507. A frame 515 is fixedly provided on the substrate 503 so as to be in contact with a portion outside the connection portion of the conductive wire 509. The frame 515 is fixed to the lens barrel 519 of the objective lens 517.

  In the electronic endoscope 501 having the above-described configuration, the glass plate 513 is bonded to the light receiving surface 511 of the solid-state imaging device 507, the frame 515 is abutted and fixed to the substrate 503, and the lens barrel 519 of the objective lens 517 is attached to the frame 515. To fix. Thereby, the diameter of the insertion portion 521 is reduced and the axial length of the distal end rigid portion 523 is shortened.

Japanese Patent Laid-Open No. 3-12124

  In the electronic endoscope 501 described in Patent Document 1, the frame 515 is fixed to the substrate 503, and the frame 515 is fixed to the lens barrel 519 of the objective lens 517. Therefore, the diameter of the solid-state imaging device 507 or more is required. Therefore, it becomes an obstacle to further reduction in diameter. Further, since the number of parts increases, the cost also increases.

  The present invention has been devised in view of conventional circumstances, and an object thereof is to provide an endoscope that can be reduced in size and cost.

  The present invention is provided along a lens unit that houses a lens in a lens support member, an image sensor whose imaging surface is covered with an element cover glass, a transmission cable electrically connected to the image sensor, and the lens unit. The lens unit having the optical axis of the lens coincided with the center of the imaging surface and the element cover glass are fixed with an adhesive resin, and at least a part of the lens unit, the imaging Provided is an endoscope in which an element, a part of the transmission cable, and a part of the illuminating means are covered and fixed by a mold resin, and the mold resin is exposed to the outside.

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

Overall configuration diagram showing an example of an endoscope system using the endoscope of each embodiment The perspective view which shows an example of a structure of the front-end | tip part of the endoscope of each embodiment. Sectional drawing which shows an example of the front-end | tip part of the endoscope of 1st Embodiment The perspective view which shows an example of a structure of the part except mold resin in the front-end | tip part of the endoscope of 1st Embodiment. The perspective view which shows an example of a structure of the front-end | tip part of the endoscope of 2nd Embodiment. (A) Cross-sectional view showing an example of a configuration in which the separation resin of the third embodiment is filled with an adhesive resin, (B) shows an example of a configuration in which an air layer is provided in the separation portion of the fourth embodiment. Cross section (A) Sectional drawing which shows an example of the front-end | tip part of the endoscope of 5th Embodiment, (B) The principal part enlarged view of (A). Sectional drawing which shows an example of a structure of the front-end | tip part of the endoscope of 6th Embodiment Sectional drawing which shows an example of a structure of the front-end | tip part of the endoscope of 7th Embodiment Front view showing an example of a tip portion representing an arrangement example of illumination means Sectional drawing which shows an example of the light guide comprised by connecting an optical transmission rod member and an optical fiber The perspective view which shows an example of the front-end | tip part provided with the optical transmission rod member which has an elliptical cross section Characteristic diagram showing an example of the relationship between the thickness of the mold part and the transmittance (A) The figure which shows an example of the captured image when there is stray light, (B) The figure which shows an example of the captured image when there is no stray light Characteristic diagram showing an example of the relationship between the additive amount and tensile strength in the mold part The figure which shows an example of the relationship between the addition amount of the additive in a mold part, resistance value, and light-shielding rate (A) Sectional drawing which shows an example of the front-end | tip part of the endoscope of a prior art example, (B) The principal part enlarged view of (A).

  Hereinafter, embodiments that specifically disclose an endoscope according to the present invention will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

  FIG. 1 is an overall configuration diagram illustrating an example of an endoscope system using the endoscope of each embodiment. FIG. 2 is a perspective view illustrating an example of the configuration of the distal end portion of the endoscope according to each embodiment. FIG. 3 is a cross-sectional view illustrating an example of a distal end portion of the endoscope according to the first embodiment. FIG. 4 is a perspective view illustrating an example of a configuration of a portion excluding the mold resin at the distal end portion of the endoscope according to the first embodiment.

  FIG. 1 is a perspective view showing the entire configuration of the endoscope system 13 including the endoscope 11 and the video processor 19. 2, the configuration of the distal end portion 15 of the endoscope 11 shown in FIG. 1 is shown in a perspective view. 3, the structure of the front-end | tip part 15 shown in FIG. 2 is shown with sectional drawing. FIG. 4 is a perspective view showing a configuration in which the mold resin 17 is removed from the distal end portion 15 shown in FIG.

  Note that the directions used in the description in the present specification are the same as those in each direction. Here, “upper” and “lower” correspond to the upper and lower sides of the video processor 19 placed on the horizontal plane, respectively, and “front (front)” and “rear” refer to the endoscope main body (hereinafter “endoscope 11”). Corresponds to the distal end side of the insertion portion 21 and the proximal end side of the plug portion 23 (in other words, the video processor 19 side).

  As shown in FIG. 1, the endoscope system 13 includes, for example, an endoscope 11 that is a medical flexible endoscope and 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). On the other hand, it has a configuration including a video processor 19 for performing known image processing and the like. The endoscope 11 includes an insertion portion 21 that extends substantially in the front-rear direction and is inserted into 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 to the front wall 25. In this socket part 27, the rear part of the plug part 23 of the endoscope 11 is inserted, whereby the endoscope 11 sends and receives power and various signals (video signals, control signals, etc.) to and from the video processor 19. Is possible.

  The power and various signals described above are guided from the plug portion 23 to the flexible portion 29 via the transmission cable 31 (see FIG. 2 or FIG. 3) inserted through the inside of the flexible portion 29. Image data output from the image sensor 33 provided at the distal end portion 15 is transmitted from the plug portion 23 to the video processor 19 via the transmission cable 31. The video processor 19 performs predetermined image processing such as color correction and gradation correction on the image data transmitted from the plug unit 23, and outputs the image processed image data to a display device (not shown). The display device is a monitor device having a display device such as a liquid crystal display panel, for example, and displays an image of a subject imaged by the endoscope 11 (for example, an image showing a state in a blood vessel).

  As shown in FIG. 3, the endoscope 11 according to the present embodiment has a lens unit 35, an image sensor 33, an adhesive resin 37, and a light guide 57 as an example of illumination means at the distal end portion 15. . The lens unit 35 accommodates at least one lens by the lens support member 39. In the imaging device 33, an imaging surface 41 which is an imaging surface of an optical image condensed by at least one lens is covered with an element cover glass 43. A capacitor 45 for preventing static electricity is attached to the surface of the image sensor 33 opposite to the element cover glass 43. The adhesive resin 37 is made of, for example, a UV / thermosetting resin. The adhesive resin 37 fixes the lens unit 35 with the optical axis of the lens coincident with the center of the imaging surface 41 to the element cover glass 43 with a separation portion 47. As a result, the lens unit 35 and the image sensor 33 are directly bonded and fixed by the bonding resin 37. The adhesive resin 37 is, for example, an adhesive that requires heat treatment in order to obtain final hardness, but cures to a certain degree of hardness even when irradiated with ultraviolet rays.

  The insertion portion 21 has a flexible soft portion 29 whose rear end is connected to the plug portion 23, and a distal end portion 15 connected to the distal end of the soft portion 29. The flexible portion 29 has an appropriate length corresponding to various methods such as endoscopic examination and endoscopic surgery. The soft part 29 is configured by covering the outer periphery of a thin metal plate wound in a spiral shape with a net and further covering the outer periphery thereof, and is formed to have sufficient flexibility. The flexible part 29 connects between the tip part 15 and the plug part 23.

  In the endoscope 11, the maximum outer diameter of the mold resin 17 is formed in the range of 0.7 to 2 mm. In the endoscope 11, by setting the maximum outer diameter Dmax to be less than 2 mm, for example, insertion into a human blood vessel is possible. At present, when the imaging element 33 is square, a diagonal dimension of 1.6 mm is put into practical use. Therefore, the endoscope 11 includes a light guide 57 (described later) as an illuminating unit, and the maximum outer diameter Dmax is 2 mm. Furthermore, as the image pickup element 33, a device having a diagonal dimension of 0.5 mm can be manufactured. As a result, the endoscope 11 can include the light guide 57 as an illuminating unit and a minimum outer diameter Dmax of 0.7 mm.

  Since the endoscope 11 is formed in such a small diameter, it can be inserted into a small body cavity. The narrow body cavity is not limited to the blood vessels of the human body, and includes, for example, the ureter, pancreatic duct, bile duct, bronchiole and the like. That is, the endoscope 11 can be inserted into a human blood vessel, ureter, pancreatic duct, bile duct, bronchiole, and the like. In other words, the endoscope 11 can be used for observation of a lesion in a blood vessel. The endoscope 11 is effective in identifying atherosclerotic plaque. Further, the present invention can be applied to observation with an endoscope at the time of cardiac catheter examination. Furthermore, the endoscope 11 is also effective in detecting thrombus and arteriosclerotic yellow plaque. In arteriosclerotic lesions, color tone (white, light yellow, yellow) and surface (smooth, irregular) are observed. In the thrombus, a color tone (red, white, dark red, yellow, brown, mixed color) is observed.

  Further, 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 a fermenter papilla that opens to the duodenum. Bile is made from the liver and passes through the bile duct, and pancreatic juice is made from the pancreas and passes through the pancreatic duct and drains from the papilla in the duodenum. The endoscope 11 can be inserted from a fermenter papilla, which is an opening of the bile duct and pancreatic duct, and enables observation of the bile duct or pancreatic duct.

  Furthermore, the endoscope 11 can be inserted into the bronchus. The endoscope 11 is inserted from the oral cavity or nasal cavity of the specimen in the supine position. The endoscope 11 passes through the pharynx and larynx and is inserted into the trachea while visually checking the vocal cords. The bronchi get thinner every time they branch. According to the endoscope 11 having the maximum outer diameter Dmax of less than 2 mm, the lumen can be confirmed up to the sub-segment bronchus.

  As shown in FIG. 3, the distal end portion 15 includes an imaging element 33, a cylindrical lens support member 39 including a lens and the like, a lens unit 35 that supports the imaging element 33 at the rear end, and the imaging element 33. A circuit board 49 mounted on the rear part and a light guide 57 as an example of an illuminating means are provided. Hereinafter, although the case where the illumination means is the light guide 57 will be described as an example, the illumination means may be an LED directly attached to the insertion tip surface of the tip portion 15. In this case, the optical fiber 59 is unnecessary. The lens support member 39 is made of, for example, metal. By using a hard material for the lens support member 39, the distal end portion 15 forms a hard portion.

  The lens support member 39 may be a sheet material or the like in addition to metal. The lens support member 39 only needs to achieve positioning when aligning the optical axes of the lenses of the lens unit 35. When the lens unit 35 is molded with the molding resin 17, the relative positions of the lenses are fixed. For this reason, the lens support member 39 can be made of a material having a lower strength, a smaller thickness, and a lighter weight than a conventional lens barrel. Thereby, it becomes possible to contribute to the diameter reduction of the front-end | tip part 15 in the endoscope 11. FIG.

  The transmission cable 31 is electrically connected at the rear part of the circuit board 49, and the connection part of the circuit board 49 is covered with a molding resin 17 for sealing. In the following description, the term “adhesive” does not have a strict meaning of a substance used for bonding the surfaces of solid objects, but is a substance that can be used to bond two objects or has been cured. 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 material.

  The lens support member 39 includes a plurality of (three in the illustrated example) lenses L1 to L3 formed of an optical material (glass, resin, etc.) and a diaphragm member 51 sandwiched between the lenses L1 and L2. It is incorporated in a state of being close to the direction of the optical axis LC. The lens L1 and the lens L3 are fixed to the inner peripheral surface of the lens support member 39 with an adhesive over the entire circumference. The front end of the lens support member 39 is sealed (sealed) by the lens L1, and the rear end is sealed (sealed) by the lens L3, so that air, moisture, or the like does not enter the lens support member 39. Therefore, air or the like cannot escape from one end of the lens support member 39 to the other end. In the following description, the lenses L1 to L3 are collectively referred to as an optical lens group LNZ.

  For example, nickel is used as a metal material constituting the lens support member 39. Nickel has a relatively high rigidity and high corrosion resistance, and is suitable as a material constituting the tip portion 15. Instead of nickel, for example, a copper nickel alloy may be used. The copper nickel alloy also has high corrosion resistance and is suitable as a material constituting the tip portion 15. Moreover, as a metal material which comprises the lens support member 39, Preferably, the material which can be manufactured by electroforming (electroplating) is selected. Here, the reason why electroforming is used is that the dimensional accuracy of a member manufactured by electroforming is extremely high, less than 1 μm (so-called submicron accuracy), and the variation when a large number of members are manufactured is small. As will be described later, the lens support member 39 is an extremely small member, and an error in the inner and outer diameter dimensions affects the optical performance of the endoscope 11 (that is, the image quality of the captured image). By configuring the lens support member 39 with, for example, a nickel electroformed tube, it is possible to obtain the endoscope 11 capable of capturing a high-quality image while ensuring high dimensional accuracy despite a small diameter.

  As shown in FIGS. 3 and 4, the imaging element 33 is configured by a small CCD (Charge Coupled Device) or CMOS (Complementary Metal-Oxide Semiconductor) imaging device having a square shape when viewed from the front-rear direction, for example. Light incident from the outside forms an image on the imaging surface 41 of the imaging element 33 by the optical lens group LNZ in the lens support member. The circuit board 49 mounted on the rear portion (rear side) of the image sensor 33 has an outer shape slightly smaller than that of the image sensor 33 when viewed from the rear. The image sensor 33 includes, for example, an LGA (Land grid array) on the back surface, and is electrically connected to an electrode pattern formed on the circuit board 49.

  As shown in FIG. 2, the endoscope 11 includes the entire image sensor 33, at least a part of the lens unit 35 on the image sensor 33 side, a part of the transmission cable 31, and a part of the light guide 57. 17 is covered and fixed, and the mold resin 17 is exposed to the outside. A radiopaque marker may be included in the distal end portion 15 of the endoscope 11. Thereby, the endoscope 11 can easily confirm the tip position under fluoroscopy.

  In the present embodiment, four light guides are arranged at equal intervals in the circumferential direction of the lens unit 35. Each light guide 57 is composed of one optical fiber 59. According to this configuration, a shadow is hardly generated in the captured image, and a clear image can be obtained. For the optical fiber 59, for example, a plastic optical fiber (POF) is preferably used. The plastic optical fiber is made of plastics for both the core and the clad using silicon resin or acrylic resin as a material. The optical fiber 59 may be, for example, a bundle fiber (bundle fiber) in which a plurality of optical fiber strands are bundled and end fittings are attached to both ends thereof. The optical fiber 59 has a distal end at the distal end 15 serving as an emission end surface, and a proximal end 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. The endoscope 11 connects the plug portion 23 to the socket portion 27 so that light from the LED propagates through the optical fiber 59 of the light guide 57 and is emitted from the tip. According to this configuration, it is possible to configure a single optical fiber from the light source to the illumination light emission end, and it is possible to reduce light loss.

  Next, the operation of the endoscope 11 of the present embodiment having the above configuration will be described.

  In the endoscope 11 of the present embodiment, the lens unit 35 and the image sensor 33 are fixed in a state where they are held at a predetermined distance by the adhesive resin 37. In the fixed lens unit 35 and the imaging device 33, the optical axis of the lens unit 35 and the center of the imaging surface 41 are aligned. In addition, the distance between the lens unit 35 and the image sensor 33 is aligned at a distance at which incident light from a subject passing through the lens unit 35 is focused on the imaging surface 41 of the image sensor 33. The lens unit 35 and the image sensor 33 are fixed after being aligned.

  A separation portion 47 is formed between the fixed lens unit 35 and the image sensor 33. The shape of the spacing portion 47 is determined by relatively aligning the lens unit 35 and the image sensor 33 and fixing each other with an adhesive resin 37. That is, the separation portion 47 serves as an adjustment gap for alignment between the lens unit 35 and the image sensor 33. This adjustment gap is never lost. In the specific example of the dimensions described above, the adjustment is performed at least between about 30 μm and about 100 μm. The tolerance at this time is ± 20 μm. Therefore, the minimum adjustment gap in this case remains at 10 μm.

  In the endoscope 11, after the positioning of the lens unit 35 and the image sensor 33 is completed with the separation portion 47 serving as an adjustment gap, the separation portion 47 is used as a fixing space for the adhesive resin 37. Thereby, the lens unit 35 and the image sensor 33 can be directly fixed. Thereby, an interposing member such as a frame or a holder for fixing the lens unit 35 to the image sensor 33, which has been necessary in the past, is not necessary. Further, since the frame or the holder can be omitted, the number of parts is reduced and the fixing structure is simplified. Thereby, the diameter of the distal end portion 15 of the endoscope 11 can be reduced, and even when the diameter is further reduced, it can be configured with a minimum size. In addition, component costs can be reduced. Furthermore, since there are few intervening parts at the time of fixing the lens unit 35 and the image pick-up element 33, the work man-hour required for the operation | work concerning alignment and fixation can be reduced, and highly accurate position alignment becomes possible easily. In addition, the manufacturing cost can be reduced and the productivity can be improved. In addition, since the illumination unit is provided, it is possible to use the endoscope 11 according to the present embodiment alone to perform imaging in a dark part.

  In the endoscope 11, the entire image sensor 33 is covered with the mold resin 17. More specifically, the mold resin 17 also covers the outer cover of the transmission cable 31 connected to the image sensor 33 and the light guide 57. The mold resin 17 also covers at least a part of the lens unit 35 (a part adjacent to the image sensor 33). “At least” means that the mold resin 17 may cover the entire outer periphery of the lens support member 39. The mold resin 17 covers the imaging element 33 and the lens unit 35, thereby continuously covering the separation portion 47 therebetween. Accordingly, the mold resin 17 is continuously formed over the imaging element 33 and the lens unit 35, thereby contributing to an increase in the fixing strength between the imaging element 33 and the lens unit 35. Further, the mold resin 17 also improves the airtightness, watertightness, and light shielding property of the separation portion 47. Furthermore, the mold resin 17 also improves the light shielding property when the optical fiber 59 for the light guide 57 is embedded.

  In the endoscope 11, the element cover glass 43 and the light emitting surface of the lens on the imaging element side are fixed by the adhesive resin 37. Thereby, the lens unit 35 and the image sensor 33 are fixed with high strength by the adhesive resin 37.

  The adhesive resin 37 preferably has a light transmitting property and has a refractive index close to that of air. When a UV / thermosetting resin is used as the adhesive resin 37, the outer surface portion can be cured by ultraviolet irradiation, and the inside of the filled adhesive that cannot be irradiated with ultraviolet rays can be cured by heat treatment.

  Further, in the endoscope 11, when the light emitting surface of the lens facing the element cover glass 43 is a concave surface, the edge portion 55 that is an end face of the ring around the lens is bonded to the element cover glass 43. At this time, the outer periphery of the lens and the outer periphery of the lens support member 39 may be simultaneously fixed by the adhesive resin 37. By providing the air layer 53 between the lens and the image sensor 33, the optical performance of the lens can be enhanced. For example, the refractive index of the emitted light from the lens to the air layer 53 can be increased. This facilitates optical design such as increasing the resolution and increasing the angle of view. As a result, the image quality is improved.

  The endoscope 11 includes the light guide 57 so that it can be used alone and can be photographed in a dark part. In addition, since the light guide 57 is molded on the distal end portion 15 with the molding resin 17, the light guide 57 acts as a structural material, and the connection strength between the flexible portion 29 and the distal end portion 15 also in the small-diameter endoscope 11. Can be improved.

  As described above, according to the endoscope 11 of the present embodiment, size reduction, cost reduction, and productivity improvement can be achieved.

  Next, a modified example in which the configuration of the endoscope 11 is partially changed will be described as another embodiment.

  FIG. 5 is a perspective view illustrating an example of the configuration of the distal end portion of the endoscope according to the second embodiment. In 2nd Embodiment, the 1st modification of a structure of the front-end | tip part 15 of the endoscope shown in FIG.3 and FIG.4 is shown.

  As shown in FIG. 5, the endoscope of the second embodiment is additionally provided with adhesive resin 37 at the four corners of the image sensor 33 in order to improve the strength. In this case, after aligning the imaging device 33 with the rear end of the lens unit 35, among the rear end portions of the lens unit 35 that are in contact with the imaging device 33, four portions facing the corners of the imaging device 33 are provided. Adhesive resin 37 is applied (in FIG. 5, three out of four are drawn). In this state, the application portion of the adhesive resin 37 is exposed, and the adhesive resin 37 is cured in a short time of about several seconds by ultraviolet irradiation, so that the time required for the process can be shortened. Thereby, according to the endoscope of the second embodiment, the strength of the bonding portion between the image sensor 33 and the lens unit 35 can be increased.

  6A and 6B are views showing a third embodiment and a fourth embodiment as other modifications of the distal end portion of the endoscope. FIG. 6A is a cross-sectional view illustrating an example of a configuration in which the separation resin according to the third embodiment is filled with an adhesive resin. FIG. 6B is a cross-sectional view illustrating an example of a configuration in which an air layer is provided in the separation portion of the fourth embodiment. The third embodiment shows a second modification of the configuration of the distal end portion of the endoscope, and the fourth embodiment shows a third modification of the configuration of the distal end portion of the endoscope.

  In the endoscope according to the third embodiment, as shown in FIG. 6A, the separation resin 47 between the lens unit 35 and the element cover glass 43 is filled with an adhesive resin 37. When the final surface on the imaging side of the lens L3 has a concave surface facing the element cover glass 43 as in the illustrated example, for example, between the plane of the element cover glass 43 and the concave surface of the lens L3, such as transparent The resin 37 for translucent is filled. In this case, the distance between the edge 55 of the lens periphery of the second surface L3R2 of the lens L3 (that is, the right side surface of the lens L3, and so on) and the element cover glass 43 is, for example, 0 to 100 μm. In the present embodiment, the strength of the bonded portion can be further improved by filling the bonding resin 37. Further, if the adhesive resin 37 is, for example, an ultraviolet curable resin, the adhesive resin 37 can be cured in a short time, and the time required for manufacturing the endoscope of the present embodiment can be shortened. Note that the final surface on the imaging side of the lens L3, which is the surface facing the element cover glass 43, may have a convex surface. In the case of a convex surface, the distance between the center portion of the second surface L3R2 of the lens L3 and the element cover glass 43 is, for example, 0 to 100 μm.

  In the endoscope according to the fourth embodiment, an air layer 53 is provided in a separation portion 47 between the lens unit 35 and the element cover glass 43 as shown in FIG. When the final surface on the imaging side of the lens L3 has a concave surface facing the element cover glass 43 as in the illustrated example, an adhesive resin 37 is provided between the flat surface of the element cover glass 43 and the concave surface of the lens L3. The air layer 53 is formed without filling. In this case, the distance between the edge 55 of the lens periphery of the second surface L3R2 of the lens L3 and the element cover glass 43 is, for example, 0 to 100 μm. In the present embodiment, the provision of the air layer 53 increases the refractive index difference on the final surface of the lens unit 35 on the imaging side, thereby increasing the degree of freedom in lens design.

  7A and 7B are diagrams illustrating an example of the configuration of the distal end portion of the endoscope according to the fifth embodiment. FIG. 7A is a cross-sectional view showing an example of the distal end portion of the endoscope of the fifth embodiment. FIG. 7B is an enlarged view of a main part of FIG. 5th Embodiment shows the 4th modification of a structure of the front-end | tip part of an endoscope.

  In the endoscope of the fifth embodiment, the final surface on the imaging side of the lens L3 of the lens unit 35 is formed flat. When the final surface on the imaging side of the lens L3 is configured as a plane as in the illustrated example, the lens unit 35 and the element cover glass 43 are opposed to each other by a predetermined distance, and the adhesive resin 37 is raised and applied to the outer peripheral portion. Then, the lens unit 35 and the element cover glass 43 are bonded and fixed. Here, the distance of the separation portion 47 between the lens unit 35 and the element cover glass 43 is set to, for example, 10 to 40 μm due to a difference in optical design.

  FIG. 8 is a cross-sectional view showing an example of the configuration of the distal end portion of the endoscope according to the sixth embodiment. 6th Embodiment shows the 5th modification of a structure of the front-end | tip part of an endoscope.

  The endoscope of the sixth embodiment shows another configuration example of the lens L3 of the lens unit 35. In the lens unit 35, in order from the subject side to the imaging side, the first surface L1R1 of the lens L1 (that is, the surface on the left side of the lens L1) is the concave surface, and the second surface L1R2 (that is, the lens L1). The surface on the right side of the drawing (the same applies hereinafter) is a plane, and the first surface L2R1 of the lens L2 (that is, the surface on the left side of the drawing on the lens L2; the same applies hereinafter) is the plane, and the second surface L2R2 (that is, The first surface L3R1 of the lens L3 which is a convex surface and the final lens (that is, the left surface of the lens L3; the same applies hereinafter) is the concave surface and the second surface L3R2 which is the final surface (that is, the lens). L3 on the right side of the drawing (the same applies hereinafter) has a convex surface.

  A separation portion 47 between the second surface L3R2 of the lens L3 that is a convex surface and the element cover glass 43 is filled with an adhesive resin 37. The lens unit 35 and the image sensor 33 are directly bonded and fixed by the adhesive resin 37. The adhesive resin 37 is made of a transparent adhesive resin material. If the refractive index of the adhesive resin 37 is nad and the refractive index of the lens L3 is n3, for example, satisfying the relationship | n3-nad> 0.01. Is used. That is, the refractive index nad of the adhesive resin 37 has a refractive index difference as large as possible with respect to the refractive index n3 of the lens L3 at the imaging side end (specifically, for example, has a difference larger than 0.01). Preferably). For example, when the refractive index n3 of the lens L3 is 1.55, the adhesive resin 37 having a refractive index nad of 1.52 is used. As long as the difference in refractive index can be secured, the magnitude relationship between the refractive index n3 of the lens L3 and the refractive index nad of the adhesive resin 37 may be reversed.

  In addition, the distance of the separation portion 47 between the second surface L3R2 of the lens L3 and the imaging surface 41 of the imaging element 33 is set to, for example, 0 to 100 μm at the protruding portion of the convex surface center portion of the second surface L3R2. That is, the dimension range is from the state where the central portion of the second surface L3R2 and the imaging surface 41 are in contact to the state where they are separated by 100 μm. As a result, the distance in the optical axis direction between the lens unit 35 and the image sensor 33 can be adjusted in the range of 0 to 100 μm to perform focus position adjustment (focusing) and can be easily assembled.

  In addition, at least a part of the imaging side of the lens unit 35, the outer peripheral portion of the imaging element 33, and the vicinity of the distal end side connecting portion of the transmission cable 31 are used as sealing resin members such as black mold resin having a light shielding property 17 is sealed. At the connection and fixing part between the lens unit 35 and the image sensor 33, the mold resin 17 having a light-shielding property such as black is provided on the outer peripheral portion of the light-transmitting adhesive resin 37 such as a transparent material that transmits the light beam of the subject image. A double structure is provided and covered.

  In the sixth embodiment, the refractive effect on the second surface L3R2 of the lens L3 is increased by making the difference in refractive index between the lens L3 and the adhesive resin 37 greater than 0.01. As a result, the second surface L3R2 of the lens L3, which is the final surface on the imaging side of the optical lens group LNZ, can effectively function to obtain refractive power, and the number of optical surfaces that can be used in the optical lens group LNZ increases. . As a result, regarding the optical performance (resolution, chromatic aberration, distortion, etc.) of the optical lens group LNZ, the number of lenses for obtaining the required optical performance can be reduced, and the size and cost can be reduced. Further, by making the second surface L3R2 of the lens L3 convex and bonding with the adhesive resin 37 on the curved surface, the contact area of the adhesive resin 37 is increased, and the adhesive strength between the lens unit 35 and the element cover glass 43 is improved. it can. Further, the durability and fixing strength of the endoscope distal end can be improved by adopting a double structure of the translucent adhesive resin 37 and the light-shielding mold resin 17. Further, by setting the interval of the separation portion 47 to 0 to 100 μm at the center of the lens L3, the tolerance of the thickness dimension of each component of the lens unit 35 in the optical axis direction and the assembly size of the lens unit 35 and the image sensor 33 are obtained. Since the tolerance can be relaxed, the assemblability can be improved and the part cost can be reduced.

  FIG. 9 is a cross-sectional view showing an example of the configuration of the distal end portion of the endoscope according to the seventh embodiment. 7th Embodiment shows the 6th modification of a structure of the front-end | tip part of an endoscope.

  The endoscope of the seventh embodiment shows still another configuration example of the lens L3 of the lens unit 35. In the lens unit 35, the first surface L1R1 of the lens L1 is a concave surface, the second surface L1R2 is a flat surface, the first surface L2R1 of the lens L2 is a flat surface, and the second surface L2R2 is a convex surface in order from the subject side to the imaging side. The first surface L3R1 of the lens L3, which is a lens, has a convex surface, and the second surface L3R2, which is the final surface, has a concave surface. That is, the sixth embodiment shown in FIG. 8 is a configuration example in which the unevenness of the lens L3 is reversed. Here, only the parts different in configuration from the sixth embodiment will be described.

  A separation portion 47 between the second surface L3R2 of the lens L3 that is a concave surface and the element cover glass 43 is filled with an adhesive resin 37. The distance between the separation portions 47 is, for example, 0 to 100 μm at the edge of the peripheral portion of the concave surface of the second surface L3R2 (that is, the lens periphery of the second surface L3R2). That is, the dimension range is from the state in which the peripheral portion of the second surface L3R2 and the imaging surface 41 are in contact to the state in which the imaging surface 41 is separated by 100 μm.

  According to the seventh embodiment, as in the sixth embodiment, the difference in the refractive index between the lens L3 and the adhesive resin 37 is made larger than 0.01, so that the number of lenses for obtaining necessary optical performance can be reduced. It is possible to reduce the size and cost. Further, by making the second surface L3R2 of the lens L3 concave, and adhering on the curved surface with the adhesive resin 37, the contact area of the adhesive resin 37 is increased, and the adhesive strength can be improved. Further, by setting the distance of the separation portion 47 to 0 to 100 μm at the peripheral portion of the lens L3, the thickness dimension tolerance in the optical axis direction of the lens unit 35 and the assembly dimension tolerance between the lens unit 35 and the image sensor 33 are alleviated. Therefore, the assemblability can be improved and the part cost can be reduced. Further, in the endoscope of the present embodiment, since the adhesive resin 37 is filled only in the separation portion 47, the fixing strength between the lens L3 and the element cover glass 43 is secured, and the outer peripheral portion of the lens unit 35 is secured. Since there is no protruding portion, it is possible to expect a reduction in the diameter of the endoscope.

  In the sixth embodiment shown in FIG. 8 and the seventh embodiment shown in FIG. 9, only the peripheral portion of the lens L3 is bonded as in the fourth embodiment shown in FIG. It is good also as a structure which provides an air layer in the lens center part by adhere | attaching with resin for resin. In this case, sufficient refractive power can be obtained on the second surface L3R2 of the lens L3 regardless of the refractive index of the adhesive resin.

  Here, an example of the dimensions of the endoscope of the present embodiment will be shown. In addition, the numerical value shown below shows one specific example, and various examples can be considered according to a use, a use environment, etc.

  As an example, the lens unit 35 is assumed to have a length of S = 1.4 mm in the front-rear direction. The cross section of the lens support member 39 is circular with an outer diameter D = 1.00 mm, and the inner diameter is circular with d = 0.90 mm. In this case, the thickness of the lens support member 39 in the radial direction is (Dd) / 2 = 50 μm. In addition, the imaging element 33 has a square shape with a side length T = 1.00 mm when viewed from the front, and an imaging surface 41 having a square shape when viewed from the front is provided at the center thereof.

  Here, the circle that forms the outer periphery (outer diameter = D) of the lens support member 39 has a relationship that is substantially inscribed in the square formed by the imaging element 33 and circumscribed in the square formed by the imaging surface 41. Then, the center of the imaging surface 41 (intersection of diagonal lines of the imaging surface 41), the center of the lens unit 35 (center of the circle formed by the inner periphery of the lens unit 35), and the center of the lens support member 39 (the outer periphery of the lens support member 39 is The position of the center of the circle formed is the same, and the optical axis LC passes therethrough. More precisely, the lens unit 35 is positioned with respect to the image sensor 33 so that the normal passing through the center of the imaging surface 41 is the optical axis LC and the optical axis LC penetrates the center of the lens unit 35. It is matched.

  When the transmission cable 31 is connected to the image sensor 33, the output of the image sensor 33 can be processed by the video processor 19 and displayed on the display device. By using a predetermined test chart (for example, a resolution chart) as a subject, the position of the lens unit 35 can be easily adjusted, and the time required for the alignment process can be shortened.

  It is desirable that the adhesive resin 37 is slightly exposed from between the lens unit 35 and the image sensor 33 at the stage where the position adjustment between the lens unit 35 and the image sensor 33 is completed. When the amount of the adhesive resin 37 is insufficient, the adhesive resin 37 is injected between the lens unit 35 and the image sensor 33. The injected adhesive resin 37 is filled between the lens unit 35 and the image sensor 33 by capillary action.

  Next, the coating of the lenses L1, L2, and L3 of the lens unit 35 in the first to seventh embodiments will be described.

  On the surface of the lens, a single-layer or multi-layer thin film is deposited in order to prevent a decrease in the amount of light and the occurrence of flare ghost. As the material of the thin film, metal oxides such as titanium oxide (TiO2), tantalum pentoxide (Ta2O5), hafnium oxide (HfO2), zirconium oxide (ZrO2), aluminum oxide (Al2O3), silver (Ag), aluminum ( Metals such as Al) and nickel (Ni), silicon oxide (SiO2), silicon carbide (SiC), silicon (Si), magnesium fluoride (MgF2), and the like are used. In general, magnesium fluoride is used for the outermost layer in the case of a single layer or multiple layers in order to obtain the antifouling effect on the outermost surface. However, in the first to seventh embodiments, the second surface L3R2 that is the final surface of the lens L3 that is the final lens is fixed to the image sensor 33 by the adhesive resin 37, but magnesium fluoride is coated on the outermost surface. As a result, the adhesive strength is significantly reduced. Therefore, it is desirable to use metal oxide, metal, silicon oxide, silicon carbide, silicon, or the like other than magnesium fluoride on the outermost surface of the second surface L3R2 of the lens L3.

  Further, by using a silane coupling agent such as trimethylsilane (C3H10Si) that chemically bonds an inorganic material and an organic material on the outermost surface of the second surface L3R2 of the lens L3, a lens that is an inorganic material The bonding strength between L3 and the bonding resin 37 that is an organic material may be increased.

  FIG. 10 is a front view illustrating an example of a tip portion representing an example of arrangement of illumination means. Further, in the endoscope 11, the image sensor 33 is formed in a square shape. The four optical fibers 59 are disposed substantially at the center of each side of the image sensor 33.

  According to this configuration, a space sandwiched between the square imaging element 33 and the circular mold part 65 substantially circumscribing the imaging element 33 can be effectively used, and a plurality of pieces can be obtained without increasing the outer diameter of the distal end part 15. An optical fiber 59 can be provided. In addition, the endoscope 11 includes a plurality of optical fibers 59, so that a shadow is not easily generated in the captured image, a clear image can be obtained, and the outer diameter of the distal end portion is reduced while facilitating manufacture. A plurality of illumination means can be provided without increasing the size.

  FIG. 11 is a cross-sectional view showing an example of a light guide configured by connecting an optical transmission rod member 61 and an optical fiber 59. In the endoscope 11, the illumination unit may include an optical transmission rod member 61 provided along the lens unit 35 and an optical fiber 59 connected to the optical transmission rod member 61.

  According to this configuration, the base end side (soft portion 29 side) of the optical fiber 59 can be formed with a single large diameter, and can be branched into four immediately before the distal end portion 15. Each branched optical fiber 59 is connected to each optical transmission rod member 61. By adopting such a configuration, a large-diameter plastic optical fiber can be used. By using a large-diameter plastic optical fiber, the optical fiber 59 in the soft part 29 can be made difficult to break.

  FIG. 12 is a perspective view showing an example of the distal end portion 15 provided with the elliptical light transmission rod member 67 having an elliptical cross section. Further, an elliptical light transmission rod member 67 having a diameter larger than that of the light transmission rod member 61 may be used at the tip of the light guide 57 instead of the light transmission rod member 61.

  According to this structure, the elliptical light transmission rod member 67 formed flat can also be formed. Thereby, the endoscope 11 can increase the amount of illumination light without increasing the outer diameter of the distal end portion.

  FIG. 13 is a characteristic diagram showing an example of the relationship between the thickness of the mold part 65 made of the mold resin 17 and the transmittance. FIG. 13 shows a measurement example of transmittance when carbon black is added as an additive to a mold resin material (epoxy resin). In FIG. 13, black circles and broken lines indicate the case where 5 wt% (wt%) of carbon black is added, and black rhombuses and alternate long and short dash lines indicate the case where 1 wt% (wt%) of carbon black is added.

  When 5% by weight of carbon black is added, the light transmittance is about 0.5% (light shielding rate 99.5%) even if the thickness is 30 μm or less without depending on the thickness of the mold part. High shading performance can be obtained. When 1% by weight of carbon black is added, the transmittance increases as the thickness of the mold portion decreases. When 1% by weight is added, the transmittance can be suppressed to 8.0% or less if the thickness of the mold part is 30 μm or more. Therefore, the mold part 65 can fully satisfy | fill the conditions of the transmittance | permeability 10% or less by setting thickness T to 30 micrometers or more. For example, when the thickness of the mold part is 50 μm or more, the transmittance is 4.5% or less when 1% by weight is added, and the transmittance is 0.5% or less when 5% by weight is added.

  If the transmittance in the mold part 65 is 10% or less, a good captured image with little influence of stray light can be obtained in the imaging unit. If the transmittance of the mold part 65 is 6% or less, the influence of stray light can be sufficiently suppressed even if the sensitivity of the image sensor 33 is high. When the transmittance is higher than 10%, the effect of stray light is generated and there is a problem as a captured image.

  14A and 14B are diagrams illustrating examples of captured images when stray light is generated. FIG. 14A is a diagram illustrating an example of a captured image when stray light is present. FIG. 14B is a diagram illustrating an example of a captured image when there is no stray light. When stray light occurs as shown in FIG. 14A, whiteout due to stray light occurs, for example, in a ring shape in the captured image, and a clear image cannot be obtained. The imaging unit needs to be in a state where stray light is not generated as shown in FIG.

  When an additive is added to the mold part 65, as shown in the example of FIG. 13, the light shielding performance improves as the additive amount (content) is increased, but conversely, the adhesive strength of the mold part decreases. is there. Therefore, it is necessary to add an appropriate amount to the mold resin material according to the adhesive strength characteristics of the additive.

  FIG. 15 is a characteristic diagram showing an example of the relationship between the additive amount and tensile strength in the mold part 65. FIG. 15 shows an example of measurement of tensile strength when carbon black is added to the mold resin material (epoxy resin) as an additive. Here, the tensile strength corresponds to the adhesive strength of the mold part 65. As shown in FIG. 15, when the addition amount is 1% by weight, the tensile strength decreases only by about 2.5%. When the addition amount is 5% by weight, the tensile strength is reduced by about 12%. If the tensile strength is reduced by about 20%, sufficient adhesive strength as a mold member may not be obtained. Therefore, when carbon black is added, the amount added is preferably 5% by weight or less.

Further, when a conductive material such as carbon black is used as an additive, the electrical resistance decreases as the amount added increases, and conductivity is added. FIG. 16 is a diagram illustrating an example of the relationship between the additive amount, the resistance value, and the light shielding ratio in the mold unit 65. FIG. 16 shows a measurement example of the resistance value and the light blocking ratio when carbon black is added as an additive to the mold resin material (epoxy resin). As the addition amount of carbon black, three cases of no addition (0 wt% addition), 1 wt% addition, and 5 wt% addition were measured. The light blocking ratio is an example when the thickness of the mold part 65 is 50 μm. In the case of no addition, the resistance value is 1.8 to 5.0 × 10 ¹³ . When 1% by weight is added, the resistance value is 2.5 to 3.0 × 10 ¹³ , and the light shielding ratio is 95% or more. When 5% by weight is added, the resistance value is 3.5 to 5.0 × 10 ^10. The light shielding rate is 99% or more. In the case of addition of 5% by weight, the value of electric resistance is reduced by 1000 times or more compared to the case of addition of 1% by weight. For this reason, it is necessary to add an appropriate amount to the mold resin material in accordance with the conductive characteristics of the additive and the insulating characteristics required for the internal components (electronic circuit or the like) to be sealed.

  When the electric resistance in the mold part 65 is small, a leakage current or the like occurs in the circuit board 49 and the transmission cable 31 connected to the image sensor 33, and the electric characteristics around the signal processing part of the image pickup unit may deteriorate. On the other hand, by providing appropriate conductivity in the mold unit 65, when static electricity is generated in the imaging unit, the impact of electrostatic discharge can be reduced, an excessive current to the imaging device 33 can be suppressed, and the static electricity of the imaging device 33 can be suppressed. Electric breakdown can be suppressed. That is, it is possible to take surge countermeasures for the imaging unit.

  As described above, according to each embodiment, by adding an additive to the resin material of the mold part 65, the light transmittance in the mold part 65 is reduced to 10% or less, and the thickness of the mold part 65 is increased. Can be reduced. As a result, the image pickup unit can be reduced in size while having sufficient light shielding characteristics.

  While various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood. In addition, the constituent elements in the above-described embodiment may be arbitrarily combined without departing from the spirit of the invention.

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

11 Endoscope 17 Mold resin 31 Transmission cable 33 Imaging element 35 Lens unit 37 Adhesive resin (UV / thermosetting resin)
39 Lens support member 41 Imaging surface 43 Element cover glass 57 Light guide 59 Optical fiber 61 Optical transmission rod member 65 Mold part LC Optical axes L1, L2, L3 Lens Dmax Maximum outer diameter

The present invention is provided along a lens unit that houses a lens in a lens support member, an image sensor whose imaging surface is covered with an element cover glass, a transmission cable electrically connected to the image sensor, and the lens unit. The lens unit having the optical axis of the lens coincided with the center of the imaging surface and the element cover glass are fixed with an adhesive resin, and at least a part of the lens unit, the imaging Provided is an endoscope in which an element, a part of the transmission cable, and a part of the illuminating means are covered and fixed by a mold resin.

The present invention is provided along a lens unit that houses a lens in a lens support member, an image sensor whose imaging surface is covered with an element cover glass, a transmission cable electrically connected to the image sensor, and the lens unit. The lens unit having the optical axis of the lens coincided with the center of the imaging surface and the element cover glass are fixed with an adhesive resin, and at least a part of the lens unit, the imaging element, a portion of a part and the lighting unit of the transmission cable is fixed is covered by the mold resin, and the molding resin is that is exposed to the outside, to provide an endoscope.

Claims (7)

A lens unit that houses a lens in a lens support member;
An imaging device whose imaging surface is covered by an element cover glass;
A transmission cable electrically connected to the imaging device;
Illumination means provided along the lens unit,
The lens unit having the optical axis of the lens coincided with the center of the imaging surface and the element cover glass are fixed with an adhesive resin,
At least a part of the lens unit, the imaging element, a part of the transmission cable, and a part of the illumination unit are covered and fixed with a mold resin, and the mold resin is exposed to the outside.
Endoscope. The endoscope according to claim 1, wherein
The maximum outer diameter of the mold resin is in the range of 0.7 to 2 mm.
Endoscope. The endoscope according to claim 1 or 2,
The illumination means is configured using an optical fiber.
Endoscope. The endoscope according to claim 1 or 2,
The illumination means is configured using an optical transmission rod member provided along the lens unit, and an optical fiber connected to the optical transmission rod member.
Endoscope. The endoscope according to claim 1, wherein
A plurality of the illumination means are provided in the circumferential direction of the lens unit.
Endoscope. The endoscope according to claim 5, wherein
The imaging element is formed in a square shape,
The four illuminating means are disposed at substantially the center of each side portion of the image sensor.
Endoscope. The endoscope according to any one of claims 1 to 6,
The mold part made of the mold resin is composed of a resin material containing an additive, and has a light transmittance of 10% or less.
Endoscope.