Imaging unit and endoscope

Abstract

An imaging unit according to an embodiment of the present invention comprises an objective optical system that is composed of a plurality of lenses, a lens holding frame that houses the objective optical system, and a housing tube into which a proximal end side portion of the lens holding frame is inserted, wherein the lens holding frame is provided with a conductive path portion having electrical conductivity, the housing tube has electrical conductivity and is grounded, a distal end lens disposed closest to the object side among the plurality of lenses is fixed to an inner peripheral surface of the lens holding frame by means of a metal fixing part, and the conductive path portion electrically connects the fixing part and the housing tube.

Description

Imaging Unit and Endoscope

[0001] The present invention relates to an imaging unit and an endoscope.

[0002] There is known an electronic endoscope including a frame member having conductivity and holding an observation optical system, a ground metal member having conductivity and grounded via an imaging cable connected to an imaging element, and a conductive connection portion electrically connecting the frame member and the ground metal member (for example, Patent Document 1). Further, in an electronic endoscope, the tip lens disposed on the most object side among a plurality of lenses constituting the observation optical system may be fixed to the frame member by a fixing portion made of metal such as solder. In the above electronic endoscope, when the tip lens is fixed to the frame member by the fixing portion, the static electricity propagated to the fixing portion flows into the ground via the frame member, the conductive connection portion, the ground metal member, and the imaging cable. This suppresses the static electricity propagated to the fixing portion from flowing into the imaging element.

[0003] Japanese Patent No. 5112575

[0004] In the above electronic endoscope, since the fixing portion and the imaging cable are electrically connected via a plurality of members including the frame member, the conductive connection portion, and the ground metal member, the number of parts of the electronic endoscope has increased. Therefore, there has been a concern that the manufacturing cost of the electronic endoscope increases.

[0005] In view of the above circumstances, an object of the present invention is to provide an imaging unit and an endoscope capable of suppressing the static electricity propagated to the fixing portion from flowing into the imaging element and suppressing an increase in the number of parts.

[0006] An imaging unit according to an aspect of the present invention for achieving the above object includes an objective optical system composed of a plurality of lenses, a lens holding frame housing the objective optical system, and a housing tube into which a proximal end side portion of the lens holding frame is inserted. The lens holding frame is provided with a conductive path portion having conductivity. The housing tube has conductivity and is grounded. A tip lens disposed on the most object side among the plurality of lenses is fixed to an inner peripheral surface of the lens holding frame via a fixing portion made of metal. The conductive path portion electrically connects the fixing portion and the housing tube.

[0007] An endoscope in one aspect of the present invention is equipped with the above-mentioned imaging unit at the tip of the insertion section.

[0008] According to the present invention, it is possible to provide an imaging unit and an endoscope that can suppress the flow of static electricity propagated to the fixed part into the image sensor, and can also suppress an increase in the number of parts.

[0009] This is a perspective view showing the endoscope system of the first embodiment. This is a cross-sectional view showing the imaging unit of the first embodiment. This is a plan view of the imaging unit of the first embodiment as seen from the object side. This is a cross-sectional view showing the imaging unit of the second embodiment. This is a cross-sectional view showing the imaging unit of the third embodiment. This is a cross-sectional view showing the imaging unit of the fourth embodiment. This is a plan view of the imaging unit of the fourth embodiment as seen from the object side. This is a cross-sectional view showing the imaging unit of the fifth embodiment. This is a plan view of the imaging unit of the fifth embodiment as seen from the object side. This is a cross-sectional view showing the imaging unit of the sixth embodiment. This is a cross-sectional view showing the imaging unit of the seventh embodiment.

[0010] The imaging unit and endoscope according to embodiments of the present invention will be described below with reference to the drawings. Note that the scope of the present invention is not limited to the following embodiments, and modifications can be made as appropriate within the scope of the technical idea of ​​the present invention. Furthermore, in the following drawings, the scale and number of components in each structure may differ from the actual structure in order to make the components easier to understand.

[0011] In each figure, the Z-axis is shown as appropriate. The direction in which the Z-axis extends is the direction in which the optical axis J of the imaging unit in the embodiment described below extends. The optical axis J shown as appropriate in each figure is a virtual axis. The optical axis J is the central axis of the imaging unit. In the following description, the direction in which the optical axis J extends, that is, the direction parallel to the Z-axis, is called the "optical axis direction". The side of the optical axis direction in which the Z-axis arrow points (+Z side) is the "object side (distal side)", and the side of the optical axis direction opposite to the side in which the Z-axis arrow points (-Z side) is the "proximal end side (proximal side)".

[0012] In the following explanation, the radial direction centered on the optical axis J is simply referred to as the "radial direction." The area outside the radial direction centered on the optical axis J may be simply referred to as the "outer radial direction." The area inside the radial direction centered on the optical axis J may be simply referred to as the "inner radial direction." In the following explanation, the circumferential direction centered on the optical axis J is simply referred to as the "circumferential direction." The circumferential direction is indicated by the arrow θ in each figure.

[0013] <First Embodiment> Figure 1 is a perspective view showing the endoscope system 1 of this embodiment. Figure 2 is a cross-sectional view showing the imaging unit 20 of this embodiment. Figure 3 is a plan view of the imaging unit 20 of this embodiment as seen from the object side (+Z side).

[0014] The endoscopic system 1 shown in Figure 1 consists of an endoscope 2 capable of capturing an optical image of a subject and generating an image signal of the subject, a processor 3, a light source device 4 to which the endoscope 2 is detachably connected, and a monitor 5 that displays the image signal generated by the processor 3 as an image of the subject. The processor 3 and the monitor 5 are connected by a connecting cable 5a.

[0015] The endoscope 2 comprises an elongated insertion section 6, an operating section 7 connected to the base end of the insertion section 6, and a universal cable 8 extending from the operating section 7 and connected to a light source device 4. The application of the endoscope 2 in this embodiment is not particularly limited; for example, it may be a medical endoscope or an industrial endoscope.

[0016] The insertion section 6 is the part that is inserted into the body, for example, when observing a subject. The insertion section 6 is configured with an insertion tip section 6a, a curved section 6b, and a flexible tube section 6c arranged in this order from the object side, which is the tip in the direction of insertion into the subject, toward the base end connected to the operation section 7. The insertion tip section 6a is made of a resin tube and a metal tube such as stainless steel. As shown in Figure 2, in this embodiment, the insertion tip section 6a is substantially cylindrical and extends in the direction of the optical axis. The insertion tip section 6a includes an imaging unit 20 and a housing 70. That is, the imaging unit 20 is located at the tip of the insertion section 6 of the endoscope 2. The endoscope 2 is equipped with the imaging unit 20 at the tip of the insertion section 6.

[0017] Inside the curved section 6b and the flexible tube section 6c shown in Figure 1, a signal cable 34 (see Figure 2, etc.) that electrically connects the imaging unit 20, the operation unit 7, and the processor 3, and a light guide bundle (not shown) that transmits illumination light to the insertion tip section 6a are inserted.

[0018] The operating section 7 is provided with an operating knob 7a, a forceps channel 7b, and a switch 7c. The operating knob 7a is an operating means for bending the curved section 6b in four directions: up, down, left, and right. Note that the curved section 6b is not limited to a configuration that can be bent in four directions: up, down, left, and right, but may also be configured to be bent in two directions, for example, up and down only, or in two directions, left and right only. The switch 7c is a switch used to adjust the focal position of the optical image of the subject formed by the light source device 4 and the imaging unit 20. The forceps channel 7b is an opening that communicates with the proximal end of the treatment instrument channel that extends from inside the operating section 7 through the insertion section 6 to the tip of the insertion tip section 6a.

[0019] Inside the universal cable 8 are a signal cable 34 (see Figure 2, etc.) and a light guide bundle (not shown). At the base end of the universal cable 8 is a scope connector 8b that optically couples illumination light from the light source device 4, which supplies illumination light, to the incident end of the light guide bundle. The signal cable 34 inside the universal cable 8 extends into the scope cable that branches off from the scope connector 8b. At the end of the scope cable is an electrical connector 8a that connects the signal cable 34 to the processor 3. When the electrical connector 8a is connected to the processor 3, the signal cable 34 enables communication between the processor 3 and electrical components such as the image sensor 31 (see Figure 2) of the imaging unit 20.

[0020] As shown in Figure 2, the imaging unit 20 is substantially cylindrical in shape and extends in the direction of the optical axis. The imaging unit 20 forms an optical image of the subject and converts this optical image into an image signal. The imaging unit 20 comprises a lens holding frame 21, a housing tube 25, an outer shell 26, an objective optical system 28, an image sensor 31, and a fixing part 38.

[0021] The lens holding frame 21 is substantially cylindrical in shape and extends in the direction of the optical axis. The lens holding frame 21 surrounds the optical axis J. As shown in Figure 3, when viewed from the direction of the optical axis, the lens holding frame 21 is substantially circular in shape. As shown in Figure 2, the lens holding frame 21 houses the objective optical system 28, the image sensor 31, and the housing 70 inside. The lens holding frame 21 holds the objective optical system 28, the image sensor 31, and the housing 70. In this embodiment, the lens holding frame 21 is made of resin. The lens holding frame 21 is insulating. The lens holding frame 21 has a first frame portion 22, a second frame portion 23, an outer circumferential surface 21f of the holding frame, an inner circumferential surface 21h of the holding frame, and a tip surface 21k. A conductive path portion 40 is provided in the lens holding frame 21. As shown in Figure 3, the lens holding frame 21 is provided with a first through hole 21a, a second through hole 21b, a third through hole 21c, and a fourth through hole 21d.

[0022] As shown in Figure 2, the first through-hole 21a and the second through-hole 21b are holes that penetrate the lens holding frame 21 in the direction of the optical axis. Although not shown in the illustration, the third through-hole 21c and the fourth through-hole 21d shown in Figure 3 are holes that penetrate the lens holding frame 21 in the direction of the optical axis. As shown in Figure 3, when viewed from the direction of the optical axis, the first through-hole 21a is approximately circular in shape with the optical axis J as the center. The first through-hole 21a, the second through-hole 21b, the third through-hole 21c, and the fourth through-hole 21d are spaced apart from each other. As shown in Figure 2, the objective optical system 28 and the image sensor 31 are housed inside the first through-hole 21a. As shown in Figure 3, the contents 70 are housed inside the second through-hole 21b, the third through-hole 21c, and the fourth through-hole 21d, respectively.

[0023] The outer circumferential surface 21f of the retaining frame shown in Figure 2 is the outer circumferential surface of the lens retaining frame 21. The configuration of the outer circumferential surface 21f of the retaining frame will be described in detail later. The inner circumferential surface 21h of the retaining frame is the inner circumferential surface of the first through hole 21a. The inner circumferential surface 21h of the retaining frame is the inner circumferential surface of the lens retaining frame 21. Viewed from the direction of the optical axis, the inner circumferential surface 21h of the retaining frame is approximately circular in shape with the optical axis J as the center. The inner circumferential surface 21h of the retaining frame surrounds the objective optical system 28 and the image sensor 31 from the radially outer side. The tip surface 21k is the outer surface of the lens retaining frame 21 that faces the object side (+Z side).

[0024] The first frame portion 22 is the object-side (+Z side) portion of the lens holding frame 21. The first frame portion 22 surrounds the optical axis J and is substantially cylindrical in shape, extending in the direction of the optical axis. The first frame portion 22 has a first outer peripheral surface 22c, a rear end surface 22e, and a first inner peripheral surface 22g. A hole 22h is provided in the first frame portion 22.

[0025] The first outer surface 22c is the outer surface of the first frame portion 22 that faces radially outward. Viewed from the direction of the optical axis, the first outer surface 22c is approximately circular in shape, surrounding the optical axis J. The rear end surface 22e is the outer surface of the first frame portion 22 that faces the base end side (-Z side). The radial outer edge of the rear end surface 22e is connected to the base end of the first outer surface 22c. Viewed from the direction of the optical axis, the rear end surface 22e is approximately annular in shape, surrounding the optical axis J. The outer surface of the first frame portion 22 that faces the object side (+Z side) is the front end surface 21k. The radial outer edge of the front end surface 21k is connected to the object end of the first outer surface 22c.

[0026] The first inner circumferential surface 22g is the inner circumferential surface of the first through-hole 21a in the first frame portion 22. Viewed from the direction of the optical axis, the first inner circumferential surface 22g is substantially circular in shape with the optical axis J as the center. The first inner circumferential surface 22g surrounds the objective optical system 28 from the radially outer side. The hole portion 22h is a hole that penetrates the portion of the first frame portion 22 between the first inner circumferential surface 22g and the first outer circumferential surface 22c in the radial direction. As a result, the inside of the first through-hole 21a and the outside of the lens holding frame 21 are connected via the hole portion 22h. The radially inner end of the hole portion 22h is connected to the first inner circumferential surface 22g. The radially outer end of the hole portion 22h is connected to the first outer circumferential surface 22c.

[0027] The second frame portion 23 is the base end (-Z side) portion of the lens holding frame 21. The second frame portion 23 surrounds the optical axis J and is substantially cylindrical, extending in the axial direction. The outer diameter of the second frame portion 23 is smaller than the outer diameter of the first frame portion 22. The second frame portion 23 is positioned closer to the base end than the first frame portion 22. The second frame portion 23 is connected to the first frame portion 22 in the optical axis direction. The second frame portion 23 has a second outer circumferential surface 23a and a second inner circumferential surface 23c.

[0028] The second outer circumferential surface 23a is the outer surface of the second frame portion 23 that faces radially outward. Viewed from the optical axis direction, the second outer circumferential surface 23a is substantially circular in shape, surrounding the optical axis J. The object-side (+Z side) end of the second outer circumferential surface 23a connects to the radially inner edge of the rear end surface 22e. The second inner circumferential surface 23c is the inner circumferential surface of the first through hole 21a in the second frame portion 23. Viewed from the optical axis direction, the second inner circumferential surface 23c is substantially circular in shape, centered on the optical axis J. The object-side end of the second inner circumferential surface 23c connects to the base end (-Z side) of the first inner circumferential surface 22g. The second inner circumferential surface 23c surrounds the object-side portions of the image sensor 31 and the signal cable 34 from the radially outward direction.

[0029] As described above, the outer circumferential surface 21f of the retaining frame is the outer circumferential surface of the lens retaining frame 21. In this embodiment, the outer circumferential surface 21f of the retaining frame is composed of a first outer circumferential surface 22c, a rear end surface 22e, and a second outer circumferential surface 23a. As described above, the inner circumferential surface 21h of the retaining frame is the inner circumferential surface of the first through hole 21a. The inner circumferential surface 21h of the retaining frame is the inner circumferential surface of the lens retaining frame 21. In this embodiment, the inner circumferential surface 21h of the retaining frame is composed of a first inner circumferential surface 22g and a second inner circumferential surface 23c.

[0030] The housing tube 25 is cylindrical, enclosing the optical axis J and extending in the direction of the optical axis. In this embodiment, the housing tube 25 is substantially cylindrical, extending in the direction of the optical axis. The housing tube 25 is made of metal. Stainless steel or the like can be used as the material constituting the housing tube 25. The housing tube 25 is electrically conductive. In this embodiment, the housing tube 25 has higher conductivity than the lens holding frame 21. The inner diameter of the housing tube 25 is larger than the outer diameter of the second frame portion 23. The second frame portion 23 is inserted into the housing tube 25 in the direction of the optical axis. That is, the base end side (-Z side) portion of the lens holding frame 21 is inserted into the housing tube 25. Although not shown in the figures, the housing tube 25 is grounded. More specifically, the housing tube 25 is grounded to the outside of the endoscope 2. That is, the housing tube 25 is grounded to the outside.

[0031] The outer shell 26 is cylindrical, enclosing the optical axis J and extending in the direction of the optical axis. The outer shell 26 surrounds the housing tube 25 from the radially outer side. The material that makes up the outer shell 26 can be resin or silicone rubber, etc. In this embodiment, the outer shell 26 is made of resin. The outer shell 26 has insulating properties.

[0032] The objective optical system 28 forms an optical image of the subject. More specifically, the objective optical system 28 images the optical image of the subject onto the light-receiving surface 31a of the image sensor 31. The objective optical system 28 is composed of a plurality of lenses 28a arranged in a line along the optical axis J. Each of the plurality of lenses 28a is held on the inner circumferential surface 21h of the lens holding frame 21. More specifically, each of the plurality of lenses 28a is held on the first inner circumferential surface 22g. In this way, the lens holding frame 21 holds the objective optical system 28 housed inside. In this embodiment, the objective optical system 28 is composed of four lenses 28a. The number of lenses 28a constituting the objective optical system 28 may be three or less, or five or more. Also, the shape of each lens 28a is not limited to this embodiment. The objective optical system 28 includes a front lens 29.

[0033] The tip lens 29 is the lens 28a that is positioned furthest towards the object (+Z side) among the multiple lenses 28a. The surface of the tip lens 29 facing the object is exposed to the object side from the lens holding frame 21. A metal film 29a is formed on the radially outward-facing surface of the tip lens 29. That is, a metal film 29a is formed on the radially outward-facing surface of at least one of the multiple lenses 28a. The metal film 29a is formed on the radially outward-facing surface of the tip lens 29 by a physical vapor deposition method such as sputtering. In this embodiment, the metal film 29a is made of gold.

[0034] The tip lens 29 is fixed to the inner circumferential surface 21h of the retaining frame, i.e., the inner circumferential surface of the lens retaining frame 21, via a metal fixing part 38. The fixing part 38 is conductive. In this embodiment, the fixing part 38 is made of solder. The fixing part 38 is substantially annular in shape with the optical axis J as the center. The inner circumferential surface of the fixing part 38 is joined to the metal film 29a, and the outer circumferential surface of the fixing part 38 is joined to the inner circumferential surface of the lens retaining frame 21. The fixing part 38 is exposed from the lens retaining frame 21 toward the object side (+Z side). The fixing part 38 may be made of a metal other than solder. Furthermore, the tip lens 29 may be fixed to the inner circumferential surface of the lens retaining frame 21 by welding. In addition, the fixing part 38 may be a fastening member such as a metal screw.

[0035] The image sensor 31 captures the optical image of the subject formed by the objective optical system 28 and converts it into an image signal. The image sensor 31 is, for example, an image sensor such as a CCD or CMOS. The image sensor 31 is positioned on the proximal end side (-Z side) of the objective optical system 28. The light-receiving surface 31a of the image sensor 31 faces the object side (+Z side). The light-receiving surface 31a of the image sensor 31 faces the objective optical system 28 in the optical axis direction. The image sensor 31 is fixed to the second inner circumferential surface 23c of the lens holding frame 21. In this way, the lens holding frame 21 holds the image sensor 31. In this embodiment, the first distance L1, which is the distance between the fixing part 38 and the image sensor 31, is shorter than the second distance L2, which is the distance between the fixing part 38 and the housing tube 25. An imaging substrate 32 is connected to the image sensor 31.

[0036] The imaging substrate 32 is, for example, a flexible printed circuit board (FPC board). Electronic components such as a digital IC that generates a drive signal for the image sensor 31 and a capacitor that stabilizes the power supply for the digital IC are mounted on the imaging substrate 32. The imaging substrate 32 is positioned on the base side (-Z side) of the image sensor 31. A signal cable 34 is connected to the imaging substrate 32.

[0037] The signal cable 34 connects the imaging substrate 32 and the processor 3 (see Figure 1) in a communication manner. The base end (-Z side) of the signal cable 34 is connected to the processor 3 shown in Figure 1. The signal cable 34 passes through the inside of the universal cable 8, the flexible tube section 6c, and the curved section 6b. As shown in Figure 2, the signal cable 34 extends in the direction of the optical axis. In this embodiment, the signal cable 34 is a cable bundle formed by bundling multiple cables 34a together. The object side (+Z side) end of each cable 34a is joined to the imaging substrate 32, for example, by solder. In this way, the signal cable 34 is joined to the imaging substrate 32.

[0038] The conductive path 40 is a conductive path that electrically connects the fixed part 38 and the housing tube 25. As described above, the conductive path 40 is provided on the lens holding frame 21. In this embodiment, the conductive path 40 is made of metal. The conductive path 40 is conductive. In this embodiment, the conductive path 40 is made of a metal with low electrical resistivity, such as gold and copper. This reduces the electrical resistance of the conductive path 40. In this embodiment, the conductive path 40 is made of gold. The conductive path 40 may also be made of copper. The conductive path 40 has a first conductive part 41, a second conductive part 42, and a third conductive part 43.

[0039] The first conductive portion 41 is positioned on the inner circumferential surface 21h of the retaining frame, that is, on the inner circumferential surface of the lens retaining frame 21. The first conductive portion 41 is substantially annular in shape with respect to the optical axis J. In this embodiment, the first conductive portion 41 is positioned on the first inner circumferential surface 22g in a portion that overlaps with the tip lens 29 when viewed from the radial direction. When viewed from the radial direction, a part of the first conductive portion 41 overlaps with the hole 22h. The first conductive portion 41 surrounds the fixing portion 38 from the radially outer side. The first conductive portion 41 is in contact with the fixing portion 38. As a result, the first conductive portion 41 is electrically connected to the fixing portion 38. Furthermore, the tip lens 29 is fixed to the first conductive portion 41 via the fixing portion 38 and the metal film 29a. As a result, the tip lens 29 is fixed to the lens retaining frame 21.

[0040] The second conductive portion 42 is positioned inside the hole 22h. In other words, the second conductive portion 42 is positioned inside the lens holding frame 21. The second conductive portion 42 extends radially inside the hole 22h. Viewed radially, the second conductive portion 42 overlaps with the tip lens 29. The radially inner end of the second conductive portion 42 is connected to the first conductive portion 41. As a result, the second conductive portion 42 is electrically connected to the first conductive portion 41.

[0041] The third conductive portion 43 is positioned on the outer peripheral surface 21f of the retaining frame, that is, on the outer peripheral surface of the lens retaining frame 21. In this embodiment, the third conductive portion 43 has a first portion 43a, a second portion 43c, and a third portion 43e. The first portion 43a is positioned on the first outer peripheral surface 22c. The first portion 43a extends in the direction of the optical axis. The object-side (+Z side) portion of the first portion 43a is connected to the radially outer end of the second conductive portion 42. As a result, the third conductive portion 43 is electrically connected to the second conductive portion 42. The base-side (-Z side) end of the first portion 43a is located at the base-side end of the first outer peripheral surface 22c.

[0042] The second portion 43c is positioned on the rear end face 22e. The second portion 43c extends radially. The radially outer end of the second portion 43c is connected to the base end (-Z side) of the first portion 43a. This electrically connects the second portion 43c to the first portion 43a.

[0043] The third portion 43e is positioned on the second outer surface 23a. The third portion 43e extends in the direction of the optical axis. The object-side (+Z side) end of the third portion 43e is connected to the radially inward end of the second portion 43c. This electrically connects the third portion 43e to the second portion 43c. The radially outward-facing surface of the third portion 43e is in contact with the inner surface of the housing tube 25. This electrically connects the third portion 43e to the housing tube 25. Thus, the third conductive portion 43 electrically connects the second conductive portion 42 to the housing tube 25. As described above, the first conductive portion 41 is electrically connected to the fixed portion 38, and the second conductive portion 42 is electrically connected to the first conductive portion 41. Thus, the conductive path portion 40 electrically connects the fixed portion 38 to the housing tube 25.

[0044] In the present embodiment, the conductive path portion 40 is formed on the lens holding frame 21 by plating using a three-dimensional molding substrate technique after forming the hole portion 22h in the lens holding frame 21. The processing method for forming the hole portion 22h in the lens holding frame 21 is preferably laser processing using, for example, a krypton fluoride (KrF) excimer laser beam. Note that the lens holding frame 21 and the conductive path portion 40 may be integrally manufactured by a three-dimensional lamination device (3D printer).

[0045] When the endoscope 2 captures an image of a subject such as a human, static electricity may propagate from the skin or the like of the subject such as a human to the insertion tip portion 6a. In the present embodiment, as described above, the fixing portion 38 has conductivity and is exposed from the lens holding frame 21 to the object side (+Z side), so such static electricity easily propagates to the fixing portion 38. When the static electricity propagated to the fixing portion 38 flows into the imaging element 31, noise may be superimposed on the image signal when the imaging element 31 converts the optical image of the subject captured into an image signal. Therefore, there has been a concern that the quality of the image of the subject formed by the endoscope 2, that is, the image displayed on the monitor 5 (see FIG. 1) may deteriorate. On the other hand, in the present embodiment, as described above, the fixing portion 38 is electrically connected to the housing tube 25 via the conductive path portion 40, and the housing tube 25 is grounded. Thereby, the static electricity propagated to the fixing portion 38 flows into the ground via the conductive path portion 40 and the housing tube 25, so that it is possible to suppress the static electricity propagated to the fixing portion 38 from flowing into the imaging element 31. Therefore, it is possible to suppress a decrease in the quality of the image formed by the endoscope 2.

[0046] Furthermore, in the present embodiment, the fixing portion 38 and the housing tube 25 can be electrically connected only by the conductive path portion 40 provided in the lens holding frame 21. Therefore, it is possible to suppress the static electricity propagated to the fixing portion 38 from flowing into the imaging element 31 and to suppress an increase in the number of parts of the imaging unit 20 and the endoscope 2.

[0047] As shown in FIG. 2, the accommodating object 70 is passed through the inside of the lens holding frame 21 in the optical axis direction. As shown in FIG. 3, in the present embodiment, the insertion tip portion 6a includes a plurality of accommodating objects 70. In the present embodiment, the plurality of accommodating objects 70 include an air and water supply unit 71, a light guide unit 72, and a treatment tool unit 73.

[0048] As shown in FIG. 2, the air and water supply unit 71 is passed through the inside of the second through hole 21b in the optical axis direction and is attached to the inner peripheral surface of the second through hole 21b. The air and water supply unit 71 is a flow path for supplying liquids such as air and water to the outer surface of the tip lens 29. By supplying air and liquid to the outer surface of the tip lens 29, body fluids and blood attached to the tip lens 29 can be removed. The air and water supply unit 71 is connected to a pump (not shown) that pumps air and liquid.

[0049] The light guide unit 72 shown in FIG. 3 is passed through the inside of the third through hole 21c in the optical axis direction and is attached to the inner peripheral surface of the third through hole 21c. The light guide unit 72 is an optical path for irradiating the subject with illumination light supplied from the light source device 4 (see FIG. 1). Although not shown, the end on the proximal end side (-Z side) of the light guide unit 72 is connected to a light guide bundle. The treatment tool unit 73 is passed through the inside of the fourth through hole 21d in the optical axis direction and is attached to the inner peripheral surface of the fourth through hole 21d. The treatment tool unit 73 houses treatment tools such as forceps, snares, and injection needles, and cables connected to the treatment tools. Such a cable is connected to the operation unit 7.

[0050] According to this embodiment, the imaging unit 20 includes an objective optical system 28 composed of a plurality of lenses 28a, a lens holding frame 21 that houses the objective optical system 28, and a housing tube 25 into which the base end portion of the lens holding frame 21 is inserted. The lens holding frame 21 is provided with a conductive path portion 40, the housing tube 25 is conductive and grounded, and the tip lens 29, which is positioned furthest towards the object (+Z side) of the plurality of lenses 28a, is fixed to the inner circumferential surface of the lens holding frame 21 via a metal fixing portion 38, and the conductive path portion 40 electrically connects the fixing portion 38 and the housing tube 25. Therefore, as described above, static electricity propagated to the fixing portion 38 flows into the ground via the conductive path portion 40 and the housing tube 25, thus preventing static electricity propagated to the fixing portion 38 from flowing into the image sensor 31. Consequently, a decrease in the quality of the image formed by the endoscope 2 can be suppressed. Furthermore, in this embodiment, as described above, the fixed part 38 and the housing tube 25 can be electrically connected only by the conductive path portion 40 provided in the lens holding frame 21, thus suppressing an increase in the number of parts of the imaging unit 20. Therefore, in this embodiment, it is possible to suppress static electricity propagated to the fixed part 38 from flowing into the image sensor 31, and to suppress an increase in the number of parts of the imaging unit 20.

[0051] According to this embodiment, the lens holding frame 21 is made of resin. Therefore, since the lens holding frame 21 is insulating, it is possible to more effectively suppress static electricity flowing through the conductive path 40 from flowing into the image sensor 31 via the lens holding frame 21. Consequently, it is possible to more effectively suppress a decrease in the quality of the image formed by the endoscope 2.

[0052] According to this embodiment, the housing tube 25 has higher conductivity than the lens holding frame 21. Therefore, the electrical resistance of the housing tube 25 is easily reduced, and static electricity flowing into the housing tube 25 can be suitably discharged to the ground. This makes it possible to more suitably suppress static electricity propagated to the fixed part 38 from flowing into the image sensor 31.

[0053] According to this embodiment, the housing tube 25 is grounded to the outside. Therefore, it is possible to more effectively suppress static electricity flowing into the housing tube 25 from flowing into the image sensor 31. Consequently, it is possible to more effectively suppress static electricity propagated to the fixed part 38 from flowing into the image sensor 31.

[0054] According to this embodiment, the conductive path portion 40 includes a first conductive portion 41 arranged on the inner circumferential surface of the lens holding frame 21 and electrically connected to the fixing portion 38, a second conductive portion 42 arranged inside the lens holding frame 21 and electrically connected to the first conductive portion 41, and a third conductive portion 43 arranged on the outer circumferential surface of the lens holding frame 21 and electrically connecting the second conductive portion 42 to the housing tube 25. Therefore, since the second conductive portion 42 and the third conductive portion 43 can be arranged radially outward from the inner circumferential surface of the lens holding frame 21, the distance between the second conductive portion 42 and the third conductive portion 43 and the image sensor 31 can be increased. This effectively suppresses the propagation of static electricity flowing through the second conductive portion 42 and the third conductive portion 43 to the image sensor 31. Therefore, it is possible to more effectively suppress a decrease in the quality of the image formed by the endoscope 2.

[0055] According to this embodiment, the second conductive portion 42 extends radially, that is, radially around the optical axis J, and overlaps with the tip lens 29 when viewed from the radial direction. Therefore, the distance between the second conductive portion 42 and the image sensor 31 can be increased compared to the case where the second conductive portion 42 is located towards the base end (-Z side) as it extends radially outward. This makes it possible to more effectively suppress the propagation of static electricity flowing through the second conductive portion 42 to the image sensor 31. Therefore, it is possible to more effectively suppress a decrease in the quality of the image formed by the endoscope 2.

[0056] According to this embodiment, the conductive path portion 40 is formed on the lens holding frame 21 by plating. Therefore, since the entire conductive path portion 40 can be easily formed, it is possible to suppress an increase in the number of work steps required to form the conductive path portion 40 on the lens holding frame 21. Consequently, it is possible to suppress an increase in the number of work steps required to manufacture the imaging unit 20.

[0057] Furthermore, in this embodiment, the thickness of the conductive path 40 can be made thinner compared to cases where the conductive path 40 is composed of plate-shaped and columnar members, or cables, etc. Therefore, it is easier to suppress the radial enlargement of the imaging unit 20.

[0058] According to this embodiment, the fixing part 38 is constructed by soldering. Therefore, compared to the case where the fixing part 38 is a fastening member such as a screw, there is no need to provide holes in the tip lens 29 and lens holding frame 21 through which the fastening member passes, or female screw holes into which the fastening member is tightened. As a result, the processing time for the tip lens 29 and lens holding frame 21 can be suppressed, and thus the manufacturing time for the imaging unit 20 can be suppressed. Furthermore, compared to the case where the tip lens 29 is fixed to the lens holding frame 21 by welding, the temperature of both the tip lens 29 and the lens holding frame 21 when fixing the tip lens 29 to the lens holding frame 21 can be reduced. As a result, deterioration of the shape accuracy of both the tip lens 29 and the lens holding frame 21 can be suppressed.

[0059] According to this embodiment, the conductive path portion 40 is made of copper or gold. Therefore, as described above, the electrical resistance of the conductive path portion 40 can be reduced, and thus the electrical resistance between the fixed portion 38 and the housing tube 25 can be reduced. Consequently, static electricity propagated to the fixed portion 38 can be stably discharged to the ground, and thus the flow of static electricity propagated to the fixed portion 38 into the image sensor 31 can be more effectively suppressed.

[0060] In this embodiment, a metal film 29a is formed on the radially outward-facing surface of at least one of the multiple lenses 28a, which in this embodiment is the tip lens 29. The bonding strength between the metal film 29a and the fixing part 38 is greater than the bonding strength between the lens 28a and the fixing part 38. Therefore, the bonding strength between the tip lens 29 and the lens holding frame 21 can be increased compared to the case where a metal film 29a is not formed on the radially outward-facing surface of the tip lens 29. This improves the positional accuracy of the tip lens 29 relative to the lens holding frame 21, thereby suitably improving the quality of the optical image formed by the objective optical system 28. Consequently, the quality of the image formed by the endoscope 2 can be more suitably improved.

[0061] According to this embodiment, the first distance L1, which is the distance between the fixed part 38 and the image sensor 31, is shorter than the second distance L2, which is the distance between the fixed part 38 and the housing tube 25. Therefore, the image sensor 31 can be positioned closer to the objective optical system 28, which makes it possible to miniaturize the imaging unit 20 in the optical axis direction.

[0062] According to this embodiment, the endoscope 2 is equipped with an imaging unit 20 at the tip of the insertion section 6. As described above, static electricity propagated to the fixed section 38 flows into the ground via the conductive path section 40 and the housing tube 25. Also, as described above, the fixed section 38 and the housing tube 25 can be electrically connected solely by the conductive path section 40 provided on the lens holding frame 21. Therefore, it is possible to suppress static electricity propagated to the fixed section 38 from flowing into the image sensor 31, and to suppress an increase in the number of parts of the endoscope 2.

[0063] <Second Embodiment> Figure 4 is a cross-sectional view showing the imaging unit 220 of this embodiment. In this embodiment, the imaging unit 220 includes a lens holding frame 221, a housing tube 25, an outer shell 26, an objective optical system 28, an image sensor 31, and a fixing part 38. In the following description, components that are the same as those in the first embodiment described above are denoted by the same reference numerals, and their descriptions are omitted.

[0064] The lens holding frame 221 is substantially cylindrical in shape and extends in the direction of the optical axis. The lens holding frame 221 holds the objective optical system 28, the image sensor 31, and the housing 70, respectively. The lens holding frame 221 has a first frame portion 222, a second frame portion 23, an outer circumferential surface 21f, an inner circumferential surface 21h, and a tip surface 21k. A conductive path portion 240 is provided in the lens holding frame 221.

[0065] The first frame portion 222 surrounds the optical axis J and is substantially cylindrical in shape, extending in the direction of the optical axis. The first frame portion 222 has a first outer peripheral surface 22c, a rear end surface 22e, and a first inner peripheral surface 22g. The first frame portion 222 is provided with a hole 222h.

[0066] The hole 222h is a hole connecting the first inner circumferential surface 22g and the rear end surface 22e. In this embodiment, the hole 222h has a first hole 222j and a second hole 222k. The first hole 222j is a hole recessed radially outward from the first inner circumferential surface 22g. The second hole 222k is a hole recessed toward the object side (+Z side) from the rear end surface 22e. The object-side end of the second hole 222k is connected to the first hole 222j. The other configurations of the first frame 222 in this embodiment are the same as the other configurations of the first frame 22 in the first embodiment described above.

[0067] The conductive path 240 is a conductive path that electrically connects the fixed part 38 and the housing tube 25. In this embodiment, the conductive path 240 is made of metal. The conductive path 240 is conductive. In this embodiment, the conductive path 240 is made of a metal with low electrical resistivity, such as gold and copper. The conductive path 240 has a first conductive part 41, a second conductive part 242, and a third conductive part 243.

[0068] The second conductive portion 242 is located inside the hole 222h. That is, the second conductive portion 242 is located inside the lens holding frame 221. The second conductive portion 242 has a first portion 242a and a second portion 242c. The first portion 242a extends radially inside the first hole 222j. Viewed radially, the first portion 242a overlaps with the tip lens 29. The radially inner end of the first portion 242a is connected to the first conductive portion 41. Thus, the second conductive portion 242 is electrically connected to the first conductive portion 41. The second portion 242c extends in the optical axis direction inside the second hole 222k. The object-side (+Z side) end of the second portion 242c is connected to the first portion 242a. Thus, the second portion 242c is electrically connected to the first portion 242a.

[0069] The third conductive portion 243 is positioned on the outer peripheral surface 21f of the retaining frame, that is, on the outer peripheral surface of the lens retaining frame 221. In this embodiment, the third conductive portion 243 is positioned on the second outer peripheral surface 23a. The third conductive portion 243 extends in the direction of the optical axis. The object-side (+Z side) end of the third conductive portion 243 is connected to the base-side (-Z side) end of the second portion 242c. As a result, the third conductive portion 243 is electrically connected to the second conductive portion 242. The radially outward-facing surface of the third conductive portion 243 is in contact with the inner peripheral surface of the housing tube 25. As a result, the third conductive portion 243 is electrically connected to the housing tube 25. Thus, the third conductive portion 243 electrically connects the second conductive portion 242 and the housing tube 25. Therefore, the conductive path portion 240 electrically connects the fixed portion 38 and the housing tube 25. Viewed radially, the entire third conductive portion 243 overlaps with the housing tube 25. In other words, the entire third conductive portion 243 is covered radially from the outside by the housing tube 25. This prevents the third conductive portion 243 from being exposed to the outside of the imaging unit 220. Note that, when viewed radially, a portion of the third conductive portion 243 does not need to overlap with the housing tube 25.

[0070] In this embodiment, the conductive path portion 240 is a single component formed by connecting the first conductive portion 41, the second conductive portion 242, and the third conductive portion 243. In this embodiment, the lens holding frame 221 is formed by insert molding using the conductive path portion 240 as an insert member. Therefore, in this embodiment, the lens holding frame 221 and the conductive path portion 240 can be manufactured more easily compared to the case where the conductive path portion 240 is formed on the lens holding frame 221 by plating. Consequently, an increase in the manufacturing man-hours for the imaging unit 220 and the endoscope 202 can be suppressed. Other configurations of the conductive path portion 240 in this embodiment are the same as other configurations of the conductive path portion 40 in the first embodiment described above. Other configurations of the imaging unit 220 in this embodiment are the same as other configurations of the imaging unit 20 in the first embodiment described above.

[0071] In this embodiment, when viewed from the radial direction centered on the optical axis J, the entire third conductive portion 243 overlaps with the housing tube 25. Therefore, as described above, exposure of the third conductive portion 243 to the outside of the imaging unit 220 can be suppressed. As a result, the propagation of static electricity to the third conductive portion 243 can be suppressed. This effectively prevents static electricity flowing through the third conductive portion 243 from flowing into the image sensor 31. Consequently, a decrease in the quality of the image formed by the endoscope 202 can be effectively suppressed. Furthermore, in this embodiment, the fixed portion 38 and the housing tube 25 can be electrically connected only by the conductive path portion 240 provided on the lens holding frame 221. Therefore, an increase in the number of parts of the imaging unit 220 and the endoscope 202 can be suppressed.

[0072] <Third Embodiment> Figure 5 is a cross-sectional view showing the imaging unit 320 of this embodiment. In this embodiment, the imaging unit 320 includes a lens holding frame 21, a housing tube 25, an outer shell 26, an objective optical system 28, an image sensor 31, and a fixing part 38. The lens holding frame 21 is provided with a conductive path part 340. In the following description, components that are the same as those in the first embodiment described above are denoted by the same reference numerals, and their descriptions are omitted.

[0073] The conductive path 340 is a conductive path that electrically connects the fixed part 38 and the housing tube 25. In this embodiment, the conductive path 340 is made of metal. The conductive path 340 is conductive. In this embodiment, the conductive path 340 is made of a metal with low electrical resistivity, such as gold and copper. The conductive path 340 has a first conductive part 41, a second conductive part 342, and a third conductive part 43.

[0074] The second conductive portion 342 is located inside the hole 22h. That is, the second conductive portion 342 is located inside the lens holding frame 21. The second conductive portion 342 extends radially inside the hole 22h. In this embodiment, the second conductive portion 342 is a columnar member extending radially. The second conductive portion 342 may also be a radially extending cable. The radially inner end of the second conductive portion 342 is joined to the first conductive portion 41. As a result, the second conductive portion 342 is electrically connected to the first conductive portion 41. The radially outer end of the second conductive portion 342 is joined to the third conductive portion 43. As a result, the second conductive portion 342 is electrically connected to the third conductive portion 43. Therefore, the conductive path portion 340 electrically connects the fixing portion 38 and the housing tube 25.

[0075] In this embodiment, the first conductive portion 41 and the third conductive portion 43 are each formed on the lens holding frame 21 by plating using three-dimensional molded substrate technology. The first conductive portion 41 and the third conductive portion 43 and the second conductive portion 342 may be joined by soldering or by welding. The other configurations of the conductive path portion 340 in this embodiment are the same as the other configurations of the conductive path portion 40 in the first embodiment described above. The other configurations of the imaging unit 320 in this embodiment are the same as the other configurations of the imaging unit 20 in the first embodiment described above.

[0076] In this embodiment, the first conductive portion 41 and the third conductive portion 43 are formed by plating, and the second conductive portion 342 is a radially extending member. Therefore, the thickness of both the first conductive portion 41 and the third conductive portion 43 can be reduced. Consequently, the radial enlargement of the imaging unit 20 can be suppressed.

[0077] Furthermore, in this embodiment, the conductive path 340 electrically connects the fixed part 38 and the housing tube 25, thereby suppressing static electricity propagated to the fixed part 38 from flowing into the image sensor 31. Moreover, in this embodiment, as described above, since the fixed part 38 and the housing tube 25 can be electrically connected by the conductive path 340 alone, it is possible to suppress an increase in the number of parts of the imaging unit 320 and the endoscope 302.

[0078] <Fourth Embodiment> Figure 6 is a cross-sectional view showing the imaging unit 420 of this embodiment. Figure 7 is a plan view of the imaging unit 420 of this embodiment as seen from the object side (+Z side). As shown in Figure 6, in this embodiment, the imaging unit 420 includes a lens holding frame 421, a housing tube 25, an outer shell 26, an objective optical system 28, an image sensor 31, a fixing part 38, and a sealing part 427. A conductive path part 440 is provided in the lens holding frame 421. In the following description, components that are the same as those in the first embodiment described above are denoted by the same reference numerals, and their descriptions are omitted.

[0079] As shown in Figure 6, the lens retaining frame 421 is substantially cylindrical in shape and extends in the direction of the optical axis. The lens retaining frame 421 surrounds the optical axis J. The lens retaining frame 421 has a first frame portion 422, a second frame portion 23, an outer circumferential surface 421f of the retaining frame, an inner circumferential surface 21h of the retaining frame, and a tip surface 21k. A conductive path portion 440 is provided in the lens retaining frame 421.

[0080] The first frame portion 422 surrounds the optical axis J and is substantially cylindrical in shape, extending in the direction of the optical axis. The first frame portion 422 has a first outer peripheral surface 422c and a first inner peripheral surface 22g. As shown in Figure 7, the first frame portion 422 is provided with a recess 422m. As shown in Figure 6, the first frame portion 422 is provided with a hole 422h.

[0081] As shown in Figure 7, the recess 422m is a hole that recesses radially inward from a part of the radially outward-facing surface of the first frame portion 422. Viewed from the optical axis direction, the recess 422m is roughly in the shape of a fan-shaped trapezoid centered on the optical axis J. The central angle of the recess 422m is approximately 60°. As shown in Figure 6, the recess 422m opens on both the object side (+Z side) and the base end side (-Z side).

[0082] In this embodiment, the first outer peripheral surface 422c is the radially outward-facing surface on the inner surface of the recess 422m. As shown in Figure 7, when viewed from the optical axis direction, the first outer peripheral surface 422c is arc-shaped with respect to the optical axis J. The central angle of the first outer peripheral surface 422c is approximately 60°. As shown in Figure 6, the object-side (+Z side) end of the first outer peripheral surface 422c connects to the radially outward end of the tip surface 21k. The base-side (-Z side) end of the first outer peripheral surface 422c connects to the second outer peripheral surface 23a. The retaining frame outer peripheral surface 421f is the outer peripheral surface of the lens retaining frame 421. In this embodiment, the retaining frame outer peripheral surface 421f is composed of the first outer peripheral surface 422c and the second outer peripheral surface 23a.

[0083] The hole 422h is a hole that penetrates radially through the portion of the first frame portion 422 between the first inner circumferential surface 22g and the first outer circumferential surface 422c. The radially inner end of the hole 422h is connected to the first inner circumferential surface 22g. The radially outer end of the hole 422h is connected to the first outer circumferential surface 422c. The other configurations of the lens holding frame 421 in this embodiment are the same as the other configurations of the lens holding frame 21 in the first embodiment described above.

[0084] The conductive path 440 is a conductive path that electrically connects the fixed part 38 and the housing tube 25. In this embodiment, the conductive path 440 is made of metal. The conductive path 440 is conductive. In this embodiment, the conductive path 440 is made of a metal with low electrical resistivity, such as gold and copper. The conductive path 440 has a first conductive part 41, a second conductive part 442, and a third conductive part 443.

[0085] The second conductive portion 442 is positioned inside the hole 422h. In other words, the second conductive portion 442 is positioned inside the lens holding frame 421. The second conductive portion 442 extends radially inside the hole 422h. The radially inner end of the second conductive portion 442 is connected to the first conductive portion 41. As a result, the second conductive portion 442 is electrically connected to the first conductive portion 41.

[0086] The third conductive portion 443 is positioned on the outer peripheral surface 421f of the retaining frame, that is, on the outer peripheral surface of the lens retaining frame 421. In this embodiment, the third conductive portion 443 has a first portion 443a and a second portion 443c. The first portion 443a is positioned on the first outer peripheral surface 422c. The first portion 443a extends in the direction of the optical axis. The object-side (+Z side) portion of the first portion 443a is connected to the radially outer end of the second conductive portion 442. As a result, the third conductive portion 443 is electrically connected to the second conductive portion 442. The base-side (-Z side) end of the first portion 443a is located at the base-side end of the first outer peripheral surface 422c.

[0087] The second portion 443c is positioned on the second outer surface 23a. The second portion 443c extends in the direction of the optical axis. The object-side (+Z side) end of the second portion 443c is connected to the base-side (-Z side) end of the first portion 443a. This electrically connects the second portion 443c to the first portion 443a. The radially outward-facing surface of the second portion 443c is in contact with the inner surface of the housing tube 25. This electrically connects the third conductive portion 443 to the second conductive portion 442 and the housing tube 25. Therefore, the conductive path portion 440 electrically connects the fixed portion 38 and the housing tube 25. Viewed radially, the entire second portion 443c overlaps with the housing tube 25. In other words, the entire second portion 443c is covered radially outward by the housing tube 25. This prevents the second portion 443c from being exposed to the outside of the imaging unit 420. The other configurations of the conductive path portion 440 in this embodiment are the same as the other configurations of the conductive path portion 40 in the first embodiment described above.

[0088] As shown in Figures 6 and 7, the sealing portion 427 is positioned inside the recess 422m. As shown in Figure 6, the sealing portion 427 is columnar in shape and extends in the direction of the optical axis. In this embodiment, the sealing portion 427 is made of resin. The sealing portion 427 is insulating. The base end (-Z side) of the sealing portion 427 is in contact with the housing tube 25 in the direction of the optical axis. The sealing portion 427 may be positioned opposite the housing tube 25 in the direction of the optical axis with a gap between them. As shown in Figure 7, viewed from the direction of the optical axis, the sealing portion 427 is approximately a fan-shaped trapezoid with the optical axis J as the center. The central angle of the sealing portion 427 is approximately 60°. The sealing portion 427 is fixed to the inner surface of the recess 422m. This fixes the sealing portion 427 to the lens holding frame 421. In this embodiment, the sealing portion 427 is bonded and fixed to the inner surface of the recess 422m with an adhesive (not shown). The sealing portion 427 may be fixed to the inner surface of the recess 422m by other methods such as welding. As shown in Figure 6, the sealing portion 427 covers the entire first portion 443a of the third conductive portion 443 from the radially outer side. In other words, the sealing portion 427 covers a part of the third conductive portion 443. This prevents the first portion 443a from being exposed to the outside of the imaging unit 420. Other configurations of the imaging unit 420 in this embodiment are the same as other configurations of the imaging unit 20 in the first embodiment described above.

[0089] According to this embodiment, the imaging unit 420 is provided with a resin sealing portion 427 that covers a part of the third conductive portion 443 from the radially outward side, that is, from the radially outward side centered on the optical axis J. Therefore, as described above, it is possible to prevent a part of the third conductive portion 443 from being exposed to the outside of the imaging unit 420. As a result, it is possible to prevent a part of the third conductive portion 443 from coming into contact with the subject during use of the endoscope 402, and thus prevent wear of a part of the third conductive portion 443. Therefore, the durability of the imaging unit 420 can be improved.

[0090] In this embodiment, as described above, the entire first portion 443a is covered from the radially outer side by the sealing portion 427. Also, as described above, the entire second portion 443c is covered from the radially outer side by the housing tube 25. This prevents the entire third conductive portion 443 from being exposed to the outside of the imaging unit 420. As a result, during use of the endoscope 402, contact between the entire third conductive portion 443 and the subject is prevented, thus more effectively suppressing wear of the third conductive portion 443. Therefore, the durability of the imaging unit 420 can be more effectively improved.

[0091] Furthermore, in this embodiment, as described above, since the entire third conductive portion 443 can be prevented from being exposed to the outside of the imaging unit 420, the propagation of static electricity to the third conductive portion 443 can be suppressed. As a result, the static electricity flowing through the third conductive portion 443 can be effectively prevented from flowing into the image sensor 31.

[0092] Furthermore, in this embodiment, the conductive path 440 electrically connects the fixed part 38 and the housing tube 25, thereby suppressing static electricity propagated to the fixed part 38 from flowing into the image sensor 31. Moreover, in this embodiment, as described above, since the fixed part 38 and the housing tube 25 can be electrically connected by the conductive path 440 alone, it is possible to suppress an increase in the number of parts of the imaging unit 420 and the endoscope 402.

[0093] <Fifth Embodiment> Figure 8 is a cross-sectional view showing the imaging unit 520 of this embodiment. Figure 9 is a plan view of the imaging unit 520 of this embodiment as seen from the object side (+Z side). As shown in Figure 8, in this embodiment, the imaging unit 520 includes a lens holding frame 521, a housing tube 25, an outer shell 26, an objective optical system 28, an image sensor 31, a fixing part 38, and a sealing part 427. A conductive path part 540 is provided in the lens holding frame 521. In the following description, components that are the same as those in the fourth embodiment described above are denoted by the same reference numerals, and their descriptions are omitted.

[0094] As shown in Figure 8, the lens retaining frame 521 is substantially cylindrical in shape and extends in the direction of the optical axis. The lens retaining frame 521 surrounds the optical axis J. The lens retaining frame 521 has a first frame portion 522, a second frame portion 23, an outer circumferential surface 421f of the retaining frame, an inner circumferential surface 21h of the retaining frame, and a tip surface 21k.

[0095] The first frame portion 522 surrounds the optical axis J and is substantially cylindrical in shape, extending in the direction of the optical axis. The first frame portion 522 has a first outer peripheral surface 422c and a first inner peripheral surface 22g. As will be described later, in this embodiment, the second conductive portion 542 is arranged on the tip surface 21k, so there is no need to provide a hole in the first frame portion 522 that penetrates the first frame portion 522 radially. In other words, in this embodiment, there is no need to provide a hole in the lens holding frame 521. As shown in Figure 9, the first frame portion 522 is provided with a recess 422m.

[0096] As shown in Figure 8, the conductive path 540 is a conductive path that electrically connects the fixed part 38 and the housing tube 25. In this embodiment, the conductive path 540 is made of metal. The conductive path 540 is conductive. In this embodiment, the conductive path 540 is made of a metal with low electrical resistivity, such as gold and copper. The conductive path 540 has a first conductive part 41, a second conductive part 542, and a third conductive part 543. The first conductive part 41 is arranged on the inner circumferential surface of the lens holding frame 521. The first conductive part 41 is electrically connected to the fixed part 38.

[0097] As shown in Figures 8 and 9, the second conductive portion 542 is positioned on the tip surface 21k, that is, on the surface of the lens holding frame 521 facing the object side (+Z side). The second conductive portion 542 extends radially. As shown in Figure 8, the radially inner end of the second conductive portion 542 is connected to the object-side end of the first conductive portion 41. Thus, the second conductive portion 542 is electrically connected to the first conductive portion 41.

[0098] The third conductive portion 543 is positioned on the outer peripheral surface 421f of the retaining frame, i.e., on the outer peripheral surface of the lens retaining frame 521. The third conductive portion 543 has a first portion 543a and a second portion 443c. The first portion 543a is positioned on the first outer peripheral surface 422c. The first portion 543a extends in the direction of the optical axis. The object-side (+Z side) end of the first portion 543a is connected to the radially outer end of the second conductive portion 542. This electrically connects the third conductive portion 543 to the second conductive portion 542. The base-side (-Z side) end of the first portion 543a is connected to the second portion 443c. The radially outward-facing surface of the second portion 443c is in contact with the inner peripheral surface of the housing tube 25. This electrically connects the second conductive portion 542 and the housing tube 25. Therefore, the conductive path 540 electrically connects the fixed portion 38 and the housing tube 25.

[0099] In this embodiment, the conductive path portion 540 is formed on the lens holding frame 521 by plating using three-dimensional molded substrate technology. The lens holding frame 521 and the conductive path portion 540 may be manufactured integrally by a three-dimensional additive manufacturing apparatus (3D printer). Other configurations of the conductive path portion 540 in this embodiment are the same as other configurations of the conductive path portion 440 in the fourth embodiment described above. Other configurations of the imaging unit 520 in this embodiment are the same as other configurations of the imaging unit 420 in the fourth embodiment described above.

[0100] According to this embodiment, the conductive path portion 540 includes a first conductive portion 41 arranged on the inner circumferential surface of the lens holding frame 521 and electrically connected to the fixing portion 38, a second conductive portion 542 arranged on the surface of the lens holding frame 521 facing the object side (+Z side) and electrically connected to the first conductive portion 41, and a third conductive portion 543 arranged on the outer circumferential surface of the lens holding frame 521 and electrically connecting the second conductive portion 542 to the housing tube 25. Therefore, as described above, in this embodiment, there is no need to provide holes in the lens holding frame 521. This makes it possible to suppress an increase in the manufacturing man-hours of the lens holding frame 521. Consequently, it is possible to suppress an increase in the manufacturing man-hours of the imaging unit 520 and the endoscope 502.

[0101] Furthermore, in this embodiment, the conductive path 540 electrically connects the fixed part 38 and the housing tube 25, thereby suppressing static electricity propagated to the fixed part 38 from flowing into the image sensor 31. Moreover, in this embodiment, as described above, since the fixed part 38 and the housing tube 25 can be electrically connected by the conductive path 540 alone, it is possible to suppress an increase in the number of parts of the imaging unit 520 and the endoscope 502.

[0102] <Sixth Embodiment> Figure 10 is a cross-sectional view showing the imaging unit 620 of this embodiment. As shown in Figure 10, in this embodiment, the imaging unit 620 includes a lens holding frame 21, a housing tube 25, an outer shell 26, an objective optical system 28, an image sensor 31, and a fixing part 38. A conductive path 640 is provided in the lens holding frame 21. In the following description, components that are the same as those in the first embodiment described above are denoted by the same reference numerals, and their descriptions are omitted.

[0103] The conductive path 640 is a conductive path that electrically connects the fixed part 38 and the housing tube 25. In this embodiment, the conductive path 640 is made of metal. The conductive path 640 is conductive. In this embodiment, the conductive path 640 is made of a metal with low electrical resistivity, such as gold and copper. The conductive path 640 has a first conductive part 641, a second conductive part 42, and a third conductive part 43.

[0104] The first conductive portion 641 is positioned on the inner circumferential surface 21h of the retaining frame, that is, on the inner circumferential surface of the lens retaining frame 21. The first conductive portion 641 is made of metal. The first conductive portion 641 is substantially annular in shape with respect to the optical axis J. Viewed radially, a portion of the first conductive portion 641 overlaps with the hole 22h. The first conductive portion 641 is connected to the second conductive portion 42. As a result, the first conductive portion 641 is electrically connected to the second conductive portion 42. The first conductive portion 641 is in contact with the fixed portion 38. As a result, the first conductive portion 641 is electrically connected to the fixed portion 38. Therefore, the conductive path portion 640 electrically connects the fixed portion 38 and the housing tube 25. The base end (-Z side) of the first conductive portion 641 is located closer to the base than the objective optical system 28 and closer to the object (+Z side) than the image sensor 31. As a result, each lens 28a constituting the objective optical system 28 is held on the first inner surface 22g via the first conductive portion 641. That is, each lens 28a is held on the inner surface 21h of the retaining frame via the first conductive portion 641.

[0105] In this embodiment, the conductive path portion 640 is formed on the lens holding frame 21 by plating using three-dimensional molded substrate technology. The lens holding frame 21 and the conductive path portion 640 may be manufactured integrally by a three-dimensional additive manufacturing apparatus (3D printer). The second conductive portion 42 may be a columnar member extending in the radial direction or a cable extending in the radial direction. In this case, the radially inner end of the second conductive portion 42 is joined to the first conductive portion 641, and the radially outer end of the second conductive portion 42 is joined to the third conductive portion 43. Other configurations of the conductive path portion 640 in this embodiment are the same as other configurations of the conductive path portion 40 in the first embodiment described above. Other configurations of the imaging unit 620 in this embodiment are the same as other configurations of the imaging unit 20 in the first embodiment described above.

[0106] According to this embodiment, the first conductive portion 641 is made of metal, and the proximal end (-Z side) of the first conductive portion 641 is located on the proximal end side of the objective optical system 28. Therefore, the strength of the portion of the inner circumferential surface of the lens holding frame 21 that holds each lens 28a can be increased. As a result, the radial positional accuracy of each lens 28a relative to the lens holding frame 21 can be improved, and thus the quality of the optical image formed by the objective optical system 28 can be suitably improved. Consequently, the quality of the image formed by the endoscope 602 can be suitably improved.

[0107] Furthermore, in this embodiment, the conductive path 640 electrically connects the fixed part 38 and the housing tube 25, thereby suppressing static electricity propagated to the fixed part 38 from flowing into the image sensor 31. Moreover, in this embodiment, since the fixed part 38 and the housing tube 25 can be electrically connected by the conductive path 640 alone, it is possible to suppress an increase in the number of parts of the imaging unit 620 and the endoscope 602.

[0108] <Seventh Embodiment> Figure 11 is a cross-sectional view showing the imaging unit 720 of this embodiment. As shown in Figure 11, in this embodiment, the imaging unit 720 includes a lens holding frame 21, a housing tube 25, an outer shell 26, an objective optical system 728, and an image sensor 31. The lens holding frame 21 is provided with a conductive path portion 640. In the following description, components that are the same as those in the sixth embodiment described above are denoted by the same reference numerals, and their descriptions are omitted.

[0109] The objective optical system 728 forms an optical image of the subject. The multiple lenses 28a constituting the objective optical system 728 are held on the first inner surface 22g via the first conductive portion 641. The objective optical system 728 includes an end lens 729.

[0110] The tip lens 729 is the lens 28a that is positioned furthest towards the object (+Z side) among the plurality of lenses 28a. In this embodiment, no metal film is formed on the radially outward-facing surface of the tip lens 729. In this embodiment, the tip lens 729 is bonded and fixed to the first inner circumferential surface 22g by adhesive. The tip lens 729 may also be fixed to the first inner circumferential surface 22g by welding. Other configurations of the objective optical system 728 in this embodiment are the same as other configurations of the objective optical system 28 in the sixth embodiment described above. Other configurations of the imaging unit 720 in this embodiment are the same as other configurations of the imaging unit 620 in the sixth embodiment described above.

[0111] In this embodiment, as described above, no metal film is formed on the radially outward-facing surface of the tip lens 729. Therefore, since there is no need to perform the work of forming a metal film on the radially outward-facing surface of the tip lens 729, the manufacturing man-hours for the tip lens 729 can be easily reduced. Consequently, the manufacturing man-hours for the imaging unit 720 and the endoscope 702 can be easily reduced. Furthermore, in this embodiment, as described above, the tip lens 729 is bonded and fixed to the first inner circumferential surface 22g with adhesive. Therefore, compared to the case where the tip lens 729 is fixed to the first inner circumferential surface 22g with solder, the temperatures of both the tip lens 729 and the lens holding frame 21 when fixing the tip lens 729 to the lens holding frame 21 can be reduced. Consequently, deterioration of the shape accuracy of both the tip lens 729 and the lens holding frame 21 can be suppressed.

[0112] Although embodiments of the present invention have been described above, the configurations and combinations thereof in the embodiments are merely examples, and additions, omissions, substitutions, and other modifications to the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited by the embodiments.

[0113] 2, 202, 302, 402, 502, 602, 702... Endoscope 6... Insertion section 20, 220, 320, 420, 520, 620, 720... Imaging unit 21, 221, 421, 521... Lens holding frame 25... Housing tube 28, 728... Objective optical system 28a... Lens 29, 729... Tip lens 29a... Metal film 31... Image sensor 38... Fixing section 40, 240, 340, 440, 540, 640... Conductive path section 41, 641... First conductive section 42, 242, 342, 442, 542... Second conductive section 43, 243, 443, 543... Third conductive section 427... Sealing section J... Optical axis

Claims

1. An imaging unit comprising: an objective optical system composed of multiple lenses; a lens holding frame housing the objective optical system; and a housing tube into which the base end portion of the lens holding frame is inserted, wherein the lens holding frame is provided with a conductive path portion having conductivity; the housing tube is conductive and grounded; the front lens, which is positioned closest to the object among the multiple lenses, is fixed to the inner circumferential surface of the lens holding frame via a metal fixing portion; and the conductive path portion electrically connects the fixing portion and the housing tube.

2. The imaging unit according to claim 1, wherein the lens holding frame is made of resin.

3. The imaging unit according to claim 1, wherein the housing tube has higher conductivity than the lens retaining frame.

4. The imaging unit according to claim 1, wherein the housing tube is grounded to the outside.

5. The imaging unit according to claim 1, further comprising an image sensor positioned on the proximal end side of the objective optical system and capturing an optical image formed by the objective optical system.

6. The imaging unit according to claim 1, wherein the conductive path portion comprises: a first conductive portion disposed on the inner circumferential surface of the lens holding frame and electrically connected to the fixing portion; a second conductive portion disposed inside the lens holding frame and electrically connected to the first conductive portion; and a third conductive portion disposed on the outer circumferential surface of the lens holding frame and electrically connecting the second conductive portion and the housing tube.

7. The imaging unit according to claim 6, wherein the second conductive portion extends radially with respect to the optical axis and overlaps with the tip lens when viewed from the radial direction.

8. The imaging unit according to claim 6, wherein, when viewed from the radial direction centered on the optical axis, the entire third conductive portion overlaps with the housing tube.

9. The imaging unit according to claim 6, wherein the first conductive portion is made of metal, and the proximal end of the first conductive portion is located on the proximal side of the objective optical system.

10. The imaging unit according to claim 1, wherein the conductive path portion comprises: a first conductive portion disposed on the inner circumferential surface of the lens holding frame and electrically connected to the fixing portion; a second conductive portion disposed on the surface of the lens holding frame facing the object side and electrically connected to the first conductive portion; and a third conductive portion disposed on the outer circumferential surface of the lens holding frame and electrically connecting the second conductive portion and the housing tube.

11. The imaging unit according to claim 1, wherein the conductive path portion is formed on the lens holding frame by plating.

12. The imaging unit according to claim 6, wherein each of the first conductive portion and the third conductive portion is formed by plating, and the second conductive portion is a member extending radially with respect to the optical axis.

13. The imaging unit according to claim 6, further comprising a resin sealing portion that covers a part of the third conductive portion from the radially outer side centered on the optical axis.

14. The imaging unit according to claim 1, wherein the lens holding frame is formed by insert molding using the conductive path portion as an insert member.

15. The imaging unit according to claim 1, wherein the fixing portion is formed by solder.

16. The imaging unit according to claim 1, wherein the conductive path portion is made of copper or gold.

17. The imaging unit according to claim 1, wherein a metal film is formed on the radially outward-facing surface of at least one of the plurality of lenses, with respect to the optical axis.

18. The imaging unit according to claim 5, wherein the distance between the fixed portion and the image sensor is shorter than the distance between the fixed portion and the housing tube.

19. The imaging unit according to claim 5, which is positioned at the tip of the insertion section of the endoscope.

20. An endoscope comprising the imaging unit described in claim 1 at the tip of the insertion section.

Images