JP2002238837A - Image pickup unit for endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup unit for an endoscope capable of acquiring a good observation image without increasing the number of part items and assembling man-hours, and having autoclave resistance. SOLUTION: The axial positioning of a distal end lens 23 is performed by inserting a jig 40 indicated in a two-dot chain line, into a hole part 24 from a hole part opening 24a. In this state, solder 7 is poured between the distal end lens 23 and a lens frame 21, and the solder 7 is solidified to airtightly joint and fix the distal end lens 23 in a position spaced by a specified distance from a recessed part bottom face 22a of the lens frame 21. The jig is then removed, and the proximal end face side of the distal end lens 23 and the inner surface of the lens frame 21 are washed to wash away flux and impurities. A spacing member 27 and a proximal end lens group 26 are inserted in this order into the hole part 24 from the hole part opening 24a, and a lens 25 positioned at the rearmost end of the proximal end lens group 26 is adhesively fixed to the lens frame 21 to constitute an objective lens unit 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endoscope compatible with autoclave sterilization (high-pressure / high-temperature steam sterilization).

[0002]

2. Description of the Related Art Endoscopes, which can be inserted into a body cavity or the like to observe a deep part inside the body cavity or the like, and perform a medical treatment or the like by using a treatment tool as needed, are widely used in the medical field.

[0003] For endoscopes used in the medical field, it is essential to surely sterilize and sterilize an endoscope once used in order to prevent infectious diseases and the like. Recently, autoclave sterilization, which can be used immediately after sterilization without complicated work and has a low running cost, is becoming mainstream in the field of endoscopes.

In this autoclave sterilization, an object to be sterilized is exposed to high-temperature steam at about 120 ° C. to 135 ° C. under high pressure to sterilize it. At this time, the high-pressure steam permeates almost all polymer materials such as resin, rubber, and resin adhesive.
For this reason, during autoclave sterilization, water vapor infiltrates into the endoscope and enters the imaging unit in which the objective lens, solid-state image sensor, substrate, signal line, signal cable, etc. are arranged, and the water vapor enters the endoscope. There was a possibility that a serious problem would occur.

[0005] In order to prevent the steam from the autoclave sterilization from entering the imaging unit, the present applicant has
Japanese Patent Application No. 2000-25566 shows an endoscope in which a lens frame is covered with a metal frame to which a front cover glass is soldered and fixed, and a base end of the metal frame is welded by laser irradiation to form an airtight structure.

In the endoscope, when an optical member such as a cover glass is soldered to a metal frame, an oxidizing agent such as a flux is used to improve the wettability of the solder. If this flux remains, it causes a defect in an image captured by the CCD, and therefore must be removed after the soldering operation. Therefore, the endoscope has a structure in which an opening is provided on one surface side of the cover glass to prevent the metal frame from being in contact with the one surface of the cover glass in order to improve the cleaning property of the flux.

[0007] Further, there is known a method of welding a lens frame and an element frame to which a solid-state image sensor is fixed in order to prevent steam from entering the inside of the imaging unit during autoclave sterilization. In this method, focus adjustment of an image is performed before welding the element frame and the lens frame, and the lens frame after the focus adjustment is fixed with an adhesive. However, there is a possibility that the adhesive may be peeled off when the thermal effect of the laser directly affects the portion where the adhesive is applied. Also,
If the adhesive was directly under the laser irradiation, the adhesive would evaporate instantaneously, possibly causing an explosion. Therefore, in the endoscope, after adjusting the focus of the image,
The lens frame was adhered and fixed, a separate pipe member was externally fitted to the lens frame and the cover glass frame, and both ends of the pipe member were laser-welded.

[0008]

However, the endoscope disclosed in Japanese Patent Application No. 2000-25566 requires a metal frame and a pipe member in addition to a lens frame and an element frame in order to constitute an imaging unit. Not only does the number of parts increase, but also the assemblability deteriorates and the imaging unit becomes large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an imaging unit for an endoscope which can obtain a good observation image without increasing the number of parts and the number of assembling steps and has autoclave resistance. I am aiming.

[0010]

An imaging unit of an endoscope according to the present invention is air-tightly joined to a lens frame having a through-hole and a concave portion formed at the tip of the lens frame and constituting the through-hole. A tip lens, at least one proximal lens disposed in a hole having a diameter smaller than the diameter of the concave portion, the diameter of the through hole communicating with the concave portion, and the proximal lens and And a spacing member disposed between the base lens and the bottom surface of the concave portion.

Also, a solid-state image pickup device on which a light beam passing through a lens group in a lens frame constituting an observation optical system forms an image, the solid-state image pickup device is held at one end, and the lens frame is held at the other end. An image pickup unit for an endoscope, comprising: an element frame for holding the element frame and the element frame and the lens frame joined by using both connection and fixing means of adhesion and welding. The welding joint and the bonding joint having different diameters are provided apart from each other.

According to this structure, since a space portion having a predetermined interval is formed between the base end surface of the front lens and the bottom surface of the concave portion formed in the lens frame, the flux can be easily cleaned.

[0013] Further, since the welding joint, which is the joint between the lens frame and the element frame, and the bonding joint are separated from each other, the adhesion of the adhesive to the welding joint or the welding can be prevented. Failure of the bonding joint due to heat at that time is prevented.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 relate to a first embodiment of the present invention. FIG. 1 is a diagram illustrating a configuration of an imaging unit of an endoscope, FIG. 2 is a diagram illustrating a lens frame, and FIG. It is a figure explaining the relation with a spacing member.

As shown in FIG. 1, an imaging unit 1 for an endoscope
Is composed of an objective lens unit 2 that constitutes an observation optical system, a CCD 3 that is a solid-state imaging device having an imaging surface arranged at a focal position of the objective lens unit 2, and a circuit board 4 that is electrically connected to the CCD 3. It is mainly composed. The signal lines 5 are electrically connected to the terminal portions 4a of the circuit board 4, respectively, and these signal lines 5 are inserted through the signal cable 6 and connected to a video processor (not shown). ing.

The objective lens unit 2 includes a lens frame 21 having a substantially convex shape, a tip lens 23 hermetically bonded to a predetermined position of a recess 22 formed at the tip of the lens frame 21, A proximal lens group 26 composed of a plurality of lenses 25, a spacing ring 25b, a diaphragm 25c, and the like disposed in the hole 24 communicating with the front end lens 23 and the distal lens 23 and the proximal lens group 26. It is mainly constituted by a substantially pipe-shaped spacing member 27 disposed between the first lens 25a disposed behind the lens 23 and the first lens 25a.

The CCD 3 is arranged such that the imaging surface is integrally fixed to the base end surface of a cover glass 32 fixed to the base end of the element frame 31. For this reason, the light beam that has passed through the distal lens 23 and the proximal lens group 26 of the objective lens unit 2 passes through the cover glass 32 and forms an image on the imaging surface of the CCD 3.

As shown in FIG. 2, a plating portion 28 such as Ni, for example, for improving the wettability of solder is provided on the inner side surface and the bottom surface of the concave portion 22 of the lens frame 21 as indicated by thick solid lines in the drawing. It is. On the other hand, a portion of the inner peripheral surface of the hole portion 24 of the lens frame 21 indicated by a thick broken line in the drawing is used to prevent flare and ghost due to reflection on the inner peripheral surface, for example,
A -Cu black processing unit 29 is provided.

The plating section 28 and the black processing section 29 may be provided by forming the lens frame 21 by machining and then masking and separately providing the plating section 28 and the black processing section 29, respectively. There is a method in which a plated portion 28 is provided at the stage where the concave portion 22 is formed by machining, and thereafter, a hole 24 is formed, the plated portion 28 is masked, and a black processing portion 29 is provided in the hole 24.

The method of assembling the objective lens unit 2 will be described with reference to FIG. As shown in the figure, when assembling the objective lens unit 2, first, a tip lens 23 coated with, for example, a flux as an oxidizing agent used for activating solder on the outer peripheral surface is arranged in a concave portion 22 of a lens frame 21. At this time, the base end surface of the front lens 23 is brought into contact with the bottom surface 22 a of the concave portion 22.

Next, in order to position the tip lens 23 in the axial direction, the tip lens 23 is brought into contact with the base end face 21a of the lens frame 21 to project from the bottom face 22a of the recess 22 by a predetermined dimension, for example, as shown by a two-dot chain line. The tool 40 is inserted into the hole 24 from the hole opening 24a. Then, a space is formed at a predetermined interval between the base end surface 23a of the tip lens 23 and the bottom surface 22a of the concave portion 22.
The solder 7 is poured between the tip lens 23 and the lens frame 21 from the outer periphery on the tip side of.

When the solder fillet 7a is formed over the entire circumference of the base lens of the tip lens 23, the flow of the solder 7 is stopped and the solder 7 is awaited to be hardened.
The solidification of the solder 7 allows the tip lens 2
3 is hermetically bonded and fixed at a position separated from the bottom surface 22a of the concave portion of the lens frame 21 by a predetermined distance.

Next, the jig 40 is removed, and the base end side of the front lens 23 and the inner surface of the lens frame 21 are washed to remove the flux and impurities. Thereafter, the spacing member 27 and the base lens group 26 are inserted in the hole 24 from the hole opening 24a in this order, and the base lens group 26 is arranged at a predetermined position. Then, the lens 25 located at the rearmost end of the base lens group 26 is bonded and fixed to the lens frame 21. Thus, the objective lens unit 2 is completed. The dimension from the distal lens 23 to the proximal lens group 26 can be changed by adjusting the length of the spacing member 27.

Here, the airtight joining between the lens frame 21 and the element frame 31 will be described. When the lens frame 21 and the element frame 31 are integrally and airtightly joined, first, the positional relationship between the lens frame 21 and the element frame 31 is adjusted to adjust the focus. Then, the lens frame 21 and the element frame 31 are hermetically bonded and fixed by laser welding in this bonded state.

Therefore, as shown in FIG. 2, the lens frame 21 is provided with an element frame arrangement portion 21b in which the tip of the element frame 31 is extrapolated. The element frame arrangement portion 21b has a large-diameter portion 21c serving as a welding joint and a small-diameter portion 21d serving as a bonding joint. On the other hand, as shown in FIG.
A large-diameter hole portion 31c extrapolated to 1c and a small-diameter hole portion 31d extrapolated to the small-diameter portion 21d are provided.

For this reason, in this embodiment, the small-diameter portion 21d of the lens frame 21 with the adhesive 34 applied to the outer peripheral surface is
Focus adjustment is performed with the element frame 31 inserted into the small-diameter hole 31d. After the adhesive 34 is cured, a portion indicated by an arrow A, for example, separated from the adhesive portion is irradiated with a laser beam to be hermetically joined and fixed by welding.

Reference numeral 41 denotes a reinforcing frame externally arranged on the base end side of the element frame 31. Reference numeral 42 denotes a resin insulating tube that covers the entire reinforcing frame 41 and the end of the signal cable 6 so that the reinforcing frame 41 is not exposed. The space surrounded by the reinforcing frame 41 and the insulating tube 42 is filled with an adhesive 43 having low vapor permeability.

As described above, by providing a space at a predetermined interval between the base end surface of the front lens and the bottom surface of the hole formed in the lens frame, it is easy to clean the oxidizing agent and impurities after hermetic bonding with solder. It can be carried out.

Also, at the time of joining by soldering, by providing a space portion at a predetermined interval, the solder fillet can be formed over the entire circumference of the base lens surface side of the front lens without the solder flowing into the hole. As a result, the assembling strength and airtightness of the front lens to the lens frame are further ensured.

Further, in order to join the lens frame and the element frame, the joint for welding and the joint for bonding are separated and separated by a step, so that the adhesive is avoided while avoiding the heat-affected range of laser welding. The coating can be performed, and the laser can be reliably welded without defocusing after the focus adjustment.

As a result, the autoclave resistance can be maintained without increasing the number of parts and the number of assembly steps.
An imaging unit of the endoscope that can obtain a good observation image is configured.

FIG. 4 is a view for explaining another configuration of the imaging unit of the endoscope according to the second embodiment of the present invention. As shown in the figure, in the present embodiment, the large-diameter portion 21c provided on the element frame placement portion 21b of the lens frame 21 is a bonding joint, and the small-diameter portion 21d is a welding joint. For this reason, in the present embodiment, focus adjustment is performed in a state where the large diameter portion 21c of the lens frame 21 with the adhesive 34 applied to the outer peripheral surface is inserted into the large diameter hole 31c of the element frame 31. The arrow A separated from the bonding portion after the adhesive 34 has hardened.
A laser beam is applied to the part shown in (1) to hermetically join and fix it by welding. Reference numeral 35 denotes a pool provided between the base end of the large-diameter portion 21c and the front end of the small-diameter hole 31d, and the adhesive 34 is stored as shown in the drawing.

In this embodiment, the spacing member 2
A narrowed portion 27a having a relatively small inner diameter is integrally provided on the tip side of 7A, and a black processing portion 29 is provided on the inner peripheral surface. Other configurations are the same as those of the first embodiment,
The same members are denoted by the same reference numerals and description thereof will be omitted.

As described above, since the joint for bonding the lens frame and the element frame is provided on the distal end side of the laser welded portion, the adhesive is erroneously laser-welded when the lens frame is inserted and arranged in the element frame. It can be prevented from adhering to the part. This makes it easier to apply the adhesive while avoiding the heat-affected range of laser welding.

Further, by providing the space member with the aperture portion, the reflected light from the plated portion of Ni or the like is suppressed, and by providing the black processing portion on the inner surface of the space member, the inner peripheral surface is formed. Flare and ghost due to reflection can be prevented. Other functions and effects are the same as those of the first embodiment.
This is the same as the embodiment.

It should be noted that the present invention is not limited to only the above-described embodiments, but can be variously modified without departing from the gist of the invention.

[Appendix] According to the above-described embodiment of the present invention as described in detail above, the following configuration can be obtained.

(1) A lens frame having a through hole, a tip lens hermetically joined to a concave portion forming the through hole formed at the tip of the lens frame, and the through hole communicating with the concave portion. At least one proximal lens having a diameter configured to be smaller than the diameter of the concave portion and disposed in the hole;
Disposed between the proximal lens and the distal lens,
An imaging unit for an endoscope, comprising: a spacing member that forms a space with a predetermined spacing between a base end surface of the tip lens and a bottom surface of the concave portion.

(2) The imaging unit according to attachment 1, wherein an optical stop is integrated with the spacing member.

(3) The imaging unit according to Supplementary Note 1 or 2, wherein at least the inner peripheral surface of the spacing member is blackened.

(4) A solid-state image pickup device on which a light beam passing through a lens group in a lens frame constituting an observation optical system forms an image, and the solid-state image pickup device is held at one end and the lens is held at the other end. An imaging unit for an endoscope, comprising an element frame for holding a frame, and joining the element frame and the lens frame using both bonding and welding connection and fixing means, wherein the lens frame and the element frame include: An imaging unit for an endoscope in which welding joints and bonding joints having different diameters are provided apart from each other.

(5) A joint for welding is provided at a large diameter portion of the lens frame and a large diameter hole of the element frame, and a joint for adhesion is provided at a small diameter portion of the lens frame and a small diameter hole of the element frame. An imaging unit for an endoscope according to supplementary note 4 provided in the unit.

(6) Bonding portions for bonding are provided at the large diameter portion of the lens frame and the large diameter hole of the element frame, and welding portions are formed at the small diameter portion of the lens frame and the small diameter hole of the element frame. An imaging unit for an endoscope according to supplementary note 4 provided in the unit.

[0044]

As described above, according to the present invention, it is possible to provide an imaging unit for an endoscope which can obtain a good observation image without increasing the number of parts and the number of assembling steps and has autoclave resistance. .

[Brief description of the drawings]

FIGS. 1 to 3 relate to a first embodiment of the present invention, and FIG. 1 is a diagram illustrating a configuration of an imaging unit of an endoscope.

FIG. 2 illustrates a lens frame.

FIG. 3 is a diagram illustrating a relationship between a lens frame, a lens, and a spacing member.

FIG. 4 is a diagram illustrating another configuration of the imaging unit of the endoscope according to the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Imaging unit 2 ... Objective lens unit 3 ... CCD 4 ... Circuit board 21 ... Lens frame 22 ... Depression 23 ... Tip lens 24 ... Hole 26 ... Base lens group 27 ... Spacing member

Claims (2)

[Claims] 1. A lens frame having a through-hole, a tip lens hermetically joined to a recess forming the through-hole formed at the tip of the lens frame, and the through-hole communicating with the recess. At least one hole having a smaller diameter than the diameter of the recess.
Two proximal lenses, disposed between the proximal lens and the distal lens,
An interval member for forming a space at a predetermined interval between a base end surface of the tip lens and a bottom surface of the concave portion. 2. A solid-state imaging device on which a light beam passing through a lens group in a lens frame constituting an observation optical system forms an image, and the solid-state imaging device is held at one end and the lens frame is held at the other end. An endoscope imaging unit that joins the element frame and the lens frame using both bonding and welding connection and fixing means, wherein the lens frame and the element frame have a diameter. An imaging unit for an endoscope, wherein welding joints and bonding joints having different dimensions are provided separately.