Title: Manufacturing method of front-end component of endoscope
Abstract: The invention relates to a method of manufacturing a front-end optical component of an endoscope realizing resistance to humidity. In the method of manufacturing a front-end optical component in which a lens is mounted on the front end of a metallic lens-barrel provided on the front end of the inserting portion of an endoscope, the configuration is made such that a lens raw material is placed on the front-end side in the lens-barrel, the lens raw material is press-formed in a heat-softened state with a pair of upper and lower shaping dies, thereby tightly joining the outer edge of the pressed lens raw material to the inner peripheral surface of the lens-barrel.
Patent Number: 6,977,053 Issued on 12/20/2005 to Mukasa, et al.
| Inventors:
|
Mukasa; Katsunori (Saitama, JP);
Fujita; Hiroaki (Saitama, JP)
|
| Assignee:
|
Fujinon Corporation (Saitama, JP)
|
| Appl. No.:
|
246488 |
| Filed:
|
September 17, 2002 |
Foreign Application Priority Data
| Sep 27, 2001[JP] | 2001-297485 |
| Current U.S. Class: |
264/1.7; 65/39; 65/59.4; 264/2.7 |
| Intern'l Class: |
B29D 011/00 |
| Field of Search: |
264/11,17,133,27
65/39,591,594
425/808
|
References Cited [Referenced By]
U.S. Patent Documents
| 4988375 | Jan., 1991 | Bornhauser.
| |
| Foreign Patent Documents |
| 10-29825 | Feb., 1998 | JP.
| |
| 10-170794 | Jun., 1998 | JP.
| |
| 10-234652 | Sep., 1998 | JP.
| |
Primary Examiner: Vargot; Mathieu D.
Attorney, Agent or Firm: Jordan and Hamburg LLP
Claims
1. A method of manufacturing a front-end optical component in which a lens is
mounted on the front end of a metallic lens-barrel provided on the front end of
the inserting portion of an endoscope, comprising the steps of:
placing a lens raw material on the front-end side in the lens-barrel,
press-forming the lens raw material in a heat-softened state with a pair of upper
and lower shaping dies,
tightly joining the outer edge of the pressed lens raw material to the inner
peripheral surface of the lens-barrel; and
wherein the front end of the lens-barrel is placed so as to straddle an outer
periphery of a transfer surface shaped on a top surface of the lower die of said
pair of upper and lower shaping dies, a guide die is provided so as to enclose
the periphery of the lens-barrel, the upper die has a transfer surface shaped on
a bottom surface thereof and is provided in the lens-barrel so as to able to be
inserted in and withdrawn from it, a portion of the lens raw material press-formed
by the upper and lower dies is formed projecting toward the front-end side of the
lens-barrel from its inside, and the projection-shaped portion is polished and finished.
2. The method of manufacturing a front-end optical component of an endoscope
according to claim 1, wherein a coefficient of linear thermal expansion of a metallic
material configuring said lens-barrel is selected to be equal to or more than the
coefficient of linear thermal expansion of the lens raw material such that the
lens-barrel can fasten the lens raw material in a cooling process after heat pressurizing.
3. The method of manufacturing a front-end optical component of an endoscope
according to claim 1, wherein the coefficient of linear thermal expansion of a
metallic material configuring the lens-barrel is 100 to 170, and the coefficient
of linear thermal expansion of the lens raw material is 70 to 160.
4. The method of manufacturing a front-end optical component of an endoscope
according to claim 3 wherein a difference between the coefficients of linear thermal
expansion of the lens-barrel and the lens raw material is not more than 100 at most.
5. The method of manufacturing a front-end optical component of an endoscope
according to claim 2, wherein the coefficient of linear thermal expansion of a
metallic material configuring the lens-barrel is 100 to 170, and the coefficient
of linear thermal expansion of the lens raw material is 70 to 160.
6. The method of manufacturing a front-end optical component of an endoscope
according to claim 5 wherein a difference between the coefficients of linear thermal
expansion of the lens-barrel and the lens raw material is not more than 100 at most.
7. A method of manufacturing a front-end optical component in which a lens is
mounted on the front end of a metallic lens-barrel provided on the front end of
the inserting portion of an endoscope, comprising the steps of:
placing a lens raw material on a front-end side in a lens-barrel,
press-forming lens raw material in a heat-softened state with a pair of upper
and lower shaping dies, and
tightly joining the outer edge of the pressed lens raw material to an inner peripheral
surface of the lens-barrel; and
wherein a guide die is mounted on the lower die having a transfer surface shaped
on a top surface thereof, a step portion is shaped on an inner peripheral surface
of the guide die, a flange portion shaped on an outer peripheral surface of the
lens-barrel is engaged with the step such that the lens-barrel may be supported
by the guide die, thereby shaping space between the front end of the lens-barrel
and the lower die, the lens raw material is placed on the transfer surface of the
lower die, the upper die having a transfer surface shaped on the bottom surface
thereof is inserted into the lens-barrel to press-form the lens raw material, a
portion of the press-formed lens raw material is formed projecting toward the front-end
side of the lens barrel from its inside so as to cover the front end of the lens-barrel,
and the projection-shaped portion is polished and finished except for the covered
front end portion of the lens-barrel.
8. The method of manufacturing a front-end optical component of an endo scope
according to claim 7, wherein a coefficient of linear thermal expansion of a metallic
material configuring said lens-barrel is selected to be equal to or more than a
coefficient of linear thermal expansion of the lens raw material such that the
lens-barrel can fasten the lens raw material in a cooling process after heat pressurizing.
9. The method of manufacturing a front-end optical component of an endoscope
according to claim 7 wherein a coefficient of linear thermal expansion of a metallic
material configuring the lens-barrel is 100 to 170, and a coefficient of linear
thermal expansion of the lens raw material is 70 to 160.
10. The method of manufacturing a front-end optical component of an endoscope
according to claim 9, wherein a difference between the coefficients of linear thermal
expansion of the lens-barrel and the lens raw material is not more than 100 at most.
11. The method of manufacturing a front-end optical component of an endoscope
according to claim 8 wherein the coefficient of linear thermal expansion of a metallic
material configuring the lens-barrel is 100 to 170, and the coefficient of linear
thermal expansion of the lens raw material is 70 to 160.
12. The method of manufacturing a front-end optical component of an endoscope
according to claim 11 wherein a difference between the coefficients of linear thermal
expansion of the lens-barrel and the lens raw material is not more than 100 at most.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of manufacturing a front-end optical component
in which a lens is mounted on the front end of the lens-barrel provided at the
front-end of the inserting portion of an endoscope.
2. Description of the Related Art
Although a front-end optical component configuring the inserting portion
of an endoscope has a lens mounted at the front end of the lens-barrel, the lens
is bonded and fixed to the inside surface of the lens-barrel with a epoxy-based
adhesive. For example, in the front-end optical components of the endoscopes disclosed
in the gazettes of Japanese Patent Laid-Open No. 10-234652 and Japanese Patent
Laid-Open No. 10-170794, both of the lens are fixed to the lens-barrels with adhesives.
The main body of the front-end portion in the inserting portion of an endoscope
is provided with observing means having an objective optical system positioned
in the proximity of illuminating means. The objective optical system is usually
configured by a plurality of lenses, and these lenses are mounted in a lens-barrel.
Herein, a first lens located on the nearest side to a body to be observed of the
lens-barrel is a planoconcave lens, of which concave surface is adapted to be located
within the lens-barrel. For example, during testing, a pollution substance, such
as a body fluid, can adhere to the surface of the first lens exposed to the outside
at the front end of the inserting portion, and the adherence of the pollution substance
may impair the visual field of observation. Therefore, the inserting portion is
provided with a lens surface-cleaning mechanism for washing out pollution substances
from the surface of the first lens. The lens surface-cleaning mechanism is provided
with a nozzle for issuing a jet of cleaning fluid toward the outside surface of
the first lens, and issues a jet of cleaning fluid, usually washing water, from
this nozzle to wash out pollution substances. Then, the mechanism blows pressurized
air on the lens surface to remove washing water remaining on the lens surface.
Further, when existing in a body cavity, the first lens is in a state of about
the same temperature as the body temperature. In the case of an electronic endoscope,
the first lens can be in a state of a higher temperature than the body temperature
due to the existence of a heating element, such as a solid image sensor. On the
other hand, the washing water is not particularly heated up, and therefore the
temperature of the washing water is held about at the same temperature as the room
temperature. For this reason, when the washing water is jetted on the outside surface
of the first lens, the first lens can be quickly cooled. As a result of cooling
the first lens, if moisture is contained in the air in the lens-barrel, fogging
or condensation can be caused on the inside surface side of the first lens. Moreover,
because the inside surface of the first lens is configured by a concavely curved
surface and its curvature is large, the temperature decrease is most remarkable
at the central portion thinnest in thickness and its neighborhood in the first
lens, thus resulting in fogging or condensation concentrated on the central portion
in the concave surface of the first lens. Since light beams necessary for image
formation is concentrated in the central portion of the concave surface of the
first lens, least fogging of this region would cause rapid decrease in the image
quality of observational images obtained, thereby resulting in a very difficult-to-look
image. Further, in some other cases, when the front end of the inserting portion
is also quickly cooled, there is also a fear that fogging or condensation may take
place on the first lens and the like.
In this manner, since fogging or condensation can possibly take place on the
lens
(first lens) of the front-end optical component of an endoscope, as a measure for
preventing this, no moisture-containing gas such as dry air and nitrogen gas has
been filled in the space in the lens-barrel.
In the first place, taking in moisture into the lens-barrel is caused by that
the first lens is bonded to the lens-barrel with an adhesive and moisture can pass
through this adhesive. The adhesive is pervious to water in nature, and therefore
moisture enters into the lens-barrel through an adhesive layer between the first
lens and the lens-barrel, resulting in fogging of the first lens.
SUMMARY OF THE INVENTION
Therefore, the invention has an object to provide a method of manufacturing
a front-end optical component able to prevent the entry of moisture into a lens-barrel,
in which a lens is fixed, without using an adhesive, on the front-end side of a
lens-barrel configuring the front-end optical component of an endoscope.
In order to achieves the above object, in a method of manufacturing a front-end
optical component in which a lens is mounted on the front end of a metallic lens-barrel
provided on the front end of the inserting portion of an endoscope, the invention
configures the front-end optical component in such a manner that a lens raw material
is placed on the front-end side in the lens-barrel, the lens raw material is press-formed
in a heat-softened state with a pair of upper and lower shaping dies, thereby tightly
joining the outer edge of the pressed lens raw material to the inner peripheral
surface of the lens-barrel.
According to the invention, a lens raw material is placed on the front-end
side in the lens-barrel, the lens raw material is press-formed in a heat-softened
state with a pair of upper and lower shaping dies, thereby tightly joining the
outer edge of the pressed lens raw material to the inner peripheral surface of
the lens-barrel, and further, the coefficient of linear thermal expansion of a
metallic material configuring the lens-barrel is selected to be equal to or more
than the coefficient of linear thermal expansion of the lens raw material such
that the lens-barrel can fasten the lens raw material in a cooling process after
heat pressurizing. Thereby, the lens raw material and the front end side of the
lens-barrel can be joined to each other into one piece without using of an adhesive
as in a conventional method. Because of no use of an adhesive, there is no fear
of the intrusion of humidity into the lens barrel through the adhesive layer.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross sectional view for showing a manufacturing process for a front-end
optical component according to the invention;
FIG. 2 shows a cross sectional view in press forming;
FIG. 3 is a cross sectional view for showing the state of the lens raw material
joined to the lens-barrel, which is taken out from the shaping die;
FIG. 4 shows across sectional view of a front-end optical component obtained
by polishing the lens raw material;
FIG. 5 shows a cross sectional view of a shaping die in press forming, showing
another embodiment;
FIG. 6 is a cross sectional view of an entity taking out from the shaping die
as shown in FIG. 5; and
FIG. 7 is a cross sectional view for showing a front-end optical component obtained
by polishing the lens raw material.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, a transfer surface
10A is shape on the top surface of a lower
die
10, a transfer surface
11A is shaped on the bottom surface of
a upper die
11, and a lens raw material
1 is adapted to be press-formed
by a pair of the upper and lower shaping dies
10 and
11. A guide
die
12 is mounted on the lower die
10, and the barrel die
12
and the lower die
10 together supports a metallic lens-barrel
2.
The upper die
11 is adapted to be inserted into the lens-barrel
2.
Further, the lens raw material
1 is placed on the transfer surface
10A
of the lower die
10, and positioned on the front-end side of the lens-barrel
2. The front end of the lens-barrel
2 is placed on the lower die
10 to straddle the outer periphery of the transfer surface
10A.
FIG. 2 is a cross sectional view for showing a state in which the upper die
11 is inserted into the lens-barrel
2 to press the lens raw material
1 in cooperation with the lower die
10. Herein, the outer edge of
the pressed lens raw material
1 is tightly joined to the inner peripheral
surface of the front-end side of the lens-barrel
2.
After the lens raw material
1 is properly cooled down in the pressed
state shown in FIG. 2, the shaping dies is opened and then the lens barrel
2
and the lens raw material
1 are taken out. FIG. 3 shows an entity taken
out at this time. In FIG. 3, a portion of the lens raw material
1 pressed
between the upper and lower dies
10 and
11 is shaped projecting toward
the front-end side of the lens barrel
2 from its inside, and this projection-shaped
portion is polished and finished into a plane (see FIG. 4). FIG. 4 is a cross sectional
view for showing the state of a completed front-end optical component of an endoscope,
and the lens raw material
1 is configured into a lens
1A. The lens
1A is a planoconcave lens.
Stainless steel is preferable as a metallic material used for the lens-barrel
2. The stainless steel used in the embodiment was selected to have a coefficient
of linear thermal expansion of 125×10
-7 (1° C.) and the coefficient
of linear thermal expansion of the lens raw material
1 was selected to be
124×10
-7 (1° C.). Preferably, the material of the lens-barrel
2 has a coefficient of linear thermal expansion equal to or more than that
of the lens raw material
1. In a cooling process subsequent to heat pressurizing
of the lens raw material
1, in order that the lens-barrel
2 expanded
by heating and thereafter shrinking by cooling can fasten the lens raw material,
the coefficient of linear thermal expansion of a metallic material configuring
the lens-barrel
2 should be equal to or more than that of the lens raw material.
SUS 430, SUS 430 F, SUS 444, and SUS 444F or the like can be suitably used as the
stainless steel. The coefficients of linear thermal expansion of these stainless
steel materials are in the order of 100 to 170×10
-7. When a general
optical glass is used as the lens raw material
1, its coefficient of linear
thermal expansion is in the order of 70 to 120×10
-7. In the case
of using SFS 01 of a lead oxide-based glass among optical glass materials, its
coefficient of linear thermal expansion is 100×10
-7. The coefficient
of linear thermal expansion of the lens raw material
1 used in the embodiment,
SFLD 21 (made in Sumita Optical Glass Corporation) is 124×10
-7.
A difference between the coefficients of linear thermal expansion of the lens-barrel
2 and the lens raw material
1 is desirably not less than 0 and not
more than 100. If the difference is larger this value, there is a fear that the
lens-barrel may too strongly fasten the lens during cooling.
FIG. 5 is a cross sectional view of a shaping die for showing another embodiment.
Herein, a guide die
12 is mounted on a lower die
10 having a transfer
surface
10A shaped on the top surface thereof, a step portion
12A
is shaped on the inner peripheral surface of this barrel die
12. A flange
portion
2A shaped on the outer peripheral surface of the lens-barrel
2
is engaged with the step portion
12A such that the lens-barrel
2
may be supported by the barrel die
12, thereby providing a space between
the front end of the lens-barrel
2 and the lower die
10. The lens
raw material
1 is placed on the transfer surface
10A of the lower
die
10, and then a upper die
11 having a transfer surface
11A
shaped on the bottom surface thereof is inserted into the lens-barrel
2,
thereby press-forming the lens raw material
1. Then, a portion of the press-formed
lens material
1 is adapted to be shaped projecting toward the front-end
side of the lens-barrel
2 from its inside so as to cover the front end of
the lens-barrel
2. FIG. 6 shows an entity taken out from the shaping dies
after cooling the lens raw material. In FIG. 6, the front-end surface of the lens-barrel
2 is covered with the lens raw material
1. This lens raw material
is polished and finished in a plane in the same manner as described previously
(see FIG. 7). As shown in FIG. 7, the outside periphery side of the lens
1A
covers the front end of the lens-barrel
2. This is because an electric current-passing
tool may be included in treatment tools sent out from a treatment tool-inserting
channel of the inserting portion adjacent to the front-end optical component of
an endoscope, and such a tool may make contact with the front end of the metallic
lens-barrel
2, thus having an adverse effect on the front-end optical component
by energizing it. Thus, the front end of the lens-barrel
2 is covered with
the outer edge of the lens
1A, and thus the treatment tool makes contact
with the outer edge of the lens
1A covering the front end of the lens-barrel
2 but it does not touch on the lens-barrel
2, thus eliminating a
fear of energization of the lens-barrel
2.
*
