Endoscope having adhesives with different bonding strengths

An endoscope includes: an objective optical section including a first barrel; an image pickup optical section including a solid image pickup device, an optical member forming an optical image through the objective optical section on an image pickup surface of the solid image pickup device, and a second barrel housing the optical member and the solid image pickup device, the second barrel fixed to the first barrel after positional adjustment in an axial direction relative to the first barrel; a holding member formed of material having a linear expansion coefficient lower than linear expansion coefficients of the first and second barrels, and fixed to outer surfaces of the first and second barrels; a first adhesive that bonds the first barrel and the second barrel; and a second adhesive having a bonding strength higher than that of the first adhesive, which bonds the holding member to the first and second barrels.

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit of Japanese Application No. 2012-175243 filed in Japan on Aug. 7, 2012, the contents of which are incorporated by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an endoscope that includes a first barrel and a second barrel in an image pickup optical system.

2. Description of the Related Art

Conventionally, endoscopes are used in, e.g., an industrial field and a medical field. With an endoscope, observation is performed by inserting an elongated insertion portion into, e.g., a structure or a living body. In general, in a distal end portion included in an insertion portion, an illumination optical system and an image pickup optical system included in an observation optical section are incorporated. The illumination optical system illuminates an inside of the structure or an inside of the living body. The image pickup optical system shoots an image of the inside of the structure or the inside of the living body illuminated by the illumination optical system.

The image pickup optical system includes, for example, an objective optical section and an image pickup optical section, and after focusing adjustment, the objective optical section and the image pickup optical section are integrally fixed. More specifically, the objective optical section includes a plurality of optical lenses and a first barrel, which is a lens barrel.

In the first barrel, the plurality of optical lenses is housed and fixed. The image pickup optical section includes a solid image pickup device, such as a CCD or a C-MOS sensor, and a second barrel, which is a device barrel. In the second barrel, the solid image pickup device is housed and fixed. Then, the lens barrel in the objective optical section and the device barrel in the image pickup optical section are fitted together. Then, focusing is performed by adjusting positions in an axial direction of the lens barrel and the device barrel. After completion of the focusing, the lens barrel and the device barrel are integrally fixed to form the image pickup optical system.

For example, Japanese Patent Application Laid-Open Publication No. 2006-267166 discloses an objective section of an endoscope. In the objective section of the endoscope, two objective barrels that incorporate objective members for forming an optical image of an object (corresponding to barrels in the present invention) can be bonded and adhered to each other in an air-tight manner without a decrease in optical performance. In Japanese Patent Application Laid-Open Publication No. 2006-267166, a covering that covers the entire outer circumferential faces of boundary portions of the two objective barrels with no space is provided in such a manner that the covering extends across both of the outer circumferential faces of the two objective barrels, and then, the two objective barrels and the covering are adhered to each other in an air-tight manner via brazing, soldering or welding.

SUMMARY OF THE INVENTION

An endoscope according to an aspect of the present invention includes: an objective optical section including a plurality of optical lenses, and a first barrel that houses the optical lenses, the optical lenses being integrally and fixedly provided therein; an image pickup optical section including a solid image pickup device, an optical member that forms an optical image passed through the objective optical section on an image pickup surface of the solid image pickup device, and a second barrel that houses the optical member and the solid image pickup device, the optical member and the solid image pickup device being integrally and fixedly provided therein, the second barrel being arranged so as to fit with the first barrel, and being fixed to the first barrel in an integrated manner via bonding after adjustment in position in an axial direction relative to the first barrel; a holding member including a material having a linear expansion coefficient lower than a linear expansion coefficient of the first barrel and a linear expansion coefficient of the second barrel, the holding member being fixed to a predetermined position on an outer surface of the first barrel and a predetermined position on an outer surface of the second barrel via bonding; a first adhesive that bonds the first barrel and the second barrel to each other; and a second adhesive having a bonding strength higher than the bonding strength of the first adhesive, the second adhesive bonding the holding member to the outer surface of the first barrel and the outer surface of the second barrel.

The above and other objects, features and advantages of the invention will become more clearly understood from the following description referring to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

InFIG. 1, reference numeral1denotes an endoscope apparatus. The endoscope apparatus1includes an endoscope body2and an endoscope3. The endoscope body2can freely be carried. The endoscope3is connected to the endoscope body2.

The endoscope body2includes a substantially-box shaped sheathing chassis5. At a front face of the sheathing chassis5, a display section6such as a liquid-crystal display (LCD) panel is disposed. On the display section6, e.g., an endoscopic image and an operation menu are displayed. One end of a left carriage arm7and one end of a right carriage arm7, the left and right carriage arms7being paired, are pivotally connected to left and right sides of the sheathing chassis5across the display section6, respectively. One end of the handle portion8is joined to the other end side of the carriage arm7connected to the right side of the sheathing chassis5, and the other end of the handle portion8is joined to the carriage arm7connected to the left side of the sheathing chassis5.

In the present embodiment, the sheathing chassis5incorporates, e.g., a CPU for image processing, various types of electric components, a light source section, a battery unit, which is a power supply section (none of them illustrated). The light source section includes a light emitting device, for example, an LED.

The endoscope3mainly includes an insertion portion10and an operation portion11. The operation portion11of the endoscope3and the endoscope body2are connected via a universal cable12. In the present embodiment, the universal cable12extends out from the operation portion11.

The insertion portion10includes a distal end portion15, a bending portion16and a flexible tube portion17in this order from the distal end side. The bending portion16is disposed on the proximal end side of the distal end portion15and is bendable in two directions, upward and downward, or in four directions, upward, downward, leftward or rightward. The flexible tube portion17is disposed on the proximal end side of the bending portion16and is connected to the distal end side of the operation portion11.

As illustrated inFIG. 2, a distal end forming member15aincluded in the distal end portion15of the insertion portion10is provided with an illumination optical system20and an image pickup optical system30included in an observation optical section50.

The illumination optical system20includes an illuminating light emitting section21and a light guide fiber bundle (hereinafter abbreviated as “light guide”)22.

The illuminating light emitting section21is provided at a distal end face of the distal end portion15so as to have a predetermined shape. The illuminating light emitting section21is one obtained by forming a transparent material such as optical glass into a plate shape or a lens shape.

The light guide22is a holding member, which will be described later. The light guide22illustrated inFIGS. 2 and 3includes a core material and a clad material each including a high-transmission optical glass for illumination, which is a material having a linear expansion coefficient lower than a linear expansion coefficient of a material included in each of barrels38and44, which will be described later.

A distal end face of the light guide22is formed so as to face the illuminating light emitting section21. On the other hand, a proximal end portion of the light guide22is inserted through the insertion portion10, the operation portion11and the universal cable12. Then, a proximal end face of the light guide22is arranged so as to be opposed to the light source section in the endoscope body2when the universal cable12is connected to the endoscope body2.

With this configuration, illuminating light emitted from the light source section is transmitted via the light guide22and passes through the illuminating light emitting section21to be emitted toward a site to be observed.

The image pickup optical system30includes an objective optical section31and an image pickup optical section32, which are illustrated inFIGS. 2 and 3.

As illustrated inFIG. 2, the objective optical section31includes, for example, a plurality of optical lenses33,34,35,36and37and a first barrel38, which is a lens barrel. The first barrel38is made of, for example, stainless steel. The first barrel38houses the optical lenses33,34,35,36and37, which are integrally and fixedly provided via, e.g., bonding. The first barrel38is not limited to one made of stainless steel, and may be a member made of a metal such as brass (metal member).

The image pickup optical section32includes an image pickup apparatus42with a solid image pickup device41mounted therein, a prism43and a second barrel44.

For the solid image pickup device41, e.g., a CCD or a CMOS sensor is employed.

A plurality of signal wires45is connected to the proximal end side of the image pickup apparatus42. The signal wires45are bundled into one signal cable46, which is inserted through the insertion portion10, the operation portion11and the universal cable12. The plurality of signal wires45is electrically connected to the CPU and the electric components in the endoscope body2as a result of the universal cable12being connected to the body2.

The prism43is an optical member, and forms an optical image passed through the optical lenses33,34,35,36and37in the objective optical section31, on a non-illustrated image pickup surface of the solid image pickup device41. Reference numeral47denotes a positioning and securing member, which fixes the prism43at a predetermined position inside the barrel44.

The second barrel44is made of stainless steel as with the first barrel38. The second barrel44houses the prism43, the positioning and securing member47and the solid image pickup device41therein.

The solid image pickup device41is fixed to a surface of the prism43in an integrated manner via a transparent adhesive. A part of the image pickup apparatus42, the prism43and the positioning and securing member47are integrally fixed inside the second barrel44via bonding.

In other words, the linear expansion coefficient of the first barrel38and the linear expansion coefficient of the second barrel44are each higher than a linear expansion coefficient of each of the core material and the clad material included in the light guide22.

As illustrated inFIG. 2, the second barrel44is arranged so as to fit over the first barrel38. More specifically, the first barrel38includes a first joining portion38ron the proximal end side. On the other hand, the second barrel44includes a second joining portion44fon the distal end side.

In the present embodiment, an inner circumferential face of the second joining portion44fis arranged on an outer circumferential face of the first joining portion38r, whereby the first barrel38and the second barrel44are disposed in series. In this disposition state, the first barrel38and the second barrel44are slidable relative to each other in a longitudinal direction of the barrels.

Reference numeral38pinFIG. 3denotes each of first positioning surfaces provided at outer faces of the first barrel38. Axial flat surfaces24provided at opposite side portions across a recess portion of a distal end recess portion23of the light guide22are arranged so as to be in contact with the respective first positioning surfaces38p.

Reference numeral44pdenotes a second positioning surface provided at an outer face of the second barrel44. The axial flat surfaces24of the light guide22are arranged so as to be also in contact with the respective second positioning surfaces44p.

The first barrel38and the second barrel44are integrally fixed via a first adhesive51. More specifically, the first barrel38and the second barrel44are fixed to each other via bonding after focusing adjustment is made so that an optical image passed through the optical lenses33,34,35,36and37and the prism43is formed on the image pickup surface of the solid image pickup device41in a predetermined manner.

When the aforementioned bonding is performed, a worker first applies a predetermined amount of first adhesive51to a predetermined position in the outer circumferential face of the first joining portion38r. Next, the worker arranges the second joining portion44fso as to fit on the first joining portion38rwith the first adhesive51applied thereon.

Next, the worker makes a focusing adjustment by moving the first joining portion38rand the second joining portion44fin the axial direction. Subsequently, the worker holds the first joining portion38rand the second joining portion44fat the respective positions resulting from the focusing adjustment to cure the first adhesive51.

As a result, an image pickup optical system30, which is illustrated inFIG. 3, in which the first barrel38and the second barrel44are fixed to each other via bonding, namely, the objective optical section31and the image pickup optical section32are integrated is provided.

Note that during the focusing adjustment, the worker performs positioning surface adjustment work to make positions of the first positioning surface38pand the second positioning surface44pwith respect to the axis correspond to each other.

As illustrated inFIGS. 2 to 4, in the present embodiment, the light guide22is firmly fixed to the image pickup optical system30in an integrated manner via a second adhesive52. More specifically, the light guide22includes the distal end recess portion23on the distal end side.

An shape of an inner face of the distal end recess portion23correspond to a shape of an outer circumferential face of a first light guide adhering surface38g, which is an outer face of the first barrel38, and a shape of an outer circumferential face of a second light guide adhering surface44g, which is an outer face of the second barrel44. In other words, the shape of the outer circumferential face of the first light guide adhering surface38gand the shape of the outer circumferential face of the second light guide adhering surface44g, which is an outer face of the second barrel44, are the same.

The inner face of the distal end recess portion23of the light guide22is fixed to both surfaces of the first light guide adhering surface38gof the first barrel38and the second light guide adhering surface44gof the second barrel44via bonding.

When the above-described mentioned bonding is performed, the worker first applies a predetermined amount of second adhesive52to respective predetermined positions in the first light guide adhering surface38gand the first positioning surfaces38pof the first barrel38and respective predetermined positions in the second light guide adhering surface44gand the second positioning surfaces44pof the second barrel44.

Next, the worker arranges the inner face of the distal end recess portion23of the light guide22and the axial flat surfaces24respectively on the first light guide adhering surface38gand the first positioning surfaces38pand the second light guide adhering surface44gand the second positioning surfaces44pwith the second adhesive52applied thereon.

Subsequently, the worker holds such disposition state to cure the second adhesive52.

As a result, as illustrated inFIG. 4, the distal end recess portion23of the light guide22is provided integrally with the image pickup optical system30.

In the present embodiment, a bonding strength of the second adhesive52is set to be higher than a bonding strength of the first adhesive51. In other words, a bonding force of the second adhesive52is set to be stronger than a bonding force of the first adhesive51.

In the above description, the inner face of the distal end recess portion23of the light guide22is arranged on, e.g., the light guide adhering surfaces38gand44gwith the second adhesive52applied thereon. However, it is possible that after the inner face of the distal end recess portion23of the light guide22is arranged on the light guide adhering surfaces38gand44g, the second adhesive52is applied to bond and fix the distal end recess portion23of the light guide22to the image pickup optical system30.

In other words, the second adhesive52may be an adhesive having fluidity, namely, having a viscosity lower than that of the first adhesive51.

Furthermore, where the endoscope is used under a high temperature environment, the second adhesive52is an adhesive having a heatproof temperature higher than that of the first adhesive51.

Note that inFIG. 2, reference numeral16adenotes each of a plurality of bending pieces included in the bending portion16. Adjacent bending pieces16aare joined in such a manner that the bending pieces16aare pivotable with respect to an axis substantially perpendicular to a center axis of the insertion portion10.

Reference numeral18denotes a bending rubber. The bending rubber18covers a bending portion set including the plurality of bending pieces16ajointed to one another.

Non-illustrated bending operation wires are inserted through the bending portion16and the flexible tube portion17. Distal ends of the bending operation wires are fixed to a distal end bending piece16fincluded in a distal end of the bending portion set. Proximal ends of the bending operation wires are fixed to a non-illustrated bending operation mechanism provided inside the operation portion11.

An operation of the endoscope3configured as described above will be described.

When the endoscope3is used under a high temperature environment, a temperature of the first barrel38in the objective optical section31and a temperature of the second barrel44included in the image pickup optical section32, which are included in the image pickup optical system30incorporated in the distal end portion15of the insertion portion10, each become a high temperature. On the other hand, when the endoscope3is transported under a low temperature environment, the temperature of the first barrel38and the temperature of the second barrel44each become a low temperature.

In the present embodiment, an expansion amount and a contraction amount of the light guide22axially expanded/contracted by heat are smaller than an expansion amount and a contraction amount of each of the barrels38and44axially expanded/contracted by heat. Furthermore, in the present embodiment, the first barrel38and the second barrel44are fixed to each other via the first adhesive51. Furthermore, the barrels38and44in the image pickup optical system30and the distal end recess portion23of the light guide22are integrally fixed to each other via the second adhesive52having a bonding force stronger than that of the first adhesive51.

In other words, the first barrel38and the second barrel44are firmly and integrally fixed to the light guide22that less expands/contracts depending on change in temperature, via the second adhesive52. As a result, expansion/contraction of the first barrel38and the second barrel44depending on change in environmental temperature after focusing adjustment is inhibited by the light guide22.

Accordingly, it is possible to prevent defocusing occurring as a result of displacement in the axial direction of the positions of the first barrel38and the second barrel44due to change in temperature.

Furthermore, as a result of the heatproof temperature of the second adhesive52being set to be higher than the heatproof temperature of the first adhesive51, even in case the bonding strength of the first adhesive51decreases under a high temperature environment, the second adhesive52and the light guide22withstand the high temperature, enabling the positional relationship between the first barrel38and the second barrel44to be maintained.

In the above-described embodiment, the first barrel38and the second barrel44are integrated via the first adhesive51to form the image pickup optical system30, and subsequently, the distal end recess portion23of the light guide22is integrally fixed to an outer face of the first barrel38and an outer face of the second barrel44via the second adhesive52.

However, the assembling procedure according to the present invention is not limited to the above-described procedure, and may be a procedure such as illustrated inFIGS. 5 and 6. In the case of this assembling procedure, for the second adhesive52, an adhesive having a curing time period longer than a curing time period of the first adhesive51is used.

In the present embodiment, a worker first applies a predetermined amount of second adhesive52to respective predetermined positions in second light guide adhering surface44gand second positioning surfaces44pof a second barrel44.

Next, as illustrated inFIG. 5, the worker arranges predetermine areas of an inner face and axial flat surfaces24of the distal end recess portion23of the light guide22on the second light guide adhering surface44gand the second positioning surfaces44pwith the second adhesive52applied thereon.

Subsequently, the worker holds the disposition state to cure the second adhesive52. As a result, a second barrel portion set44A illustrated inFIGS. 5 and 6in which the distal end recess portion23of the light guide22is integrated with the second barrel44is formed.

Next, the worker applies a predetermined amount of first adhesive51to a predetermined position in an outer circumferential face of a first joining portion38rof a first barrel38. Also, the worker applies a predetermined amount of second adhesive52to predetermined positions in a first light guide adhering surface38gand first positioning surfaces38pof the first barrel38.

Next, the worker arranges the first joining portion38rwith the first adhesive51applied thereon so as to fit in the second joining portion44fwith the first positioning surfaces38pof the first barrel38and the axial flat surfaces24of the distal end recess portion23of the light guide22included in the second barrel portion set44A in contact with each other.

Next, the worker makes a focusing adjustment by moving the first barrel38and the second barrel portion set44A in an axial direction. Subsequently, the worker holds the first barrel38and the second barrel portion set44A at the positions resulting from the focusing adjustment to cure the first adhesive51as well as curing the second adhesive52. As a result, the observation optical section50illustrated inFIG. 6is formed.

As described above, after formation of the second barrel portion set44A, the first barrel38is fixed to the second barrel44and the light guide22included in the second barrel portion set44A. As a result, the need for the aforementioned positioning surface adjustment work to make positions of the first positioning surfaces38pand the second positioning surfaces44pwith respect to the axis to be aligned is eliminated, enabling enhancement in workability of assembling the observation optical section50.

Furthermore, as a result of an adhesive having a curing time period longer than the curing time period of the first adhesive51being used for the second adhesive52, a focusing adjustment can be made with plenty of time.

In the above-described embodiments, the light guide22is used for the illumination optical system20. In addition, the above-described embodiments have the configuration in which the inner face of the distal end recess portion23of the light guide22is bonded and fixed to the first light guide adhering surface38gof the first barrel38and also to the second light guide adhering surface44gof the second barrel44. However, a through hole in the axial direction may be formed in the first barrel38and a distal end portion of the light guide, which corresponds to the shape of the through hole, may be arranged in the through hole. In this configuration, the second adhesive52is applied to the inner surface of the through hole and the distal end portion of the light guide22is bonded and fixed to the inner surface of the through hole. However, the illumination optical system according to the present invention is not limited to a light guide, and as illustrated inFIGS. 7 and 8, a configuration in which, for example, light emitting devices25such as LEDs may be provided at a distal end portion15of an endoscope3A. In other words, in the present embodiment, an illumination optical system20A is formed by the light emitting devices25.

In this configuration, a first barrel38and a second barrel44are integrally fixed to a three-dimensional circuit substrate60via a second adhesive52. The three-dimensional circuit substrate60is a holding member and is made of ceramic, which is a material having a linear expansion coefficient lower than a linear expansion coefficient of each of the first barrel38and the second barrel44. The three-dimensional circuit substrate60is formed so as to have, for example, an axially-elongated flat rectangular parallelepiped shape.

More specifically, in the present embodiment, the first barrel38and the second barrel44are arranged on a surface61, which is a flat surface of the three-dimensional circuit substrate60. Thus, the first barrel38is provided with a first close-contact surface38cto be arranged so as to be in close contact with the surface61of the three-dimensional circuit substrate60, and the second barrel44is provided with a second close-contact surface44cto be arranged so as to be in close contact with the surface61of the three-dimensional circuit substrate60.

Also, the solid image pickup device41is arranged on the surface61side of the three-dimensional circuit substrate60. Furthermore, pads (not illustrated) for electrical connection of signal wires45are provided on the surface61side of the three-dimensional circuit substrate60.

The rest of configuration is similar to those of the above-described embodiments, and members that are the same as those of the above-described embodiments are provided with reference numerals that are the same as those of the above-described embodiments, and a description thereof will be omitted.

With this configuration, as with the above-described embodiments, the first barrel38and the second barrel44are firmly and integrally fixed to the three-dimensional circuit substrate60that less expands/contracts depending on change in temperature, via the second adhesive52.

As a result, it is possible to prevent defocusing occurring as a result of displacement in the axial direction of the positions of the first barrel38and the second barrel44due to change in temperature.

In the above-described embodiments, the second barrel is a member made of a metal (metal member). However, a part of the second barrel, the part fitting with the first barrel, may include, for example, a transparent resin, which is a material that transmits light.

With this configuration, as a result of an adhesive that is cured by ultraviolet light being used for a first adhesive, an accuracy of fixation of the first barrel and the second barrel to each other can be set to be high.