Endoscope insertion portion

An endoscope insertion portion capable of illuminating a diseased part corresponding to a part of an endoscope image by irradiation light in an amount approximately the same as that in non-enlarged display, when displaying the part of the endoscope image in an enlarged manner. The endoscope insertion portion of this invention includes: an insertion portion having a distal end surface; a first illumination optical system for irradiating light onto a subject; a second illumination optical system for irradiating light onto the subject; a first image pickup portion including on the distal end surface a first optical member for introducing light from the subject; and a second image pickup portion including a second optical member for introducing light from the subject, the second optical member being disposed in an area sandwiched by the first illumination optical system and the second illumination optical system.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an endoscope insertion portion including a first image pickup portion and a second image pickup portion having a higher observation magnification compared to the first image pickup portion.

2. Description of the Related Art

Conventionally, the endoscope has been widely used in a medical field, and the like. The endoscope, for example, can provide observation of an organ and the like within a body cavity by inserting an elongated insertion portion into the body cavity as a subject, and various treatments using a treatment instrument inserted into a treatment instrument insertion channel as needed. A bending portion is provided at a distal end of the insertion portion, so that an observation direction of an observation window at a distal end portion can be changed by operating an operation portion of the endoscope.

As the endoscope described above, for example, Japanese Unexamined Patent Application Publication No. 06-154155 proposes the endoscope including in the distal end portion of the insertion portion a first objective optical system and a second objective optical system as observation optical systems and an illumination optical system for emitting illumination light supplied from a light source device as an illumination portion to a subject, and solid image pickup devices as image pickup devices corresponding to the respective objective optical systems at image forming positions of the first objective optical systems and the second objective optical systems.

SUMMARY OF THE INVENTION

An endoscope insertion portion of the present invention comprises: an insertion portion including a distal end surface; a first illumination optical system for irradiating light onto a subject, the first illumination optical system being disposed on the distal end surface; a second illumination optical system for irradiating light onto the subject, the second illumination optical system being disposed on the distal end surface; a first image pickup portion including a first optical member for introducing light from the subject, the first optical member being provided on the distal end surface; and a second image pickup portion having a higher observation magnification than that of the first image pickup portion, including a second optical member for introducing light from the subject, the second optical member being disposed in an area sandwiched between the first illumination optical system and the second illumination optical system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

First, a configuration of an endoscope system according to an embodiment of the present invention will be described based onFIG. 1.FIG. 1is an explanatory view schematically showing the endoscope system according to the embodiment of the present invention.

As shown inFIG. 1, an endoscope system1according to a first embodiment of the present invention includes in the present embodiment: an endoscope2capable of performing a normal light observation and a fluorescent light observation; a light source device3for supplying illumination light to the endoscope2; a processor4serving as a signal processing device for performing signal processing with respect to the endoscope2having an endoscope insertion portion; a monitor5serving as a display portion for displaying endoscope images for the normal light observation and the fluorescent light observation in response to a video signal outputted from the processor4and inputted to the monitor; an air/water feeding device6for feeding air or water; and a forward water-feeding device6afor feeding water forward.

The endoscope2includes an elongated insertion portion11for easier insertion into a body cavity as a subject, an operation portion12linked to a proximal end of the insertion portion11, and a universal cable13extended from a side portion of the operation portion12. A connector14provided at an end portion of the universal cable13is detachably connected to the light source device3.

In addition, the insertion portion11of the endoscope2has a configuration as an endoscope insertion portion, and includes a rigid distal end portion15formed at a distal end thereof, a bending portion16formed at a proximal end of the distal end portion15, and a flexible tube portion17having a flexibility formed from a proximal end of the bending portion16to the operation portion12.

In the insertion portion11, a light guide21for transmitting illumination light is inserted. The light guide21is inserted in the universal cable13via the operation portion12to be connected to a light guide connector, not shown, of which proximal end portion22is projected out from the connector14.

In addition, a distal end part of the light guide21is fixed in the distal end portion15. Note that, at a distal end part of the distal end portion15, an illumination lens25of an illumination unit to be described later serving as an illumination optical system is provided and illumination light is emitted from the light guide21via the illumination lens25. Furthermore, on a distal end surface of the distal end portion15, a distal end cover24is provided.

Note that, in the present embodiment, the light guide21diverges in the operation portion12, for example, and inserted in the insertion portion11, divided into two parts. Then, distal end surfaces of the respective divided two parts of the light guide21are arranged in the vicinity of rear surfaces of the two illumination lenses25provided on the distal end cover24, respectively.

Moreover, though illustration is omitted inFIG. 1, the insertion portion11has inside thereof a treatment instrument channel (also referred to as a forceps channel) as a first duct for allowing a treatment instrument such as a forceps to be inserted, for example. The distal end of the treatment instrument channel is open on a distal end surface of the distal end cover24.

The treatment instrument channel diverges in the vicinity of a proximal end side of the insertion portion11. One diverging part of the treatment instrument channel is inserted to reach a treatment instrument insertion port, not shown, provided on the operation portion12. In addition, the other diverging part of the treatment instrument channel passes through the insertion portion11and the universal cable13to communicate with a suction channel, and proximal end of the diverging part is connected to a suction means, not shown, via the connector14.

Two image pickup units are provided in the distal end portion15. In the present embodiment, a normal-light-observing image pickup unit (hereinafter referred to as a normal light image pickup unit)31A which is an image pickup portion for normal light observation, and a fluorescent-light-observing image pickup unit (hereinafter referred to as a fluorescent light image pickup unit)31B which is an image pickup portion for special light observation are incorporated.

Note that, in the present embodiment, the image pickup portion for the special light observation, described above, is the fluorescent-light-observing image pickup unit capable of performing fluorescent light. However, the image pickup portion is not limited especially to the unit for fluorescent light observation, and may be, for example, a night vision-observing image pickup unit, an infrared-light-observing image pickup unit, or the like.

In addition, in the present embodiment, a tele-zoom operation is possible in the normal light image pickup unit31A as described later, the normal light image pickup unit31A can obtain an image of the subject with a higher observation magnification compared with the fluorescent light image pickup unit31B.

To the normal light image pickup unit31A and the fluorescent light image pickup unit31B, one ends of signal cables38a,38bare connected, respectively. The other ends of the signal cables38a,38bare inserted in the operation portion12and the universal cable13, and switchably connected to a common signal cable43on a relay substrate42provided in the connector14.

The common signal cable43is connected to the processor4by passing through in a scope cable44which is connected to the connector14.

The processor4has inside thereof, driving circuits45a,45bwhich drive the normal light image pickup unit31A and the fluorescent light image pickup unit31B, respectively, a signal processing circuit46for performing signal processing on the image pickup signals outputted respectively from the two image pickup devices via the relay substrate42, and a control circuit47for controlling operation states of the signal processing circuit46and the like.

In addition, the operation portion12of the endoscope2includes control switches48a,48b, an air/water feeding button63, a bending operation knob, not shown, a switch (also referred to as a tele-zoom button), not shown, for performing tele-zoom operation of the normal light image pickup unit31A, a forward water-feeding button, not shown, and the above-described treatment instrument insertion port, not shown.

The control switches48a,48bare connected to the control circuit47of the processor4via signal lines49a,49b, respectively. In the present embodiment, the control switch48agenerates a switching instruction signal, for example, and the control switch48bgenerates a freeze instruction signal, for example.

The relay substrate42performs a switching operation so as to switch from a state where one of the signal cables38a,38bwhich are connected to the image pickup devices respectively is connected to the common signal cable43to a state the other cable is connected to the signal cable43, in response to an operation of the control switch48a, for example.

Specifically, when the control switch48ais operated, for example, a switching signal is outputted to the relay substrate42via a switching signal line49cinserted in the scope cable44and electrically connected to the control circuit47. The relay substrate42, to which a switching signal line49cis connected, is in a state where an input terminal to which a signal is inputted from the control circuit is normally in an L (LOW) level and a switching control terminal is pulled down. In this state, the signal cable38aof the normal light image pickup unit31A is connected to the common signal cable43. In addition, also in a case of activation start state, the switching control terminal is set to be in the low level. That is, the switching control terminal of the relay substrate42is set to be for the normal light observation, unless switching instruction operation is performed.

When a user operates the control switch48ain this state, a control signal is applied from the control circuit47via the switching signal line49cto the input terminal of the relay substrate42such that the level of the input terminal becomes H (HIGH) level, and the switching control terminal of the relay substrate42is pulled up. Then, in the state, the signal cable38bof the fluorescent light image pickup unit31B is connected to the common signal cable43.

In addition, when the user operates the control switch48ain the above-described state, a control signal is applied from the control circuit47via the switching signal line49cto the input terminal of the relay substrate42such that the level of the input terminal becomes L level, and the switching control terminal is pulled down. Then, in the state, the signal cable38aof the normal light image pickup unit31A is connected to the common signal cable43.

In addition, in response to the operation of the control switch48a, the control circuit47outputs a control signal also to a control circuit58in the light source device3via a control signal line49din the scope cable44. Then, the control circuit58controls the respective portions of the light source device3such that normal observation light or excitation light for fluorescent light observation can be generated in response to the control signal outputted from the control circuit47. Furthermore, the control circuit47causes the respective image pickup devices of the normal light image pickup unit31A and the fluorescent light image pickup unit31B to perform corresponding operations by controlling an operation state of the signal processing circuit46.

The light source device3as an illumination portion includes a lamp51for generating white light including a wavelength of excitation light, a collimator lens52for rendering the light of the lamp51aparallel light flux, a rotation filter53which is disposed in an optical path of the collimator lens52and includes in a circuit direction thereof an RGB filter for transmitting respective wavelength components of R (RED), G (GREEN) and B (BLUE) in a visible light wavelength band (from 380 nm to 780 nm), for example, and a condenser lens54for condensing light transmitted through the rotation filter53to emit the light to a proximal end portion22of the light guide21.

In addition, the rotation filter53provided with the RGB filter has outside of the circuit direction an excitation light filter for transmitting the excitation light of a wavelength band shorter than that of visible light. The rotation filter53is rotated and driven by a motor55. Moreover, the motor55is mounted to a rack56and configured to move in a direction orthogonal to an illumination optical axis by a gear-equipped motor57engaged with the rack56, as shown by an arrow.

The gear-equipped motor57is controlled by a control circuit58. The control circuit58is connected with the control circuit47of the processor4via the control signal line49dand performs control action in response to an operation of the control switch48a.

In addition, at the distal end portion15, an air/water feeding nozzle60serving as an air/water feeding portion is disposed such that a spouting port thereof faces outer surfaces of the respective objective lenses (later, also referred to as observation lenses) of the normal light image pickup unit31A and the fluorescent light image pickup unit31B which are disposed on the distal end cover24.

The air/water feeding nozzle60is, as described later, connected to an air/water feeding duct61configured to be diverged at a proximal end thereof into two ducts of an air feeding duct61aand a water feeding duct61b, and integrated at a distal end thereof into one duct with the two ducts merged.

The air feeding duct61aand the water feeding duct61bwhich are communicating with the air/water feeding nozzle60are inserted to reach the connector14of the universal cable13, and connected to the air/water feeding device6incorporating a pump, not shown, for feeding air and water.

The air feeding duct61aand the water feeding duct61bare interposed with the air/water feeding button63in the operation portion12located at halfway of the ducts. Then, air and water are fed by operating the above-described air/water feeding button63.

This allows the air/water feeding nozzle60to spray gas such as air or liquid such as distilled water to the outer surfaces of the respective objective lenses of the normal light image pickup unit31A and the fluorescent light image pickup unit31B disposed in a spouting direction of the air or liquid, to clean and remove body fluid, extraneous matter, or the like, thereby ensuring an image pickup and an observation field of view in a clean state.

Although omitted inFIG. 1, the insertion portion11has inside thereof a forward water-feeding channel as a second duct for feeding liquid such as distilled water to a region to be inspected in a body cavity. And the distal end of the forward water-feeding channel opens on a distal end surface of the distal end cover24.

The forward water-feeding channel is connected to the forward water-feeding device6a, and has a forward water-feeding button not shown provided in the operation portion12. When the forward water-feeding button is operated, liquid such as distilled water is sprayed from the distal end surface of the insertion portion11in an insertion direction into the body cavity. This allows the body fluid and the like attached to the region to be inspected in the body cavity to be cleaned. Note that, as shown inFIG. 1, a foot switch6bis connected to a cable extending from the forward water-feeding device6a, therefore a user can spray liquid such as distilled water from the distal end surface of the insertion portion11in the insertion direction into the body cavity by operating the foot switch6b.

As shown inFIGS. 2 to 4, to the distal end cover24provided on the distal end portion15of the insertion portion11, provided are an observation lens31aof the normal light image pickup unit31A, an observation lens31bof the fluorescent light image pickup unit31B, two illumination lenses25a,25bas observation windows configuring a first illumination optical system and a second illumination optical system, an aperture portion26of the treatment instrument channel, and an aperture portion27of the forward water-feeding channel. In addition, on the distal end cover24, the air/water feeding nozzle60is disposed such that a spouting port60afaces the observation lenses31a,31b, as described above.

The observation lens31adisposed on the distal end cover24of the distal end portion15condenses the light incident on the normal light image pickup unit31A. Moreover, the observation lens31bdisposed on the distal end cover24of the distal end portion15condenses the light incident on the normal light image pickup unit31B.

Note that,FIGS. 2 and 3are perspective views showing the distal end cover part of the endoscope ofFIG. 1.FIG. 4is a plan view of the distal end cover of the endoscope ofFIG. 1viewed from the front. In addition, the two observation lenses31a,31bare the optical members.

To be concrete, the observation lens31aas the observation window and an optical member configuring an image pickup portion for normal light observation is disposed at the approximately center of the distal end surface of the generally circular-shaped distal end cover24when viewed the distal end portion15from the distal end thereof, and the illumination lenses25a,25bare provided on the right and left when viewed facing the paper surface ofFIG. 4, respectively, so as to sandwich the observation lens31a. Furthermore, on the distal end surface of the distal end cover24, provided are the aperture portion27of the forward water-feeding channel on the upper right side of the observation lens31afacing the paper surface ofFIG. 4, the air/water feeding nozzle60on the upper left side, the observation lens31bas the observation window and the optical member configuring the image pickup portion for the special light observation on the lower right side and the aperture portion26of the treatment instrument channel on the lower left side, respectively.

Note that, detailed description will be made later on arrangements of the respective observation lenses31a,31b, provided on the distal end cover24, the respective aperture portions26,27, and the air/water feeding nozzle60in the present embodiment.

Next, an internal configuration of the distal end part of the insertion portion11of the endoscope2according to the present embodiment will be described with reference toFIGS. 5 to 11. Note thatFIG. 5is a cross-sectional view of the distal end portion and the bending portion cut along V-V line ofFIG. 4.FIG. 6is a cross-sectional view of the distal end portion cut along VI-VI line ofFIG. 4.FIG. 7is a cross-sectional view showing a diverging part of the air/water feeding duct of the endoscope ofFIG. 1.FIG. 8is a partial cross-sectional view showing the distal end portion cut along VIII-VIII line ofFIG. 4.FIG. 9is a cross-sectional view showing the distal end portion cut along IX-IX line ofFIG. 4.FIG. 10is a cross-sectional view showing the distal end portion cut along X-X line ofFIG. 5.FIG. 11is a cross-sectional view showing the bending portion cut along XI-XI line ofFIG. 5.

As shown inFIG. 5, the bending portion16of the endoscope2has a plurality of circular ring-shaped bending pieces7rotatably provided thereto in a linked manner.

The respective bending pieces7have four wire guards7afixed on inner circumferential surfaces thereof by means of adhesion. The four wire guards7aare, as shown inFIG. 10, fixed on the inner circumferential surface of each of the bending pieces7at positions deviated from one another about the insertion axis by approximately 90 degrees.

Moreover, the plurality of bending pieces7are covered with a bending braid9formed by knitting thin wires in a pipe shape so as to cover the outer circumferences thereof, and moreover, on the bending braid9, an outer covering is covered so as to keep watertightness. The bending portion16is formed by the bending pieces7having the above-described configuration, the bending braids9, and the outer covering10.

The outer covering10covers the bending portion16with one end of an outer circumferential part of the outer covering fastened to the distal end portion and the other end of an outer circumferential part fastened to the flexible tube portion17.

In addition, the four bending operation wires8serving as bending operation means extending from the bending portion16toward the proximal end are inserted in the insertion portion11. The four bending operation wires8have distal end parts which are held and fixed so as to be deviated from one another about the insertion axis by approximately 90 degrees by four fixing portions18a(SeeFIG. 11. Note that only one of them is shown inFIG. 5) of a fixing ring18provided in the distal end portion15, and configured such that the proximal ends thereof are each inserted into the wire guards7aprovided in each of the bending pieces7.

Note that, the distal end portion15and the respective bending pieces7are joined such that the respective bending operation wires8, which are held and fixed by the respective fixing portions18aof the fixing ring18provided in the distal end portion15and inserted into the respective wire guards7aof each of the bending pieces7, are almost linearly disposed in a state where the insertion axis of the bending portion16is almost linear.

In addition, as shown inFIG. 1, the proximal end portions of the bending operation wires8are provided in the operation portion12, and the bending operation wires8are connected to a bending operation mechanism not shown connected to a bending operation knob to be alternately pulled and relaxed.

Pulling and relaxing the respective four bending operation wires8by a predetermined operation of the bending operation knob cause the bending portion16to be operated and bent in four directions. Note that the above-described four directions are directions generally coincide with four directions of up, down, left, and right of the endoscope image picked up by the respective image pickup units31A,31B to be displayed on the monitor5, as described later.

In addition, the two bending operation wires8serving as first bending operation means for operating the bending portion16in the up and down directions and the two bending operation wires8serving as second bending operation means for operating the bending portion16in the left and right directions make a pair, respectively. That is, the two bending operation wires8respectively inserted and held by the two wire guards7apositioned in directions corresponding to the up and down directions in the bending pieces7in the bending portion16are the first bending operation means, and the two bending operation wires8respectively inserted and held by the two wire guards7apositioned in directions corresponding to the left and right directions in the bending pieces7in the bending portion16are the second bending operation means.

In the distal end portion15, provided are a columnar member15amade of a rigid metal and including a plurality of, or seven hole portions in the present embodiment, and a circular ring-shaped reinforcing ring15bexternally fitted with the proximal end side outer circumferential part of the columnar member15a. In addition, the fixing ring18having the four fixing portions18ais fitted by insertion on an inner circumferential side of the reinforcing ring15bof the distal end portion15. Furthermore, the proximal end part of the reinforcing ring15bis connected to the bending piece7located at the distal-most end.

The two hole portions among the seven hole portions formed of the columnar member15ain the distal end portion15form distal end parts of the treatment instrument channel19and the forward water-feeding channel20, and in the remaining five hole portions, disposed respectively are the normal light image pickup unit31A, the fluorescent light image pickup unit31B, and the air/water feeding nozzle60which are described above, and two illumination lens units to be described later.

Note that, one hole portion of the seven hole portions of the columnar member15ais fixed, for example, by first observation-optical-system-fixing means such as a screw and adhesive, and configures first observation-optical-system-disposing means in which the normal light observation unit31A including the observation lens31ais disposed. In addition, another one hole portion is fixed, for example, by second observation-optical-system fixing means such as screw and adhesive, and configures second observation-optical-system-disposing means in which the fluorescent light observation unit31B including the observation lens31bis disposed. Moreover, in another two hole portions, two illumination lens units, which include illumination lenses25serving as the first and the second illumination optical systems, respectively, are each fixedly disposed by first and second illumination-optical-system-fixing means such as a screw and adhesive, for example. One of the two holes configures first illumination optical system-disposing means and the other configures second illumination-optical-system-disposing means.

Another hole portion among the seven hole portions, in which the air/water feeding nozzle60as the air/water feeding portion is disposed, configures air/water-feeding-portion-disposing means for fixedly disposing the air/water feeding nozzle60by first air/water-feeding portion-fixing means such as a screw and adhesive, for example. Furthermore, another hole portion among the seven hole portions in which the treatment instrument channel19as a first endoscope duct is disposed configures first endoscope-duct-disposing means, and yet another hole portion in which the forward water-feeding channel20as a second endoscope duct is disposed configures a second endoscope-duct-disposing means. Note that the treatment instrument channel19is fixedly disposed in one hole portion among the seven hole portions by first endoscope-duct-fixing means such as a screw and adhesive, for example, and the forward water-feeding channel20is fixedly disposed in another one hole portion by second endoscope-duct-fixing means such as a screw and adhesive, for example.

The treatment instrument channel19includes: the aperture portion26which opens on the distal end cover24provided on the distal end surface of the distal end portion15, a generally cylindrical tube member19afitted by insertion in the hole portion of the columnar member15aof the distal end portion15, and a treatment instrument duct19bformed of a flexible tube of which distal end part covers a proximal end part of the tube member19aand connected and fixed thereto by a spool.

The treatment instrument duct19bis inserted in the insertion portion11, and of which proximal end is open at the operation portion12, that is, open in the treatment instrument insertion port not shown inFIG. 1, as described above.

In addition, the forward water-feeding channel20similarly having the aperture portion27on the distal end cover24includes a generally cylindrical tube member20afitted by insertion in the hole portion of the columnar member15aof the distal end portion15, and a forward water-feeding duct20bwhich covers a proximal end part of the tube member20aand of which distal end part is connected and fixed by a spool.

The forward water-feeding duct20bis inserted through the insertion portion11, the operation portion12and the universal cable13, to reach the connector14, and is connected to the forward water-feeding device6a. Note that, as described above, the forward water-feeding duct20bas the forward water-feeding channel20includes the forward water-feeding button not shown placed in the operation portion12.

As shown inFIG. 6, the air/water feeding nozzle60is a tubular member bent in an approximate L shape, and of which proximal end part is fitted by insertion in the hole portion of the columnar member15aof the distal end portion15such that the distal end side spouting port60afaces outer surface sides of the respective observation lenses31a,31b.

To a proximal end side of the hole portion of the columnar member15ain which the air/water feeding nozzle60is disposed, a distal end part of the tube member62is fitted by insertion, and a proximal end part of the tube member62is connected to the air/water feeding duct61. Note that the tube member62and the air/water feeding duct61are connected and fixed by a spool.

The air/water feeding duct61has, as shown inFIG. 7, a proximal end part connected to a diverging tube50, and diverging end portions of the diverging tube50are connected to distal end parts of the air feeding duct61aand the water feeding duct61b, respectively. This allows the air/water feeding duct61to communicate with the air feeding duct61aand the water feeding duct61b. Note that the respective ducts61,61a,61bare connected and fixed to the diverging tube50by the spool, and the respective connecting parts and around the entirety of the diverging tube50are applied with adhesive, for example, thereby allowing the respective connecting parts to be kept airtight (watertight).

In addition, into the two of the seven hole portions formed in the columnar member15aof the distal end portion15, illumination lens units23are fitted by insertion from a distal end side of the holes, respectively, and to proximal end parts of the holes, distal end parts of the light guides21are fitted by insertion, respectively. As shown inFIGS. 8 and 9, each of the illumination lens units23includes a plurality of illumination lenses25, and a holding barrel23afor holding the illumination lenses25. Note that the two illumination lens units23in the present embodiment include the illumination lenses25a,25bwhich are the distal-most end lenses among the illumination lenses, respectively.

The light guide21of which distal end part is covered with a cylindrical member21ais coated by an outer covering29binding up a plurality of fibers. A proximal end part of the cylindrical member21ais connected and fixed to a tube28of which distal end part is spool-fixed, and into the tube28, the light guide21coated by the outer covering29is inserted.

Returning toFIG. 6, the normal light image pickup unit31A includes a lens unit32, and image pickup device33which is a CCD or a CMOS and the like, and a circuit substrate34.

The lens unit32includes first to fourth lens groups32A to32D, and first to fourth lens barrels32ato32d. In the present embodiment, the first lens group32A formed by four objective lenses including the observation lens31a, the second lens32B formed by one objective lens, the third lens group32C formed by two objective lenses, and the fourth lens group32D formed by three objective lenses are held by the first lens barrel32a, the second lens barrel32b, the third lens barrel32c, and fourth lens barrel32d, respectively.

In addition, the second lens barrel32bholding the second lens32B is a moving barrel advanceable and retractable for zooming with respect to a photographing optical axis direction. Note that, when the user operates zooming operation lever, not shown, provided in the operation portion12, the second lens barrel32bis advanced or retracted with respect to the photographing optical axis direction by driving means such as a motor or actuator, not shown, provided in the normal light image pickup unit31A, for example. With such a configuration of the endoscope2, the normal light image pickup unit31A is capable of displaying a part of the endoscope image obtained in a field of view of the observation lens31ain an enlarged manner on the monitor5, for example.

Note that, the driving means for advancing and retreating the second lens barrel32bwith respect to the photographing optical axis is supplied with a drive-stop signal by the signal line38cshown inFIG. 10. The signal line38cis inserted from the normal light image pickup unit31A, through inside of the insertion portion11, to the operation portion12.

The image pickup device33includes on a light receiving surface side a cover lens33awhich is juxtaposed on a proximal end side of the objective lens positioned at the proximal-most end of the fourth lens barrel32d, and outputs to a circuit substrate34an electrical signal corresponding to an optical image. The circuit substrate34has electrical parts and a wiring pattern, and photoelectrically converts the optical image from the image pickup device33into an electrical image signal to output the image signal to the signal cable38a. Note that, to the circuit substrate34, a plurality of signal lines of the signal cable38aare connected by means of soldering and the like.

The cover lens33a, the image pickup device33, the circuit substrate34and the distal end part of the signal cable38arespectively have outer circumferential portions which are integrally covered with, for example, an insulation sealing resin and coated with a reinforcing circular ring portion35aand an insulating tube35b.

In addition, the signal cable38atransmits the image signal obtained from the image pickup device33of the normal light image pickup unit31A and the circuit substrate34to the signal processing circuit46of the processor4, via the relay substrate42of the connector14and the signal cable43which are shown inFIG. 1.

On the other hand, the fluorescent light image pickup unit31B includes, similarly as the normal light image pickup unit31A, the lens unit36, an image pickup device38such as a CCD or a CMOS and the like, and a circuit substrate39.

The lens unit36includes first and second lens groups36A,36B, and first and second lens barrels32a,32b. In the present embodiment, the first lens group36A formed of seven objective lenses including the observation lens31band the second lens36B are held by the first lens barrel36aand the second lens barrel36b, respectively.

The image pickup device38includes on a light receiving surface side a cover lens40which is juxtaposed on a proximal end side of the objective lens positioned at the proximal-most end of the second lens barrel36band outputs to the circuit substrate39an electrical signal corresponding to an optical image. The circuit substrate39has electrical parts and a wiring pattern similarly as the circuit substrate34of the normal light image pickup unit31A, and to the circuit substrate39, a plurality of signal lines included in the signal cable38aare connected by means of soldering and the like. In addition, the circuit substrate39photoelectrically converts the optical image from the image pickup device38into an electrical image signal to output the image signal to the signal cable38b.

The cover lens40, the image pickup device33, the circuit substrate34and the distal end part of the signal cable38arespectively have outer circumferential portions which are integrally covered with, for example, an insulation sealing resin and coated with a reinforcing circular ring portion35aand an insulating tube35b.

In addition, the signal cable38btransmits the image signal obtained from the image pickup device38and the circuit substrate39of the fluorescent light image pickup unit31B to the signal processing circuit46of the processor4, via the relay substrate42and the signal cable43of the connector14which are shown inFIG. 1.

The normal light image pickup unit31A and the fluorescent light image pickup unit31B described above are fitted by insertion into predetermined hole portions provided in the columnar member15aof the distal end portion15, respectively, and firmly fixed with fixing members such as screws along with adhesive and the like.

Furthermore, in the present embodiment, the observation lens31adisposed at the distal end of the normal light image pickup unit31A has a larger lens diameter (diameter as outer diameter) compared with the observation lens31bdisposed at the distal end of the fluorescent light image pickup unit31B.

The disposition directions of the respective image pickup units31A,31B in the distal end portion15are determined such that the respective light receiving surfaces of the two image pickup devices33,38are orthogonal with respect to the insertion axis of the insertion portion11, and a horizontal transfer direction and a vertical transfer direction, as charge transfer directions, of the image pickup device33coincide with a horizontal transfer direction and a vertical transfer direction as the charge transfer directions of the image pickup device38, respectively.

Subject images photographed by the respective image pickup units31A,31B are displayed on the monitor5, and the up/down direction and left/right direction of the monitor5coincide with the vertical transfer directions and the horizontal transfer directions of the CCD elements and the CMOS elements of the respective image pickup devices33,38, respectively. That is, the up, down, left, and right directions of the endoscope images photographed by the respective image pickup units31A,31B coincide with the up, down, left, and right directions of the monitor5.

The up, down, left, and right directions of the bending portion16of the insertion portion11are determined so as to correspond to the up, down, left, and right directions of the endoscope image displayed on the monitor5. Accordingly, the four bending operation wires8inserted in the bending portion16are pulled and relaxed by predetermined operations of the bending operation knob provided in the operation portion12, as described above, thereby allowing the bending portion16to be bendable in four directions, that is, the up, down, left, and right directions corresponding to the up, down, left, and right directions of the endoscope image displayed on the monitor5.

That is, in the respective image pickup units31A,31B, even if the normal light observation and the fluorescent light observation are switched each other, the up, down, left, and right directions of the endoscope image displayed on the monitor5always coincide with those of the bending operation directions of the bending portion16, and the disposition directions of the image pickup units31A,31B in the distal end portion15are determined such that the horizontal transfer direction and the vertical transfer direction of the image pickup device33coincide with the horizontal transfer direction and the vertical direction of the image pickup device38, respectively.

With such a configuration, the user can perform a bending operation of the bending portion16in up, down, left, and right directions without feeling a sense of discomfort with respect to the up, down, left, and right directions of the endoscope image displayed on the monitor5when the endoscope image is switched between the normal light observation image and the fluorescent light observation image.

Note that, in the following description, the up/down direction as a first direction will be described as the direction approximately coincident with the up/down direction of the endoscope image displayed on the monitor5and the up/down direction in which the bending portion16is operated and bent. In addition, the monitor5is generally disposed such that the up/down direction thereof approximately coincides with the plumb up/down direction. Furthermore, the left/right direction as a second direction approximately orthogonal to the above-described up/down direction will be described as a direction approximately coincident with the left/right direction of the endoscope image displayed on the monitor5and the left/right direction in which the bending portion16is operated and bent.

Here, the action of the above-described endoscope system1will be described.

As shown inFIG. 1, the user connects the connector14of the endoscope2to the light source device3, then connects one end and the other end of the scope cable44with the connector14and the processor4, respectively. In addition, the user connects the air feeding duct61aand the water feeding duct61bto the air/water feeding device6.

Then, the user turns on power switches of the light source device3and the like to set the device and the like in an operation state, respectively. At this time, the control circuits47,58of the processor4and the light source device3become a state in which they can transmit and receive a control signal and the like.

Furthermore, in a state immediately after the activation, the relay substrate42is set such that the normal light image pickup unit31A is selected. Moreover, the control circuit47performs a control operation to set the normal light observation state. That is, the control circuit47transmits a control signal to the control circuit58of the light source device3to set the light source device3in a state where illumination light for normal light observation is supplied.

In addition, the control circuit47controls to drive the CCD driving circuit45a, and sets the operation state of the signal processing circuit46in the normal light observation mode.

The user inserts the insertion portion11of the endoscope2into a body cavity to set such that a diseased part and the like as a subject to be diagnosed can be observed.

The light source device3becomes the state where the illumination light for normal light observation is supplied, as described above. In this state, the rotation filter53is rotated and driven by the motor55in a state where the RGB filter are disposed in the illumination optical path. Then red, green, and blue illumination lights are supplied to the light guide21as frame sequential lights. Synchronizing with this, the CCD driving circuit45aoutputs a CCD driving signal, and the illumination lights illuminate the diseased part in a patient's body cavity via the illumination lenses25a,25b.

The images of the illuminated subject such as the diseased part pass through the lens unit32of the normal light image pickup unit31A to be formed on the light receiving surface of the image pickup device33, and then photoelectrically converted. Then, the image pickup device33outputs the signals obtained by the photoelectric conversion, in response to application of a driving signal. The outputted signals are inputted to the signal processing circuit46through the signal cable38aand the common signal cable43selected by the relay substrate42.

The signals inputted to the signal processing circuit46are A/D converted in the circuit to be temporarily stored in an RGB memory.

After that, the signals stored in the RGB memory are simultaneously read out to be synchronized R, G, B signals, and then D/A converted to be analog R, G, B signals, thereafter being color-displayed on the monitor5.

Then, when the user desires to further inspect the diseased part which has been observed by normal light observation by performing the fluorescent light observation, the user turns on the control switch48a. Then, the control circuit47performs switching control of the relay substrate42in response to the switch instruction signal outputted from the control switch48a, and sets the light source device3in a state where excitation light for fluorescent light observation is supplied via the control circuit58.

In addition, the control circuit47controls the driving circuit45bin an operation state and sets the signal processing circuit46in a processing mode by the fluorescent light observation.

In this case, the control circuit58in the light source device3moves the rotation filter53as well as the motor55in a direction orthogonal to the illumination optical path by means of the gear-equipped motor57such that an excitation light filter is disposed on the illumination optical path.

In this state, light from the lamp51is supplied to the light guide21as the excitation light having a wavelength band around 400 to 450 nm, for example, by passing through the excitation light filter. Then, the excitation light is illuminated onto the diseased part or the like in the body cavity via the illumination lenses25a,25b.

If the diseased part or the like on which the excitation light is illuminated is a cancer tissue, they absorb the excitation light to emit stronger fluorescent light, compared with the case where the disease part or the like is a normal tissue. The light from the part emitting the fluorescent light passes through the lens unit36of the fluorescent light image pickup unit31B and image-formed on the light receiving surface of the image pickup device38to be photoelectrically converted.

Then the image pickup device38outputs the signals obtained by the photoelectric conversion and amplification in response to application of a driving signal from the driving circuit45b. The signals obtained by the photoelectric conversion and the amplification are inputted to the signal processing circuit46via the signal cable38band the common signal cable43selected by the relay substrate42.

The signals inputted in the signal processing circuit46are A/D converted in the circuit and simultaneously stored in the RGB memory, for example.

The signals stored in the RGB memory is simultaneously read out to be synchronized R, G, B signals, and then D/A converted into analog R, G, B signals, thereafter being monochrome-displayed on the monitor5.

Note that signals inputted in the signal processing circuit46may be turned into pseudo-colors to be displayed by comparing the levels of the signals with a plurality of threshold values and changing colors to be allocated to the signals depending on the comparison result.

Thus, with the present embodiment, in addition to the normal light observation, the fluorescent light observation can be performed, thereby realizing the endoscope facilitating a diagnosis compared with the endoscope capable of performing only the normal light observation. Also, with the present embodiment, the image pickup units31A,31B are respectively provided, so that it is possible to obtain the special light observation image as a first observation image, that is, the fluorescent light observation image, and the normal light observation image as a second observation image. That is, the image pickup unit31B as the first image pickup portion can obtain the special light observation image as the first observation image based on the light condensed by the observation lens31bdisposed on the distal end cover24of the distal end portion15. In addition, the image pickup unit31A as the second image pickup portion can obtain the normal light observation image as the second observation image based on the light condensed by the observation lens31adisposed on the distal end cover24of the distal end portion15.

In a case of performing the fluorescent light observation, in particular, the images based on weaker light are often picked up compared with the case of normal observation. Therefore, it is desirable to employ an image pickup device having a high S/N (signal to noise) ratio in the fluorescent light observation. In a case where the image pickup for normal observation is used also as the one for fluorescent light observation, the picked-up image tends to have a low S/N ratio. However, in the present embodiment, the image pickup device38dedicated and suitable for the fluorescent light observation is employed, thereby allowing the fluorescent light image with high S/N ratio to be obtained.

Also, the switching relay substrate42is provided, thereby allowing a configuration in which only one of the two image pickup units31A,31B is connected to the processor4, so that the endoscope system1can be formed to have a compact configuration compared with the one in which it is necessary to constantly drive the two image pickup units31A,31B, and perform signal processing with respect to the units.

Furthermore, in the present embodiment, one air/water feeding nozzle60is employed to keep the both observation lenses31a,31bclean by spraying gas or water on the outer surfaces of the lenses, thereby ensuring the excellent observation field of view. As a result, the insertion portion11have a smaller diameter, thereby reducing pain imposed on a patient when a user inserts the insertion portion into the patient's body cavity and also expanding regions in body cavities where the endoscope is insertable.

In addition, the endoscope2according to the present invention has the same external configuration as an existing endoscope including only the image pickup unit for normal light observation, and can be used also as the endoscope for normal light observation similarly as the existing endoscope, by connecting, via the scope cable44, to a processor, not shown, for driving and performing signal processing with respect to the existing endoscope including only the image pickup unit for normal light observation. That is, the endoscope2can be also used by connecting with the existing processor, while keeping a similar compatibility with the existing endoscope including only the image pickup unit for normal light observation.

The endoscope2according to the present invention has various characteristics (effects) with structure described below.

First, detailed description will be made on disposition of the air/water feeding nozzle60, and the respective observation lenses31a,31bwhich are provided on the distal end cover24, with reference toFIG. 12.

FIG. 12is a front view showing the distal end surface of the distal end cover.

Note that, in the description below, the centers of the distal end cover24, the observation lens31aof the normal light image pickup unit31A, and the observation lens31bof the fluorescent light image pickup unit31B are referred to as O0, O1, and O2, respectively. In addition, a center of the illumination lens25aas a first center to be described later and a center of the illumination lens25bas a second center are referred to as O3and O4, respectively. A center of the aperture portion16of the treatment instrument channel19and a center of the aperture portion27of the forward water-feeding channel20are referred to as O5and O6, respectively. Furthermore, a line passing through the center O0of the distal end surface of the distal end cover24in the up/down bending direction of the bending portion16and a line in the left/right bending direction of the bending portion16are defined as a vertical line X and a horizontal line Y, respectively. Note that, the vertical line X in the present embodiment is equal to the plumb line in the following description.

As described above, the air/water feeding nozzle60is provided on the upper left side of the distal end surface of the distal end cover24when viewed facing the paper surface ofFIG. 12such that the spouting port60afaces toward the observation lens31a. Note that the air/water feeding nozzle60may be provided on the upper right side of the distal end surface of the distal end cover24when viewed facing the paper surface ofFIG. 12such that the spouting port60afaces toward the observation lens31a. At this time, the air/water feeding nozzle60and the respective observation lenses31a,31bare so disposed as to be almost linearly juxtaposed on the distal end surface of the distal end cover24.

In the present embodiment, the air/water feeding nozzle60is provided on the distal end surface of the distal end cover24such that the gas or liquid such as air or distilled water spouted from the spouting port60aof the air/water feeding nozzle60is spouted in the arrow line AR direction in the drawing. The air/water feeding nozzle60spouts to diffuse the gas or liquid such as air or distilled water from the spouting port60ainto a gas/liquid spouting range A. Note that the arrow line AR is a line in a direction approximately orthogonal to the distal end surface of the air/water feeding nozzle60having the spouting port60aand passing through the center of the hole surface of the spouting port60a.

The disposition direction of the air/water feeding nozzle60about an axis, that is, a direction in which the spouting port60afaces, is determined such that the observation optical axis passing the center O1of the observation lens31aintersects the arrow line AR described above. In other words, the direction in which the spouting port60aof the air/water feeding nozzle60faces is determined such that the arrow line AR which is the spouting direction of the gas or liquid such as air or distilled water has a predetermined angle θ1as a first angle with respect to the vertical line X.

Meanwhile, the observation lens31bof the fluorescent light image pickup unit31B is provided on the lower right side of the distal end surface of the distal end cover24facing the paper surface ofFIG. 10such that the outer surface of the observation lens31bhas at least a part intersecting the arrow line AR when viewing the distal end cover24from the distal end side thereof. In addition, the observation lens31bis provided on the distal end surface of the distal end cover24such that the center O2thereof is positioned on the lower side than a segment of the arrow line AR.

As described above, the air/water feeding nozzle60and two observation lenses31a,31bare almost linearly juxtaposed on the distal end surface of the distal end cover24.

In detail, a line a connecting the center O1of the observation lens31aof the normal light image pickup unit31A and the center O2of the observation lens31bof the fluorescent light image pickup unit31B is slightly deviated to the lower side by a predetermined angle θ2with respect to the arrow line AR, when viewed from the distal end cover24from the distal end surface side thereof. In other words, a line b connecting the hole surface center of the spouting port60aof the air/water feeding nozzle60and the center O2of the observation lens31bis slightly deviated to the lower side by a predetermined angle θ3with respect to the arrow line AR, when viewed from the distal end cover24from the distal end surface side thereof.

This allows the respective disposing positions of the observation lenses31a,31bon the distal end cover24to be determined, and in accordance with the positions, the direction of the spouting port60a(the arrow line AR direction) of the air/water feeding nozzle60is determined. Moreover, the angles θ2, θ3are set within a range such that the whole outer surface of the observation lens31bis located within the gas/liquid spouting range A of the air/water feeding nozzle60.

Note that the gas/liquid spouting range A of the air/water feeding nozzle60is set so as to contain the whole outer surface of the observation lens31aof the normal light image pickup unit31A, when viewed from the distal end side of the distal end cover24.

In addition, the observation lens31ahaving a larger lens diameter (diameter as the outer diameter) than the outer diameter of the observation lens31bis provided on the distal end surface of the distal end cover24so as to be close to the air/water feeding nozzle60.

That is, the distal end cover24has the air/water feeding nozzle60at a position on an upper side than the horizontal line Y approximately bisecting the bending up/down direction of the bending portion16with respect to a direction viewed from the distal end surface side, that is, up/down direction of the vertical transfer direction in which the image pickup devices33,38included in the respective image pickup units31A,31B perform processings. In other words, the air/water feeding nozzle60is provided to the distal end cover24away from the horizontal line Y in a direction opposite to the spouting direction (arrow line AR direction).

Furthermore, the distal end cover24has the air/water feeding nozzle60provided such that a cross section of the air/water feeding nozzle60in a direction orthogonal to the longitudinal axis (axis parallel with the insertion direction) thereof is not positioned on the vertical line X which bisects a left/right direction (which is reverse to the bending left/right direction of the bending portion16) with respect to the direction viewed from the distal end surface side of the distal end cover, that is, the left/right direction of the vertical transfer direction in which the image pickup devices33,38included in the respective image pickup units31A,31B perform processings.

Note that, in the present embodiment, the air/water feeding nozzle60and the spouting port60aare provided at a position on the distal end surface of the distal end cover24so as to be separated by a predetermined distance in the left direction from the vertical line X, when viewed from the distal end surface side of the distal end cover24. That is, the air/water feeding nozzle60is disposed such that a longitudinal axis thereof is located at a position deviated to the upper side than the horizontal line Y bisecting the distal end cover24into upper and lower parts, and deviated to the left side from the vertical line X bisecting the distal end cover24into left and right parts, when viewed from the distal end surface side of the distal end cover24.

As described above, the endoscope2of the present embodiment includes, on the distal end surface of the distal end cover24, the air/water feeding nozzle60, the observation lens31aof the normal light image pickup unit31A, and the observation lens31bof the fluorescent light image pickup unit31B which are almost linearly disposed. As a result, the endoscope2of the present embodiment is configured such that gas or water is sprayed from one air/water feeding nozzle60onto the outer surfaces of the respective observation lenses31a,31bto set the lenses in a clean state, thereby ensuring an excellent observation field of view.

In addition, the air/water feeding nozzle60is disposed such that the longitudinal axis thereof is located on the upper side than the horizontal line Y bisecting the distal end cover24into upper and lower parts, and at a position deviated by a predetermined distance from the vertical line X bisecting the distal end cover24into left and right parts. Therefore, when the insertion portion11is in an almost straight state, the air/water feeding duct61communicating with the air/water feeding nozzle60is inserted almost straight into the distal end portion15and the bending portion16, without contacting the four fixing portions18aof the fixing ring18provided in the distal end portion15and the four wire guards7aprovided respectively to each of the bending pieces7provided in the bending portion16.

Moreover, disposition of the above-described air/water feeding nozzle60prevents the air/water feeding duct61from contacting the four bending operation wires8respectively held by insertion into the four wire guards of each of the bending pieces7in the bending portion16. Therefore, in the endoscope2according to the present embodiment, movement of the bending operation wires8due to pulling and relaxing is not obstructed and the degradation of the bending operation wires8due to scratch can be prevented.

As a result, in the endoscope2according to the present embodiment, the insertion portion11, particularly, the distal end portion15and the bending portion16have smaller diameter, thereby reducing the pain imposed on the patient at the time of insertion and expanding regions of body cavities where the endoscope is insertable.

In addition, the endoscope2is generally used by a user such that the up/down bending direction of the bending portion16coincides with the up and down in the plumb direction. Accordingly, the liquid such as distilled water spouted from the spouting port60aof the air/water feeding nozzle60flows down to the lower side due to influence of gravitational force, on a far side from the spouting port60a.

Furthermore, when the gas or liquid such as air or distilled water is spouted from the spouting port60aof the air/water feeding nozzle60and also suction is performed through the treatment instrument channel19, the gas or the water is subject to a pulling force in the direction of the aperture portion26due to a suction force from the aperture portion26of the treatment instrument channel19provided on the lower side of the distal end cover24, resulting in a change of the flow direction of the gas or the air to the down bending direction side.

In view of such a circumstance, in the endoscope2of the present embodiment, on the distal end surface of the distal end cover24, the observation lens31bof the fluorescent light image pickup unit31B is disposed such that the line a connecting the center O2of the observation lens31band the center O1of the observation lens31aof the normal light image pickup unit31A is deviated by the predetermined angle θ2in the down bending direction of the bending portion16with respect to the arrow line AR which is the spouting direction of the liquid such as distilled water spouted from the spouting port60aof the air/water feeding nozzle60.

Accordingly, the observation lens31bwhich is located further from the air/water feeding nozzle60than the observation lens31aon the distal end surface of the distal end cover24is efficiently sprayed with the liquid such as distilled water flown down lower to the down bending direction side than the spouting direction due to the influence of gravitational force, and thereby cleaned to be a clean state. As a result, the excellent observation field of view is ensured. Furthermore, the observation lens31bis also efficiently sprayed with the gas or air such as air or distilled water of which flow direction is changed to the down bending direction side due to the suction, and thereby cleaned to be a clean state and the excellent observation field of view is ensured.

In addition, in the endoscope2inserted in a body cavity of a patient, filth and the like are attached to the insertion portion11. To the distal end surface of the distal end cover24, in particular, the filth and the like are easily attached, because the distal end surface is an approximately vertical surface with respect to the insertion direction. Therefore, it is desirable that the observation lens31aof the normal light image pickup unit31A and the observation lens31bof the fluorescent light image pickup unit31B are surely cleaned of the attached filth and the like in order to ensure the observation field of view of the respective lenses.

In general, in an observation using the endoscope2, the normal light observation is performed more frequently compared with the fluorescent light observation. Therefore, it is desirable to ensure the excellent observation field of view and a sufficient amount of received light in the normal light observation. The normal light image pickup unit31A of the present embodiment is provided near the center of the distal end surface of the distal end portion15, and is provided with the observation lens31ahaving a larger lens diameter (diameter as the outer diameter) than that (diameter as the outer diameter) of the observation lens31bfor guiding light incident on the fluorescent light image pickup unit31B for image pickup, thereby ensuring the excellent observation field of view and the sufficient amount of received light.

The endoscope of the present embodiment, in particular, has an enlargement function, so that a plurality of lens groups32A to32D are required so as to suppress aberration at the time of telephotographing/zooming. As a result, the light beam height becomes higher, which leads to the larger lens diameter (diameter as the outer diameter).

In other words, the observation lens31ahas the larger lens diameter (diameter as the outer diameter) than that of the observation lens31b, that is, has a larger outer surface area, and condenses the incident light on the image pickup device33of the normal light image pickup unit31A provided on an image forming side of the incident light.

Moreover, as for the gas or the liquid such as air or distilled water spouted from the spouting port60aof the air/water feeding nozzle60, spouting force thereof is larger on the side closer to the spouting port60a, and as going further side of the spouting direction, the spouting force becomes smaller and the density becomes lower by diffusion.

In view of such a circumstance, as shown inFIG. 11, in the endoscope2of the present embodiment, the observation lens31aof the normal light image pickup unit31A having a larger lens diameter (diameter as the outer diameter) than that (diameter as the outer diameter) of the observation lens31bof the fluorescent light image pickup unit31B is disposed at a position closer to the air/water feeding nozzle60on the distal end surface of the distal end cover24. Note that, as described above, the whole outer surface of the observation lens31ais contained in the gas/liquid spouting range A to which air or distilled water is spouted from the spouting port60aof the air/water feeding nozzle60.

With such a configuration, the endoscope2has at the position closer to the air/water feeding nozzle60the observation lens31ahaving the large lens diameter (diameter as the outer diameter) to which body fluid, filth, and the like are easily attached, thereby improving the cleaning efficiency without being subject to the influence due to a decrease in the spouting force and the density of the gas or fluid such as air or distilled water spouted from the spouting port60a.

Note that, in the endoscope2of the present embodiment, as described above, the air/water feeding nozzle60, the observation lens31aof the normal light image pickup unit31A, and the observation lens31bof the fluorescent light image pickup unit31B are almost linearly juxtaposed on the distal end surface of the distal end cover24shown inFIG. 12. In addition, on the distal end surface of the distal end cover24, no other components are provided on the arrow line AR which is the spouting direction of the gas or liquid such as air or distilled water spouted from the spouting port60aof the air/water feeding nozzle60.

That is, on the arrow line AR, no other components are provided at an area from the observation lens31bof the fluorescent light image pickup unit31B to the distal end surface on the outer circumferential side of the distal end cover24.

With such a configuration, the gas or liquid which has been used for cleaning the filth and the like attached to the respective observation lenses31a,31bflows to an outer edge portion of the distal end cover24in the arrow line AR direction as the spouting direction, without flowing toward the other components. As a result, the distal end surface of the distal end cover24of the endoscope2is surely cleaned, when the gas or liquid such as air or distilled water is spouted from the air/water feeding nozzle60.

Next, with reference toFIGS. 12,13, and14, detailed description will be made on dispositions of the two illumination lenses25a,25b, the aperture portion26of the treatment instrument channel19, and the aperture portion27of the forward water-feeding channel20, which are provided on the distal end cover24.

As described above, on the distal end surface of the distal end cover24, two illumination lenses25a,25bare disposed at the positions in the left/right bending direction, respectively, so as to sandwich the observation lens31aof the normal light image pickup unit31A which is provided at near the center of the distal end surface. Furthermore, on the distal end surface of the distal end cover24, the aperture portion26of the treatment instrument channel19and the aperture portion27of the forward water-feeding channel20are disposed at a position on the lower left side of the observation lens31aand at a position on the upper right side of the observation lens31a, respectively. In other words, the illumination lenses25aand25bconfiguring the illumination optical systems are respectively disposed such that the observation lens31aof the normal light image pickup unit31A approximately lines up on a straight line connecting the centers O3and O4of the illumination lenses25aand25b.

In a case where the distal end portion15on which the illumination lenses25aand25bare disposed at the above described positions is inserted in the body cavity, for example, as shown inFIG. 14, in a field of view area R of the observation lens31aas the endoscope image displayed on the monitor5, an area brightly lighted with the irradiation light emitted from the illumination lens25aconfiguring the illumination optical system and an area brightly lighted with the irradiation light emitted from the illumination lens25bconfiguring the illumination optical system are shown as areas R1and R2in a pattern view, respectively. Accordingly, the area where the area R1and the area R2overlap each other is illuminated with the irradiation lights emitted from both of the illumination lenses25aand25b. In addition, in a case where the area in the endoscope image displayed on the monitor5which can be displayed in an enlarged manner by the operation of the zooming operation lever, not shown, by the user is an area R3as a part of the field of view area R of the observation lens31a, as shown inFIG. 14, for example, the area R3is included inside of the area where the area R1and the area R2overlap each other. In other words, the observation lens31ais provided sandwiched between the illumination lenses25aand25bsuch that entirety of the area R3which can be displayed in an enlarged manner by the normal light image pickup unit31A is included inside of the area where the area R1and the area R2overlap each other.

Therefore, when the image is displayed in an enlarged manner, the user can observe a diseased part in the area R3in a state where the diseased part is illuminated with the irradiation lights emitted from both of the illumination lenses25aand25b, that is, in a state where the diseased part is illuminated with the irradiation light in an amount approximately the same as that in a non-enlarged display.

In addition, as shown inFIG. 12, the aperture portion26of the treatment instrument channel19and the aperture portion27of the forward water-feeding channel20are provided on the distal end surface of the distal end cover24such that the entireties of the hole surfaces thereof are positioned outside of the gas/liquid spouting range A into which gas or liquid such as air or distilled water is spouted to diffuse from the spouting port60aof the air/water feeding nozzle60.

In detail, as shown inFIG. 13, the aperture portion26of the treatment instrument channel19is disposed in an area B on the distal end surface of the distal end cover24which is an area at the lower part of the distal end surface of the distal end cover24when dividing the distal end surface into two parts along the arrow line AR which shows the spouting direction of the gas or liquid such as air or distilled water spouted from the spouting port60aof the air/water feeding nozzle60, and which is exclusive of the gas/liquid spouting range A.

In addition, the aperture portion27of the forward water-feeding channel20is disposed in an area C on the distal end surface of the distal end cover24which is an area at the upper part of the distal end surface of the distal end cover24when dividing the distal end surface into two parts along the arrow line AR, and which is exclusive of the gas/liquid spouting range A.

In other words, the respective aperture portions26,27are disposed on the distal end surface of the distal end cover24at approximately symmetrical positions with respect to the arrow line AR showing the spouting direction of gas or liquid such as air or distilled water, respectively. That is, the respective aperture portions26,27are disposed at the positions on the distal end surface of the distal end cover24such that the center O5of the aperture portion26and the center O6of the aperture portion27are separated from each other by a predetermined distance.

As described above, in the endoscope2of the present embodiment, the aperture portion26of the treatment instrument channel19and the aperture portion27of the forward water-feeding channel20are disposed outside of the gas/liquid spouting range A of the air/water feeding nozzle60on the distal end surface of the distal end cover24. Therefore, in the endoscope2of the present embodiment, the gas or liquid such as air or distilled water spouted from the air/water feeding nozzle60is prevented from flowing into the respective aperture portions26,27.

This enables the gas or liquid such as air or distilled water spouted from the air/water feeding nozzle60to be surely sprayed onto the further side observation lens31bof the fluorescent light image pickup unit31B. As a result, the observation lens31bof the fluorescent light image pickup unit31B is surely and efficiently sprayed with the gas or liquid and cleaned to be a clean state, thereby ensuring the excellent observation field of view.

In addition, the respective aperture portions26,27are disposed on the distal end surface of the distal end cover24such that the respective centers O5, O6are separated from each other by a predetermined distance. With such a configuration, when spouting the liquid such as distilled water from the aperture portion27of the forward water-feeding channel20while performing suctioning action through the aperture portion26of the treatment instrument channel19, the endoscope2can spout the liquid toward the diseased part in the body cavity without being subject to influence of suction force toward the aperture portion26. That is, the endoscope2of the present invention has a configuration in which the spouting direction of the liquid spouted from the aperture portion27is not disturbed by the suction force from the aperture portion26.

The endoscope2of the present invention having the above-described various features (effects) includes on the distal end surface of the distal end cover24the air/water feeding nozzle60, the observation lens31aof the normal light image pickup unit31A, and the observation lens31bof the fluorescent light image pickup unit31B which are approximately linearly disposed. Accordingly, in the endoscope2of the present embodiment, gas or liquid is sprayed from one air/water feeding nozzle60onto the outer surface of the respective observation lenses31a,31band keep the lenses in a clean state, thereby ensuring the excellent observation field of view.

Note that, the afore-mentioned special light observation is not limited to the fluorescent light observation, but may be an enlarged observation for obtaining an enlarged observation image as a special light observation image, in which the image can be enlarged to a high enlargement magnification compared with the normal light observation image by means of an enlarging optical system having an enlargement magnification of a histological level for observing a cell or gland structure (desirably equal to or more than 100 times level enlargement magnification).

Note that the present invention is not limited to the above-described embodiment, and various changes thereof could be made without departing from the spirit or scope of the invention.