JP2012205849A - Electronic endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To emit a sufficient quantity of short-wavelength light as illumination light, and to narrow a distal end section.SOLUTION: An imaging section 36 and a light source section 37 are incorporated in the distal end section 16a in the electric endoscope. The imaging section 36 includes an objective optical system unit 34, a prism 38, and a CCD 39. The optical axis of an objective optical system 27 of the objective optical system unit 34 is disposed parallel to the direction of insertion of the distal end section 16a, and the CCD 39 is disposed parallel to the direction of insertion. The prism 38 forms an image of the image light inside a subject taken by the objective optical system 27 in the CCD 39. A semiconductor light source 45 which emits blue light is disposed on the proximal end side in the direction of insertion of the distal end section 16a relative to the prism 38, and the blue light from the semiconductor light source 45 is guided by an optical fiber bundle 33 to an illumination lens 28.

Description

  The present invention relates to an electronic endoscope that observes the inside of a subject.

  In the medical field, many diagnoses and treatments using an electronic endoscope are performed. An electronic endoscope has an objective optical system for capturing image light in a subject at the distal end of an insertion portion that is inserted into the subject, and an image sensor on which the image light captured by the objective optical system is imaged And an illumination optical system for irradiating illumination light into the subject.

  In a medical electronic endoscope, when an abnormal structure of a blood vessel in a living tissue is observed, it is required to acquire an observation image in which the blood vessel is emphasized with respect to a peripheral part. Hemoglobin, which is a blood component, has a high blue light absorption rate and a low red light absorption rate. That is, blue light is absorbed by the surface layer, but red light reaches the inside of the blood vessel and scatters. Therefore, in order to observe with an increased contrast between the blood vessel and the peripheral site, it is necessary to irradiate the subject with more blue light from the illumination optical system.

  In a conventional electronic endoscope, an optical fiber bundle disposed through the inside of the insertion section and the hand operation section is provided, and this optical fiber bundle emits blue light emitted from a light source disposed outside the electronic endoscope. (For example, Patent Document 1). As the optical fiber bundle, one having a NA (Numerical Aperture) as large as possible is used. Since an optical fiber bundle having a large NA has a large light irradiation angle, the inside of the subject can be illuminated in a wide range. In the electronic endoscope described in Patent Document 2, a semiconductor light source such as an LED that emits blue light is provided at the distal end portion of the insertion portion, and the subject is irradiated with the blue light emitted from the LED.

  On the other hand, in an electronic endoscope, in order to reduce the burden on the patient at the time of insertion, further reduction in the diameter of the distal end portion is required. Therefore, as in the electronic endoscope described in Patent Document 3, the optical axis of the objective optical system is arranged in parallel to the axial direction (insertion direction) of the insertion portion, and the imaging element is parallel to the optical axis of the objective optical system. A prism that is arranged and refracts the optical path of the image light taken in by the objective optical system and enters the light receiving surface of the image sensor is provided at the rear end of the objective optical system. As a result, since the imaging element having a large area can be arranged in parallel with the axial direction of the insertion portion, it is possible to efficiently arrange components in the internal space of the tip portion and contribute to the reduction in diameter.

Japanese Patent Laid-Open No. 2001-170009 JP 2009-297290 A JP 2002-136474 A

  However, as in the electronic endoscope described in Patent Document 1, when light supplied from an external light source is guided by a light guide made of an optical fiber, the amount of light is greatly attenuated due to transmission loss. The attenuation factor increases as the size of the optical fiber increases. Further, if it is attempted to obtain a sufficient amount of light with an optical fiber having a long overall length, it is necessary to provide a high-power semiconductor light source, which is not preferable in terms of cost and safety. Further, when an optical fiber having a large NA is used, if the distance from the light source to the tip portion is long, the number of reflections inside increases, so that the attenuation of short-wavelength light becomes significant.

  In addition, in an electronic endoscope in which a light source is provided at the distal end as in Patent Document 2, an objective optical system and the like are disposed in the vicinity of the distal end together with the light source. When the objective optical system and the light source are arranged side by side, the distal end This will prevent the diameter of the part from being reduced. Furthermore, a small LED that can obtain a sufficient amount of light is expensive, which hinders cost reduction of the electronic endoscope. In Patent Document 3, no consideration is given to the arrangement of a light source in an electronic endoscope in order to irradiate illumination with a short wavelength, or attenuation when guiding illumination light with an optical fiber.

  The present invention has been made in view of the above problems, and can irradiate a short-wavelength light as illumination light with a sufficient amount of light within the distal end portion of the insertion portion, and reduce the diameter of the distal end portion. An object of the present invention is to provide an electronic endoscope that can achieve the above.

  An electronic endoscope according to the present invention is provided at a distal end portion of an insertion portion to be inserted into a subject, an imaging element disposed inside the distal end portion and in parallel with an insertion direction of the insertion portion, and the distal end portion An objective optical system that is disposed in parallel with the insertion direction at a position exposed from the distal end surface of the lens, and that takes in the image light in the subject for observation, and refracts the image light captured by the objective optical system An optical path conversion member for forming an image on the image sensor, and a light source that emits short-wavelength light, disposed on the proximal end side in the insertion direction with respect to the optical path conversion member inside the distal end portion, It comprises an illumination optical system for irradiating illumination light into the subject from the tip surface, and an optical fiber bundle for guiding light from the light source to the illumination optical system.

  The light source is preferably a semiconductor light source. The optical fiber bundle preferably has an NA of 0.5 or more.

  The short wavelength light emitted from the light source is preferably blue light having a wavelength of 550 nm or less.

  The optical path conversion member is preferably a prism. It is preferable to provide a condensing member for condensing light from the light source onto the optical fiber bundle, on the base end side of the optical path conversion member and between the optical fiber bundle and the light source.

  According to the present invention, a light source that emits short-wavelength light is disposed on the proximal end side of the optical path conversion member that refracts image light captured by the objective optical system and forms an image on the imaging device. Since the light is guided to the illumination optical system by the optical fiber, an observation image having a large contrast between the blood vessel and the peripheral portion can be obtained.

It is an external appearance perspective view of an electronic endoscope system. It is a perspective view which shows the structure of the front-end | tip part of an electronic endoscope. It is sectional drawing of the front-end | tip part cut | disconnected along the objective optical system and the illumination optical system. It is a graph which shows the extinction coefficient of hemoglobin. It is a graph which shows the attenuation factor of an optical fiber. It is sectional drawing which shows the modification provided with the optical fiber bundle guided to two illumination optical systems.

  As shown in FIG. 1, the electronic endoscope system 10 includes an electronic endoscope 11, a processor device 12, an air / water supply device 13, and the like. The air / water supply device 13 includes a well-known air supply device (pump or the like) 13a for supplying air, and stores cleaning water in a cleaning water tank 13b provided outside. The electronic endoscope 11 is connected to an insertion portion 16 to be inserted into a subject, a hand operating portion 17 connected to a proximal end portion of the insertion portion 16, a processor device 12, and an air / water supply device 13. Connector 18, and a universal cord 19 that connects between the hand operating section 17 and the connector 18.

  The insertion portion 16 is provided at the distal end thereof, and includes a distal end portion 16a having a built-in CCD type image sensor (see FIG. 3, hereinafter referred to as CCD) 39 as an imaging element for in-subject imaging, and a distal end portion 16a. It comprises a bendable bending portion 16b provided continuously at the base end, and a flexible flexible tube portion 16c provided continuously at the base end of the bending portion 16b.

  The connector 18 is a composite type connector to which the processor device 12 and the air / water supply device 13 are respectively connected. The hand operating section 17 includes an angle knob 21 for bending the bending section 16b vertically and horizontally, and an air / water supply button 22 for ejecting air and water from an air / water supply nozzle 30 (see FIG. 2). An operating member is provided. The hand operating section 17 is provided with a forceps inlet 23 for inserting a treatment instrument such as an electric knife into a forceps channel (not shown).

  The processor device 12 controls the overall operation of the electronic endoscope system 10. The processor device 12 supplies power to the electronic endoscope 11 via the image pickup device cable 43 and the light source cable 51 (see FIG. 3) inserted into the universal cord 19 and the insertion portion 16, and the CCD 39 and the semiconductor light source 45. The drive of (refer FIG. 3) is controlled. Further, the processor device 12 acquires an imaging signal output from the CCD 39 via the imaging element cable 43, and performs various image processing to generate image data. The image data generated by the processor device 12 is displayed as an observation image on a monitor 24 connected to the processor device 12 by a cable.

  As shown in FIGS. 2 and 3, the distal end portion 16 a includes a distal end portion main body 25, a distal end protective cap 26 fixed to the distal end side of the distal end portion main body 25, an objective optical system 27, and an illumination lens 28 as an illumination optical system. A forceps outlet 29 and an air / water supply nozzle 30. The distal end main body 25 is formed with through holes 25 a and 25 b that hold components such as the objective optical system unit 34 and the optical fiber bundle 33 along the axial direction of the insertion portion 16. The rear end of the distal end portion main body 25 is connected to a bending piece 31 on the distal end side that constitutes the bending portion 16b.

  The tip protection cap 26 includes a tip plate portion 26 a that covers the tip side of the tip portion main body 25 and a cylindrical portion 26 b that covers the outer peripheral surface of the tip portion main body 25. An outer skin layer 32 covering the outer peripheral surface of the curved portion 16b extends to the distal end body 25, the distal end of the outer skin layer 32 and the rear end of the cylindrical portion 26b are brought into contact with each other, and the ends are fixed with an adhesive or the like. . The distal end plate portion 26 a is formed with a distal end surface 26 c that is flat and orthogonal to the axial direction (insertion direction) of the insertion portion 16 and is located on the distal end side. Through holes 26d to 26f and a forceps outlet 29 are formed in the distal end plate portion 26a.

  The objective optical system 27 and the lens barrel 35 constitute an objective optical system unit 34. The lens barrel 35 holds the objective optical system 27. The objective optical system 27 is a fixed focus type, and an optical axis is arranged along a direction parallel to the insertion direction of the insertion portion 16. In the objective optical system unit 34, the outer peripheral surface of the lens barrel 35 is fitted into the through hole 25 a of the tip body 25, and the outer peripheral surface of the lens 27 a on the most distal side is fitted into the through hole 26 d of the tip protection cap 26. The front end surface of 35 is attached to the front end protection cap 26 in abutment. Thereby, in the objective optical system 27, the lens 27a is arranged at a position exposed from the through hole 26d, and the surface to be the light incident surface is located on the same plane as the tip surface 26c, and from a direction parallel to the insertion direction. Capture the image light.

  The illumination lens 28 is attached to a position exposed from the through hole 26e, and the surface thereof is located on the same plane as the tip surface 26c. At the back of the illumination lens 28, an emission end of an optical fiber bundle 33 to be described later faces. The illumination lens 28 irradiates the illumination light guided by the optical fiber bundle 33 toward the observation range where the objective optical system unit 34 captures the image light.

  The forceps outlet 29 communicates with the forceps inlet 23 of the hand operation unit 17 via a forceps conduit (not shown). Various treatment tools inserted from the forceps inlet 23 are guided to the forceps conduit and can be treated by protruding the tip from the forceps outlet 29. The air / water supply nozzle 30 is provided so as to be exposed from the through-hole 26 f, and jets air or cleaning water supplied from the air / water supply device 13 toward the objective optical system 27. The attached dirt can be washed away.

  An imaging unit 36 and a light source unit 37 are incorporated in the distal end portion 16a. The imaging unit 36 includes an objective optical system unit 34, a prism 38 (optical path conversion member), and a CCD 39. The CCD 39 is arranged inside the distal end portion 16a and parallel to the insertion direction of the distal end portion 16a, that is, parallel to the optical axis direction of the objective optical system unit 34. The CCD 39 is disposed in a storage portion 25 c formed inside the distal end portion main body 25. The storage portion 25c is an opening having a shape cut out from the rear end surface of the distal end portion main body 25, and communicates with the through holes 25a and 25b.

  A prism 38 is attached to the rear end portion of the lens barrel 35. The prism 38 is a 45 ° right angled isosceles triangle prism, and a mirror 38a for reflecting incident light is formed on a slope facing the right angle. A cover glass 40 is connected to the emission surface 38 b of the prism 38.

  The CCD 39 is made of, for example, an interline CCD, and a bare chip having an imaging surface (not shown) provided on the surface is used. A cover glass 40 is attached to the imaging surface of the CCD 39 through a square frame spacer 41. The image light in the subject taken in by the objective optical system 27 is refracted at right angles by the mirror 38a of the prism 38, imaged on the imaging surface of the CCD 39, and converted into an imaging signal.

  A circuit board 42 having substantially the same thickness as the CCD 39 is bonded to the base end face of the CCD 39. The CCD 39 and the circuit board 42 are electrically connected. An image sensor cable 43 is connected to a terminal formed at the rear end of the circuit board 42. The image sensor cable 43 bundles a plurality of signal lines 43 a and covers the bundled signal lines 43 a with a tube 44. Each signal line 43a is connected to a terminal of the circuit board 42 by soldering or the like. Since the image sensor cable 43 is arranged on the base end side of the CCD 39 via the circuit board 42, there is a space on the base end side of the prism 38.

  A light source unit 37 is disposed on the base end side in the insertion direction with respect to the prism 38 and at a position facing the prism 38. The light source unit 37 includes a semiconductor substrate 46 provided with a semiconductor light source 45, a condenser lens 47, a lens frame 48, and a support piece 49. An LED is used as the semiconductor light source 45.

  A connection terminal 50 is provided on the semiconductor substrate 46. A light source cable 51 is connected to the connection terminal 50 by soldering or the like. The light source cable 51 is bundled together with the image sensor cable 43.

The semiconductor light source 45 emits blue light, which is light with a short wavelength, and specifically emits light with a wavelength of 550 nm or less as blue light. Furthermore, the blue light emitted from the semiconductor light source 45 preferably has a wavelength of 350 nm or more and 550 nm or less, and more preferably 400 nm or more and 550 nm or less. As shown in FIG. 4, hemoglobin in blood has an extinction coefficient of mM cm ⁻¹ depending on the wavelength of illumination light. Hb represents the extinction coefficient of oxyhemoglobin, and HbO2 represents the extinction coefficient of reduced hemoglobin. These extinction coefficients indicate the magnitude (absorbance), and it can be seen that red light (700 nm or more) has a low absorptance and blue light (550 nm or less) described above has a high absorptance.

  The condensing lens 47 is disposed between the optical fiber bundle 33 and the semiconductor light source 45, collects blue light emitted from the semiconductor light source 45, and guides it to the optical fiber bundle 33. The lens frame 48 houses the condensing lens 47 inside, and the semiconductor substrate 46 is fixed to the base end side.

  The optical fiber bundle 33 is formed by bundling a large number of optical fibers (for example, made of quartz) and covering the outer peripheral surface with a tube. The optical fiber bundle 33 is held at the distal end body 25 at the distal end side and at the lens frame 48 at the distal end side, and guides blue light from the semiconductor light source 45 to the illumination lens 28. As the optical fiber bundle 33, an optical fiber bundle having a large NA, preferably an optical fiber bundle having an NA of 0.5 or more is used.

  The lens frame 48 is fixed to the support piece 49. The support piece 49 is connected to the circuit board 42 by a flexible board 52. Thereby, the circuit board 42 and the lens frame 48 are connected via the flexible board 52 and the support piece 49, and movement in the axial direction is restricted. The lens frame 48 that is restricted from moving in the axial direction, and the condensing lens 47 and the semiconductor substrate 46 held by the lens frame 48 are accommodated in the accommodating portion 25 c of the tip end body 25 together with the CCD 39 and the circuit substrate 42. The mounting structure of the condensing lens 47 and the semiconductor substrate 46 is not limited to the above structure, and may be any mounting structure that allows the condensing lens 47 and the semiconductor substrate 46 to be disposed inside the distal end body 25. The lens frame 48 or the semiconductor substrate 46 may be fixed to the circuit board 42 or the tip body 25.

  As described above, the CCD 39 is arranged in parallel with the insertion direction of the distal end portion 16 a, and the prism 38 for forming the image light in the subject captured by the objective optical system 27 on the CCD 39 is provided. On the other hand, the semiconductor light source 45 that emits blue light is disposed on the base end side in the insertion direction of the distal end portion 16a, and the blue light from the semiconductor light source 45 is guided to the illumination lens 28 by the optical fiber bundle 33. Can be accommodated inside the tip end portion 16a and the size thereof can be shortened. Therefore, the blue light emitted from the semiconductor light source 45 has little transmission loss, and when observing using the electronic endoscope 11, sufficient blue light can be irradiated into the subject. Further, since the optical fiber bundle 33 guides blue light with a short dimension, an optical fiber bundle having a large NA of 0.5 or more can be used. Since the optical fiber bundle 33 having a large NA has a sufficient irradiation angle, the illumination lens 28 to which the blue light is guided by the optical fiber bundle 33 can irradiate the subject with blue light in a wide range. When the illumination light of the blue light is irradiated from the illumination lens 28 to the observation range in the subject, the imaging unit 36 that images the observation range has a large contrast between the blood vessel and the peripheral portion, and the blood vessel is emphasized. An observation image can be acquired and displayed on the monitor 24.

  In the conventional electronic endoscope, light is guided from an external light source to the illumination optical system at the distal end of the insertion portion with an optical fiber bundle of about 3 m, so that transmission loss is large. As shown in FIG. 5, when a long optical fiber bundle is used, the attenuation factor is large for short-wavelength light. L1, L2, and L3 indicate attenuation rates when optical fiber bundles having dimensions of 1 m, 5 m, and 10 m, respectively, are used. In these optical fiber bundles, it can be seen that light having a short wavelength of 550 nm or less has a large attenuation rate. In the present invention, since the optical fiber bundle 33 can be formed with a short dimension, this does not occur. Further, as the semiconductor light source 45, a sufficient amount of light can be obtained with general-purpose components, so that the cost of the electronic endoscope can be reduced.

  In the distal end portion 16a, the semiconductor light source 45 and the condenser lens 47 are arranged on the proximal end side of the prism 38 having a sufficient space. Therefore, the components are efficiently arranged in the internal space of the distal end portion 16a to reduce the diameter. Can be achieved. Further, since the optical fiber bundle 33 having a large NA is used, it is possible to use an illumination lens 28 having a small diameter. For example, if the diameter of the objective optical system 27 is 3 mm, the optical fiber can be used. The bundle 38 is a bundle of 1000 to 6000 optical fibers of about 30 μm, has a diameter of 1.3 mm, and the illumination lens 28 has only to have a diameter of 1.5 mm. Therefore, the diameter of the tip portion 16a can be further reduced.

  In the first embodiment, the configuration including the optical fiber bundle 33 that guides light from the semiconductor light source 45 provided at the distal end portion 16a to the one illumination lens 28 is raised. Like the front end portion 60, optical fiber bundles 62a and 62b branched in the middle from the semiconductor light source 45 toward the two illumination lenses 61a and 61b may be used. In FIG. 6, parts similar to those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the second embodiment, the distal end portion 60 is provided with two illumination lenses 61a and 61b with the objective optical system 27 interposed therebetween. The optical fiber bundles 62a and 62b are held at the tip end body 25 and the base end portion at the lens frame 48, respectively, and guide the blue light from the semiconductor light source 45 to the illumination lenses 61a and 61b. Thereby, the dimension of optical fiber bundle 62a, 62b can be shortened similarly to the said 1st Embodiment. As the optical fiber bundles 62a and 62b, an optical fiber bundle having a large NA, preferably an optical fiber bundle having an NA of 0.5 or more is used for the above-described embodiment.

  In the above embodiment, the LED is used as the semiconductor light source. However, the present invention is not limited to this, and may be an LD, for example. In the above-described embodiment, the fixed-focus objective optical system is provided at the tip. However, the present invention is not limited to this, and a variable-focus objective optical system that switches the focus by moving a part of the objective optical system may be used. Good. In the above embodiment, the prism 38 is provided as an optical path conversion member for imaging the image light in the subject captured by the objective optical system 27 on the CCD 39. However, the present invention is not limited to this, and a plate-like mirror or the like is also provided. Good. Furthermore, in the above-described embodiment, a CCD is used as an imaging device that captures image light in a subject. However, the present invention is not limited to a CCD and may be a CMOS.

DESCRIPTION OF SYMBOLS 10 Electronic endoscope system 11 Electronic endoscope 16 Insertion part 16a, 60 Tip part 28, 61a, 61b Illumination lens 27 Objective optical system 33, 62a, 62b Optical fiber bundle 45 Semiconductor light source

Claims (6)

An imaging device provided at a distal end portion of an insertion portion to be inserted into a subject, and arranged in parallel to the insertion direction of the insertion portion and inside the distal end portion;
An objective optical system that is disposed at a position exposed from the distal end surface of the distal end portion and parallel to the insertion direction, and that takes in image light in the subject for observation;
An optical path changing member for refracting the image light taken in by the objective optical system to form an image on the image sensor;
A light source that emits short-wavelength light, disposed on the proximal end side in the insertion direction with respect to the optical path conversion member inside the distal end portion,
An illumination optical system for irradiating illumination light into the subject from the tip surface;
An electronic endoscope comprising an optical fiber bundle that guides light from the light source to the illumination optical system.   The electronic endoscope according to claim 1, wherein the light source is a semiconductor light source.   The electronic endoscope according to claim 2, wherein the optical fiber bundle has an NA of 0.5 or more.   The electronic endoscope according to any one of claims 1 to 3, wherein the short-wavelength light emitted from the light source is blue light having a wavelength of 550 nm or less.   The electronic endoscope according to claim 1, wherein the optical path conversion member is a prism.   The condensing member for condensing the light from the light source to the optical fiber bundle is provided between the base end side of the optical path conversion member and the optical fiber bundle and the light source. Item 6. The electronic endoscope according to any one of Items 1 to 5.

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