JP2014121363A - Light source device and endoscope system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device capable of reducing an optical loss of the light other than excitation light of a fluorescent body by an inexpensive configuration.SOLUTION: A light source device for supplying illumination light to a light guide of an endoscope comprises: semiconductor light sources 31-33; a light guide rod 40; and a reduction optical system. The semiconductor light source 31 includes a fluorescent body 36, and a light emitting device 66 having a laser diode LD1 that emits excitation light of the fluorescent body 36, and emits white light for normal light observation .The semiconductor light source 31, the fluorescent body 36, the light guide rod 40, and the reduction optical system are arranged so that the optical axis coincides with an optical axis L of the light guide. The semiconductor light sources 32 and 33 have light-emitting devices 76 and 78 respectively, and are arranged at a position where the light of the light-emitting devices 76 and 78 is caused to be incident on a margin 73 of an incident end face 70 of the light guide rod 40.

Description

  The present invention relates to a light source device for supplying illumination light to an endoscope, and an endoscope system using the same.

  In the medical field, endoscopic diagnosis using an endoscopic system is widespread. The endoscope system includes an endoscope, a light source device for supplying illumination light to the endoscope, and a processor device that processes an image signal output from the endoscope. The endoscope has an insertion part that is inserted into a living body, and an illumination window that irradiates the observation part with illumination light and an observation window for photographing the observation part are arranged at the tip of the insertion part. The endoscope has a built-in light guide made of a fiber bundle in which optical fibers are bundled. The light guide guides the illumination light supplied from the light source device to the illumination window. An imaging element such as a CCD is disposed in the back of the observation window. The inside of the living body can be observed by imaging an observation site irradiated with illumination light with an imaging device, generating an observation image with a processor device based on an image signal obtained thereby, and displaying the observation image on a monitor.

  In recent endoscopic diagnosis, special light observation using special light limited to a specific wavelength in addition to normal light observation that observes the overall properties of the surface of in vivo tissues under white light Has also been done. For special light observation, photographing is performed by using narrow-band light in the wavelength range with high absorbance to blood hemoglobin as illumination light, and an observation image in which blood vessels are emphasized is generated and observed, or blood hemoglobin is observed. In some cases, an observation image obtained by imaging the oxygen saturation is generated and observed.

  Conventionally, xenon lamps and halogen lamps that emit white light have been used as light sources as light sources, but recently, instead of these, semiconductor light sources having light emitting elements such as laser diodes (LDs) and LEDs are used. The thing is also proposed (refer patent document 1, 2).

  In the light source device described in Patent Literature 1, as a white light source that generates white light for normal light observation, it is excited by a semiconductor laser that emits narrow band light (blue light) with a central wavelength of 445 nm and narrow band light with a central wavelength of 445 nm. A semiconductor light source combined with a phosphor emitting green to yellow fluorescence is used. The phosphor is obtained by solidifying a powdery fluorescent material with a binder, and has a diffusing action in which incident light is diffused by the fluorescent material or the binder and the light quantity distribution of the emitted light is made uniform. In Patent Document 1, in addition to the above semiconductor light source, a semiconductor laser for special light observation that emits narrow band light with a central wavelength of 405 nm, which has a high absorbance to blood hemoglobin, and a treatment light with a central wavelength of 635 nm for killing a tumor. A semiconductor light source using a semiconductor laser that emits light, a semiconductor laser that emits narrow-band light having a center wavelength of 473 nm for compensating the blue component of white light, and the like as a light emitting element is provided.

  In Patent Document 1, first and second condensing lenses are provided as a condensing optical system that condenses light from a plurality of semiconductor light sources onto a light guide of an endoscope. The phosphor for the white light source is disposed between the condenser lenses. The light from the plurality of semiconductor light sources enters the first condenser lens, and the light emitted from the first condenser lens enters the phosphor. The light incident on the phosphor is diffused inside and emitted as divergent light having a divergence angle from the emission surface (light emitting surface). The second condenser lens collects the divergent light incident from the phosphor on the incident end of the light guide. As described above, the light source device described in Patent Document 1 has a configuration in which, in addition to excitation light that needs to pass through the phosphor to generate white light, all other special light is incident on the light guide through the phosphor. It is.

  Similar to the white light source of Patent Document 1, the light source device described in Patent Document 2 is a phosphor-type white LED that is a white light source using a phosphor, a blue LED or a green LED for special light observation, and each LED. A branched fiber bundle for condensing the light on the light guide of the endoscope.

  A branch type fiber bundle is similar to a normal light guide in that a plurality of optical fibers are bundled, but a normal light guide has one entrance end and one exit end, whereas a branch type In the fiber bundle, the incident end is branched into a plurality of portions, and each branch portion where the incident end is formed is integrated into one on the way and integrated into one output end.

  Each LED is arranged opposite to the incident end of each branch portion of the branch type fiber bundle. On the other hand, the incident end of the light guide of the endoscope is disposed opposite to the exit end of the branched fiber bundle. The light of each color LED incident on each branch is guided to one exit end and enters the light guide of the endoscope. In the branch type fiber bundle, the optical fiber corresponding to each branch part is randomly dispersed on the output end face in order to uniformize the light quantity distribution on the output end face of the LED light of each color incident from the entrance end of each branch part. Has been placed.

  In the light source device described in Patent Document 2, the light of the white light source LED and the light of the other special light observation LEDs are incident from different branch portions. For this reason, unlike the light source device described in Patent Document 1, the special light enters the light guide of the endoscope without passing through the phosphor.

JP 2012-105715 A JP 2011-041758 A

  In Patent Document 1, since not only the excitation light of the phosphor for the white light source but also other special light is incident on the light guide of the endoscope through the phosphor, the special light is lost due to the passage of the phosphor. There is a problem that is large. In addition, depending on the wavelength of the special light, the phosphor may be excited, and there is a problem that unnecessary fluorescence is mixed into the special light when observing the special light.

  On the other hand, in the light source device described in Patent Document 2, the incident end of the white light source light and the incident end of the special light are separated by the branched fiber bundle. There is no problem that sometimes unnecessary fluorescence is mixed. However, the branch type fiber bundle has a problem that the parts cost is high because it takes time to manufacture, such as forming a plurality of branch parts, and arranging the optical fibers of each branch part at the emission end at random. Further, because of the structure of the fiber bundle, the gap between the optical fibers in the cross section of the bundle cannot be completely eliminated, so that optical loss due to the gap is inevitably generated.

  For this reason, in a light source device having a light source that uses a phosphor such as a white light source for normal light observation and a light source that does not use a phosphor such as a light source for special light observation, a light source that does not use a phosphor. Development of an inexpensive configuration with low light loss was expected.

  However, when considering an inexpensive light source device that reduces light loss of light other than the excitation light of the phosphor, white light is used for normal light observation, which can be said to be the main in endoscopic diagnosis, so In order not to lose the amount of light at the center of the emitted white light spot, the optical axes of the semiconductor light source, phosphor, and other optical members involved in the generation of white light are made to coincide with the optical axis of the light guide of the endoscope It is necessary. In consideration of these restrictions, it is necessary to consider a method for guiding light other than the excitation light of the phosphor to the light guide of the endoscope with a small loss.

  The present invention has been made in view of the above problems, and provides a light source device capable of reducing light loss of light other than phosphor excitation light with an inexpensive configuration, and an endoscope system using the same. For the purpose.

  In order to achieve the above object, a light source device for supplying illumination light to a light guide of an endoscope according to the present invention includes first and second semiconductor light sources and a light guide rod. The first semiconductor light source includes a first light emitting element and a phosphor that emits fluorescence when excited by the light of the first light emitting element, and emits light mixed with the light of the first light emitting element and the fluorescence from the light emitting surface of the phosphor. To emit. The second semiconductor light source has a second light emitting element, and emits monochromatic light composed only of the light from the second light emitting element without using a phosphor. The light guide rod has an incident end surface having a larger area than the light emitting surface of the phosphor, and has a larger area than the light emitting surface of the phosphor at the incident end surface. And has an emission end face that emits incident light, and guides light emitted from the first and second semiconductor light sources toward the light guide. The first semiconductor light source is disposed with its optical axis parallel to the optical axis of the light guide rod and with the light emitting surface of the phosphor joined to the incident end surface of the light guide rod. The second semiconductor light source is disposed at a position where the light of the second light emitting element is incident in the margin.

  The second semiconductor light source is arranged in such a posture that its optical axis is directed to the optical axis of the light guide rod. A plurality of second semiconductor light sources are provided.

  The light guide rod has a square cross section orthogonal to the optical axis, and the phosphor has a circular cross section orthogonal to the optical axis. The blanks are formed at the four corners of the incident end face of the light guide rod. A plurality of second semiconductor light sources having different incident angles of light with respect to the margin are assigned to one margin. The same number of second semiconductor light sources are assigned to the margins formed at the four corners.

  A light diffusion surface is formed in the margin. As a method of setting the margin as the light diffusion surface, for example, a glass bead layer is provided in the margin, the margin is roughened, or a sheet-like LSD is attached to the margin. You may carry out combining these.

  The light guide rod has a tapered shape in which the side surface connecting the incident end surface and the exit end surface is inclined with respect to the optical axis so that the area of the exit end surface is larger than the incident end surface.

  The light emitting surface of the phosphor and the incident end surface of the light guide rod are joined so that their centers coincide.

  A reflector for reflecting the light of the second light emitting element to enter the margin may be provided.

  The first light emitting element emits excitation light having a central wavelength of 445 nm, and the phosphor is excited by the excitation light and emits fluorescence in a wavelength region extending from the green region to the red region. White light is generated as mixed light by the excitation light and fluorescence.

  The second light emitting element emits at least one of narrowband light having a central wavelength of 405 nm for blood vessel enhancement observation and narrowband light having a central wavelength of 473 nm for observation of oxygen saturation of blood hemoglobin.

  The first and second light emitting elements have either laser diodes or LEDs.

  The present invention also provides an endoscope system including an endoscope with a built-in light guide that guides illumination light, and a light source device that supplies illumination light to the light guide. Two semiconductor light sources and a light guide rod are provided. The first semiconductor light source includes a first light emitting element and a phosphor that emits fluorescence when excited by the light of the first light emitting element, and emits light mixed with the light of the first light emitting element and the fluorescence from the light emitting surface of the phosphor. To emit. The second semiconductor light source has a second light emitting element, and emits monochromatic light composed only of the light from the second light emitting element without using a phosphor. The light guide rod has an incident end surface having a larger area than the light emitting surface of the phosphor, and has a larger area than the light emitting surface of the phosphor at the incident end surface. And has an emission end face that emits incident light, and guides light emitted from the first and second semiconductor light sources toward the light guide. The first semiconductor light source is disposed with its optical axis parallel to the optical axis of the light guide rod and with the light emitting surface of the phosphor joined to the incident end surface of the light guide rod. The second semiconductor light source is disposed at a position where the light of the second light emitting element is incident in the margin.

  According to the present invention, the light guide rod is used instead of the fiber bundle, and the light of the second light emitting element is incident from the margin of the incident end face of the light guide rod without passing through the phosphor. Light loss of light other than light can be reduced.

It is an external view of the endoscope system of the present invention. It is a front view of the front-end | tip part of an endoscope. It is a block diagram which shows the electric constitution of an endoscope system. It is a graph which shows the spectrum of illumination light. It is a graph which shows the absorption spectrum of hemoglobin. It is a graph which shows the scattering coefficient of a biological tissue. It is a graph which shows the spectral characteristic of the color microfilter of an image pick-up element. It is explanatory drawing which shows the irradiation timing and imaging timing of illumination light in each of (A) normal light observation mode, (B) blood vessel emphasis observation mode, and (C) oxygen saturation observation mode. It is explanatory drawing which shows the image processing procedure in each of (A) normal light observation mode, (B) blood vessel emphasis observation mode, and (C) oxygen saturation observation mode. It is a principal part perspective view of a light source device. It is a perspective view of the semiconductor light source which emits white light. It is principal part sectional drawing of a light source device. It is a top view which shows the incident end surface of a light guide rod. It is explanatory drawing which shows arrangement | positioning of the semiconductor light source which emits narrow-band light with a center wavelength of 405 nm and 473 nm. It is a graph which shows the radiation intensity distribution of the white light which injects into a light guide. It is a graph which shows the radiation intensity distribution of the narrowband light of the center wavelengths 405nm and 473nm which injects into the margin of a light guide rod. It is a graph which shows the radiation intensity distribution of the narrowband light of the center wavelength 405nm and 473nm which injects into a light guide. It is explanatory drawing which shows another example of arrangement | positioning of the semiconductor light source which emits narrow-band light with a center wavelength of 405 nm and 473 nm. It is principal part sectional drawing of the light source device which provided the reflector.

  In FIG. 1, an endoscope system 10 includes an endoscope 11 that images an observation site in a living body, a processor device 12 that generates an observation image of the observation site based on an image signal obtained by imaging, and an observation site. Is provided with a light source device 13 for supplying illumination light to the endoscope 11 and a monitor 14 for displaying an observation image. An operation input unit 15 such as a keyboard or a mouse is connected to the processor device 12.

  The endoscope system 10 uses white light as illumination light, a normal light observation mode for observing an observation site under white light, and a blood vessel existing in the observation site using special light as illumination light. A blood vessel enhancement observation mode and an oxygen saturation observation mode are provided. The blood vessel enhancement observation mode and the oxygen saturation observation mode are special light observation modes for grasping the characteristics of the blood vessel pattern, the oxygen saturation, and the like, and making a diagnosis such as tumor quality discrimination. In the blood vessel enhancement observation mode and the oxygen saturation observation mode, narrowband light in a wavelength region having a high absorbance for blood hemoglobin is used as the special light. In the blood vessel enhancement observation mode, a blood vessel enhancement image in which blood vessels are enhanced is displayed. In the oxygen saturation observation mode, an oxygen saturation image indicating the oxygen saturation of blood hemoglobin is displayed.

  The endoscope 11 includes an insertion portion 16 inserted into a digestive tract of a living body, an operation portion 17 provided at a proximal end portion of the insertion portion 16, and between the operation portion 17, the processor device 12, and the light source device 13. And a universal cord 18 to be connected.

  The insertion portion 16 includes a distal end portion 19, a bending portion 20, and a flexible tube portion 21 that are continuously provided from the distal end. As shown in FIG. 2, an illumination window 22 for irradiating the observation site with illumination light, an observation window 23 for capturing an image of the observation site, and an air supply for cleaning the observation window 23 are provided on the distal end surface of the distal end portion 19. An air supply / water supply nozzle 24 for supplying water and a forceps outlet 25 for performing various treatments by projecting a treatment tool such as forceps and an electric knife are provided. In the back of the observation window 23, an image sensor 44 and an objective optical system 51 for image formation (both see FIG. 3) are incorporated.

  The bending portion 20 includes a plurality of connected bending pieces, and is bent in the vertical and horizontal directions by operating the angle knob 26 of the operation portion 17. By bending the bending portion 20, the direction of the distal end portion 19 is directed in a desired direction. The flexible tube portion 21 is flexible so that it can be inserted into a tortuous duct such as the esophagus or the intestine. The insertion unit 16 includes a communication cable that communicates a drive signal for driving the image sensor 44 and an image signal output from the image sensor 44, and a light guide 43 that guides illumination light supplied from the light source device 13 to the illumination window 22. (See FIG. 3) is inserted.

  In addition to the amble knob 26, the operation unit 17 includes a forceps port 27 for inserting a treatment instrument, an air / water supply button 28 that is operated when air / water is supplied from the air / water supply nozzle 24, and a still image. A release button (not shown) for photographing is provided.

  A communication cable and a light guide 43 extending from the insertion portion 16 are inserted into the universal cord 18, and a connector 29 is attached to one end of the processor device 12 and the light source device 13. The connector 29 is a composite type connector composed of a communication connector 29a and a light source connector 29b. The communication connector 29a and the light source connector 29b are detachably connected to the processor device 12 and the light source device 13, respectively. One end of a communication cable is disposed on the communication connector 29a, and an incident end of the light guide 43 is disposed on the light source connector 29b.

  In FIG. 3, the light source device 13 includes three types of semiconductor light sources 31, 32, and 33 having different emission wavelengths, and a light source control unit 34 that drives and controls them. The semiconductor light source 31 corresponds to a first semiconductor light source, and the semiconductor light sources 32 and 33 correspond to a second semiconductor light source. The light source control unit 34 controls the drive timing and synchronization timing of each unit of the light source device 13.

  The semiconductor light sources 31 to 33 have laser diodes LD1, LD2, and LD3 that respectively emit narrowband light in a specific wavelength range. As shown in FIG. 4, in the blue (B) region, the laser diode LD1 emits narrowband light N1 whose wavelength region is limited to 440 ± 10 nm and whose center wavelength is 445 nm, for example. In the blue region, the laser diode LD2 emits narrowband light N2 whose wavelength region is limited to 410 ± 10 nm and whose center wavelength is 405 nm, for example. In the blue region, the laser diode LD3 emits narrowband light N3 whose wavelength region is limited to 470 ± 10 nm and whose center wavelength is 473 nm, for example. As the laser diodes LD1 to LD3, InGaN-based, InGaNAs-based, or GaNAs-based ones can be used. The laser diodes LD1 to LD3 are preferably broad area laser diodes having a wide stripe width (waveguide width) capable of increasing output.

The semiconductor light source 31 is a light source that emits white light for normal light observation. The semiconductor light source 31 has a phosphor 36 in addition to the laser diode LD1. As shown in FIG. 4, the phosphor 36 is excited by the 445 nm blue narrow-band light N1 emitted from the laser diode LD1, and emits the fluorescence FL in the wavelength region extending from the green (G) region to the red (R) region. Emits light. The phosphor 36 absorbs part of the narrowband light N1 to emit fluorescence FL, and transmits the remaining narrowband light N1 that has not been absorbed. The narrowband light N1 that passes through the phosphor 36 is diffused by the phosphor 36. White light is generated by the mixed light of the transmitted narrow-band light N1 and the excited fluorescence FL. As the phosphor 36, for example, a YAG-based or BAM (BgMgAl ₁₀ O ₁₇ ) -based phosphor is used.

  The semiconductor light source 32 is a light source for blood vessel enhancement observation. In FIG. 5 showing the absorption spectrum of blood hemoglobin, the absorption coefficient μa of blood hemoglobin has a wavelength dependence, increases rapidly in the region where the wavelength is 450 nm or less, and has a peak in the vicinity of 405 nm. Yes. Moreover, although it is a low value compared with the wavelength of 450 nm or less, it also has a peak at wavelengths of 530 nm to 560 nm. When the observation site is irradiated with light having a wavelength having a large extinction coefficient μa, the blood vessel has a large absorption, so that an image having a large contrast between the blood vessel and the other portion is obtained.

  Further, as shown in FIG. 6, the light scattering characteristics of the living tissue also have wavelength dependence, and the scattering coefficient μS increases as the wavelength becomes shorter. Scattering affects the depth of light penetration into living tissue. That is, the greater the scattering, the more light that is reflected near the mucosal surface layer of the biological tissue and the less light that reaches the mid-deep layer. Therefore, the shorter the wavelength, the lower the depth of penetration, and the longer the wavelength, the higher the depth of penetration. In view of such light absorption characteristics of hemoglobin and light scattering characteristics of living tissue, the wavelength of light for blood vessel enhancement is selected.

  Since the 405 nm narrow-band light N2 emitted from the semiconductor light source 32 has a low depth of penetration, the absorption by the surface blood vessels is large. For this reason, the narrow-band light N2 is used as light for surface blood vessel enhancement. By using the narrowband light N2, the superficial blood vessel can be depicted with high contrast in the observation image. Further, the green component of white light emitted from the semiconductor light source 31 is used as the light for emphasizing the middle-layer blood vessel. In the absorption spectrum shown in FIG. 5, the light absorption coefficient gradually changes in the green region of 530 nm to 560 nm as compared with the blue region of 450 nm or less. It is not required to be. Therefore, as will be described later, a green component that is color-separated from white light by the G-color microcolor filter of the image sensor 44 is used for medium-depth blood vessel enhancement.

  The semiconductor light source 33 is a light source for observing oxygen saturation. In FIG. 5, the solid line absorption spectrum Hb shows the absorption spectrum of reduced hemoglobin not bonded to oxygen, and the one-dot chain line absorption spectrum HbO2 shows the absorption spectrum of oxidized hemoglobin bonded to oxygen. Thus, reduced hemoglobin and oxyhemoglobin have different light absorption characteristics, and a difference occurs in the light absorption coefficient μa except for the isosbestic point (intersection of each spectrum Hb and HbO 2) showing the same light absorption coefficient μa. If there is a difference in the extinction coefficient μa, even if the light having the same light intensity and the same wavelength is irradiated, the reflectance changes if the oxygen saturation changes. In the oxygen saturation observation mode, narrowband light N3 having a wavelength of 473 nm emitted from the semiconductor light source 33 is used as a wavelength having a difference in the absorption coefficient μa, and the oxygen saturation is measured.

  In FIG. 3, the light source control unit 34 controls the turning on / off of the laser diodes LD <b> 1 to LD <b> 3 and the amount of light via a driver 37 connected to the laser diodes LD <b> 1 to LD <b> 3. Specifically, the light source control unit 34 turns on the laser diodes LD <b> 1 to LD <b> 3 by giving a drive pulse of current from the driver 37. Then, by performing PWM (Pulse Width Modulation) control for controlling the duty ratio of the drive pulse, the drive current value is changed to control the light emission amount of each of the narrowband lights N1 to N3. The control of the drive current value may be PAM (Pulse Amplitude Modulation) control that changes the amplitude of the drive pulse.

  A light guide rod 40 and a reduction optical system 41 are provided on the downstream side of the optical path of the semiconductor light sources 31 to 33. As described in detail later, the light guide rod 40 integrates the optical paths of the semiconductor light sources 31 to 33 into one optical path. Since the light guide 43 of the endoscope 11 has one incident end, the light path of the light from the semiconductor light sources 31 to 33 is guided by the light guide rod 40 before the light from the semiconductor light sources 31 to 33 is supplied to the endoscope 11. Are integrated. The reduction optical system 41 is disposed in the vicinity of the receptacle connector 42 to which the light source connector 29b is connected. The light emitted from the light guide rod 40 is supplied to the incident end of the light guide 43 disposed in the light source connector 29b via the reduction optical system 41. Although not shown, each of the light source connector 29b and the receptacle connector 42 is provided with protective glass.

  The endoscope 11 includes a light guide 43, an imaging element 44, an analog processing circuit 45 (AFE: Analog Front End), and an imaging control unit 46. The light guide 43 is a fiber bundle obtained by bundling a plurality of optical fibers. When the light source connector 29 b is connected to the light source device 13, the incident end of the light guide 43 disposed on the light source connector 29 b faces the reduction optical system 41 of the light source device 13. The exit end of the light guide 43 located at the distal end portion 19 is branched into two at the front stage of the illumination window 22 so that light is guided to the two illumination windows 22.

  An irradiation lens 48 is disposed behind the illumination window 22. The light supplied from the light source device 13 is guided to the irradiation lens 48 by the light guide 43 and irradiated from the illumination window 22 toward the observation site. The irradiation lens 48 is a concave lens, and widens the divergence angle of the light emitted from the light guide 43. Thereby, illumination light can be irradiated to the wide range of an observation site | part.

  In the back of the observation window 23, an objective optical system 51 and an image sensor 44 are arranged. The image of the observation site enters the objective optical system 51 through the observation window 23 and is formed on the imaging surface 44 a of the imaging element 44 by the objective optical system 51.

  The imaging element 44 is composed of a CCD image sensor, a CMOS image sensor, or the like, and has an imaging surface 44a in which a plurality of photoelectric conversion elements constituting pixels such as photodiodes are arranged in a matrix. The image sensor 44 photoelectrically converts the light received by the imaging surface 44a and accumulates signal charges corresponding to the amount of received light in each pixel. The signal charge is converted into a voltage signal by an amplifier and read out. The voltage signal is output from the image sensor 44 to the AFE 45 as an image signal.

  The image pickup device 44 is a color image pickup device, and micro-color filters of three colors B, G, and R having spectral characteristics as shown in FIG. 7 are assigned to each pixel on the image pickup surface 44a. The white light emitted from the semiconductor light source 31 is split into three colors of B, G, and R by the micro color filter. The arrangement of the micro color filter is, for example, a Bayer arrangement.

  As shown in FIG. 8, the image sensor 44 performs an accumulation operation for accumulating signal charges in the pixels and a read operation for reading the accumulated signal charges within an acquisition period of one frame. As shown in FIG. 8A, in the normal light observation mode, the laser diode LD1 is turned on in synchronization with the accumulation operation timing of the image pickup device 44, and is composed of mixed light of narrowband light N1 and fluorescence FL as illumination light. White light (N1 + FL) is irradiated onto the observation site, and the reflected light is incident on the image sensor 44. The image sensor 44 separates white light with a micro color filter. The B pixel receives reflected light corresponding to the narrow-band light N1, the G pixel receives reflected light corresponding to the G component in the fluorescence FL, and the R pixel receives reflected light corresponding to the R component in the fluorescence FL. Receive light. The image sensor 44 sequentially outputs the image signals B, G, and R for one frame in which the pixel values of the B, G, and R pixels are mixed according to the frame rate in accordance with the readout timing. Such an imaging operation is repeated while the normal light observation mode is set.

  In the blood vessel enhancement observation mode, as shown in FIG. 8B, in addition to the semiconductor light source 31, the semiconductor light source 32 is turned on in accordance with the accumulation operation timing of the image sensor 44. When the semiconductor light sources 31 and 32 are turned on, the narrow band light N2 is added together with the white light similar to the normal light observation mode, and the mixed light (N1 + FL + N2) is irradiated to the observation site as illumination light.

  As in the normal light observation mode, the illumination light in which the narrow band light N2 is added to the white light is split by the B, G, and R micro color filters of the image sensor 44. The B pixel of the image sensor 44 receives the narrowband light N2 in addition to the narrowband light N1. The G pixel receives the G component of the fluorescence FL. The R pixel receives the R component of the fluorescence FL. Even in the blood vessel enhancement observation mode, the image sensor 44 sequentially outputs the image signals B, G, and R according to the frame rate in accordance with the readout timing. Such an imaging operation is repeated while the blood vessel enhancement observation mode is set.

  In the oxygen saturation observation mode, as shown in FIG. 8C, first, the semiconductor light source 31 is turned on in accordance with the accumulation operation timing of the image sensor 44. When the semiconductor light source 31 is turned on, the observation site is irradiated with white light as in the normal light observation mode. In the next frame, the semiconductor light source 31 is turned off, the semiconductor light source 33 is turned on, and the narrow-band light N3 is irradiated to the observation site. Even in the oxygen saturation observation mode, the image sensor 44 sequentially outputs the image signals B, G, and R according to the frame rate in accordance with the readout timing.

  However, in the oxygen saturation observation mode, unlike the normal light observation mode and the blood vessel enhancement observation mode, the white light and the narrowband light N3 are alternately irradiated. Therefore, the image signals B and G corresponding to the white light in the first frame are used. , R are output, and in the next frame, the image signals B, G, R corresponding to the narrowband light N3 are output, and the information carried by the image signals B, G, R corresponding to each illumination light Also changes every other frame. Such an imaging operation is repeated while the oxygen saturation observation mode is set.

  In FIG. 3, the AFE 45 includes a correlated double sampling circuit (CDS), an automatic gain control circuit (AGC), and an analog / digital converter (A / D) (all not shown). The CDS performs a correlated double sampling process on the analog image signal from the image sensor 44, and removes noise caused by resetting the signal charge. AGC amplifies an image signal from which noise has been removed by CDS. The A / D converts the image signal amplified by AGC into a digital image signal having a gradation value corresponding to a predetermined number of bits and inputs the digital image signal to the processor device 12.

  The imaging control unit 46 is connected to the controller 56 in the processor device 12 and inputs a drive signal to the imaging device 44 in synchronization with a reference clock signal input from the controller 56. The imaging element 44 outputs an image signal to the AFE 45 at a predetermined frame rate based on the drive signal from the imaging control unit 46.

  In addition to the controller 56, the processor device 12 includes a DSP (Digital Signal Processor) 57, an image processing unit 58, a frame memory 59, and a display control circuit 60. The controller 56 includes a CPU, a ROM that stores a control program and setting data necessary for control, a RAM that loads the program and functions as a working memory, and the like. To control.

  The DSP 57 acquires an image signal output from the image sensor 44. The DSP 57 separates an image signal in which signals corresponding to B, G, and R pixels are mixed into B, G, and R image signals, and performs pixel interpolation processing on the image signals of the respective colors. In addition, the DSP 57 performs signal processing such as gamma correction and white balance correction on each of the B, G, and R image signals.

  The frame memory 59 stores image data output by the DSP 57 and processed data processed by the image processing unit 58. The display control circuit 60 reads the image processed image data from the frame memory 59, converts it into a video signal such as a composite signal or a component signal, and outputs it to the monitor 14.

  As shown in FIG. 9A, in the normal light observation mode, the image processing unit 58 uses the normal light based on the image signals B, G, and R color-separated into B, G, and R colors by the DSP 57. A display image for observation is generated. This display image is output to the monitor 14 as an observation image. The image processing unit 58 updates the display image every time the image signals B, G, and R in the frame memory 59 are updated.

  As shown in FIG. 9B, in the blood vessel enhancement observation mode, the image processing unit 58 generates a display image for blood vessel enhancement observation based on the image signals B, G, and R. The image signal B in the blood vessel enhancement observation mode includes information on the narrow band light N2 in addition to the B component of white light (including a part of the narrow band light N1 and the fluorescence FL). It is drawn with high contrast. In lesions such as cancer, compared to normal tissues, there is a feature in the pattern of blood vessels such as the density of superficial blood vessels tend to be high, so in blood vessel enhancement observation for the purpose of tumor quality discrimination, It is preferable that the superficial blood vessel is clearly depicted.

  When emphasizing the superficial blood vessels, for example, a superficial blood vessel region is extracted based on the image signal B, and contour enhancement processing or the like is performed on the extracted region. Then, the image signal B that has undergone the contour enhancement processing is combined with a full-color image generated from the image signals B, G, and R. By doing so, the superficial blood vessels are more emphasized. The same processing may be performed on the middle- and deep-layer blood vessels in addition to the surface blood vessels. When emphasizing the middle-and-deep blood vessel, the region of the middle-and-deep blood vessel is extracted from the image signal G that includes a lot of information about the middle-and-deep blood vessel, and contour enhancement processing is performed on the extracted region. The completed image signal G is combined with a full-color image generated from the image signals B, G, and R.

  The display image for blood vessel enhancement observation is generated based on the three color image signals B, G, and R, as in the case of normal light observation, so that the observation site can be displayed in full color. The image signal B in the observation mode has a higher blue density than the image signal B in the normal light observation mode. For this reason, when a display image for blood vessel enhancement observation is generated, color correction may be performed so that the same color as that of the display image for normal light observation is obtained. The image processing unit 58 generates a display image for blood vessel enhancement observation every time the image signals B, G, and R in the frame memory 59 are updated.

  As a method for generating a display image for blood vessel enhancement observation, the image signal R is generated using only two colors of the image signals B and G without using the image signal R, and the image signal B is generated by the B channel and the G channel of the monitor 14. In addition, a method of displaying the observation region in a pseudo color, such as a method of assigning a signal corresponding to the image signal G to the R channel of the monitor 14, may be employed.

  As shown in FIG. 9C, in the oxygen saturation observation mode, the image processing unit 58 is acquired under the image signals G1 and R1 acquired under white light and the narrowband light N3. Based on the obtained image signal B2, oxygen saturation calculation processing is performed. The pixel value of the image signal B2 includes blood volume information in addition to oxygen saturation. In order to obtain the oxygen saturation more accurately, it is necessary to separate blood volume information from the pixel value of the image signal B2. The image processing unit 58 performs an inter-image calculation with the image signal B using the image signal R showing a high correlation with the blood volume, and separates oxygen saturation and blood volume information.

  Specifically, the image processing unit 58 collates the pixel values at the same position of the image signals B2, G1, and R1, and determines the signal ratio B2 / G1 between the pixel value of the image signal B2 and the pixel value of the image signal G1. The signal ratio R1 / G1 between the pixel value of the image signal R1 and the pixel value of the image signal G1 is obtained. The image signal G1 is used as a reference signal representing the brightness level of the observation region in order to normalize the pixel values of the image signal B2 and the image signal R1. Then, based on a table in which the correlations between the signal ratios B2 / G1 and R1 / G1, the oxygen saturation and the blood volume are stored in advance, the oxygen saturation from which the blood volume information is separated is calculated. Then, the full color image generated based on the image signals B1, G1, and R1 is subjected to color conversion in accordance with the calculated oxygen saturation value to generate a display image for oxygen saturation observation.

  10 to 12, the semiconductor light source 31 includes a light source unit 61, a fluorescent unit 62 in which a fluorescent material 36 is filled in a cylindrical protective case 62a having a light shielding property, and a fluorescent unit 62 that emits light from the light source unit 61. And a single optical fiber 63 for guiding the light into the inside. 11 and 12, the light source unit 61 includes a light emitting element 66 (first light emitting element) having a laser diode LD1 and a case 67 that houses the light emitting element 66. The case 67 is provided with a connecting portion 67 a for connecting one end of the optical fiber 63, and a condensing lens 68 is built in the case 67. That is, the semiconductor light source 31 is a so-called receptacle type semiconductor light source.

  In the light emitting element 66, a laser diode LD1 as a semiconductor chip is attached to one surface of a disk-shaped stem 66a serving as a support, and the laser diode LD1 is covered with a resin-made cylindrical transparent cap 66b. A lead wire 66c extends from the back surface of the stem 66a.

  The laser diode LD1 is a semiconductor chip in which a P layer made of a P-type semiconductor and an N layer made of an N-type semiconductor are joined with an active layer interposed therebetween, and emits laser light from the active layer by laser oscillation. Laser light is highly divergent, but is divergent light whose beam shape spreads from the light emitting point in a substantially conical shape. The laser light is condensed at the incident end of the optical fiber 63 by the condenser lens 68.

  The emission end of the optical fiber 63 is connected to the fluorescent part 62. An insertion hole into which the optical fiber 63 is inserted is formed at the center of the phosphor 36 filled in the fluorescent part 62. The optical fiber 63 is inserted into the phosphor 36 with a connection ferrule (not shown) attached to its end.

  The phosphor 36 is obtained by dispersing and solidifying a powdery fluorescent material in a binder made of a resin material, and has a cylindrical shape that follows the protective case 62a. Since the fluorescent material is dispersed, the emission point of the excited fluorescence FL is the entire emission surface 69 of the phosphor 36. Further, since the narrow-band light N1 transmitted through the phosphor 36 is also diffused in the phosphor 36 by the light diffusing action of the binder, the entire light emitting surface 69 serves as a light emitting point.

  The light emitted from the phosphor 36 is divergent light that spreads in a substantially conical shape from the light emitting point, like the laser diode LD1, but has a larger area and divergence angle than the laser diode LD1.

  An incident end surface 70 of the light guide rod 40 for changing the divergence angle of incident light is joined to the light emitting surface 69 of the phosphor 36 with an adhesive or the like. The light emitting surface 69 and the incident end surface 70 are joined so that their centers coincide. In FIG. 10, the light guide rod 40 has the incident end face 70, an exit end face 71 that emits light incident on the entrance end face 70, and four side surfaces 72 that connect the entrance end face 70 and the exit end face 71. The light guide rod 40 is formed of solid transparent glass or the like, has a square cross-sectional shape orthogonal to the optical axis L of the light guide 43, and the side surface 72 has a larger area of the emission end surface 71 than the incident end surface 70. Has a tapered shape inclined with respect to the optical axis L. The light guide rod 40 propagates in the direction of the light guide 43 while reducing the divergence angle while totally reflecting the light incident from the incident end surface 70 on the four side surfaces 72 serving as an interface with air, and from the output end surface 71. Exit.

  As shown in FIG. 13, the length D <b> 1 of one side of the incident end face 70 of the light guide rod 40 is substantially the same as the diameter D <b> 2 of the fluorescent part 62. Since the incident end face 70 is square and the fluorescent portion 62 is cylindrical, the four corners of the incident end face 70 protrude from the light emitting surface 69 when viewed from the fluorescent portion 62 side. The four corners of the incident end face 70 that protrude from the periphery of the fluorescent part 62 when the area of the incident end face 70 is larger than the light emitting surface 69 are hereinafter referred to as blanks 73.

  As shown by hatching, a glass bead layer 74 is formed in the margin 73. The glass bead layer 74 is formed by applying an ultraviolet curable resin mixed with glass beads to the margin 73 and then applying the ultraviolet rays to cure the ultraviolet curable resin. In place of the glass bead layer 74, the margin 73 is roughened by sandblasting or the like, and a sheet-like LSD (Light Shaping Diffuser) made of polycarbonate or the like is attached to the margin 73, or a combination of these is performed ( The margin 73 may be used as a light diffusing surface by roughening + glass bead layer formation, roughening + LSD pasting, or the like).

  The light guide rod 40 has a length in the direction of the optical axis L and an inclination angle of the side surface 72 with respect to the optical axis L in consideration of the diameter of the light guide 43. Specifically, the spot diameter of light incident on the light guide 43 through the reduction optical system 41 is set to substantially match the diameter of the light guide 43.

  Further, the divergence angle of the light incident on the light guide 43 through the reduction optical system 41 is set in accordance with the NA (numerical aperture) of the optical fiber that is the strand of the light guide 43 that is a fiber bundle. As is well known, an optical fiber is composed of a core having a high refractive index and a clad having a low refractive index disposed around the core, and light incident from the incident end of the optical fiber is at the boundary between the core and the clad. It propagates in the direction of the optical axis L while being totally reflected. In order to propagate the light, it is necessary to make the light incident on the incident end of the optical fiber at an incident angle that satisfies the total reflection condition.

  NA is an index representing how much light can be collected by the optical fiber, and is defined by the sine of the maximum light receiving angle θmax (NA = sin θmax). The larger the maximum light receiving angle θmax, the larger the NA value. If the incident angle of the light beam incident on the optical fiber is less than or equal to the maximum light receiving angle θmax, total reflection occurs at the boundary between the core and the clad within the optical fiber, so that the incident light propagates in the optical axis L direction of the light guide 43. Light is guided. When the incident angle exceeds the maximum light receiving angle θmax, the incident light is transmitted without being totally reflected, so that the light guide 43 is not guided. Incident light that is not guided becomes a light transmission loss. In order to reduce this light transmission loss, the light guide rod 40 and the reduction optical system 41 restrict the beam divergence angle of the semiconductor light source 31 to be equal to or less than the maximum light reception angle θmax.

  The semiconductor light source 31, the fluorescent part 62 (phosphor 36), the light guide rod 40, and the reduction optical system 41 are arranged so that their optical axes coincide with the optical axis L of the light guide 43. On the other hand, a plurality of semiconductor light sources 32 and 33 used for blood vessel enhancement observation and oxygen saturation observation are arranged so that the optical axis thereof faces the optical axis of the light guide rod 40 so as to surround the semiconductor light source 31. .

  10 and 12, the plurality of semiconductor light sources 32 and 33 are fixedly held by a bowl-shaped holding frame 75 attached to the case 67. The holding frame 75 is curved in a concave shape toward the incident end surface 70 of the light guide rod 40. The semiconductor light source 32 includes a light emitting element 76 and a condenser lens 77. Similarly, the semiconductor light source 33 includes a light emitting element 78 and a condenser lens 79. The light emitting elements 76 and 78 both correspond to the second light emitting element. The holding frame 75 has a hollow structure including an inner frame 75a that forms the inner side of the bowl and an outer frame 75b that forms the outer side. The condensing lenses 77 and 79 are disposed on the inner frame 75a, and the light emitting element 76 is disposed on the outer frame 75b. 78 are attached respectively. The light emitting elements 76 and 78 have laser diodes LD2 and LD3, respectively, and other configurations such as a stem are the same as those of the light emitting element 66 of the semiconductor light source 31. The laser beams emitted from the laser diodes LD2 and LD3 are condensed toward the margin 73 of the incident end face 70 of the light guide rod 40 by the condenser lenses 77 and 79, respectively. The condenser lenses 77 and 79 may be accommodated in the transparent caps of the light emitting elements 76 and 78, and the holding frame 75 may be a single layer of the outer frame 75b.

  FIG. 14 schematically shows the arrangement of the semiconductor light sources 32 and 33 as viewed from the outer frame 75 b side of the holding frame 75. The semiconductor light sources 32 and 33 are alternately arranged at the vertices of a square S centered on the optical axis L and orthogonal to the optical axis L and a dodecagon D that is slightly larger than the square S. Sixteen are provided. The semiconductor light sources 32, 33 are divided into four equal parts in the top, bottom, left, and right to form one set, and each set has two semiconductor light sources 32, 33. In the upper left and lower right set having the semiconductor light source 32 at the apex of the square S, one semiconductor light source 32 and two semiconductor light sources 33 are arranged at the apex of the dodecagon D so as to sandwich the semiconductor light source 32 therebetween. On the other hand, in the upper right and lower left pair in which the semiconductor light source 33 is located at the apex of the square S, one semiconductor light source 33 and two semiconductor light sources 32 are arranged so as to sandwich the semiconductor light source 33 at the apex of the dodecagon D. The upper left and lower right, and the upper right and lower left are arranged in the same manner. Each pair of upper left, lower left, lower right, and upper right makes light incident on each of the upper left, lower left, lower right, and upper right margins 73. Each set of semiconductor light sources 32 and 33 may cause light to enter one point where each margin 73 is present, or may cause light to enter a plurality of points where the positions of each margin 73 are shifted.

  In order to make the radiant intensity distribution of the narrow-band light L2 close to that of white light, the eight semiconductor light sources 32 have their angles with respect to the optical axis L changed from, for example, 10 ° by slightly changing the attachment positions and angles to the holding frame 75. It is arranged to be different in increments of 10 ° between 40 ° and −40 ° to −10 °. For this reason, the light emitted from the eight semiconductor light sources 32 enters the margin 73 at different incident angles (± 10 °, ± 20 °, ± 30 °, ± 40 ° in this example). The same applies to the semiconductor light source 33. Further, the light source controller 34 emits light as the incident angle of light with respect to the margin 73 is close to 0 ° (in this example, the semiconductor light sources 32 and 33 having an incident angle of ± 10 °), and the light is emitted as the incident angle increases. The driving of the semiconductor light sources 32 and 33 is controlled so that the amount gradually decreases. Note that FIG. 14 does not express subtle differences in the positions and angles of the semiconductor light sources 32 and 33 with respect to the margin 73 in order to avoid complexity.

  In FIG. 15, the white light incident on the light guide 43 through the light guide rod 40 and the reduction optical system 41 is a reference position where the radiation angle θi on the extension line of the optical axis L is 0 ° by the light diffusion action of the phosphor 36. The top-hat type radiation in which the radiation intensity I gradually falls from near the top of the mountain shape, has a certain radiation intensity I over a relatively wide range of the radiation angle θi, and the high-angle component with a large radiation angle θi falls slowly. The intensity distribution is shown. The divergence angle of the white light incident on the light guide 43 is about 30 ° (half width at half maximum: about 60 °) at half width at half maximum (HWHM). The radiation intensity distribution is a graph in which the horizontal axis represents the radiation angle θi and the vertical axis represents the radiation intensity I. The radiant intensity I is a radiant flux (lumen) per unit solid angle (steradian: sr), and its unit is lumen / sr. The half width at half maximum is ½ of the full width of the radiation angle θi when the radiation intensity I shows a half value with respect to the maximum value.

  Since the narrow-band lights N2 and N3 emitted from the semiconductor light sources 32 and 33 are highly linear laser beams, as shown by the solid line in FIG. 16, the steep inclination at which the radiation intensity I drops sharply from the vicinity of the peak of the mountain shape. With a Gaussian distribution. The divergence angles of the narrow-band lights N2 and N3 are about 10 ° at half maximum half width (about 20 ° at full width half maximum). The narrow-band light N2 and N3 is light with a slightly gentle drop in intensity I as shown by the broken line due to the light diffusion action of the glass bead layer 74 formed in the margin 73 (half-value half-width of about 20 °). And enters the light guide rod 40. In this case, the reference position is on an extension line of the optical axis of the semiconductor light sources 32 and 33.

  Narrow band lights N2 and N3 incident on the light guide 43 through the light guide rod 40 and the reduction optical system 41 are light incident on the margin 73 at different angles from the eight semiconductor light sources 32 and 33, more precisely, a layer of glass beads. It becomes a mixed light of light whose divergence angle is expanded through 74. Specifically, as shown in FIG. 17A, the radiation intensity distribution of the narrow-band lights N2 and N3 emitted from the eight semiconductor light sources 32 and 33 before the incident end of the light guide 43 is represented by a radiation angle θi ±. It has a form in which eight substantially similar distributions of light having vertices at 10 °, ± 20 °, ± 30 °, and ± 40 °, respectively, with the divergence angles shown in FIG. The eight distributions are symmetric with respect to the radiation angle θi0 ° of the reference position on the extension line of the optical axis L.

  The semiconductor light sources 32 and 33 having an incident angle of ± 10 ° have a larger light emission amount, and the light source control unit 34 controls the driving of the semiconductor light sources 32 and 33 so that the light emission amount gradually decreases as the incident angle increases. The maximum value of the radiation intensity I of the distribution of the radiation angle θi ± 20 ° shown by the one-dot chain line is about 0.9 times the maximum value of the radiation intensity I of the distribution of the radiation angle θi ± 10 ° shown by the solid line, two points The maximum value of the radiation intensity I of the distribution at the radiation angle θi ± 30 ° shown by the chain line is about 0.75 times, and the maximum value of the radiation intensity I of the distribution at the radiation angle θi ± 40 ° shown by the broken line is about 0.5 times. Thus, the maximum value of the radiation intensity I of the eight distributions gradually decreases as the radiation angle θi increases.

  The radiant intensity distributions of the narrow-band light N2 and N3 incident on the light guide 43 through the light guide rod 40 and the reduction optical system 41 are as shown in FIG.

  Here, since the divergence angle of the beam is preserved in the light guiding process of the light guide 43, if the divergence angle of the beam incident on the light guide 43 is different between the white light and the narrowband lights N2 and N3, the light guide 43. The divergence angle of the beam emitted from the beam differs between the white light and the narrow-band light N2 and N3, and there is a problem that the spot irradiated with the beam at the observation site is also different. In the blood vessel enhancement observation mode, white light and narrow-band light N2 are simultaneously irradiated on the observation site. If the spots of the white light and narrow-band light N2 are different, color unevenness occurs in the observation image. In the oxygen saturation observation mode, white light and narrow-band light N3 are alternately irradiated on the observation site. However, if these spots are different, accurate oxygen saturation cannot be calculated.

  On the other hand, in this example, the radiant intensity distribution of the narrowband light N2 and N3 incident on the light guide 43 shown in FIG. 17B is substantially the same as the radiant intensity distribution of the white light incident on the light guide 43 shown in FIG. The arrangement of the semiconductor light sources 32 and 33, the amount of light emission, and the like are adjusted so that the divergence angles of the beams incident on the light guide 43 are substantially the same for the white light and the narrowband light N2 and N3 (about 30 ° at half-value half width) (The full width at half maximum is about 60 °). Therefore, the spot irradiated with the beam at the observation site is substantially the same for the white light and the narrow-band light N2 and N3, and no color unevenness occurs in the observation image in the blood vessel enhancement observation mode, and accurate oxygen in the oxygen saturation observation mode. Saturation is calculated.

  Hereinafter, the operation of the above configuration will be described. When performing an endoscopic diagnosis, the endoscope 11 is connected to the processor device 12 and the light source device 13, the processor device 12 and the light source device 13 are turned on, and the endoscope system 10 is activated.

  The insertion part 16 of the endoscope 11 is inserted into the subject's digestive tract, and observation in the digestive tract is started. In the normal light observation mode, the semiconductor light source 31 is turned on, and the observation site is irradiated with white light in which the narrowband light N1 emitted from the laser diode LD1 and the fluorescence FL emitted from the phosphor 36 are mixed. The optical axis of the semiconductor light source 31, the fluorescent part 62 (phosphor 36), the light guide rod 40, and the reduction optical system 41, which is a system that emits white light for main light observation in endoscope diagnosis, is the light guide 43. Since they are arranged so as to coincide with the optical axis L, the white light emitted from the illumination window 22 is a sufficient amount of light for observation without any omission in the central portion. In addition, since the light emitting surface 69 of the phosphor 36 and the incident end surface 70 of the light guide rod 40 are joined, the white light emitted from the light emitting surface 69 enters the incident end surface 70 with almost no loss. For this reason, the light use efficiency is better than the configuration in which the light emitting surface and the incident end surface are separated and air is interposed between these surfaces.

  The observation site is imaged by the imaging element 44 during the white light irradiation, and the DSP 57 generates B, G, and R image signals. The image processing unit 58 generates a display image for normal light observation based on the B, G, and R image signals. The display control circuit 60 converts the display image for normal light observation into a video signal and displays it on the monitor 14.

  When blood vessel enhancement observation is performed, a mode switching operation is performed by the operation input unit 15, and the processor device 12 is set to the blood vessel enhancement observation mode.

  In the blood vessel enhancement observation mode, the semiconductor light source 32 is turned on in addition to the semiconductor light source 31, and white light and narrowband light N2 are simultaneously irradiated onto the observation site. The narrow-band light N2 directly enters the margin 73 of the incident end face 70 of the light guide rod 40 without passing through the fluorescent part 62 (phosphor 36). For this reason, the narrow-band light N2 has no light loss due to passing through the fluorescent part 62 (phosphor 36). In addition, the narrowband light N2 excites the phosphor 36, although not as much as the narrowband light N1, so that when passing through the fluorescent part 62 (phosphor 36), fluorescence FL is generated and the color balance of white light is lost. There is no danger of it. Further, in the case where the light emitting surface 69 of the phosphor 36 and the incident end surface 70 of the light guide rod 40 are joined with an adhesive, and the narrow-band light N2 is incident on the light guide rod 40 through the fluorescent part 62, the high energy near-ultraviolet light. There is a possibility that so-called solarization may occur in which the adhesive is yellowed or the adhesive performance of the adhesive is deteriorated due to the narrow-band light N2 that is light, but there is no concern.

  There are eight semiconductor light sources 32, and the eight semiconductor light sources 32 are arranged so that the angles with respect to the margin 73 are different from each other. Further, the semiconductor light source 32 having a shallow incident angle has a larger light emission amount, and the light source control unit 34 controls the driving of the semiconductor light source 32 so that the light emission amount gradually decreases as the incident angle increases. The narrow-band light N2 has its divergence angle widened by the light diffusing action of the glass bead layer 74 formed in the margin 73. Thereby, the divergence angles of the beams incident on the light guide 43 are substantially the same for the white light and the narrowband light N2. White light and narrow-band light N2 are irradiated from the illumination window 22 to the observation site in the digestive tract through the light guide 43.

  While the white light and the narrow-band light N2 are irradiated, the observation site is imaged by the imaging device 44, and B, G, and R image signals are generated by the DSP 57. In the blood vessel enhancement observation mode, the image processing unit 58 generates a display image for blood vessel enhancement observation based on the B, G, and R image signals. The display control circuit 60 converts a display image for blood vessel enhancement observation into a video signal and displays it on the monitor 14. Since the spot irradiated with the beam at the observation site is substantially the same for the white light and the narrow-band light N2, a display image without color unevenness is obtained. In the blood vessel enhancement observation mode, since the image signal B includes the narrowband light N2 in addition to the B component of white light, the superficial blood vessels are depicted with high contrast in the observation image.

  When performing oxygen saturation observation, mode switching operation is performed from the operation input part 15, and the operation mode of the processor apparatus 12 is set to oxygen saturation observation mode.

  In the oxygen saturation observation mode, the semiconductor light source 31 and the semiconductor light source 33 are alternately turned on every frame, and white light and narrowband light N3 are alternately irradiated on the observation site. As in the case of the narrow band light N2, the narrow band light N3 has no light loss due to passing through the fluorescent part 62 (phosphor 36).

  Further, since the narrow-band light N3 also excites the phosphor 36, the fluorescence FL is generated when it passes through the phosphor 62 (phosphor 36). In the oxygen saturation observation mode, the narrow-band light N3 is irradiated alone on the observation site, and an inter-image calculation is performed using the image signal B2 obtained thereby and the image signals G1 and R1 obtained when the white light is irradiated. Since the oxygen saturation is calculated, if the fluorescence FL is generated when the narrow-band light N3 is irradiated, noise is generated and the oxygen saturation cannot be accurately calculated.

  Further, as in the case of the narrowband light N2, the divergence angle of the beam incident on the light guide 43 is substantially the same for the white light and the narrowband light N3, and the spot irradiated with the beam at the observation site is narrower than the white light. Since it is substantially the same for the band light N2, the accuracy of the calculated oxygen saturation is increased. White light and narrow-band light N3 are sequentially irradiated from the illumination window 22 to the observation site in the digestive tract through the light guide 43.

  The image sensor 44 sequentially outputs image signals corresponding to the white light and the narrowband light N3 to the DSP 57. The DSP 57 generates an image signal of each color of B1, G1, and R1 based on the image signal acquired under the white light, and generates an image signal of B2 based on the image signal acquired under the narrowband light N3. Is generated. The image processing unit 58 calculates the oxygen saturation by performing an inter-image calculation of the image signals B2, G1, and R1. Then, the full color image generated based on the image signals B1, G1, and R1 is subjected to color conversion in accordance with the calculated oxygen saturation value to generate a display image for oxygen saturation observation.

  In the above embodiment, eight semiconductor light sources 32 and 33 are provided in order to make the radiant intensity distributions of the white light and the narrow band lights L2 and L3 closer, but the number is not limited to this. It is only necessary that the spot irradiated with the beam at the observation site is substantially the same for the white light and the narrowband light N2 and N3. For example, as shown in FIG. 18, at the apex of the square Sa corresponding to the square S of the above embodiment. The number of the four semiconductor light sources 32 may be appropriately reduced, for example, by arranging the four semiconductor light sources 33 at the vertices of the square Sb that is slightly larger than the square Sa. If the number of the semiconductor light sources 32 and 33 can be reduced, an increase in the size of the light source device 13 can be suppressed and the cost can be reduced.

  In the above embodiment, two semiconductor light sources 32 and 33 are assigned to each of the margins 73 at the four corners, and one is assigned in the example of FIG. This is because if the number of semiconductor light sources allocated to each margin 73 is biased, the radiation intensity distribution is biased. In order to obtain an unbiased radiation intensity distribution, a total of four semiconductor light sources may be arranged, one for at least one margin 73 as shown in FIG.

  For example, if the thickness of the glass bead layer 74 in the margin 73 is increased, the light diffusion action of the glass bead layer 74 is further increased, and the drop in the radiation intensity I of the narrowband light N2 and N3 is made more gradual. Even if the number of the semiconductor light sources 32 and 33 is reduced, the spot irradiated with the beam at the observation site can be made substantially the same for the white light and the narrowband light N2 and N3. If the light diffusing action of the light diffusing surface is sufficient, one semiconductor light source 32 and 33 can be used.

  Alternatively, the incident end face 70 of the light guide rod 40 is enlarged to, for example, the square S shown in FIG. 14 or the square Sb shown in FIG. The semiconductor light sources 32 and 33 are arranged parallel to the optical axis L with the angle of the semiconductor light sources 32 and 33 at the apex of the semiconductor light sources 32 and 33 being 0 °, and the narrowband light N2 having the apex of the radiation intensity I at the emission angle θi0 °. , N3 0 ° component may be incident on the light guide rod 40.

  Since the radiant intensity distribution of white light has the maximum radiant intensity I when the radiant angle θi0 °, the narrow band lights N2 and N3 are also radiated to bring the radiant intensity distributions of the white light and the narrowband lights L2 and L3 closer to each other. It is necessary to increase the radiation intensity I when θi0 °. However, in the above embodiment, as can be seen from the radiation intensity distribution of the narrow band lights N2 and N3 before the incident end of the light guide 43 of FIG. 17A, the 0 ° components of the narrow band lights N2 and N3 are small. In order to make up for the shortage of the 0 ° components of the narrow-band lights N2 and N3, a plurality of different angle components must be overlapped, and the number of semiconductor light sources 32 and 33 is increased accordingly. On the other hand, the number of the semiconductor light sources 32 and 33 can be reduced by expanding the area of the margin 73 and making the 0 ° components of the narrowband light N2 and N3 enter the light guide rod 40 as described above. In order to enlarge the area of the margin 73, the incident end face 70 of the light guide rod 40 is increased to a square S or Sb. However, the incident end face 70 is rectangular and the area of the margin 73 is set in one direction. You may enlarge greatly.

  As shown in FIG. 19, a reflector 85 may be provided in order to increase the incident light rate of the narrowband light N <b> 2 and N <b> 3 to the margin 73. The reflector 85 has a bowl-like shape like the holding frame 75 and is curved in a concave shape toward the incident end face 70 of the light guide rod 40. The reflector 85 is provided with a transmission hole 85a at a position corresponding to the optical paths of the narrowband light N2 and N3. The reflector 85 is attached to the fluorescent part 62. The reflector 85 reflects and guides the narrowband light N <b> 2 and N <b> 3 that are not directly incident on the margin 73 to the margin 73. In particular, when the margin 73 is used as a light diffusion surface, the narrowband light N2 and N3 that do not enter the margin 73 but diffuse in the direction of the fluorescent part 62 increases, and therefore it is preferable to provide the reflector 85. The inner frame 75a of the holding frame 75 may be used as a reflector.

  In the above embodiment, the margin 73 is used as a light diffusing surface in order to make the narrowband light N2 and N3 light with a slight drop in intensity I and a wide base, but the number and arrangement of the semiconductor light sources 32 and 33 are devised. If the white light incident on the light guide 43 and the narrow-band light N2 and N3 have substantially the same radiant intensity, the margin 73 does not have to be a light diffusion surface.

  The emission wavelength ranges of the narrowband light N1 to N3 and the fluorescence FL are not limited to the above examples, and can be changed as appropriate. For example, treatment light having a center wavelength of 635 nm for killing the tumor may be used as the narrowband light N3. Alternatively, a phosphor that emits fluorescence FL in the infrared wavelength region may be used.

  In the above embodiment, the light guide rod has a tapered shape in which the cross-sectional shape orthogonal to the optical axis L is square and the side surface 72 is inclined with respect to the optical axis L so that the area of the emission end surface 71 is larger than the incident end surface 70. Although 40 is illustrated, the shape of the light guide rod is not limited to this. The area of the incident end surface of the light guide rod is larger than the light emitting surface of the phosphor, and it is sufficient that a margin is formed on the incident end surface of the light guide rod when both are joined, and the cross-sectional shape orthogonal to the optical axis L is circular. A substantially conical light guide rod having a tapered shape whose side surface is inclined with respect to the optical axis L may be used so that the area of the output end surface is larger than the incident end surface. In the case of a substantially conical light guide rod, an annular margin is formed around the entire phosphor on the incident end face of the light guide rod, and light other than the excitation light of the phosphor is incident on the annular margin. Furthermore, a light guide rod having a slender body with no inclination on the side surface or a light guide rod having a square incident end face and a circular exit end face may be used. In addition, a light guide rod having a rectangular or polygonal cross-sectional shape orthogonal to the optical axis may be used. Even when the cross-sectional shape orthogonal to the optical axis is not square, the same effect as the above embodiment can be obtained.

  Moreover, although the thing which has a laser diode is illustrated as a light emitting element, you may use the light emitting element which has LED, EL, etc. other than a laser diode. Even when a light-emitting element having an LED, an EL, or the like is used, the same effect as in the above embodiment can be obtained.

  In the above-described embodiment, an example of a simultaneous method in which white light is color-separated by a micro color filter and a plurality of color images are simultaneously acquired using a color image sensor provided with B, G, and R micro color filters is described. However, the present invention may be applied to a frame sequential method in which images of respective colors are sequentially acquired using a monochrome imaging element not provided with a color filter.

  In the above embodiment, the example in which the light source device and the processor device are configured separately is described, but the two devices may be configured integrally. The present invention also provides an ultrasonic endoscope in which an image pickup element and an ultrasonic transducer are built in the tip, an industrial endoscope for inspecting cracks in piping, a rod-shaped rigid endoscope with a hard insertion portion, and the like. The present invention can also be applied to a light source device that supplies illumination light to an endoscope of the form and an endoscope system using the same.

DESCRIPTION OF SYMBOLS 10 Endoscope system 11 Endoscope 12 Processor apparatus 13 Light source apparatus 31 Semiconductor light source (1st semiconductor light source)
32, 33 Semiconductor light source (second semiconductor light source)
34 Light source control unit 36 Phosphor 40 Light guide rod 43 Light guide 44 Imaging element 46 Imaging control unit 56 Controller 58 Image processing unit 62 Fluorescence unit 66 Light emitting element (first light emitting element)
69 Light Emitting Surface of Phosphor 70 Incident End Face of Light Guide Rod 73 Margin 74 Glass Bead Layer 76, 78 Light Emitting Element (Second Light Emitting Element)
85 Reflector LD1-LD3 Laser diode

Claims (15)

In a light source device that supplies illumination light to a light guide of an endoscope,
A first light-emitting element, and a first phosphor that emits fluorescence when excited by the light of the first light-emitting element and emits mixed light of the light of the first light-emitting element and the fluorescence from the light-emitting surface of the phosphor A semiconductor light source;
A second semiconductor light source having a second light emitting element and emitting monochromatic light consisting only of light of the second light emitting element without passing through the phosphor;
An incident end face having a larger area than the light emitting surface of the phosphor, and a margin formed on the periphery of the phosphor due to an area larger than the light emitting surface of the phosphor at the incident end face; A light guide rod that emits incident light and emits light emitted from the first and second semiconductor light sources toward the light guide;
The first semiconductor light source is arranged in a state where the optical axis thereof is parallel to the optical axis of the light guide rod, and the light emitting surface of the phosphor is joined to the incident end surface of the light guide rod,
The light source device, wherein the second semiconductor light source is disposed at a position where the light of the second light emitting element is incident on the margin.   The light source device according to claim 1, wherein the second semiconductor light source is arranged in a posture in which an optical axis thereof is directed toward an optical axis of the light guide rod.   The light source device according to claim 2, wherein a plurality of the second semiconductor light sources are provided. The light guide rod has a square cross section orthogonal to the optical axis, and the phosphor has a circular cross section orthogonal to the optical axis,
4. The light source device according to claim 3, wherein the margins are formed at four corners of the incident end face of the light guide rod.   The light source device according to claim 4, wherein a plurality of the second semiconductor light sources having different incident angles of light with respect to the margin are assigned to one margin.   6. The light source device according to claim 5, wherein the same number of the second semiconductor light sources is assigned to each of the margins formed at the four corners.   The light source device according to claim 1, wherein a light diffusion surface is formed in the margin.   A light diffusing surface is formed in the margin by providing a glass bead layer in the margin, roughening the margin, attaching a sheet-like LSD to the margin, or combining these. The light source device according to claim 7, characterized in that:   The light guide rod has a tapered shape in which a side surface connecting the incident end surface and the exit end surface is inclined with respect to an optical axis so that an area of the exit end surface is larger than the incident end surface. Item 9. The light source device according to any one of Items 1 to 8.   10. The light source device according to claim 1, wherein the light emitting surface of the phosphor and the incident end surface of the light guide rod are joined so that the centers thereof coincide with each other.   11. The light source device according to claim 1, further comprising a reflector for reflecting light of the second light emitting element to enter the margin. The first light emitting element emits excitation light having a central wavelength of 445 nm,
The phosphor is excited by the excitation light to emit fluorescence in a wavelength range from a green region to a red region, and white light is generated as mixed light by the excitation light and fluorescence. The light source device according to any one of the above.   The second light emitting element emits at least one of narrow band light with a central wavelength of 405 nm for blood vessel enhancement observation and narrow band light with a central wavelength of 473 nm for observation of oxygen saturation of blood hemoglobin. Item 13. The light source device according to any one of Items 1 to 12.   The light source device according to any one of claims 1 to 13, wherein the first and second light emitting elements include either a laser diode or an LED. An endoscope with a built-in light guide for guiding illumination light;
In an endoscope system having a light source device that supplies illumination light to the light guide,
The light source device includes a first light emitting element and a phosphor that emits fluorescence when excited by light of the first light emitting element, and is mixed with light and fluorescence of the first light emitting element from a light emitting surface of the phosphor. A first semiconductor light source that emits light;
A second semiconductor light source having a second light emitting element and emitting monochromatic light consisting only of light of the second light emitting element without passing through the phosphor;
An incident end face having a larger area than the light emitting surface of the phosphor, and a margin formed on the periphery of the phosphor due to an area larger than the light emitting surface of the phosphor at the incident end face; A light guide rod that emits incident light and emits light emitted from the first and second semiconductor light sources toward the light guide;
The first semiconductor light source is arranged in a state where the optical axis thereof is parallel to the optical axis of the light guide rod, and the light emitting surface of the phosphor is joined to the incident end surface of the light guide rod,
The endoscope system according to claim 1, wherein the second semiconductor light source is disposed at a position where the light of the second light emitting element is incident on the margin.

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