JP2019048075A - Light source device for endoscope - Google Patents

Abstract

To provide an endoscope light source that allows an illumination light having a target emission spectrum to be acquired stably by easy control even when a fluorescent type semiconductor light source is used.SOLUTION: A processor device 12 includes: an excitation light emitting device for emitting an excitation light; a fluorescent light type semiconductor light source for, excited by the excitation light, emitting a fluorescent light including at least one wavelength band of a green or red wavelength band contained in an illumination light; an excitation light cut filter for cutting the excitation light; an optical member for integrating optical paths for integrating an optical path through which the fluorescent light passes, and an optical path through which a light emitted by a semiconductor light source other than the fluorescent light type semiconductor light source; and a light source control part 42 for controlling supply power to each of the semiconductor light sources.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a light source device for endoscope which supplies illumination light to an endoscope.

  In the medical field, endoscopic diagnosis using an endoscopic system is in widespread use. The endoscope system includes an endoscope, an endoscope light source device (hereinafter simply referred to as a light source device) for supplying illumination light to the endoscope, and a processor for processing an image signal output from the endoscope. And an apparatus. The endoscope has an insertion portion to be inserted into the living body, and an illumination window for irradiating illumination light to the observation site (subject) and an observation window for imaging the observation site are disposed at the tip of the insertion portion. ing. The endoscope incorporates a 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 device such as a CCD is disposed at the back of the observation window. The observation site irradiated with the illumination light is imaged by the imaging device, and the processor device generates a display image for observation based on the image signal output from the imaging device. The display image is displayed on the monitor to perform in vivo observation.

  Conventionally, xenon lamps and halogen lamps that emit white light have been used as light sources for light source devices, but recently, instead of these, laser diodes (LDs: Laser Diodes) and light emitting diodes (LEDs: Light Emitting Diodes) have been used. And the like have been proposed (see Patent Documents 1 and 2).

  In Patent Document 1, three each of blue, green and red semiconductor light sources configured of three LEDs emitting blue (B), green (G) and red (G) colors are used. A light source device has been described that combines three color lights emitted from LEDs to generate white light.

  In the xenon lamp and the halogen lamp, the ratio of the blue component, the green component, and the red component contained in the white light is constant, and the ratio of each color component can not be changed. On the other hand, the three color semiconductor light sources of blue, green and red can control the light quantity of each color of blue, green and red independently, and it is possible to freely change the ratio of the light quantity of each color A plurality of types of illumination lights having various emission spectra can be easily generated.

  As a semiconductor light source of green and red, in addition to a semiconductor light source having a light emitting element for emitting light of each color of green and red, an excitation light emitting element for emitting excitation light and an excitation light There is a fluorescent type semiconductor light source having a fluorescent substance which emits some fluorescent light. For example, in paragraph [0040] of Patent Document 2, a blue excitation light LED emitting excitation light in a violet to blue wavelength band and a green phosphor emitting green fluorescence in a green wavelength band by the blue excitation light are configured. A fluorescent green semiconductor light source is described.

  Among the LEDs that are currently commercialized, many LEDs that emit light in the violet to blue wavelength band have higher luminous efficiency and are cheaper than LEDs that emit green light. Therefore, as a green semiconductor light source of the light source device, a fluorescent green semiconductor light source as described in Patent Document 2 may be used rather than a semiconductor light source having an LED that emits green light.

Japanese Patent Application Publication No. 2007-068699 JP, 2009-297290, A

  However, for example, when the fluorescent green semiconductor light source described in Patent Document 2 is used as the green semiconductor light source of the light source device of Patent Document 1, there is a problem that illumination light of the target emission spectrum can not be stably obtained. It occurs. In the case of a fluorescent green semiconductor light source, the blue excitation light is mostly absorbed by the phosphor, but a part is not absorbed by the phosphor but is transmitted through the phosphor and illuminated onto the observation site together with the fluorescence. Therefore, changing the light amount of green light means that the light amount of blue excitation light also changes accordingly. Since the wavelength band of blue excitation light overlaps with the wavelength band of blue light emitted by the blue semiconductor light source, a change in the amount of green light affects the amount of blue light.

  In endoscopic diagnosis, depending on the purpose of observation, the amount of blue light, green light, and red light may be determined to a specific ratio to generate illumination light of a target emission spectrum. On the other hand, when the light amount of the entire display image is insufficient (underexposure), the light amount of the illumination light is increased. When the light amount is too high (overexposure), the light amount of the illumination light is controlled to be decreased. Has been done.

  In exposure control in the case of determining the ratio of the amount of light of each color light and generating the illumination light of the target emission spectrum, it is necessary to increase or decrease the total amount of light without changing the emission spectrum of the illumination light. However, in the case of using a fluorescent semiconductor light source, when increasing the output of the fluorescent semiconductor light source and changing the light amount of fluorescence, as described above, the light amount of light in which the wavelength band overlaps with the excitation light by the excitation light Since the influence is exerted, the emission spectrum of the illumination light is changed. For these reasons, when a fluorescent semiconductor light source is used, it is not possible to stably obtain illumination light of a target emission spectrum. As a solution to this problem, it is conceivable to increase or decrease the light amount of light in which the wavelength band overlaps with the excitation light, taking into account the change in excitation light due to the change in the light amount of fluorescence. Hard

  Patent Documents 1 and 2 do not describe the problem that illumination light with a target emission spectrum can not be stably obtained when a fluorescent semiconductor light source is used, and the solution is also naturally described. Not.

  The present invention has been made in view of the above problems, and, even when a fluorescent semiconductor light source is used, it is possible to stably obtain illumination light having a target emission spectrum with simple control. It aims at providing a light source device.

  The light source device for an endoscope of the present invention is a light source device for an endoscope, which supplies illumination light to a light guide of the endoscope, comprising: an excitation light emitting element that emits excitation light; And a plurality of semiconductor light sources comprising a fluorescent semiconductor light source having a fluorescent material emitting fluorescence including at least one wavelength band of green or red wavelength bands included in the light source; an excitation light cut filter for cutting excitation light; Optical path integration optical member for integrating an optical path through which fluorescence emitted from the semiconductor light source passes and an optical path through which light emitted from semiconductor light sources other than the fluorescent semiconductor light source among the plurality of semiconductor light sources travels; And a light source control unit for controlling the light source.

  The excitation light cut filter is preferably provided on the optical path between the excitation light emitting element and the light guide. It is preferable that the excitation light cut filter is provided in the optical member for optical path integration. Preferably, a dichroic filter is formed on the optical path integrating optical member, and the dichroic filter doubles as the excitation light cut filter. The excitation light preferably has a wavelength band in which at least a part of the wavelength band of the illumination light overlaps. The excitation light is preferably light in the violet to blue wavelength band. The light emitted from a semiconductor light source other than the fluorescent semiconductor light source preferably has a wavelength band overlapping with the excitation light.

  The plurality of semiconductor light sources are two semiconductor light sources that emit light in blue and green wavelength bands, the fluorescent semiconductor light source is at least one of the two semiconductor light sources, and the phosphor is green or red. It is preferable to emit any of the following.

  A light quantity measurement sensor provided for at least one of a plurality of semiconductor light sources and measuring the light quantity of light emitted by the semiconductor light source, a light guide member guiding a part of light emitted by the semiconductor light source to the light quantity measurement sensor It is preferable to control the light source control unit based on the measurement result of the light amount measurement sensor. Preferably, the light quantity measurement sensor and the light guide member are provided for the fluorescent semiconductor light source, and the light source control unit changes the power supplied to the excitation light emitting element based on the measurement result of the light quantity measurement sensor.

  According to the present invention, even when a fluorescent semiconductor light source is used, illumination light having a target emission spectrum can be stably obtained by simple control.

It is an outline view of an endoscope system of the present invention. It is a front view of the tip part of an endoscope. It is a block diagram which shows the electric constitution of an endoscope system. It is a figure which shows a blue semiconductor light source. It is a figure which shows a green semiconductor light source. It is a graph which shows the emission spectrum of the blue light which a blue semiconductor light source emits. It is a graph which shows the emission spectrum of the red light which a red semiconductor light source emits. It is a graph which shows the emission spectrum of the purple light which a purple semiconductor light source emits. It is a graph which shows the emission spectrum of blue excitation light and green fluorescence which a green semiconductor light source emits. 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 emission spectrum of the white light comprised with blue light, green fluorescence, and red light. It is a graph which shows the spectral characteristic of the micro color filter of an image pick-up element. It is explanatory drawing which shows the irradiation timing of the illumination light in normal observation mode, and the operation timing of an image pick-up element. It is explanatory drawing which shows the irradiation timing of the illumination light in blood-vessel emphasis observation mode, and the operation timing of an image pick-up element. FIG. 8 is an explanatory view showing an image processing procedure in the normal observation mode. It is an explanatory view showing the image processing procedure in blood vessel emphasis observation mode. It is a figure which shows arrangement | positioning of each semiconductor light source, and the detailed structure of an optical path integration part. It is a graph which shows the transmission characteristic of the dichroic filter of a 1st dichroic mirror. It is a graph which shows the transmission characteristic of the dichroic filter of a 2nd dichroic mirror. It is a graph which shows the transmission characteristic of the dichroic filter of a 3rd dichroic mirror. It is a figure which shows the optical path integration part which provided the 1st dichroic mirror in which the dichroic filter which has a function of the excitation light cut filter of 2nd Embodiment was formed. It is a graph which shows the transmission characteristic of the dichroic filter of a 1st dichroic mirror. It is a figure which shows the optical path integration part which provided the excitation light cut filter of 3rd Embodiment. It is a graph which shows the transmission characteristic of an excitation light cut filter. It is a figure which shows the optical path integration part which provided the light quantity measurement sensor of 4th Embodiment. It is a graph which shows the transmission characteristic of the filter arrange | positioned in front of a green light quantity measurement sensor. It is a graph which shows the transmission characteristic of the filter arrange | positioned in front of a red light quantity measurement sensor. It is a block diagram in the case of performing light quantity control using a light quantity measurement sensor. It is a figure which shows the optical path integration part which provided the excitation light cut filter and the light quantity measurement sensor. It is a figure which shows the light source part which provided the white semiconductor light source of 5th Embodiment. It is a figure which shows the other example of the green semiconductor light source of 6th Embodiment. It is a figure which shows the other example of the white semiconductor light source of 6th Embodiment.

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

  The endoscope system 10 includes a normal observation mode for observing an observation site, and a blood vessel emphasis observation mode for emphasizing and observing blood vessels present inside the mucous membrane of the observation site. The blood vessel emphasis observation mode is a mode for acquiring a pattern of blood vessels as blood vessel information and performing diagnosis such as good / bad discrimination of a tumor. In the blood vessel emphasis observation mode, the observation site is irradiated with illumination light including a large amount of light components in a specific wavelength band having high absorbance to blood hemoglobin. In the normal observation mode, a normal observation image suitable for observing the entire property of the observation site is generated as a display image, and in the blood vessel emphasis observation mode, a blood vessel emphasis observation image suitable for observation of a blood vessel pattern is generated as a display image Ru.

  The endoscope 11 connects the insertion portion 16 inserted into the digestive tract of a living body, the operation portion 17 provided at the proximal end portion of the insertion portion 16, the endoscope 11, the processor device 12 and the light source device 13 A universal cord 18 is provided.

  The insertion part 16 is comprised by the front-end | tip part 19, the bending part 20, and the flexible tube part 21 continuously provided in order from the front-end | tip. As shown in FIG. 2, an illumination window 22 for irradiating illumination light to the observation site, an observation window 23 for taking in an image of the observation site, and an air supply for cleaning the observation window 23 are provided on the tip surface of the tip portion 19. The air / water supply nozzle 24 for supplying water and the forceps outlet 25 for performing various treatments by projecting treatment tools such as forceps and electric scalpel are provided. Behind the observation window 23, an imaging device 56 and an objective optical system 60 for imaging (both see FIG. 3) are incorporated.

  The bending portion 20 is composed of a plurality of connected bending pieces, and operates the angle knob 26 of the operation portion 17 to bend in the vertical and horizontal directions. The bending of the bending portion 20 orients the tip 19 in a desired direction. The flexible tube portion 21 is flexible so that it can be inserted into a tortuous conduit such as the esophagus or intestine. A communication cable for communicating a drive signal for driving the image sensor 56 and an image signal output from the image sensor 56, and a light guide 55 for guiding illumination light supplied from the light source device 13 to the illumination window 22 See FIG. 3) and the like.

  In addition to the angle knob 26, the forceps port 27 for inserting a treatment tool, the air supply / water supply button 28 operated when air supply / water supply is performed from the air supply / water supply nozzle 24, and the still image A release button (not shown) or the like for photographing the subject is provided.

  A communication cable and a light guide 55 extended 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 side. The connector 29 is a composite type connector including a communication connector 29a and a light source connector 29b. The communication connector 29 a and the light source connector 29 b 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 55a (see FIG. 3) of the light guide 55 is disposed on the light source connector 29b.

  In FIG. 3, the light source device 13 integrates the light paths of the respective color lights of the semiconductor light sources 35 to 38 with the light source unit 40 configured of four semiconductor light sources 35, 36, 37, 38 of blue, green, red, and purple. And a light source control unit 42 for controlling the drive of each of the semiconductor light sources 35 to 38.

  The blue, red and violet semiconductor light sources 35, 37, 38 are blue LED 43 emitting light in the blue wavelength band, red LED 45 emitting light in the red wavelength band, and violet LED 46 emitting light in the purple wavelength band as light emitting elements. Respectively. In contrast, the green semiconductor light source 36 is a blue excitation light LED (hereinafter referred to simply as excitation light LED) 44 that emits blue excitation light in a violet to blue wavelength band, and green fluorescence in a green wavelength band that is excited by blue excitation light. And a green phosphor 47 emitting light.

  Each of the LEDs 43 to 46 is a junction of a P-type semiconductor and an N-type semiconductor as is well known. When a voltage is applied, electrons and holes recombine across the band gap in the vicinity of the PN junction, current flows, and energy corresponding to the band gap is emitted as light at the time of recombination. The amount of light emitted by each of the LEDs 43 to 46 increases as the value of the supplied power increases. In the green semiconductor light source 36, which is a fluorescent semiconductor light source in which the excitation light LED 44 and the green phosphor 47 are combined, the amount of green fluorescence by the green phosphor 47 also increases according to the increase in the amount of blue excitation light from the excitation light LED 44 Do.

  As shown in FIG. 4, the blue semiconductor light source 35 is a substrate 35a on which the blue LED 43 is mounted, a mold 35b formed on the substrate 35a and having a cavity for accommodating the blue LED 43, and a resin sealed in the cavity And 35c. The inner surface of the cavity acts as a reflector that reflects light. A diffusion material for diffusing light is dispersed in the resin 35c. The blue LED 43 is conductively connected to the substrate 35 a by a wire 35 d. The mounting form of such a blue semiconductor light source 35 is generally called a surface mounting type. Since the semiconductor light sources 35, 37, 38 except for the green semiconductor light source 36 have basically the same configuration, the blue semiconductor light source 35 will be described as an example, and the description of the red and violet semiconductor light sources 37, 38 will be omitted. Do.

  As shown in FIG. 5, the green semiconductor light source 36 also has a substrate 36 a and a mold 36 b like the other semiconductor light sources 35, 37 and 38, and the excitation light LED 44 is packaged in a surface mounting type. The difference from the respective semiconductor light sources 35, 37, 38 is that a green phosphor 47 is enclosed in the cavity of the mold 36b. The green phosphor 47 is obtained by dispersing a fluorescent substance and a diffusing agent in a sealing resin for sealing the excitation light LED 44. Reference numeral 36 d denotes a wiring for connecting the substrate 36 a and the excitation light LED 44.

  As shown in FIG. 6, the blue LED 43 has, for example, a wavelength component in the vicinity of 440 nm to 470 nm, which is a blue wavelength band, and emits blue light LB with a central wavelength of 455 ± 10 nm. Further, as shown in FIG. 7, the red LED 45 has a wavelength component in the vicinity of, for example, 615 nm to 635 nm, which is a red wavelength band, and emits red light LR having a central wavelength of 620 ± 10 nm. Further, as shown in FIG. 8, the violet LED 46 has, for example, a wavelength component around 395 nm to 415 nm which is a violet wavelength band, and emits violet light LV having a central wavelength of 405 ± 10 nm.

  In FIG. 9, the green semiconductor light source 36 emits mixed light (LBe + LGf) of the blue excitation light LBe emitted by the excitation light LED 44 and the green fluorescence LGf emitted by the green phosphor 47 by being excited by the blue excitation light LBe. The blue excitation light LBe has, for example, a wavelength component in the vicinity of 420 nm to 440 nm, which is a wavelength band from purple to blue, and is light with a central wavelength of 430 ± 10 nm. The green fluorescent light LGf has, for example, a wavelength component in the vicinity of 500 nm to 600 nm, which is a green wavelength band, and is light having a central wavelength of 520 ± 10 nm. The wavelength band of the blue excitation light LBe partially overlaps the wavelength band of the blue light LB emitted by the blue semiconductor light source 35 and the wavelength band of the violet light LV emitted by the purple semiconductor light source 38 (see also FIG. 19 and the like).

  The green phosphor 47 absorbs most of the blue excitation light LBe to emit green fluorescence LGf, but a part of the blue excitation light LBe is not absorbed by the green phosphor 47 and passes through the green phosphor 47. Therefore, the emission spectrum of the light emitted by the green semiconductor light source 36 includes two color components of a part of blue excitation light LBe transmitted through the green phosphor 47 as shown in the drawing and the green fluorescence LGf.

  The violet semiconductor light source 38 is a light source for blood vessel emphasis observation (semiconductor light source for obtaining blood vessel information). In FIG. 10, which shows the absorption spectrum of blood hemoglobin, the absorption coefficient μa of blood hemoglobin has wavelength dependence, sharply increases in a wavelength band of 450 nm or less, and has a peak at around 405 nm . Moreover, although it is a low value compared with the wavelength band of 450 nm or less, it has a peak also in the wavelength band of 530 nm-560 nm. When light in a wavelength band having a large light absorption coefficient μa is irradiated to the observation site, an image having a difference in contrast between the blood vessel and the other part is obtained because the blood vessel has a large absorption.

  Further, as shown in FIG. 11, the light scattering characteristics of the living tissue also have wavelength dependency, and the scattering coefficient μS becomes larger as the wavelength becomes shorter. Scattering affects the depth of light penetration into living tissue. That is, the larger the scattering, the more the light reflected near the mucous membrane surface of the living tissue, and the less the light reaching the middle deep layer. Therefore, the depth of penetration is lower as the wavelength is shorter, and the depth of penetration is higher as the wavelength is longer. The wavelength of the light for blood vessel enhancement is selected in view of the light absorption characteristics of hemoglobin and the light scattering characteristics of the living tissue.

  The violet light LV having a central wavelength of 405 ± 10 nm emitted by the violet LED 46 has a relatively short wavelength and a low depth of penetration, and therefore the absorption by the superficial blood vessel is large. For this reason, purple light LV is used as light for enhancing superficial blood vessels. By using the purple light LV, it is possible to obtain a blood vessel-emphasized observation image in which a superficial blood vessel is depicted with high contrast. In addition, light in the green wavelength band of white light LW (see FIG. 12) is used as light for emphasizing deep deep blood vessels. In the absorption spectrum shown in FIG. 10, the light absorption coefficient changes gently in the green wavelength band of 530 nm to 560 nm compared to the blue wavelength band of 450 nm or less, and therefore the light for emphasizing deep deep blood vessels is purple light LV It is not required to be as narrow as. Therefore, as described later, a green image signal color-separated from white light by the G-color micro color filter of the imaging device 56 is used for the deep blood vessel enhancement.

  In FIG. 3, drivers 50, 51, 52, and 53 are connected to the LEDs 43 to 46, respectively. The light source control unit 42 controls the lighting and extinguishing of each of the LEDs 43 to 46 and the light amount through the drivers 50 to 53. The control of the light amount is performed by changing the power supplied to each of the LEDs 43 to 46 based on the exposure control signal received from the processor device 12.

  Under the control of the light source control unit 42, the drivers 50 to 53 turn on the LEDs 43 to 46 by continuously applying a drive current to the LEDs 43 to 46. Then, according to the exposure control signal received from the processor unit 12, the power supplied to each of the LEDs 43 to 46 is changed by changing the drive current value to be applied, and blue light LB, green fluorescence LGf, red light LR, and purple light Control the light intensity of LV respectively. The light amount control of the green fluorescence LGf is performed by controlling the light amount of the blue excitation light LBe of the excitation light LED 44. Therefore, in the case of increasing the light amount of the green fluorescence LGf, the drive current value given from the driver 51 to the excitation light LED 44 is increased in order to increase the light amount of the blue excitation light LBe. Note that PAM (Pulse Amplitude Modulation) control that changes the amplitude of a drive current pulse by applying a drive current in a pulse shape instead of continuously supplying the pulse and PWM (Pulse Width Modulation) control that changes the duty ratio of the drive current pulse You may

  The optical path integration unit 41 integrates the optical paths of the respective color lights emitted by the semiconductor light sources 35 to 38 into one optical path. The light emitting portion of the light path integrating portion 41 is disposed in the vicinity of the receptacle connector 54 to which the light source connector 29 b is connected. The optical path integration unit 41 emits the light incident from the semiconductor light sources 35 to 38 to the incident end 55 a of the light guide 55 of the endoscope 11. Although not shown, protective glass is provided on each of the light source connector 29 b and the receptacle connector 54.

  The emission spectrum of the mixed light of blue light LB, green fluorescent light LGf and red light LR from the blue, green and red semiconductor light sources 35 to 37 integrated by the optical path integration unit 41 is shown in FIG. This mixed light is used as white light LW. The blue excitation light LBe is cut by the third dichroic mirror 81 (see FIG. 18) as described later, so the emission spectrum of the blue excitation light LBe is not superimposed on the emission spectrum of the white light LW. The emission spectrum of the white light LW shown in FIG. 12 is an example, and the emission spectrum of the target white light LW may be variously changed according to the color tone and the like of the desired display image. Specifically, the ratio of the light amount of the blue light LB, the green fluorescence LGf, and the red light LR (the ratio of the drive current value of each of the LEDs 43 to 45) is changed to generate the white light LW of the target emission spectrum.

  The light source control unit 42 performs exposure control of illumination light while maintaining a target emission spectrum. When the ratio of the light quantity of each color light constituting the illumination light changes, the emission spectrum of the illumination light changes and the color of the display image changes. For this reason, the light source control unit 42 changes the drive current value given to each of the LEDs 43 to 46 independently through the drivers 50 to 53 so as to increase or decrease the amount of light of each color light so that the ratio of the light amount of each color light becomes constant.

  In addition, the light source control unit 42 changes the emission spectrum of the illumination light in the normal observation mode and the blood vessel emphasis observation mode. In the blood vessel emphasis observation mode, purple light LV for surface blood vessel emphasis is irradiated in addition to the white light LW, so that the emission spectrum of the illumination light is obtained by adding the purple light LV to the white light LW. In the emission spectrum of the mixed light of the white light LW and the purple light LV, the light source control unit 42 controls the blue light LB compared to the normal observation mode so that the purple light LV becomes dominant compared to the blue light LB. Reduce the rate of light.

  In FIG. 3, the endoscope 11 includes a light guide 55, an imaging device 56, an analog processing circuit 57 (AFE: Analog Front End), and an imaging control unit 58. The light guide 55 is a fiber bundle in which a plurality of optical fibers are bundled. When the light source connector 29 b is connected to the light source device 13, the incident end 55 a of the light guide 55 disposed in the light source connector 29 b faces the emission end of the optical path integration unit 41. The light emission end of the light guide 55 located at the front 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 illumination lens 59 is disposed at the back of the illumination window 22. The illumination light supplied from the light source device 13 is guided to the irradiation lens 59 by the light guide 55 and irradiated from the illumination window 22 toward the observation site. The irradiation lens 59 is a concave lens and widens the divergence angle of the light emitted from the light guide 55. Thereby, illumination light can be irradiated to the wide range of an observation part.

  An objective optical system 60 and an imaging device 56 are disposed at the back of the observation window 23. The image of the observation site enters the objective optical system 60 through the observation window 23 and is imaged on the imaging surface 56 a of the imaging device 56 by the objective optical system 60.

  The image pickup device 56 is composed of a charge coupled device (CCD) image sensor, a complementary metal oxide semiconductor (CMOS) image sensor, etc., and a plurality of photoelectric conversion elements constituting pixels such as photodiodes are formed in a matrix on the image pickup surface 56a. Are arranged in The image sensor 56 photoelectrically converts the light received by the imaging surface 56 a and accumulates signal charges corresponding to the respective amounts of light received in the respective pixels. The signal charge is converted into a voltage signal by the amplifier and read out. The voltage signal is output from the imaging element 56 to the AFE 57 as an image signal.

  AFE (Analog Front End) 57 is a correlated double sampling circuit (CDS (Correlated Double Sampling)), an automatic gain control circuit (AGC (Auto Gain Circuit)), and an analog / digital converter (A / D (Analog / Digital) ) (All are not shown). The CDS performs correlated double sampling processing on the analog image signal from the imaging element 56 to remove noise due to the reset of the signal charge. The AGC amplifies an image signal from which noise has been removed by the CDS. The A / D converts the image signal amplified by the 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 unit 12.

  The imaging control unit 58 is connected to the controller 65 in the processor device 12, and inputs a drive signal to the imaging element 56 in synchronization with a reference clock signal input from the controller 65. The imaging element 56 outputs an image signal to the AFE 57 at a predetermined frame rate based on the drive signal from the imaging control unit 58.

  The image pickup device 56 is a color image pickup device, and on the image pickup surface 56a, micro color filters of three colors B, G, and R having spectral characteristics as shown in FIG. 13 are assigned to each pixel. The arrangement of micro color filters is, for example, a Bayer arrangement.

  The B pixel to which the B filter is assigned is sensitive to light in the wavelength band of about 380 nm to 560 nm, and the G pixel to which the G filter is assigned is sensitive to light in the wavelength band of about 450 nm to 630 nm. Also, the R pixel to which the R filter is assigned is sensitive to light in a wavelength band of about 580 nm to 800 nm. The blue light LB, the green fluorescent light LGf, and the red light LR that constitute the white light LW mainly correspond to the B pixel as the reflected light corresponding to the blue light LB, and the G pixels as the reflected light corresponding to the green fluorescent light LGf Reflected light is mainly received by the R pixel. Reflected light corresponding to the purple light LV for blood vessel emphasis observation is received by the B pixel. Although the blue excitation light LBe is cut by the third dichroic mirror 81 and is not irradiated to the observation site, if the blue excitation light LBe is irradiated, the B pixel is sensitive to the reflected light corresponding to the blue excitation light LBe. Do.

  As shown in FIGS. 14 and 15, the imaging device 56 performs an accumulation operation of accumulating signal charges in pixels and a readout operation of reading out the accumulated signal charges within an acquisition period of one frame. In FIG. 14, in the normal observation mode, each of the semiconductor light sources 35 to 37 except the purple semiconductor light source 38 is turned on according to the timing of the accumulation operation of the imaging device 56, and blue light LB, green fluorescence LGf, and red light as illumination light. White light LW (LB + LGf + LR) composed of mixed light of LR is irradiated to the observation site, and the reflected light is incident on the imaging device 56. The imaging device 56 performs color separation of the reflected light of the white light LW with the micro color filter. The reflected light corresponding to the blue light LB is received by the B pixel, the reflected light corresponding to the green fluorescence LGf is received by the G pixel, and the reflected light corresponding to the red light LR is received by the R pixel. The image sensor 56 sequentially outputs 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 reading timing. Such an imaging operation is repeated while the normal observation mode is set.

  In FIG. 15, in the blood vessel emphasis observation mode, the purple semiconductor light source 38 is turned on in addition to the respective semiconductor light sources 35 to 37 in accordance with the timing of the accumulation operation of the imaging device 56. When each of the semiconductor light sources 35 to 38 is turned on, purple light LV is added together with the white light LW which is the same as in the normal observation mode, and the mixed light (LW + LV) thereof is irradiated as the illumination light onto the observation site.

  As in the normal observation mode, the illumination light in which the purple light LV is added to the white light LW is dispersed by the micro color filter of the imaging device 56. The B pixel receives the reflected light corresponding to the purple light LV in addition to the reflected light corresponding to the blue light LB. The G pixel and the R pixel respectively receive the reflected light corresponding to the green fluorescence LGf and the reflected light corresponding to the red light LR, as in the normal observation mode. Also in the blood vessel emphasis observation mode, the imaging device 56 sequentially outputs the image signals B, G, and R according to the frame rate in accordance with the read timing. Such imaging operation is repeated while the blood vessel emphasis observation mode is set.

  In FIG. 3, the processor unit 12 includes a DSP (Digital Signal Processor) 66, an image processing unit 67, a frame memory 68, and a display control circuit 69 in addition to the controller 65. The controller 65 has a central processing unit (CPU), a read only memory (ROM) for storing control programs and setting data necessary for control, and a random access memory (RAM) for loading a program and functioning as a working memory. The CPU executes the control program to control each part of the processor device 12.

  The DSP 66 acquires an image signal output from the imaging device 56. The DSP 66 separates an image signal in which signals corresponding to the B, G, and R pixels are mixed into B, G, and R image signals, and performs pixel interpolation processing on the image signals of each color. In addition, the DSP 66 performs signal processing such as gamma correction and white balance correction on each of the B, G, and R image signals.

  Also, the DSP 66 calculates the exposure value based on the image signals B, G, and R, and raises the light amount of the illumination light when the light amount of the entire image is insufficient (underexposure). Is too high (overexposure), an exposure control signal is output to the controller 65 to control to reduce the light amount of the illumination light. The controller 65 transmits an exposure control signal to the light source control unit 42 of the light source device 13.

  The frame memory 68 stores image data output from the DSP 66 and processed image data processed by the image processing unit 67. The display control circuit 69 reads out the image data subjected to image processing from the frame memory 68, converts the image data into a video signal such as a composite signal or a component signal, and outputs the video signal to the monitor 14.

  As shown in FIG. 16, in the normal observation mode, the image processing unit 67 generates a normal observation image based on the image signals B, G, and R separated in colors of B, G, and R by the DSP 66. . The normal observation image is output to the monitor 14. The image processing unit 67 updates the normal observation image each time the image signals B, G, and R in the frame memory 68 are updated.

  As shown in FIG. 17, in the blood vessel emphasis observation mode, the image processing unit 67 generates a blood vessel emphasis observation image based on the image signals B, G, and R. The image signal B in the blood vessel enhancement observation mode includes the component of the reflected light corresponding to the purple light LV in addition to the component of the reflected light corresponding to the blue light LB constituting the white light LW. Is depicted in high contrast. In lesions such as cancer, the blood vessel pattern is characterized in that the density of superficial blood vessels tends to be higher than normal tissue, and so on. It is preferable that the superficial blood vessels be clearly depicted.

  In order to further emphasize the superficial blood vessel, for example, the region of the superficial blood vessel in the image may be extracted based on the image signal B, and the contour emphasis processing may be performed on the extracted superficial blood vessel region. Then, the image signal B subjected to the contour enhancement processing is synthesized with a full color image generated based on the image signals B, G, and R. The same process may be performed on middle and deep blood vessels in addition to superficial blood vessels. When emphasizing deep and deep blood vessels, the region of deep and deep blood vessels is extracted from the image signal G containing much information on the deep and deep blood vessels, and contour emphasis processing is applied to the extracted region of the deep and deep blood vessels. Then, the image signal G subjected to the enhancement processing is synthesized into a full color image generated from the image signals B, G and R.

  The blood vessel-emphasized observation image is generated based on the image signals B, G, and R, as in the case of the normal observation image, so that the observation site can be displayed in full color. However, the image signal B in the blood vessel emphasis observation mode has a blue density higher than that of the image signal B in the normal observation mode. Therefore, when generating a blood vessel-emphasized observation image, color correction such as suppressing the blue density may be performed so as to have the same color as the normal observation image. The image processing unit 67 generates a blood vessel-emphasized observation image each time the image signals B, G, and R in the frame memory 68 are updated.

  As a method of generating a blood vessel emphasis observation image, a blood vessel emphasis observation image is generated with only two colors of the image signals B and G without using the image signal R, and the image signal B is used as the B channel of the monitor 14 and For the G channel, for example, a method of displaying an observation portion in pseudo color, such as a method of allocating the image signal G to the R channel of the monitor 14 may be adopted.

  In FIG. 18, an optical path integration unit 41 collimates each color light emitted from each semiconductor light source 35 to 38, and includes collimator lenses 75, 76, 77, and 78, a first dichroic mirror 79, a second dichroic mirror 80, and a third dichroic mirror. 81 (corresponding to the “optical member for optical path integration” of the present invention) and a condenser lens 82 for condensing the light emitted from the optical path integration part 41 on the incident end 55 a of the light guide 55. Each of the dichroic mirrors 79 to 81 is an optical member in which a dichroic filter having a predetermined transmission characteristic is formed on a transparent glass plate.

  The green semiconductor light source 36 is disposed at a position where its optical axis coincides with the optical axis of the light guide 55. The green semiconductor light source 36 and the red semiconductor light source 37 are disposed such that their optical axes are orthogonal to each other. A first dichroic mirror 79 is provided at a position where the optical axes of the green semiconductor light source 36 and the red semiconductor light source 37 are orthogonal to each other. Similarly, the blue semiconductor light source 35 and the purple semiconductor light source 38 are also arranged so that their optical axes are orthogonal to each other, and the second dichroic mirror 80 is provided at a position where these optical axes are orthogonal to each other. At the position where all the optical paths of the blue light LB, the mixed light of the blue excitation light LBe and the green fluorescent light LGf, the red light LR and the purple light LV finally intersect due to the action of the first and second dichroic mirrors 79 and 80. A third dichroic mirror 81 is provided. The first dichroic mirror 79 is the green semiconductor light source 36, the optical axis of the red semiconductor light source 37, the second dichroic mirror 80 is the blue semiconductor light source 35, the optical axis of the violet semiconductor light source 38, and the third dichroic mirror 81 is the blue semiconductor light source 35, green Each of the semiconductor light sources 36 is disposed at an angle of 45 ° with respect to the optical axis of the semiconductor light source 36.

  As shown in FIG. 19, the dichroic filter of the first dichroic mirror 79 has a characteristic of reflecting light of a wavelength band of about 610 nm or more and transmitting light of a wavelength band of less than that. The first dichroic mirror 79 transmits mixed light of the blue excitation light LBe and the green fluorescent light LGf incident from the green semiconductor light source 36 through the collimator lens 76 to the downstream side, and enters the red semiconductor light source 37 through the collimator lens 77 Reflected red light LR. As a result, the mixed light of the blue excitation light LBe and the green fluorescence LGf and the light path of the red light LR are integrated.

  As shown in FIG. 20, the dichroic filter of the second dichroic mirror 80 has a characteristic of reflecting light in a wavelength band less than about 430 nm and transmitting light in a wavelength band longer than that. The second dichroic mirror 80 transmits the blue light LB incident from the blue semiconductor light source 35 via the collimator lens 75 to the downstream side, and reflects the purple light LV incident from the violet semiconductor light source 38 via the collimator lens 78. Thereby, the light paths of the blue light LB and the purple light LV are integrated.

  The dichroic filter of the third dichroic mirror 81 has a transmission characteristic excluding at least the blue excitation light LBe from the emission spectrum of the mixed light of the blue excitation light LBe and the green fluorescence LGf shown in FIG. 9 emitted by the green semiconductor light source 36. That is, the dichroic filter of the third dichroic mirror 81 functions as an excitation light cut filter that cuts the blue excitation light LBe.

  Specifically, as shown in FIG. 21, the dichroic filter of the third dichroic mirror 81 has a characteristic of reflecting light in a wavelength band less than about 490 nm and transmitting light in a wavelength band longer than that. . Therefore, the third dichroic mirror 81 reflects the blue excitation light LBe out of the mixed light of the blue excitation light LBe and the green fluorescence LGf transmitted through the first dichroic mirror 79, and transmits the green fluorescence LGf. The third dichroic mirror 81 transmits the red light LR reflected by the first dichroic mirror 79. Further, the third dichroic mirror 81 reflects the blue light LB transmitted through the second dichroic mirror 80 and the purple light LV reflected by the second dichroic mirror 80. The third dichroic mirror 81 integrates all the optical paths of the blue light LB, the green fluorescence LGf, the red light LR, and the purple light LV. Further, the blue excitation light LBe does not enter the incident end 55a of the light guide 55, and the irradiation of the blue excitation light LBe to the observation site is blocked.

  Hereinafter, the operation of the above configuration will be described. When performing 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 powered on, and the endoscope system 10 is activated.

  The insertion portion 16 of the endoscope 11 is inserted into the digestive tract of the subject to start observation in the digestive tract. In the normal observation mode, the semiconductor light sources 35 to 37 except the purple semiconductor light source 38 are turned on. The light source control unit 42 sets the drive current value applied to each of the LEDs 43 to 45 to a value for the normal observation mode, and starts lighting of each of the semiconductor light sources 35 to 37. Then, the light amount control is performed while maintaining the target emission spectrum.

  The blue and red semiconductor light sources 35 and 37 emit blue light LB and red light LR by the blue and red LEDs 43 and 45, respectively. The green semiconductor light source 36 emits mixed light of blue excitation light LBe from the excitation light LED 44 and green fluorescence LGf from the green phosphor 47 excited by the blue excitation light LBe. The respective color lights enter the collimator lenses 75 to 77 of the optical path integration unit 41 respectively.

  The red light LR is reflected by the first dichroic mirror 79 and transmitted through the third dichroic mirror 81. The mixed light of the blue excitation light LBe and the green fluorescence LGf passes through the first dichroic mirror 79. The blue excitation light LBe in the mixed light is reflected by the third dichroic mirror 81, and the green fluorescence LGf is transmitted through the third dichroic mirror 81. The first dichroic mirror 79 integrates the light paths of the mixed light of the red light LR, the blue excitation light LBe and the green fluorescence LGf. Further, the blue excitation light LBe is cut by the third dichroic mirror 81. Since the dichroic filter of the third dichroic mirror 81 functions as an excitation light cut filter, the configuration of the optical system of the optical path integration unit 41 can be simplified.

  The blue light LB passes through the second dichroic mirror 80 and is reflected by the third dichroic mirror 81. The optical paths of the blue light LB, the green fluorescence LGf, and the red light LR are integrated by the second and third dichroic mirrors 80 and 81. The blue light LB, the green fluorescence LGf, and the red light LR are incident on the condensing lens 82. As a result, white light LW composed of blue light LB, green fluorescence LGf and red light LR is generated. The condensing lens 82 condenses the white light LW on the incident end 55 a of the light guide 55 of the endoscope 11, and supplies the white light LW to the endoscope 11.

  In the endoscope 11, the white light LW is guided to the illumination window 22 through the light guide 55, and is irradiated to the observation site from the illumination window 22. The reflected light of the white light LW reflected at the observation site is incident on the imaging device 56 from the observation window 23. The imaging device 56 outputs the image signals B, G and R to the DSP 66 of the processor unit 12. The DSP 66 color separates the image signals B, G, and R and inputs the image signals to the image processing unit 67. The imaging operation by the imaging element 56 is repeated at a predetermined frame rate. The image processing unit 67 generates a normal observation image based on the input image signals B, G, and R. The normal observation image is output to the monitor 14 through the display control circuit 69. The normal observation image is updated according to the frame rate of the imaging device 56.

  Further, the DSP 66 calculates an exposure value based on the image signals B, G, and R, and transmits an exposure control signal corresponding to the calculated exposure value to the light source control unit 42 of the light source device 13. The light source control unit 42 determines the drive current value of each of the semiconductor light sources 35 to 37 based on the received exposure control signal so that the ratio of the light quantity of each color light becomes constant (the target emission spectrum does not change). . Then, the semiconductor light sources 35 to 37 are driven with the determined drive current value. As a result, the amounts of blue light LB, green fluorescence LGf, and red light LR constituting the white light LW by the respective semiconductor light sources 35 to 37 can be kept constant at a ratio suitable for the normal observation mode.

  In the case of changing the light amount of the green fluorescence LGf in the exposure control, the light amount of the blue excitation light LBe of the excitation light LED 44 is changed. As shown in FIG. 19 and the like, the wavelength band of the blue excitation light LBe partially overlaps the wavelength band of the blue light LB. Therefore, when the blue excitation light LBe is emitted as illumination light, the light amount of the blue light LB also changes with the change of the light amount of the blue excitation light LBe, and the emission spectrum of the illumination light changes. However, since the blue excitation light LBe is cut by the third dichroic mirror 81, the blue excitation light LBe does not affect the light amount of the blue light LB, and the light amount of the blue light LB is independent of the green fluorescence LGf. Can be controlled. Therefore, even if exposure control is performed, illumination light with an emission spectrum suitable for the normal observation mode can always be supplied to the endoscope 11, and the color of the normal observation image does not change.

  When a lesion and a suspected observation site are found in the normal observation mode, the normal observation mode is switched to the blood vessel emphasis observation mode. In the blood vessel emphasis observation mode, in addition to the semiconductor light sources 35 to 37, the purple semiconductor light source 38 is turned on. Each color light from each of the semiconductor light sources 35 to 37 becomes white light LW by the action of the above-described optical path integration unit 41 and is supplied to the endoscope 11.

  The violet semiconductor light source 38 emits violet light LV from the violet LED 46. The purple light LV is incident on the collimator lens 78. The violet light LV is reflected by the second and third dichroic mirrors 80 and 81. The purple light LV is integrated into the same light path as the white light LW by the second and third dichroic mirrors 80 and 81. The purple light LV and the white light LW are incident on the condenser lens 82. The condensing lens 82 condenses the purple light LV and the white light LW on the incident end 55 a of the light guide 55 of the endoscope 11, and supplies the purple light LV and the white light LW to the endoscope 11. Thus, purple light LV and white light LW are simultaneously irradiated to the observation site. In this case as well, since the blue excitation light LBe is cut by the third dichroic mirror 81 as in the case of the normal observation mode, illumination light of a light emission spectrum suitable for the blood vessel emphasis observation mode may always be supplied to the endoscope 11 it can.

  The imaging element 56 receives the reflected light at the observation site of the white light LW and the purple light LV, and outputs an image signal of B, G, R to the DSP 66. The DSP 66 separates the image signals B, G, and R and inputs the image signals to the image processing unit 67. The image processing unit 67 generates a blood vessel-emphasized observation image based on the B, G, and R image signals. The blood vessel-emphasized observation image is output to the monitor 14. The blood vessel-emphasized observation image is updated according to the frame rate of the imaging device 56.

  Since the illumination light of the emission spectrum suitable for the blood vessel emphasis observation mode is always emitted, the reliability of the blood vessel emphasis observation image is enhanced. Since the blood vessel-emphasized observation image is used to distinguish between good and bad tumors, etc., if the blood vessel-weighted observation image is more reliable, the result of the good and bad tumor discrimination can be made more reliable.

  Since the blue excitation light LBe affecting the light amount of the blue light LB and the purple light LV is cut by the third dichroic mirror 81, the blue light is added taking into account the change in the blue excitation light LBe accompanying the light amount change of the green fluorescence LGf. It is possible to stably obtain illumination light having a target emission spectrum without performing complicated control such as increasing or decreasing the light amount of LB or purple light LV.

Second Embodiment
In the first embodiment, the dichroic filter of the third dichroic mirror 81 that integrates the light path of the blue light LB emitted from the green semiconductor light source 36 and the mixed light of the blue excitation light LBe emitted by the green semiconductor light source 36 and the green fluorescence LGf is excited. Although the function of the light cut filter is realized, the dichroic filter of the dichroic mirror different from the third dichroic mirror 81 may be made to play the function of the excitation light cut filter.

  For example, as in the optical path integration unit 90 shown in FIG. 22, the function of the excitation light cut filter is to mix the blue excitation light LBe emitted by the green semiconductor light source 36 and the mixed light of the green fluorescence LGf and the red light LR emitted by the red semiconductor light source 37. A dichroic filter of a first dichroic mirror 91 (corresponding to the first dichroic mirror 79 in the first embodiment, corresponding to the “optical member for optical path integration” of the present invention) for integrating the optical paths may be carried. The optical path integration unit 91 of FIG. 22 is the same as the optical path integration unit 41 of the first embodiment except that the first dichroic mirror 79 of the first embodiment is replaced with the first dichroic mirror 91.

  In this case, as shown in FIG. 23, the dichroic filter of the first dichroic mirror 91 reflects light of a wavelength band of about 610 nm or more and light of a wavelength band of less than about 490 nm, and light of other wavelength bands. Have the property of transmitting light. That is, the transmission characteristics of the first dichroic mirror 79 and the third dichroic mirror 81 in the first embodiment are combined to obtain band pass characteristics. However, when such a band pass characteristic is provided, the manufacturing cost is higher than that of a short path in which light on the long wavelength side is reflected and light on the short wavelength side is transmitted or the reverse is true. As in the first embodiment, it is advantageous in terms of cost to make the dichroic filter of the third dichroic mirror 81 having a long pass characteristic take on the function of the excitation light cut filter.

Third Embodiment
In each of the above embodiments, an example in which the dichroic mirror doubles as the excitation light cut filter has been described. However, as in the optical path integration unit 95 of the third embodiment shown in FIG. It is also good. In the optical path integration unit 95, the excitation light cut filter 96 is disposed between the green semiconductor light source 36 and the first dichroic mirror 79. For example, as shown in FIG. 25, the excitation light cut filter 96 has the property of reflecting light in the violet and blue wavelength bands less than about 450 nm and transmitting light in the other green and red wavelength bands. Although not shown, the excitation light cut filter 96 may be provided between the first dichroic mirror 79 and the third dichroic mirror 81. In short, it is sufficient to block the blue excitation light LBe from entering the incident end 55a of the light guide 55, and the excitation light cut filter is a light path between the excitation light LED 44 and the light guide 55, more specifically, green It may be provided at a position where the mixed light of the blue excitation light LBe emitted by the semiconductor light source 36 and the green fluorescent light LGf and the light path of the blue light LB emitted by the blue semiconductor light source 35 is integrated. .

Fourth Embodiment
In the first embodiment, the light quantity control of each color light is performed by changing the drive current value to be applied to each of the LEDs 43 to 46 based on the exposure control signal from the processor device 12. In the semiconductor light source, the amount of output light with respect to the drive current value may fluctuate due to the influence of the semiconductor light source and the influence of deterioration with time. Therefore, a light quantity measurement sensor may be provided to measure the light quantity of each color light, and whether or not the light quantity of each color light has reached the target value may be monitored based on the light quantity measurement signal output by the light quantity measurement sensor.

  In FIG. 26, in addition to the configuration of the optical path integrating part 41 shown in FIG. 18 of the first embodiment, the optical path integrating part 100 measures blue, green and red for measuring the light quantity of each color light emitted by each semiconductor light source 35-38. The light quantity measuring sensors 101, 102, 103, and 104 are provided immediately before the semiconductor light sources 35 to 38, and reflect a part of each color light emitted from the semiconductor light sources 35 to 38 to measure the light quantity measuring sensors 101 And glass plates 105, 106, 107, and 108 for guiding light to ~ 104.

  The glass plates 105 to 108 are arranged at an angle of, for example, 35 ° with respect to the optical axis of each of the semiconductor light sources 35 to 38. Each glass plate 105-108 transmits each color light which each semiconductor light source 35-38 emits. When each color light is incident on each of the glass plates 105 to 108, Fresnel reflection occurs. Each of the glass plates 105 to 108 guides light of a part (about 4% to 8%) of each color light emitted by each of the semiconductor light sources 35 to 38 to each of the light amount measuring sensors 101 to 104 using the Fresnel reflection. Light guiding member. In addition, it may replace with a glass plate and may use other light guide members, such as an optical fiber.

  Filters 109 and 110 are provided in front of the green light amount measuring sensor 102 and the red light amount measuring sensor 103, respectively. The filter 109 is for limiting the light incident on the green light quantity measuring sensor 102 to only the light of the wavelength band of the green fluorescent light LGf which constitutes a part of the white light LW finally supplied to the endoscope 11. As shown in FIG. 27, it has characteristics of reflecting light in the red wavelength band of about 610 nm or more, light in the violet and blue wavelength bands less than about 490 nm, and transmitting light in the other green wavelength bands. Have. That is, the filter 109 has a band pass characteristic in which the transmission characteristics of the first dichroic mirror 79 and the third dichroic mirror 81 of the first embodiment are matched, like the first dichroic mirror 91 of the second embodiment. By the filter 109, only the green fluorescence LGf finally emitted as a part of the white light LW from which the blue excitation light LBe is cut enters the green light quantity measuring sensor 102. The pure light quantity of green fluorescent LGf can be measured.

  In addition, the filter 110 limits the light incident on the red light amount measuring sensor 103 to only light in the wavelength band of the red light LR which constitutes a part of the white light LW finally supplied to the endoscope 11. As shown in FIG. 28, it has the property of reflecting light in the green and blue wavelength bands less than about 610 nm and transmitting light in the red wavelength band longer than that. That is, the filter 110 has a transmission characteristic obtained by inverting the transmission characteristic shown in FIG. 19 of the first dichroic mirror 79 of the first embodiment. By the filter 110, only the red light LR which is finally emitted as a part of the white light LW enters the red light quantity measuring sensor 103. The pure light quantity of red light LR can be measured.

  In FIG. 29, each of the light quantity measuring sensors 101 to 104 receives light of each color guided by Fresnel reflection of the glass plates 105 to 108, and outputs a light quantity measuring signal according to the light quantity of each light received. Is output to the light source control unit 42. The light source control unit 42 compares the light amount measurement signal with the target light amount, and based on the comparison result, the drive current to be given to each of the semiconductor light sources 35 to 38 set in exposure control so that the light amount becomes the target value. Fine tune the value. As described above, the light amount of each color light is constantly monitored by the light amount measuring sensors 101 to 104, and the light amount can be controlled to be always along the target value by finely adjusting the drive current value to be given based on the measurement result of the light amount. . For this reason, illumination light of the target emission spectrum can be obtained more stably.

  As in the optical path integration unit 115 shown in FIG. 30, a filter is provided at a position between the green semiconductor light source 36 and the first dichroic mirror 79 (the same position as the excitation light cut filter 96 shown in FIG. 24 of the third embodiment). An excitation light cut filter 116 having the same transmission characteristic as that of 109 may be provided. In this case, the filter 109 becomes unnecessary. However, since the excitation light cut filter 116 is larger in size than the filter 109, from the viewpoint of cost and space saving, it is preferable to provide the filter 109 rather than providing the excitation light cut filter 116.

  In the fourth embodiment, the light quantity measurement sensors are arranged for all the semiconductor light sources to monitor the light quantity, but at least the blue, green and red semiconductor light sources that emit the light constituting the white light LW, and the fluorescent type The light quantity of the semiconductor light source may be monitored, and the light quantity measuring sensor may not be disposed for the other semiconductor light sources. Further, among the blue, green and red semiconductor light sources, only the light quantity of the semiconductor light source (fluorescent semiconductor light source) having a particularly large fluctuation of the output light quantity to the drive current value may be selectively monitored.

  The fluorescent semiconductor light source is not limited to the green semiconductor light source 36 in each of the above embodiments. Instead of or in addition to a green semiconductor light source, a red semiconductor light source is a blue excitation light emitting element that emits blue excitation light in a violet to blue wavelength band, and red fluorescence in a red wavelength band excited with blue excitation light You may comprise with the red fluorescent substance to emit. Also in this case, as in the above embodiments, the excitation light cut filter is a position where the light path of the mixed light of the blue excitation light and the red fluorescence emitted by the red semiconductor light source and the blue light emitted by the blue semiconductor light source is integrated It should just be provided on the optical path of the upper stream side. For example, as in the first embodiment, the dichroic filter of the third dichroic mirror 81 may have the function of an excitation light cut filter, or the excitation light cut between the first dichroic mirror 79 and the third dichroic mirror 81. A filter may be provided, or an excitation light cut filter may be provided between the red semiconductor light source and the first dichroic mirror 79.

  When the red semiconductor light source is a fluorescent semiconductor light source, the excitation light emitting element is not limited to the blue excitation light emitting element that emits blue excitation light in the violet to blue wavelength band, and emits green excitation light in the green wavelength band. It may be a green excitation light emitting element. In this case, an excitation light cut filter having a transmission characteristic of cutting green excitation light and transmitting red fluorescence is disposed, for example, between the red semiconductor light source and the first dichroic mirror 79 in the optical path integration unit 41 of FIG.

Fifth Embodiment
Further, as in a light source unit 120 shown in FIG. 31, a white semiconductor light source 121 may be used as a fluorescent semiconductor light source. The light source unit 120 is obtained by removing a green semiconductor light source 36 and a red semiconductor light source 37 from the light source unit 40 of the first embodiment, and providing a white semiconductor light source 121 instead of them. The optical path integration unit 122 is obtained by removing the collimator lens 77 and the first dichroic mirror 79 related to the green semiconductor light source 36 and the red semiconductor light source 37 from the optical path integration unit 41 of the first embodiment.

  The white semiconductor light source 121 is a blue excitation light emitting element that emits blue excitation light LBe in a blue wavelength band, and green and red that is excited by the blue excitation light LBe to emit green fluorescence LGf and red fluorescence LRf in green and red wavelength bands. It is composed of a red phosphor. In this case, the white light LW is composed of mixed light of blue light LB emitted by the blue semiconductor light source 35, and green fluorescence LGf and red fluorescence LRf emitted by the white semiconductor light source 121. Also in the present embodiment, the wavelength band of the blue excitation light LBe emitted by the white semiconductor light source 121 overlaps the wavelength band of the blue light LB emitted by the blue semiconductor light source 35. For this reason, the aspect having the blue semiconductor light source 35 and the white semiconductor light source 121 of the present embodiment as well as the aspect having the three-color semiconductor light sources 35 to 37 of the above respective embodiments is excited by excitation light emitted by the fluorescent semiconductor light source. The light amount of light in which the light and the wavelength band overlap with each other affects the light emission spectrum of the illumination light.

  A dichroic mirror 123 is disposed at a position where the lights emitted from the respective semiconductor light sources 35, 38, 121 finally intersect. The dichroic mirror 123 corresponds to the third dichroic mirror 81 of the first embodiment. The dichroic filter of the dichroic mirror 123 reflects purple light LV, blue excitation light LBe, and blue light LB, has a characteristic of transmitting green fluorescence LGf and red fluorescence LRf, and cuts excitation light to cut blue excitation light LBe Act as a filter. By this dichroic mirror 123, all the optical paths of each color light are integrated, and transmission of the blue excitation light LBe is blocked.

  Also in the present embodiment, the excitation light cut filter may be provided separately from the dichroic mirror 123 as in the third embodiment. Further, as in the fourth embodiment, for example, the light quantity measurement sensor may be provided in the white semiconductor light source 121 to monitor the light quantity.

  Moreover, the mounting form of LED of the said 1st Embodiment is one example, You may employ | adopt another form. For example, a micro lens may be provided on the light emitting surface of the sealing resin 35 c or the green phosphor 47 in FIGS. 4 and 5, or a shell having a micro lens may be formed instead of the surface mounting type. The LED may be accommodated in a case of a mold. In addition to the excitation light LED 44 as the green semiconductor light source 36, the green phosphor 47 is integrally provided on the substrate 36a, but the green phosphor 47 and the substrate 36a may be separately provided. In this case, a light guide member such as a lens or an optical fiber is added between the excitation light LED 44 and the green phosphor 47 to guide the excitation light of the excitation light LED 44 to the green phosphor 47 via the light guide member. Do.

Sixth Embodiment
Furthermore, although the example which used LED as a light emitting element was demonstrated, you may use laser diode (LD) instead of LED. For example, as shown in FIG. 32, as the excitation light emitting element, a green semiconductor light source 130 constituted of an excitation light LD 131 emitting blue excitation light and a green phosphor 132 disposed in front of the excitation light LD 131 is shown in FIG. The fourth embodiment may be used instead of the green semiconductor light source 36 of the fourth embodiment.

  In this case, the green phosphor 132 is formed on the surface of the disc-like transparent rotary plate 133 by a method such as coating. Then, the blue excitation light from the excitation light LD 131 is irradiated to the eccentric position of the rotation plate 133 while the rotation plate 133 is rotated by the rotation mechanism 134 such as a motor. By rotating the rotary plate 133, the irradiation position of the excitation light is not concentrated on one position of the green phosphor 132. When the irradiation position of the excitation light is concentrated at one place, the place becomes high temperature, which may accelerate deterioration of the green phosphor 132, but such a thing can be prevented. In addition, the code | symbol 135 is a condensing lens which condenses the blue excitation light which excitation light LD131 emits on the rotating plate 133. FIG.

  The excitation light cut filter may be integrally formed on the surface of the output side of the rotary plate 133. Further, as the light emitting element, an organic EL (Electro-Luminescence) element may be used in addition to the LED and the LD. An LD or an organic EL element may be used as a light emitting element of another semiconductor light source (blue semiconductor light source 35, violet semiconductor light source 38, etc.) as well as the fluorescent semiconductor light source.

  The white semiconductor light source 140 shown in FIG. 33 is a white version of the green semiconductor light source 130 of FIG. Similar to the green semiconductor light source 130, the white semiconductor light source 140 is configured of an excitation light LD 141 that emits blue excitation light, and green and red phosphors 142 disposed in front of the excitation light LD 141. This white semiconductor light source 140 may be used as the white semiconductor light source 121 of the fifth embodiment. In addition, since other structures, such as a rotating plate, are the same as the green semiconductor light source 130 of FIG. 32, they attach | subject the code | symbol similar to FIG. 32, and abbreviate | omit description.

  In each of the above embodiments, the excitation light cut filter that cuts the excitation light 100% is illustrated, but the present invention is not limited to this. The excitation light cut filter may be any filter as long as it can reduce the light quantity of the excitation light, for example, a filter having a transmission characteristic of cutting the excitation light by 50% is also included in the present invention. However, the closer to 100%, the better the effect can be obtained.

  The configuration of the optical path integration unit in each of the above embodiments is an example, and various modifications are possible. For example, although a dichroic mirror is used as an optical member on which a dichroic filter is formed, a dichroic prism in which a dichroic filter is formed on a prism may be used instead. Also, instead of an optical member on which a dichroic filter is formed, such as a dichroic mirror or a dichroic prism, for example, a plurality of incident ends facing each semiconductor light source and one emitting end facing an incident end of the light guide of the endoscope The light path may be integrated using a branched light guide having The branch-type light guide is a fiber bundle in which optical fibers are bundled, and a predetermined number of optical fibers are divided into a plurality at one end, and the incident end is branched into a plurality. In this case, the respective semiconductor light sources are disposed in correspondence with the respective branched incident ends. Then, an excitation light cut filter is disposed between the fluorescent semiconductor light source and the incident end of the branched light guide.

  In the above embodiments, the violet semiconductor light source 38 emitting violet light LV is illustrated as a semiconductor light source for acquiring blood vessel information for acquiring blood vessel information of a living tissue, but separately or in addition to the violet semiconductor light source 38 Other semiconductor light sources for acquiring blood vessel information may be provided. For example, in order to acquire the oxygen saturation of blood hemoglobin as blood vessel information, a semiconductor light source may be provided which emits narrow-band blue light with a central wavelength of 473 ± 10 nm. Of course, when blood vessel information observation is not performed, only the blue, green, and red semiconductor light sources may be provided without providing the semiconductor light source for acquiring blood vessel information.

  In the first embodiment, only white light is irradiated to the observation site at the same time in the normal observation mode, and white light LW and purple light LV are simultaneously irradiated to the observation site in the blood vessel enhancement observation mode, and white light is used in either mode. A mode in which white light is not used may be provided. For example, the green semiconductor light source 36 and the purple semiconductor light source 38, or the green semiconductor light source 36 and the blue semiconductor light source 35 may be turned on to acquire a blood vessel-emphasized observation image on the basis of the green fluorescence LGf.

  In each of the above embodiments, the imaging device 56 includes a color imaging device that separates white light by B, G, and R micro color filters, and simultaneously acquires B, G, and R image signals by the color imaging device. The simultaneous endoscope system and the light source device used in the endoscope system have been described as an example, but the image signal of B, G, R is provided by sequentially emitting blue, green and red color lights having a monochrome imaging element. The present invention may be applied to a plane-sequential type endoscope system for acquiring plane-sequentially and a light source device used therefor.

  Needless to say, each of the above-described embodiments can be practiced alone or in combination.

  In each of the above embodiments, the light source device and the processor device are separately described. However, two devices may be integrated. The present invention also relates to an endoscope system using a fiberscope for guiding reflected light of an observation site of illumination light with an image guide, and an ultrasonic endoscope in which an imaging device and an ultrasonic transducer are built in the tip. And it can apply also to the light source device used for it.

10 Endoscope system 11 Endoscope 13 Light source device 35 Blue semiconductor light source 36, 130 Green semiconductor light source 37 Red semiconductor light source 38 Purple semiconductor light source 40, 120 Light source part 41, 90, 95, 100, 115, 122 Optical path integration part 42 Light source control unit 43 Blue LED
44 Excitation light LED
45 red LED
46 purple LED
47, 132 Green phosphor 55 Light guide 56 Image sensor 79-81 1st-3rd dichroic mirror 91 1st dichroic mirror 96, 116 Excitation light cut filter 101-104 Light quantity measurement sensor 105-108 Glass plate 109 filter 121, 140 White semiconductor light source 123 dichroic mirror 131, 141 excitation light LD
133, 143 Rotatable plate 142 Green and red phosphors

Claims (10)

In a light source device for an endoscope which supplies illumination light to a light guide of the endoscope,
A fluorescence type semiconductor comprising an excitation light emitting element for emitting excitation light, and a phosphor for emitting fluorescence including at least one wavelength band of green or red wavelength bands included in the illumination light, which is excited by the excitation light A plurality of semiconductor light sources comprising a light source;
An excitation light cut filter for cutting the excitation light;
An optical member for integrating an optical path that integrates an optical path through which the fluorescence emitted from the fluorescent semiconductor light source passes, and an optical path through which light emitted from a semiconductor light source other than the fluorescent semiconductor light source among the plurality of semiconductor light sources travels;
And a light source control unit configured to control power supplied to each of the semiconductor light sources.   The endoscope light source device according to claim 1, wherein the excitation light cut filter is provided on an optical path between the excitation light light emitting element and the light guide.   The endoscope excitation light source device according to claim 1, wherein the excitation light cut filter is provided in the optical path integrating optical member.   The light source device for an endoscope according to claim 3, wherein a dichroic filter is formed on the optical path integrating optical member, and the dichroic filter doubles as the excitation light cut filter.   The endoscope excitation light source device according to any one of claims 1 to 4, wherein the excitation light has a wavelength band in which at least a part of a wavelength band of the illumination light overlaps.   The light source device for an endoscope according to any one of claims 1 to 5, wherein the excitation light is light in a wavelength band of violet to blue.   The light source device according to any one of claims 1 to 6, wherein light emitted from a semiconductor light source other than the fluorescent semiconductor light source has a wavelength band overlapping with the excitation light. The plurality of semiconductor light sources are two semiconductor light sources that emit light in blue and green wavelength bands,
The fluorescent type semiconductor light source is at least one of the two semiconductor light sources, and the phosphor emits either green or red fluorescence. The light source device for endoscopes described in. A light quantity measurement sensor provided for at least one of the plurality of semiconductor light sources and measuring a light quantity of light emitted from the semiconductor light sources;
A light guide member for guiding a part of light emitted from the semiconductor light source to the light quantity measurement sensor;
The light source device for endoscope according to any one of claims 1 to 8, wherein the light source control unit is controlled based on the measurement result of the light amount measurement sensor. The light quantity measurement sensor and the light guide member are provided for the fluorescent semiconductor light source,
The endoscope light source device according to claim 9, wherein the light source control unit changes the power supplied to the excitation light emitting element based on the measurement result of the light amount measurement sensor.

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