JP2020168409A - Light source device for endoscope - Google Patents

Abstract

To provide a light source device for endoscope which can stably obtain illumination light having the target emission spectrum with simple control even when using a fluorescence type semiconductor light source.SOLUTION: A plurality of semiconductor light sources include: an excitation light-emitting element which emits excitation light; and a fluorescence type semiconductor light source which is excited by the excitation light and emits fluorescence light including at least one wavelength band of the green or red wavelength bands included in the illumination light. An excitation light cut filter cuts the excitation light. An optical member for light path integration integrates a light path through which the fluorescence light passes with a light path through which the light emitted by a semiconductor light source other than the fluorescence type semiconductor light source passes. A light source control unit 42 controls the supply power to each semiconductor light source.SELECTED DRAWING: Figure 3

Description

The present invention relates to an endoscope light source device that supplies illumination light to an endoscope.

In the medical field, endoscopic diagnosis using an endoscopic system is widespread. The endoscope system includes an endoscope, an endoscope light source device for supplying illumination light to the endoscope (hereinafter, simply referred to as a light source device), and a processor that processes an image signal output by the endoscope. It is equipped with a device. The endoscope has an insertion part that is inserted into the living body, and at the tip of the insertion part, an illumination window that irradiates the observation part (subject) with illumination light and an observation window for photographing the observation part are arranged. ing. The endoscope has a built-in light guide consisting 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 image sensor such as a CCD is arranged behind the observation window. The observation site irradiated with the illumination light is imaged by the image sensor, and a display image for observation is generated by the processor device based on the image signal output by the image sensor. By displaying the displayed image on the monitor, in-vivo observation is performed.

Conventionally, a xenon lamp or a halogen lamp that emits white light has been used as a light source in a light source device, but recently, instead of these, a laser diode (LD) or a light emitting diode (LED: Light Emitting Diode) has been used. ) And the like using a semiconductor light source having a light emitting element (see Patent Documents 1 and 2).

Patent Document 1 uses three color semiconductor light sources of blue, green, and red, which are composed of three LEDs that emit blue (B), green (G), and red (G) light, respectively. A light source device that synthesizes three colors of light emitted from an LED to generate white light is described.

In xenon lamps and halogen lamps, the proportions of the blue component, the green component, and the red component contained in the white light are constant, and the proportion of each color component cannot be changed. On the other hand, the blue, green, and red semiconductor light sources can independently control the amount of light of each color of blue, green, and red, and the ratio of the amount of light of each color can be freely changed. , A plurality of types of illumination light having various emission spectra can be easily generated.

The green and red semiconductor light sources include a semiconductor light source having a light emitting element that emits light of each color of green and red, an excitation light emitting element that emits excitation light, and either green or red that is excited by the excitation light. There is a fluorescent semiconductor light source having a phosphor that emits the fluorescence. For example, paragraph [0040] of Patent Document 2 is composed of a blue excitation light LED that emits excitation light in a wavelength band from purple to blue and a green phosphor that emits green fluorescence in a wavelength band of green by this blue excitation light. Fluorescent green semiconductor light sources are described.

Many of the LEDs currently on the market have higher luminous efficiency and lower price than LEDs that emit light in the wavelength band from purple to blue, as compared with LEDs that emit green light. Therefore, as the 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 Unexamined Patent Publication No. 2007-068699 JP-A-2009-297290

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 the illumination light of the target emission spectrum cannot be stably obtained. Occurs. This is because, in a fluorescent green semiconductor light source, most of the blue excitation light is absorbed by the phosphor, but part of it is not absorbed by the phosphor and is transmitted through the phosphor and irradiated to the observation site together with fluorescence. Therefore, changing the amount of green light means that the amount of blue excitation light also changes accordingly. Since the wavelength band of the blue excitation light overlaps with the wavelength band of the blue light emitted by the blue semiconductor light source, the 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 set to a specific ratio to generate illumination light having a target emission spectrum. On the other hand, if the amount of light of the entire display image is insufficient (underexposure), the amount of illumination light is increased, and if the amount of light is too high (overexposure), the amount of illumination light is decreased. Is being done.

In the exposure control when the ratio of the amount of light of each color light is determined to generate the illumination light of the target emission spectrum, when the exposure control is performed based on the image signal based on the amount of light received by the image pickup element, the image pickup element Except for the amount of light of the excitation light received in, the exposure control must be performed according to the amount of illumination light, and the overall amount of light must be increased or decreased without changing the emission spectrum of the illumination light. However, when a fluorescent semiconductor light source is used, when the output of the fluorescent semiconductor light source is increased to change the amount of fluorescence light, the amount of light whose wavelength band overlaps with the excitation light is increased by the excitation light as described above. Since it is affected, the emission spectrum of the illumination light changes. For this reason, when a fluorescent semiconductor light source is used, it is not possible to stably obtain illumination light having a target emission spectrum. As a solution to this problem, it is conceivable to increase or decrease the amount of light whose excitation light overlaps the wavelength band by taking into account the change in excitation light due to the change in the amount of fluorescence light, but this is adopted because the control becomes complicated. It's hard.

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

The present invention has been made in view of the above problems, and is for an endoscope capable of stably obtaining illumination light having a target emission spectrum even when a fluorescent semiconductor light source is used, with simple control. It is an object of the present invention to provide a light source device.

The light source device for an endoscope of the present invention is a light source device for an endoscope that supplies illumination light to a light guide of an endoscope, and is excited by an excitation light emitting element that emits excitation light and illumination light. A plurality of semiconductor light sources including a fluorescent semiconductor light source having a phosphor that emits fluorescence including at least one of the green or red wavelength bands included in the above, an excitation light cut filter that cuts excitation light, and fluorescence. An optical path integration optical member that integrates an optical path through which fluorescence emitted by a type semiconductor light source passes and an optical path through which light emitted by a semiconductor light source other than the fluorescent semiconductor light source among a plurality of semiconductor light sources passes, and power supplied to each of the semiconductor light sources. It is characterized by including a light source control unit for controlling the above.

The excitation light cut filter is preferably provided on the optical path between the excitation light emitting element and the light guide. The excitation light cut filter is preferably provided on the optical path integration optical member. A dichroic filter is formed in the optical path integration optical member, and it is preferable that the dichroic filter also serves as the excitation light cut filter. The excitation light is preferably light in the wavelength band of purple to blue. The light emitted by a semiconductor light source other than the fluorescent semiconductor light source preferably has a wavelength band that overlaps with the excitation light.

The plurality of semiconductor light sources are two semiconductor light sources that emit light in each wavelength band of blue and green, 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 fluorescences.

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

It is an external view of the endoscope system of this invention. It is a front view of the tip part of an endoscope. It is a block diagram which shows the electrical structure of an endoscope system. It is a figure which shows the blue semiconductor light source. It is a figure which shows the green semiconductor light source. It is a graph which shows the emission spectrum of the blue light emitted by the blue semiconductor light source. It is a graph which shows the emission spectrum of the red light emitted by the red semiconductor light source. It is a graph which shows the emission spectrum of purple light emitted by a purple semiconductor light source. It is a graph which shows the emission spectrum of the blue excitation light and green fluorescence emitted by a green semiconductor light source. It is a graph which shows the absorption spectrum of hemoglobin. It is a graph which shows the scattering coefficient of a living tissue. It is a graph which shows the emission spectrum of the white light which is composed of blue light, green fluorescence, and red light. It is a graph which shows the spectral characteristic of the microcolor filter of an image sensor. It is explanatory drawing which shows the irradiation timing of illumination light and the operation timing of an image sensor in a normal observation mode. It is explanatory drawing which shows the irradiation timing of illumination light and the operation timing of an image sensor in a blood vessel emphasis observation mode. It is explanatory drawing which shows the image processing procedure in a normal observation mode. It is explanatory drawing which shows the image processing procedure in the blood vessel emphasis observation mode. It is a figure which shows the arrangement 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 the 1st dichroic mirror. It is a graph which shows the transmission characteristic of the dichroic filter of the 2nd dichroic mirror. It is a graph which shows the transmission characteristic of the dichroic filter of the 3rd dichroic mirror. It is a figure which shows the optical path integration part which provided the 1st dichroic mirror which formed the dichroic filter which has the function of the excitation light cut filter of 2nd Embodiment. It is a graph which shows the transmission characteristic of the dichroic filter of the 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 the excitation light cut filter. It is a figure which shows the optical path integration part which provided the light amount measurement sensor of 4th Embodiment. It is a graph which shows the transmission characteristic of the filter arranged in front of a green light amount measurement sensor. It is a graph which shows the transmission characteristic of the filter arranged in front of a red light amount measurement sensor. It is a block diagram in the case of performing light amount control using a light amount measurement sensor. It is a figure which shows the optical path integration part provided with the excitation light cut filter and the light amount 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 another example of the green semiconductor light source of 6th Embodiment. It is a figure which shows another example of the white semiconductor light source of 6th Embodiment.

[First Embodiment]
In FIG. 1, the endoscope system 10 includes an endoscope 11 that images an observation site in a living body, a processor device 12 that generates a display image of the observation site based on an image signal obtained by imaging, and an observation site. It is provided with a light source device 13 that supplies illumination light to the endoscope 11 and a monitor 14 that displays a display image. An operation input unit 15 such as a keyboard or a mouse is connected to the processor device 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 existing inside the mucous membrane of the observation site. The blood vessel emphasis observation mode is a mode for acquiring a blood vessel pattern as blood vessel information and making a diagnosis such as discrimination between good and bad tumors. In the blood vessel-enhanced observation mode, the observation site is irradiated with illumination light containing a large amount of light components in a specific wavelength band having high absorbance for blood hemoglobin. In the normal observation mode, a normal observation image suitable for observing the entire properties of the observation site is generated as a display image, and in the blood vessel-enhanced observation mode, a blood vessel-enhanced observation image suitable for observing the blood vessel pattern is generated as a display image. To.

The endoscope 11 connects an insertion unit 16 inserted into the digestive tract of a living body, an operation unit 17 provided at the base end portion of the insertion unit 16, the endoscope 11, a processor device 12, and a light source device 13. It has a universal code 18.

The insertion portion 16 is composed of a tip portion 19, a curved portion 20, and a flexible tube portion 21, which are connected in order from the tip. As shown in FIG. 2, on the tip surface of the tip portion 19, an illumination window 22 for irradiating the observation portion with illumination light, an observation window 23 for capturing an image of the observation portion, and an air supply for cleaning the observation window 23. An air supply / water supply nozzle 24 for supplying water and a forceps outlet 25 for projecting a treatment tool such as a forceps or an electric knife to perform various treatments are provided. An image sensor 56 and an objective optical system 60 for imaging (both see FIG. 3) are built in the back of the observation window 23.

The curved portion 20 is composed of a plurality of connected curved pieces, and by operating the angle knob 26 of the operating portion 17, it bends in the vertical and horizontal directions. By bending the curved portion 20, the direction of the tip portion 19 is directed to a desired direction. The flexible tube portion 21 is flexible so that it can be inserted into a winding tube such as the esophagus or the intestine. The insertion unit 16 includes a communication cable for communicating a drive signal for driving the image sensor 56 and an image signal output by the image sensor 56, and a light guide 55 for guiding the illumination light supplied from the light source device 13 to the illumination window 22 ( (See Fig. 3) etc. are inserted.

In addition to the angle knob 26, the operation unit 17 includes a forceps port 27 for inserting a treatment tool, an air supply / water supply button 28 operated when air supply / water supply is performed from the air supply / water supply nozzle 24, and a still image. A release button (not shown) for taking a picture of the image is provided.

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

In FIG. 3, the light source device 13 integrates a light source unit 40 composed of four semiconductor light sources 35, 36, 37, and 38 of blue, green, red, and purple, and an optical path of each color light of each of the semiconductor light sources 35 to 38. It includes an optical path integrating unit 41 and a light source control unit 42 that controls the drive of each of the semiconductor light sources 35 to 38.

The blue, red, and purple semiconductor light sources 35, 37, and 38 are light emitting elements such as a blue LED 43 that emits light in the blue wavelength band, a red LED 45 that emits light in the red wavelength band, and a purple LED 46 that emits light in the purple wavelength band. Each has. On the other hand, the green semiconductor light source 36 includes a blue excitation light LED (hereinafter, simply referred to as an excitation light LED) 44 that emits blue excitation light in the purple to blue wavelength band, and green fluorescence in the green wavelength band that is excited by the blue excitation light. It has a green phosphor 47 that emits light.

As is well known, the LEDs 43 to 46 are formed by joining a P-type semiconductor and an N-type semiconductor. Then, when a voltage is applied, electrons and holes recombine beyond the bandgap near the PN junction to allow a current to flow, and energy corresponding to the bandgap is emitted as light at the time of recombination. When the value of the power supplied to each of the LEDs 43 to 46 is increased, the amount of light emitted from each of the LEDs 43 to 46 increases. In the green semiconductor light source 36, which is a fluorescence type 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 increases as the amount of blue excitation light from the excitation light LED 44 increases. To do.

As shown in FIG. 4, the blue semiconductor light source 35 includes 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. It is composed of 35c. The inner surface of the cavity functions as a reflector that reflects light. A diffusing material that diffuses light is dispersed in the resin 35c. The blue LED 43 is electrically connected to the substrate 35a by the wiring 35d. Such a mounting form of the blue semiconductor light source 35 is generally called a surface mount type. Since the semiconductor light sources 35, 37, and 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 explanations of the red and purple semiconductor light sources 37 and 38 will be omitted. To do.

As shown in FIG. 5, the green semiconductor light source 36 also has a substrate 36a and a mold 36b like the other semiconductor light sources 35, 37, and 38, and the excitation light LED 44 is packaged in a surface mount type. The difference from the semiconductor light sources 35, 37, and 38 is that the green phosphor 47 is enclosed in the cavity of the mold 36b. The green phosphor 47 is a substance in which a fluorescent substance and a diffusing agent are dispersed in a sealing resin that seals the excitation light LED 44. Reference numeral 36d is a wiring for connecting the substrate 36a 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 having a central wavelength of 455 ± 10 nm. Further, as shown in FIG. 7, the red LED 45 has, for example, a wavelength component in the vicinity of 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 purple LED 46 has, for example, a wavelength component in the vicinity of 395 nm to 415 nm, which is a purple wavelength band, and emits purple light LV having a central wavelength of 405 ± 10 nm.

In FIG. 9, the green semiconductor light source 36 emits a mixed light (LBe + LGf) of the blue excitation light LBe emitted by the excitation light LED44 and the green fluorescence LGf emitted by the green phosphor 47 excited by the blue excitation light LBe. The blue excitation light LBe is, for example, light having a wavelength component in the vicinity of 420 nm to 440 nm, which is a wavelength band from purple to blue, and a central wavelength of 430 ± 10 nm. The green fluorescent LGf is, for example, light having a wavelength component in the vicinity of 500 nm to 600 nm, which is a green wavelength band, and 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 purple 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 and emits green fluorescent 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, a part of the blue excitation light LBe that has passed through the green phosphor 47 and the green fluorescent LGf, as shown in the figure.

The purple semiconductor light source 38 is a light source for blood vessel emphasis observation (semiconductor light source for acquiring blood vessel information). In FIG. 10 showing the absorption spectrum of blood hemoglobin, the absorption coefficient μa of blood hemoglobin has a wavelength dependence, rapidly increases in the wavelength band of 450 nm or less, and has a peak in the vicinity of 405 nm. .. Further, although it is a low value as compared with the wavelength band of 450 nm or less, it also has a peak in the wavelength band of 530 nm to 560 nm. When the observation site is irradiated with light in a wavelength band having a large extinction coefficient μa, the blood vessels absorb a large amount of light, so that an image having a difference in contrast between the blood vessels and other parts can be obtained.

Further, as shown in FIG. 11, the light scattering characteristics of living tissues also have wavelength dependence, and the shorter the wavelength, the larger the scattering coefficient μS. Scattering affects the depth of light penetration into living tissue. That is, the greater the scattering, the more light is reflected near the mucosal surface layer of the living tissue, and the less light reaches the mesopelagic zone. Therefore, the shorter the wavelength, the lower the depth of penetration, and the longer the wavelength, the higher the depth of penetration. The wavelength of light for enhancing blood vessels is selected in consideration of the absorption characteristics of hemoglobin and the light scattering characteristics of living tissues.

The purple light LV with a central wavelength of 405 ± 10 nm emitted by the purple LED 46 has a relatively short wavelength and a low invasion depth, so that it is largely absorbed by the surface blood vessels. Therefore, purple light LV is used as light for enhancing surface blood vessels. By using the purple light LV, it is possible to obtain a blood vessel-enhanced observation image in which the surface blood vessels are visualized with high contrast. Further, as the light for emphasizing the mesopelagic blood vessels, light in the green wavelength band of white light LW (see FIG. 12) is used. In the absorption spectrum shown in FIG. 10, the absorption coefficient changes slowly in the green wavelength band of 530 nm to 560 nm as compared with the blue wavelength band of 450 nm or less. Therefore, the light for enhancing the middle-deep blood vessels is purple light LV. It is not required to have a narrow band as in. Therefore, as will be described later, a green image signal color-separated from white light by the G-color microcolor filter of the image sensor 56 is used for enhancing the mesopelagic blood vessels.

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, extinguishing, and the amount of light of the LEDs 43 to 46 via the drivers 50 to 53. The amount of light is controlled 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 light the LEDs 43 to 46 by continuously applying a drive current to the LEDs 43 to 46. Then, the power supplied to each of the LEDs 43 to 46 is changed by changing the applied drive current value according to the exposure control signal received from the processor device 12, and the blue light LB, the green fluorescent LGf, the red light LR, and the purple light are changed. The amount of light of LV is controlled respectively. The light amount control of the green fluorescent LGf is performed by controlling the light amount of the blue excitation light LBe of the excitation light LED44. Therefore, when the amount of light of the green fluorescent LGf is increased, the drive current value given from the driver 51 to the excitation light LED 44 is increased in order to increase the amount of light of the blue excitation light LBe. It should be noted that PAM (Pulse Amplitude Modulation) control that changes the amplitude of the drive current pulse by giving the drive current in a pulse shape instead of continuously giving it, and PWM (Pulse Width Modulation) control that changes the duty ratio of the drive current pulse. May be done.

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

FIG. 12 shows the emission spectra of the mixed light of blue light LB, green fluorescent 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. This mixed light is used as white light LW. Since the blue excitation light LBe is cut by the third dichroic mirror 81 (see FIG. 18) as described later, 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 desired color of the displayed image and the like. Specifically, the ratio of the amount of light of the blue light LB, the green fluorescence LGf, and the red light LR (the ratio of the drive current values 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 controls the exposure of the illumination light while maintaining the target emission spectrum. When the ratio of the amount of each color light constituting the illumination light changes, the emission spectrum of the illumination light changes and the color of the displayed image changes. Therefore, the light source control unit 42 independently changes the drive current value given to the LEDs 43 to 46 through the drivers 50 to 53 so that the ratio of the light amount of each color light becomes constant, and increases or decreases the light amount of each color light.

Further, the light source control unit 42 changes the emission spectrum of the illumination light between the normal observation mode and the blood vessel emphasis observation mode. In the blood vessel enhancement observation mode, the purple light LV for enhancing the surface blood vessel is irradiated in addition to the white light LW, so that the emission spectrum of the illumination light is that the purple light LV is added to the white light LW. The light source control unit 42 uses the blue light LB as compared with the normal observation mode so that the purple light LV is dominant as compared with the blue light LB in the emission spectrum of the mixed light of the white light LW and the purple light LV. Reduce the proportion of light.

In FIG. 3, the endoscope 11 includes a light guide 55, an image sensor 56, an analog processing circuit 57 (AFE: Analog Front End), and an image pickup 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 29b is connected to the light source device 13, the incident end 55a of the light guide 55 arranged in the light source connector 29b faces the exit end of the optical path integrating portion 41. The exit end of the light guide 55 located at the tip portion 19 is branched into two at the front stage of the illumination window 22 so that the light is guided to the two illumination windows 22.

An irradiation lens 59 is arranged behind 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 is emitted from the illumination window 22 toward the observation portion. The irradiation lens 59 is composed of a concave lens, and widens the divergence angle of the light emitted from the light guide 55. As a result, the illumination light can be applied to a wide range of the observation site.

An objective optical system 60 and an image sensor 56 are arranged behind the observation window 23. The image of the observation portion is incident on the objective optical system 60 through the observation window 23, and is imaged on the image pickup surface 56a of the image pickup element 56 by the objective optical system 60.

The image sensor 56 is composed of a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, or the like, and a plurality of photoelectric conversion elements constituting pixels such as photodiodes are arranged in a matrix on the image pickup surface 56a. It is arranged in. The image sensor 56 photoelectrically converts the light received by the image pickup surface 56a, and accumulates signal charges in each pixel according to the amount of light received. The signal charge is converted into a voltage signal by the amplifier and read out. The voltage signal is output from the image sensor 56 to the AFE 57 as an image signal.

The AFE (Analog Front End) 57 includes 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 a correlation double sampling process on the analog image signal from the image sensor 56 to remove noise caused by resetting the signal charge. The AGC amplifies the image signal whose 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 image signal to the processor device 12.

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

The image pickup device 56 is a color image pickup device, and microcolor filters of three colors B, G, and R having spectral characteristics as shown in FIG. 13 are assigned to each pixel on the image pickup surface 56a. The arrangement of the microcolor filters is, for example, the 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. Further, the R pixel to which the R filter is assigned is sensitive to light in the wavelength band of about 580 nm to 800 nm. As for the blue light LB, green fluorescent LGf, and red light LR constituting the white light LW, the reflected light corresponding to the blue light LB mainly corresponds to B pixel, and the reflected light corresponding to the green fluorescent LGf mainly corresponds to G pixel and red light LR. The reflected light is received mainly by the R pixel. The reflected light corresponding to the purple light LV for blood vessel emphasis observation is received by the B pixel. The blue excitation light LBe is cut by the third dichroic mirror 81 and is not irradiated to the observation site. However, if the blue excitation light LBe is irradiated, the B pixel is sensitive to the reflected light corresponding to the blue excitation light LBe. To do.

As shown in FIGS. 14 and 15, the image sensor 56 performs a storage operation of accumulating signal charges in the pixels and a reading operation of reading out the accumulated signal charges within the 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 in accordance with the timing of the accumulation operation of the image pickup element 56, and the illumination light includes blue light LB, green fluorescent LGf, and red 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 image pickup element 56. The image sensor 56 color-separates the reflected light of the white light LW with a micro color filter. The B pixel receives the reflected light corresponding to the blue light LB, the G pixel receives the reflected light corresponding to the green fluorescent LGf, and the R pixel receives the reflected light corresponding to the red light LR. The image sensor 56 sequentially outputs one frame of image signals B, G, and R in which the pixel values of the B, G, and R pixels are mixed according to the frame rate. 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 semiconductor light sources 35 to 37 in accordance with the timing of the accumulation operation of the image sensor 56. When each of the semiconductor light sources 35 to 38 is turned on, purple light LV is added together with white light LW which is the same as in the normal observation mode, and these mixed lights (LW + LV) are irradiated to the observation portion as illumination light.

Similar to the normal observation mode, the illumination light to which the purple light LV is added to the white light LW is separated by the microcolor filter of the image pickup 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 receive the reflected light corresponding to the green fluorescent LGf and the reflected light corresponding to the red light LR, respectively, as in the normal observation mode. Even in the blood vessel emphasis observation mode, the image sensor 56 sequentially outputs the image signals B, G, and R according to the frame rate in accordance with the read timing. Such an imaging operation is repeated while the blood vessel-enhanced observation mode is set.

In FIG. 3, in addition to the controller 65, the processor device 12 includes a DSP (Digital Signal Processor) 66, an image processing unit 67, a frame memory 68, and a display control circuit 69. The controller 65 has a CPU (Central Processing Unit), a ROM (Read Only Memory) for storing control programs and setting data required for control, a RAM (Random Access Memory) for loading programs and functioning as a working memory, and the like. , The CPU controls each part of the processor device 12 by executing the control program.

The DSP 66 acquires an image signal output by the image sensor 56. The DSP 66 separates an image signal in which signals corresponding to each pixel of B, G, and R are mixed into an image signal of B, G, and R, and performs pixel interpolation processing on the image signal 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.

Further, the DSP 66 calculates the exposure value based on the image signals B, G, and R, and increases the amount of illumination light when the amount of light of the entire image is insufficient (underexposure), while increasing the amount of light. If is too high (overexposure), an exposure control signal for controlling the amount of illumination light to be reduced is output to the controller 65. 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 the image data output by the DSP 66 and the processed image data processed by the image processing unit 67. The display control circuit 69 reads the image processed image data from the frame memory 68, converts it into a video signal such as a composite signal or a component signal, and outputs the image data 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 color-separated into the colors B, G, and R by the DSP 66. .. This normal observation image is output to the monitor 14. The image processing unit 67 updates the normal observation image every time the image signals B, G, and R in the frame memory 68 are updated.

As shown in FIG. 17, in the blood vessel-enhanced observation mode, the image processing unit 67 generates a blood vessel-enhanced observation image based on the image signals B, G, and R. Since the image signal B in the blood vessel-enhanced observation mode contains a component of reflected light corresponding to the blue light LB constituting the white light LW and a component of the reflected light corresponding to the purple light LV, the surface blood vessel Is depicted with high contrast. In lesions such as cancer, the density of superficial blood vessels tends to be higher than that in normal tissues, and the pattern of blood vessels is characteristic. Therefore, in blood vessel emphasis observation for the purpose of distinguishing between good and bad tumors, It is preferable that the surface blood vessels are clearly visualized.

In order to further emphasize the surface blood vessels, for example, the region of the surface blood vessels in the image may be extracted based on the image signal B, and the extracted surface blood vessels may be subjected to contour enhancement processing or the like. Then, the image signal B subjected to the contour enhancement processing is combined with the full-color image generated based on the image signals B, G, and R. The same treatment may be performed on the mesopelagic blood vessels in addition to the superficial blood vessels. When emphasizing the mesopelagic blood vessels, the region of the mesopelagic zone is extracted from the image signal G containing a lot of information on the mesopelagic zone, and the extracted mesopelagic zone is subjected to contour enhancement processing. Then, the enhanced image signal G is combined with the full-color image generated from the image signals B, G, and R.

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

As a method for generating the blood vessel-enhanced observation image, the blood vessel-enhanced observation image is generated only by 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 the B channel of the monitor 14. A method of displaying the observation portion in pseudo color may be adopted as the G channel, such as a method of assigning the image signal G to the R channel of the monitor 14.

In FIG. 18, the optical path integration unit 41 includes collimator lenses 75, 76, 77, and 78 that collimate each color light emitted by each semiconductor light source 35 to 38, a first dichroic mirror 79, a second dichroic mirror 80, and a third dichroic mirror. It is composed of 81 (corresponding to the “optical path integration optical member” of the present invention) and a condensing lens 82 that collects the light emitted from the optical path integration unit 41 to the incident end 55a 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 arranged 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 arranged so 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 a second dichroic mirror 80 is provided at a position where these optical axes are orthogonal to each other. Further, due to the action of the first and second dichroic mirrors 79 and 80, all the optical paths of the blue light LB, the mixed light of the blue excitation light LBe and the green fluorescent LGf, the red light LR, and the purple light LV finally intersect. A third dichroic mirror 81 is provided. The first dichroic mirror 79 is the optical axis of the green semiconductor light source 36 and the red semiconductor light source 37, the second dichroic mirror 80 is the optical axis of the blue semiconductor light source 35 and the purple semiconductor light source 38, and the third dichroic mirror 81 is the blue semiconductor light source 35 and green. They are arranged 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 in a wavelength band of about 610 nm or more and transmitting light in a wavelength band lower than that. The first dichroic mirror 79 transmits the mixed light of the blue excitation light LBe and the green fluorescent LGf incident from the green semiconductor light source 36 through the collimator lens 76 to the downstream side, and is incident from the red semiconductor light source 37 through the collimator lens 77. The red light LR is reflected. As a result, the mixed light of the blue excitation light LBe and the green fluorescent LGf and the optical 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 of less than about 430 nm and transmitting light in a wavelength band higher than that. The second dichroic mirror 80 transmits the blue light LB incident from the blue semiconductor light source 35 through the collimator lens 75 to the downstream side, and reflects the purple light LV incident from the purple semiconductor light source 38 through the collimator lens 78. As a result, the optical paths of the blue light LB and the purple light LV are integrated.

The dichroic filter of the third dichroic mirror 81 has transmission characteristics 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 fluorescent 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 of less than about 490 nm and transmitting light in a wavelength band higher than that. .. Therefore, the third dichroic mirror 81 reflects the blue excitation light LBe among 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. Further, 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 blue light LB, green fluorescent LGf, red light LR, and 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 observation site of the blue excitation light LBe is blocked.

The operation of the above configuration will be described below. When performing endoscopic diagnosis, the endoscope 11 is connected to the processor device 12 and the light source device 13, the power of the processor device 12 and the light source device 13 is turned on, and the endoscope system 10 is started.

The insertion portion 16 of the endoscope 11 is inserted into the digestive tract of the subject, and observation in the digestive tract is started. In the normal observation mode, each of the semiconductor light sources 35 to 37 except the purple semiconductor light source 38 is turned on. The light source control unit 42 sets the drive current value given to each of the LEDs 43 to 45 to a value for the normal observation mode, and starts lighting each of the semiconductor light sources 35 to 37. Then, the amount of light is controlled 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 by the excitation light LED44 and green fluorescence LGf by the green phosphor 47 excited by the blue excitation light LBe. Each color light is incident on 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 passes through the third dichroic mirror 81. The mixed light of the blue excitation light LBe and the green fluorescent LGf passes through the first dichroic mirror 79. Then, the blue excitation light LBe of the mixed light is reflected by the third dichroic mirror 81, and the green fluorescent LGf is transmitted through the third dichroic mirror 81. The first dichroic mirror 79 integrates the optical paths of the red light LR, the mixed light of the blue excitation light LBe and the green fluorescent 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 fluorescent LGf, and the red light LR are integrated by the second and third dichroic mirrors 80 and 81. These blue light LB, green fluorescent LGf, and red light LR are incident on the condenser lens 82. As a result, white light LW composed of blue light LB, green fluorescent LGf, and red light LR is generated. The condenser lens 82 concentrates the white light LW on the incident end 55a 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 portion from the illumination window 22. The reflected light of the white light LW reflected at the observation site is incident on the image pickup device 56 from the observation window 23. The image sensor 56 outputs the image signals B, G, and R to the DSP 66 of the processor device 12. The DSP 66 color-separates the image signals B, G, and R and inputs them to the image processing unit 67. The image pickup operation by the image pickup 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 image sensor 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 semiconductor light source 35 to 37 so that the ratio of the amount of light of each color light becomes constant (so that the target emission spectrum does not change) based on the received exposure control signal. .. Then, each semiconductor light source 35 to 37 is driven by the determined drive current value. As a result, the amount of blue light LB, green fluorescent LGf, and red light LR constituting the white light LW by each of the semiconductor light sources 35 to 37 can be kept constant at a ratio suitable for the normal observation mode.

When changing the amount of light of the green fluorescent LGf in the exposure control, the amount of light of the blue excitation light LBe of the excitation light LED44 is changed. As shown in FIG. 19 and the like, the wavelength band of the blue excitation light LB partially overlaps with the wavelength band of the blue light LB. Therefore, when the blue excitation light LBe is emitted as the illumination light, the amount of the blue light LB changes with the change in the 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 fluorescent LGf. Can be controlled. Therefore, even if the exposure is controlled, the illumination light having 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.

If 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, the purple semiconductor light source 38 is turned on in addition to the semiconductor light sources 35 to 37. Each color light from each of the semiconductor light sources 35 to 37 becomes white light LW by the action of the optical path integrating unit 41 described above, and is supplied to the endoscope 11.

The purple semiconductor light source 38 emits purple light LV by the purple LED 46. The purple light LV is incident on the collimator lens 78. The purple light LV is reflected by the second and third dichroic mirrors 80 and 81. The second and third dichroic mirrors 80 and 81 integrate the purple light LV into the same optical path as the white light LW. These purple light LV and white light LW are incident on the condenser lens 82. The condenser lens 82 concentrates the purple light LV and the white light LW on the incident end 55a of the light guide 55 of the endoscope 11 and supplies the purple light LV and the white light LW to the endoscope 11. In this way, the purple light LV and the white light LW are simultaneously irradiated to the observation site. At this time 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, the illumination light having an emission spectrum suitable for the blood vessel emphasis observation mode can always be supplied to the endoscope 11. it can.

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

Since the illumination light having an emission spectrum suitable for the blood vessel-enhanced observation mode is always irradiated, the reliability of the blood vessel-enhanced observation image is improved. Since the blood vessel-enhanced observation image is used for good / bad discrimination of the tumor, if the reliability of the blood vessel-enhanced observation image is high, the result of the good / bad discrimination of the tumor can be reliable.

Since the blue excitation light LBe that affects the amount of blue light LB and purple light LV is cut by the third dichroic mirror 81, the change in the blue excitation light LBe due to the change in the amount of light of the green fluorescent LGf is added to the blue light. Illumination light having a target emission spectrum can be stably obtained without complicated control such as increasing or decreasing the 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 mixed light of the blue excitation light LBe and the green fluorescent LGf emitted by the green semiconductor light source 36 and the optical path of the blue light LB emitted by the blue semiconductor light source 35 is excited. Although it functions as an optical cut filter, a dichroic filter of a dichroic mirror different from the third dichroic mirror 81 may function as an 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 that the mixed light of the blue excitation light LBe and the green fluorescent LGf emitted by the green semiconductor light source 36 and the red light LR emitted by the red semiconductor light source 37 are used. It may be carried by the dichroic filter of the first dichroic mirror 91 (corresponding to the first dichroic mirror 79 of the first embodiment, corresponding to the "optical path integration optical member" of the present invention) that integrates the optical path. 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 in a wavelength band of about 610 nm or more and light in a wavelength band of less than about 490 nm, and light in other wavelength bands. It has the property of transmitting light. That is, the bandpass characteristic is a combination of the transmission characteristics of the first dichroic mirror 79 and the third dichroic mirror 81 of the first embodiment. However, if such a bandpass characteristic is provided, the manufacturing cost will be higher than that of a shortpass that reflects light on the long wavelength side and transmits light on the short wavelength side, or vice versa. It is advantageous in terms of cost that the dichroic filter of the third dichroic mirror 81 having the long-pass characteristic has the function of the excitation light cut filter as in the first embodiment.

[Third Embodiment]
In each of the above embodiments, an example in which the dichroic mirror also serves as an excitation light cut filter has been described, but the excitation light cut filter is provided separately from the dichroic mirror as in the optical path integration unit 95 of the third embodiment shown in FIG. May be good. In the optical path integration unit 95, an excitation light cut filter 96 is arranged between the green semiconductor light source 36 and the first dichroic mirror 79. As shown in FIG. 25, for example, the excitation light cut filter 96 has a property of reflecting light in the purple and blue wavelength bands of less than about 450 nm and transmitting light in the other green and red wavelength bands. Although not shown, an 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 prevent the blue excitation light LBe from being incident on the incident end 55a of the light guide 55, and the excitation light cut filter is on the optical 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 and the green fluorescent LGf emitted by the semiconductor light source 36 and the optical path of the blue light LB emitted by the blue semiconductor light source 35 are integrated, or on the optical path on the upstream side of the position. ..

[Fourth Embodiment]
In the first embodiment, the amount of light of each color light is controlled by changing the drive current value given to each of the LEDs 43 to 46 based on the exposure control signal from the processor device 12, but the heat generated by the LED or the phosphor is generated. The output light amount of the semiconductor light source may fluctuate with respect to the drive current value due to the influence of the above and the influence of deterioration with time. Therefore, a light amount measuring sensor for measuring the amount of light of each color light may be provided to monitor whether or not the amount of light of each color light reaches a target value based on the light amount measurement signal output by the light amount measurement sensor.

In FIG. 26, the optical path integration unit 100 measures the amount of light of each color light emitted by each semiconductor light source 35 to 38, in addition to the configuration of the optical path integration unit 41 shown in FIG. 18 of the first embodiment, in blue, green, and red. , Purple light intensity measurement sensors 101, 102, 103, 104, and each light intensity measurement sensor 101 provided immediately before each semiconductor light source 35 to 38 and reflecting a part of each color light emitted by each semiconductor light source 35 to 38. The glass plates 105, 106, 107, and 108 that guide light to ~ 104 are provided.

The glass plates 105 to 108 are arranged at an inclination 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 emitted by each semiconductor light source 35-38. Fresnel reflection occurs when each color light is incident on each glass plate 105 to 108. Each glass plate 105 to 108 uses this Frenel reflection to guide a part (about 4% to 8%) of each color light emitted by each semiconductor light source 35 to 38 to each light amount measurement sensor 101 to 104. It is a light guide member. Instead of the glass plate, another light guide member such as an optical fiber may be used.

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 amount measuring sensor 102 to only the light in the wavelength band of the green fluorescent LGf which constitutes a part of the white light LW finally supplied to the endoscope 11. As shown in FIG. 27, it has the property of reflecting light in the red wavelength band of about 610 nm or more and light in the purple and blue wavelength bands of less than about 490 nm and transmitting light in the other green wavelength bands. Have. That is, the filter 109 has a bandpass characteristic that combines the transmission characteristics of the first dichroic mirror 79 and the third dichroic mirror 81 of the first embodiment, like the first dichroic mirror 91 of the second embodiment. By the filter 109, only the green fluorescent LGf, in which the blue excitation light LBe is cut and finally emitted as a part of the white light LW, is incident on the green light amount measurement sensor 102. The pure light intensity of green fluorescent LGf can be measured.

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

In FIG. 29, each light amount measuring sensor 101-104 receives each color light guided by Fresnel reflection of the glass plates 105-108, and outputs a light amount measurement signal corresponding to the light amount of each received color light. 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, gives a drive current to each semiconductor light source 35 to 38 set by exposure control so that the light amount becomes the target value. Fine-tune the value. In this way, by constantly monitoring the amount of light of each color light with the light amount measurement sensors 101 to 104 and finely adjusting the drive current value given based on the measurement result of the amount of light, the amount of light can be controlled so as to always meet the target value. .. Therefore, the 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 placed 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 optical cut filter 116 having the same transmission characteristics as 109 may be provided. This eliminates the need for the filter 109. However, since the excitation light cut filter 116 is larger in size than the filter 109, it is preferable to provide the filter 109 rather than the excitation light cut filter 116 from the viewpoint of cost and space saving.

In the fourth embodiment, the light amount measuring sensors are arranged for all the semiconductor light sources to monitor the light amount, but at least the blue, green, and red semiconductor light sources that emit the light constituting the white light LW, and the fluorescent type. It is not necessary to monitor the light intensity of the semiconductor light source and arrange a light intensity measurement sensor for other semiconductor light sources. Further, among the blue, green, and red semiconductor light sources, only the light amount of the semiconductor light source (fluorescent semiconductor light source) in which the fluctuation of the output light amount with respect to the drive current value is particularly large may be selectively monitored.

The fluorescent semiconductor light source is not limited to the green semiconductor light source 36 of each of the above embodiments. In place of or in addition to the green semiconductor light source, the red semiconductor light source is a blue excitation light emitting element that emits blue excitation light in the purple to blue wavelength band, and red fluorescence in the red wavelength band that is excited by the blue excitation light. It may be composed of a red phosphor that emits light. In this case as well, as in each of the above embodiments, the excitation light cut filter is a position where the mixed light of blue excitation light and red fluorescence emitted by the red semiconductor light source and the optical path of blue light emitted by the blue semiconductor light source are integrated, or a position thereof. It suffices if it is provided on the optical path on the upstream side of. For example, as in the first embodiment, the dichroic filter of the third dichroic mirror 81 may be provided with the function of the excitation light cut filter, or the excitation light is 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 composed of 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 purple 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 that cuts green excitation light and transmits red fluorescence is arranged between the red semiconductor light source and the first dichroic mirror 79, for example, in the optical path integration unit 41 of FIG.

[Fifth Embodiment]
Further, as in the light source unit 120 shown in FIG. 31, a white semiconductor light source 121 may be used as the fluorescent semiconductor light source. The light source unit 120 removes the green semiconductor light source 36 and the red semiconductor light source 37 from the light source unit 40 of the first embodiment, and provides a white semiconductor light source 121 in place of these. Further, 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 includes a blue excitation light emitting element that emits blue excitation light LBe in the blue wavelength band, and green and green that are excited by the blue excitation light LBe and emit green fluorescent LGf and red fluorescent LRf in the green and red wavelength bands. It is composed of a red phosphor. In this case, the white light LW is composed of a mixed light of blue light LB emitted by the blue semiconductor light source 35, green fluorescent LGf and red fluorescent LRf emitted by the white semiconductor light source 121. Also in this embodiment, the wavelength band of the blue excitation light LB emitted by the white semiconductor light source 121 overlaps with the wavelength band of the blue light LB emitted by the blue semiconductor light source 35. Therefore, as in the embodiment having the three-color semiconductor light sources 35 to 37 of each of the above embodiments, the embodiment having the blue semiconductor light source 35 and the white semiconductor light source 121 of the present embodiment is also excited by the excitation light emitted by the fluorescent semiconductor light source. The problem arises that the amount of light whose wavelength band overlaps with that of light is affected, and the emission spectrum of the illumination light changes.

A dichroic mirror 123 is arranged at a position where the lights emitted by the semiconductor light sources 35, 38, and 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 has a property of reflecting purple light LV, blue excitation light LB, and blue light LB and transmitting green fluorescent LGf and red fluorescent LRf, and cuts the blue excitation light LBe. Acts as a filter. By this dichroic mirror 123, all the optical paths of each color light are integrated, and the transmission of the blue excitation light LBe is blocked.

In this embodiment as well, 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 white semiconductor light source 121 may be provided with a light amount measuring sensor to monitor the light amount.

Further, the mounting embodiment of the LED of the first embodiment is an example, and other embodiments may be adopted. For example, a microlens for adjusting the divergence angle may be provided on the light emitting surface of the sealing resin 35c or the green phosphor 47 in FIGS. 4 and 5, or a shell having a microlens formed instead of the surface mount type. The LED may be housed in a mold case. Further, as the green semiconductor light source 36, the example in which the green phosphor 47 is integrally provided on the substrate 36a in addition to the excitation light LED 44 has been described, but the green phosphor 47 and the substrate 36a may be provided separately. 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, and the excitation light of the excitation light LED 44 is guided to the green phosphor 47 via the light guide member. To do.

[Sixth Embodiment]
Further, although the example of using an LED as a light emitting element has been described, a laser diode (LD) may be used instead of the LED. For example, as shown in FIG. 32, as the excitation light emitting element, the green semiconductor light source 130 composed of the excitation light LD131 that emits blue excitation light and the green phosphor 132 arranged in front of the excitation light LD131 is the first. -It may be used instead of the green semiconductor light source 36 of 4th Embodiment.

In this case, the green phosphor 132 is formed on the surface of the disk-shaped transparent rotating plate 133 by a method such as coating. Then, while rotating the rotating plate 133 by a rotating mechanism 134 such as a motor, the blue excitation light from the excitation light LD131 is irradiated to the eccentric position of the rotating plate 133. By rotating the rotating plate 133, the irradiation position of the excitation light is not concentrated at one position of the green phosphor 132. If the irradiation position of the excitation light is concentrated in one place, the temperature of that place becomes high, which accelerates the deterioration of the green phosphor 132, but such a situation can be prevented. Reference numeral 135 is a condensing lens that collects the blue excitation light emitted by the excitation light LD131 on the rotating plate 133.

The excitation light cut filter may be integrally formed on the emission side surface of the rotating plate 133. Further, as the light emitting element, an organic EL (Electro-Luminescence) element may be used in addition to the LED and LD. Not limited to the fluorescent semiconductor light source, 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, purple semiconductor light source 38, etc.).

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 composed of an excitation light LD141 that emits blue excitation light and a green and red phosphor 142 arranged in front of the excitation light LD141. The white semiconductor light source 140 may be used as the white semiconductor light source 121 of the fifth embodiment. Since other configurations such as the rotating plate are the same as those of the green semiconductor light source 130 of FIG. 32, the same reference numerals as those of FIG. 32 are added and the description thereof will be omitted.

In each of the above embodiments, an excitation light cut filter that cuts the excitation light by 100% has been exemplified, but the present invention is not limited thereto. The excitation light cut filter may be any filter that can reduce the amount of excitation light to some extent, and for example, a filter having a transmission property that cuts excitation light by 50% is also included in the present invention. However, the closer it is to 100%, the more effective it is, which is preferable.

The configuration of the optical path integration unit in each of the above embodiments is an example, and various changes can be made. For example, a dichroic mirror is used as an optical member on which a dichroic filter is formed, but a dichroic prism in which a dichroic filter is formed on a prism may be used instead. Further, instead of the optical member forming the dichroic filter 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 the incident end of the light guide of the endoscope. The optical path may be integrated using a branched light guide with. The branched light guide is a fiber bundle in which optical fibers are bundled, and one end of the optical fiber is divided into a plurality of optical fibers by a predetermined number, and the incident end is branched into a plurality of optical fibers. In this case, each semiconductor light source is arranged so as to correspond to each of the branched incident ends. Then, an excitation light cut filter is arranged between the fluorescent semiconductor light source and the incident end of the branched light guide.

In each of the above embodiments, as a semiconductor light source for acquiring blood vessel information for acquiring blood vessel information of a living tissue, a purple semiconductor light source 38 that emits purple light LV has been exemplified, but separately or in addition to the purple semiconductor light source 38, Another semiconductor light source for acquiring blood vessel information may be provided. For example, in order to acquire the oxygen saturation of hemoglobin in blood as blood vessel information, a semiconductor light source that emits blue light in a narrow band with a central wavelength of 473 ± 10 nm may be provided. Of course, when the blood vessel information is not observed, only the blue, green, and red semiconductor light sources may be provided without providing the semiconductor light source for acquiring blood vessel information.

Further, in the first embodiment, only white light is irradiated to the observation site in the normal observation mode, and white light LW and purple light LV are simultaneously irradiated to the observation site in the blood vessel emphasis observation mode, and white light is used in both modes. A mode that does not use white light 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-enhanced observation image based on the green fluorescent LGf.

In each of the above embodiments, the image sensor 56 includes a color image sensor that color-separates white light by a micro color filter of B, G, and R, and simultaneously acquires image signals of B, G, and R by the color image sensor. The simultaneous endoscopic system and the light source device used for the system have been described as an example, but the image signal of B, G, and R is generated by sequentially irradiating each color light of blue, green, and red with a monochrome image sensor. The present invention may be applied to a surface-sequential endoscopic system for acquiring surface-sequentially and a light source device used therein.

Needless to say, each of the above embodiments can be carried out individually or in combination.

In each of the above embodiments, the light source device and the processor device have been described as separate bodies, but the two devices may be integrally configured. Further, the present invention is an endoscope system using a fiber scope that guides the reflected light of an observation portion of illumination light with an image guide, and an ultrasonic endoscope having an imaging element and an ultrasonic transducer built in at the tip. And it can also be applied 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 unit 41, 90, 95, 100, 115, 122 Optical path integration unit 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 to 3rd dichroic mirror 91 1st dichroic mirror 96, 116 Excitation light cut filter 101-104 Light intensity measurement sensor 105-108 Glass plate 109 filter 121, 140 White semiconductor light source 123 Dichroic mirror 131, 141 Excitation light LD
133, 143 rotating plate 142 green and red phosphor

Claims (9)

In a light source device for an endoscope that supplies illumination light to the light guide of the endoscope
A fluorescent semiconductor having an excitation light emitting element that emits excitation light and a phosphor that is excited by the excitation light and emits fluorescence including at least one wavelength band of green or red included in the illumination light. Multiple semiconductor light sources with light sources and
An excitation light cut filter that cuts the excitation light,
An optical path integration optical member that integrates an optical path through which the fluorescence emitted by the fluorescent semiconductor light source passes and an optical path through which light emitted by a semiconductor light source other than the fluorescent semiconductor light source among the plurality of semiconductor light sources passes.
A light source device for an endoscope, which comprises a light source control unit that controls 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 emitting element and the light guide. The endoscope light source device according to claim 1 or 2, wherein the excitation light cut filter is provided in the optical path integration optical member. The light source device for an endoscope according to claim 3, wherein a dichroic filter is formed in the optical path integration optical member, and the dichroic filter also serves as the excitation light cut filter. The light source device for an endoscope according to any one of claims 1 to 4, wherein the excitation light is light in a wavelength band from purple to blue. The light source device for an endoscope according to any one of claims 1 to 5, wherein the light emitted by a semiconductor light source other than the fluorescent semiconductor light source has a wavelength band that overlaps with the excitation light. The plurality of semiconductor light sources are two semiconductor light sources that emit light in each wavelength band of blue and green.
The fluorescent semiconductor light source is at least one of the two semiconductor light sources, and any one of claims 1 to 6 is characterized in that the phosphor emits either green or red fluorescence. The light source device for an endoscope described in 1. A light quantity measuring sensor provided for at least one of the plurality of semiconductor light sources and measuring the amount of light emitted by the semiconductor light source.
A light guide member that guides a part of the light emitted by the semiconductor light source to the light quantity measurement sensor, and
The light source device for an endoscope according to any one of claims 1 to 7, wherein the light source control unit is controlled based on the measurement result of the light amount measurement sensor. The light quantity measuring sensor and the light guide member are provided for the fluorescent semiconductor light source.
The light source device for an endoscope according to claim 8, 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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