WO2024154697A1 - Illumination light source device - Google Patents

Abstract

The present invention addresses the problem of obtaining an illumination light source device with which it is possible, when simultaneously beaming excitation light capable of exciting a fluorescent substance contained in the subject together with illumination light onto a subject, to bring the color reproducibility of mixed light of the illumination light and the excitation light closer to the color reproducibility of natural light. This illumination light source device 100 is provided with an illumination light source 110 that directs illumination light L1 onto a subject 101, an excitation light source 120 that directs excitation light L2 capable of exciting a fluorescent substance contained in the subject 101, and a control unit 140 for controlling the illumination light source 110 and the excitation light source 120. When the illumination light L1 and the excitation light L2 are simultaneously directed onto the subject 101, the control unit 140 adjusts the intensity and/or the wavelength of the illumination light L1 or the excitation light L2 so that the spectral distribution of mixed light L3 combining the illumination light L1 and the excitation light L2 is brought closer to the spectral distribution of natural light than when only the illumination light L1 is directed onto the subject 101.

Description

Illumination light source device

The present invention relates to an illumination light source device, and in particular to an illumination light source device that can be used in endoscopes and can be applied to all tubular tissues in the human body, such as the intestines, digestive organs such as the stomach, and even the respiratory system.

Conventionally, endoscopes and the like have included illumination light source devices that illuminate the inside of human body lumens by irradiating the subject with not only illumination light but also excitation light via a light-guiding member such as an optical fiber.

For example, Patent Document 1 discloses a fluorescence observation device that includes an illumination light source that emits white light as illumination light and an excitation light source that emits excitation light, and that irradiates the illumination light onto a subject in illumination light observation and irradiates the excitation light onto a subject in excitation light observation.

JP 2008-237652 A

By the way, white light, which is used as illumination light, can be created by mixing three colors of light (i.e. red light, green light, and blue light) emitted by red, green, and blue light-emitting elements. However, the white light obtained by mixing these three colors of light does not contain light of all wavelengths of visible light, like natural light (daytime sunlight), and the color reproduction of the subject is inferior to natural light.

The inventors of this invention then realized for the first time that it is possible to improve color reproducibility by simultaneously irradiating excitation light, which is not normally irradiated during illumination light observation, and mixing the wavelength components of the excitation light with the three color wavelength components of the illumination light. Furthermore, they discovered that by mixing the three wavelength components of red, green, and blue with the wavelength components of other colors (excitation light), and bringing the spectral distribution of the mixed light obtained by mixing these lights closer to the spectral distribution of natural light, it is possible to create white light with color reproducibility that is even closer to that of natural light, using a limited number of light sources contained in the illumination device.

The present invention aims to obtain an illumination light source device that can bring the color reproducibility of the mixed light of illumination light and excitation light closer to that of natural light when excitation light capable of exciting fluorescent substances contained in the subject is irradiated simultaneously with illumination light onto the subject.

The present invention provides the following:

(Item 1)
an illumination light source that irradiates an object with illumination light;
an excitation light source that irradiates excitation light capable of exciting a fluorescent substance contained in the subject;
a control unit for controlling the illumination light source and the excitation light source,
the control unit adjusts at least one of the intensity and the wavelength of the illumination light or the excitation light so that, when the illumination light and the excitation light are simultaneously irradiated onto the subject, a spectral distribution of a mixture of the illumination light and the excitation light becomes closer to a spectral distribution of natural light than when only the illumination light is irradiated onto the subject.

(Item 2)
2. The illumination light source device according to claim 1, wherein the control unit adjusts an intensity and a wavelength of the illumination light when the illumination light and the excitation light are simultaneously irradiated onto the subject.

(Item 3)
2. The illumination light source device according to claim 1, wherein the control unit adjusts an intensity and a wavelength of the excitation light when the illumination light and the excitation light are simultaneously irradiated onto the subject.

(Item 4)
the illumination light source includes a plurality of illumination light sources outputting illumination light of different wavelengths;
2. The illumination light source device according to claim 1, wherein a wavelength of the excitation light is different from a wavelength of the illumination light emitted from the plurality of illumination light sources.

(Item 5)
5. The illumination light source device according to claim 4, wherein when the illumination light and the excitation light are simultaneously irradiated onto the subject, the control unit controls so as to reduce the intensity of light from the illumination light source having a wavelength adjacent to a wavelength of the excitation light, compared to when only the illumination light is irradiated onto the subject.

(Item 6)
6. The illumination light source device according to claim 4, wherein when the illumination light and the excitation light are simultaneously irradiated onto the subject, the control unit controls the wavelength of light from the illumination light source, which has a wavelength adjacent to a wavelength of the excitation light, to be farther away from the wavelength of the excitation light than when only the illumination light is irradiated onto the subject.

(Item 7)
6. The illumination light source device according to item 5, wherein when the illumination light and the excitation light are simultaneously irradiated onto the subject, the control unit does not change the intensity of light from the illumination light source that has a wavelength that is not adjacent to that of the excitation light.

(Item 8)
the illumination light source includes a blue light source, a green light source, and a red light source;
5. The illumination light source device according to claim 4, wherein the wavelength of the excitation light source is between the wavelength of the light from the blue light source and the wavelength of the light from the green light source.

(Item 9)
9. The illumination light source device according to item 8, wherein when the illumination light and the excitation light are simultaneously irradiated onto the subject, the control unit controls to reduce the intensity of the light from the blue light source and the light from the green light source, which have wavelengths adjacent to both sides of the wavelength of the excitation light, compared to when only the illumination light is irradiated onto the subject.

(Item 10)
10. The illumination light source device according to claim 8, wherein when the illumination light and the excitation light are simultaneously irradiated onto the subject, the control unit controls the wavelengths of the light from the blue light source and the light from the green light source to be farther away from the wavelength of the light from the excitation light source than when only the illumination light is irradiated onto the subject.

(Item 11)
10. The illumination light source device according to item 9, wherein when the illumination light and the excitation light are simultaneously irradiated onto the subject, the control unit does not change the intensity of the light from the red light source that is not adjacent to the wavelength of the excitation light.

(Item 12)
The control unit has an illumination light observation mode in which only the illumination light is irradiated and a mode in which the illumination light and the excitation light are irradiated simultaneously, and an excitation light observation mode in which only the excitation light is irradiated, and is configured to be able to select between these modes, and in the mode in which the illumination light and the excitation light are irradiated simultaneously, the control unit controls the intensity of light from the excitation light source to be lower than the intensity of light from the excitation light source irradiated in the excitation light observation mode.

(Item 13)
2. The illumination light source device according to claim 1, wherein the control unit adjusts at least one of the intensity and the wavelength of the illumination light so that color reproducibility by a mixture of the illumination light and the excitation light is improved by about 10 to about 30 in terms of average color rendering index Ra compared to color reproducibility by the illumination light alone.

(Item 14)
Item 2. An endoscope comprising the illumination light source device according to item 1.

(Item 15)
A light guide member comprising the illumination light source device according to claim 1 .

(Item 16)
A method for setting a wavelength of an illumination light that is irradiated onto an object simultaneously with an excitation light that excites a fluorescent substance in the object, comprising:
a wavelength of the illumination light being set so that, when the illumination light and the excitation light are simultaneously irradiated onto the subject, a spectral distribution of a mixture of the illumination light and the excitation light is closer to a spectral distribution of natural light than when only the illumination light is irradiated onto the subject.

The objective of the present invention is to obtain an illumination light source device that can bring the color reproducibility of the mixed light of illumination light and excitation light closer to that of natural light when excitation light capable of exciting fluorescent substances contained in the subject is irradiated simultaneously with illumination light to the subject.

FIG. 1 is a diagram conceptually showing an illumination light source device according to the present invention. FIG. 2 is a diagram showing a specific configuration of the illumination light source device 10 according to the first embodiment of the present invention. FIG. 3 is a diagram showing the operation of the illumination light source device 100 according to the first embodiment shown in FIG. FIG. 4 is a diagram showing a first modified example of the illumination light source device 100 of the first embodiment shown in FIG. FIG. 5 is a diagram showing a second modified example of the illumination light source device 100 of the first embodiment shown in FIG. FIG. 6 is a diagram showing a third modified example of the illumination light source device 100 of the first embodiment shown in FIG. FIG. 7 is a diagram showing a configuration of an illumination light source device 200 according to a second embodiment of the present invention. FIG. 8 is a diagram showing the operation of the illumination light source device 200 according to the second embodiment shown in FIG.

The present invention is described below. It should be understood that the terms used in this specification are used in the same manner as commonly used in the art unless otherwise specified. Therefore, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the case of conflict, the present specification (including definitions) will take precedence.

In this specification, "about" means within a range of ±10% of the number that follows.

FIG. 1 is a conceptual diagram of the illumination light source device of the present invention.

The present invention aims to provide an illumination light source device that can bring the color reproducibility of mixed light of illumination light and excitation light close to that of natural light when irradiating an object with excitation light capable of exciting a fluorescent substance contained in the object together with illumination light,
an illumination light source 110 that irradiates an object 101 with illumination light L1;
an excitation light source 120 that irradiates the subject 101 with excitation light L2 capable of exciting a fluorescent substance contained in the subject 101;
a control unit 140 for controlling the illumination light source 110 and the excitation light source 120;
The control unit 140 solves the above problem by providing an illumination light source device 100 in which, when illumination light L1 and excitation light L2 are simultaneously irradiated onto the subject 101, at least one of the intensity and wavelength of the illumination light L1 or the excitation light L2 is adjusted so that the spectral distribution of mixed light L3 of the illumination light L1 and the excitation light L2 becomes closer to the spectral distribution of natural light than when only the illumination light L1 is irradiated onto the subject 101.

Therefore, the illumination light source device 100 of the present invention is not particularly limited in its configuration and may be any configuration as long as it adjusts at least one of the intensity and wavelength of the illumination light or the excitation light so that when the illumination light L1 and the excitation light L2 are simultaneously irradiated onto the subject 101, the spectral distribution of the mixed light of the illumination light L1 and the excitation light L2 becomes closer to the spectral distribution of natural light than when only the illumination light L1 is irradiated onto the subject.

For example, when illumination light and excitation light are irradiated simultaneously onto the subject, the control unit may adjust the intensity and wavelength of the illumination light, or may adjust either the intensity or the wavelength of the illumination light.

Furthermore, when illumination light and excitation light are irradiated simultaneously onto the subject, the control unit may adjust the intensity and wavelength of the excitation light, or it may adjust either the intensity or wavelength of the illumination light, or it may adjust both the excitation light and the illumination light.

Furthermore, it is preferable that the illumination light source includes a plurality of illumination light sources each outputting illumination light of a different wavelength, and that the wavelength of the light from the excitation light source is different from the wavelengths of the plurality of illumination lights irradiated from the illumination light source. This is because the excitation light can supplement the light of wavelengths not included in the illumination light, and thus the spectral distribution of the light illuminating the subject can be made closer to the spectral distribution of natural light by irradiating the illumination light and excitation light simultaneously.

However, when illuminating light (for example, multiple illumination lights with different wavelengths) and excitation light with a different wavelength from that of the illumination light are irradiated onto the subject at the same time, it is effective to reduce the intensity of light from the illumination light source having a wavelength adjacent to the wavelength of the excitation light so that the energy of light at and near the wavelength of the excitation light in the mixed light of the illumination light and excitation light is not stronger than the energy of the wavelength portion corresponding to natural light.

Furthermore, in this case, in the mixed light of illumination light and excitation light, in order to prevent the energy of the light at and near the wavelength of the excitation light from becoming stronger than the energy in the corresponding wavelength portion of natural light, it is also effective to move the wavelength of light from the illumination light source, which has a wavelength adjacent to the wavelength of the excitation light, away from the wavelength of the excitation light.

Furthermore, when illuminating a subject with multiple illumination lights of different wavelengths and excitation light having a wavelength different from the wavelengths of the multiple illumination lights at the same time, it may be more preferable to reduce the intensity of the light from the illumination light source having a wavelength adjacent to the wavelength of the excitation light and to move the wavelength of the light from the illumination light source having a wavelength adjacent to the wavelength of the excitation light away from the wavelength of the excitation light, for example, when the wavelength of the excitation light is close to the wavelength of the light from the illumination light source having a wavelength adjacent to it.

In addition, when illumination light and excitation light are irradiated simultaneously onto a subject, it may be preferable not to change the intensity of light from illumination light sources that are not adjacent to the wavelength of the excitation light (to be the same as when only illumination light is irradiated onto the subject).

For example, when a subject is irradiated with light from an excitation light source simultaneously as light from multiple illumination light sources that form illumination light, in the mixed light of illumination light and excitation light, the energy of light at the wavelength of the excitation light and its vicinity can be prevented from becoming stronger than the energy of the corresponding wavelength portion of natural light by, for example, reducing the intensity of light from illumination light sources having wavelengths adjacent to the wavelength of the excitation light; however, reducing the intensity of light from illumination light sources that are not adjacent to the wavelength of the excitation light may actually move the spectral distribution of the mixed light away from the spectral distribution of natural light.
(Light source)
The illumination light source is a light source used during illumination observation, and irradiates white light having wavelengths partially across the entire visible region (specifically, about 400 nm to about 650 nm). In one embodiment, the illumination light source includes a blue light source, a green light source, and a red light source, and the excitation light has a wavelength between the blue light and the green light. However, the illumination light sources may include two light sources capable of outputting white light, or may include four or more light sources having different wavelengths of emitted light.

Here, the multiple illumination light sources that make up the illumination light source can be semiconductor light-emitting elements such as light-emitting diodes (LEDs) and laser diodes (LDs).

In laser diodes, the spread of the spectral distribution of the emitted light on both sides of the central wavelength is narrower than that of light-emitting diodes, but some laser diodes allow dynamic wavelength changes by physically adjusting the resonator length using a control signal.

The illumination light source may be one whose wavelength can be changed. The means for changing the wavelength may be any means. For example, a grating may be used as the wavelength conversion element, or a wavelength-tunable semiconductor laser may be used as the illumination light source. Wavelength-tunable semiconductor lasers include, for example, a temperature-tuned DFB (distributed feedback) laser that changes the refractive index with a temperature change, a DBR (distributed reflector) laser that changes the refractive index with current injection, a wideband wavelength-tunable DBR laser equipped with a mechanism for doubling the refractive index change caused by current injection, a micromachined surface-emitting laser that changes the resonator length with a micromachine, or a micromachined external mirror type laser that changes the angle of an optical filter with a micromachine.
(Excitation light source)
The excitation light source is a light source that emits excitation light of a predetermined narrow band. The wavelength of the excitation light can be any wavelength that can excite a fluorescent substance administered to the subject for diagnostic or therapeutic purposes.

In one embodiment, the wavelength of the excitation light irradiated from the excitation light source is 490 nm, which is between blue and green light and excites the fluorescent substance. However, the present invention is not limited to this. For example, when the fluorescent substance is 5-aminolevulinic acid, the wavelength for exciting it is about 410 nm. When the fluorescent substance is a fluorescent probe using hydroxyl rhodamine green, the wavelength for exciting it is about 450 nm to 480 nm. When the fluorescent substance is a talaporfin sodium polymer, the wavelength for exciting it is about 670 nm. The wavelength of the excitation light irradiated from the excitation light source may be in the near infrared region (about 800 nm to about 1000 nm). Specifically, for example, when the fluorescent substance is ICG (indocyanine green), the wavelength for exciting it is about 800 nm. In this way, any wavelength of excitation light can be selected depending on the fluorescent substance to be excited. When the wavelength of the excitation light is in the near infrared region, the fluorescent substance is detected using a near infrared detection camera. With the above configuration, it is possible to add an image in the near-infrared region to an image in the visible light region, which makes it possible to detect lesions over a wider range. A specific method for displaying an image in the near-infrared region may be to narrow the bandwidth of the visible light region and add a region on the long wavelength side.

In particular, when the fluorescent substance is 5-aminolevulinic acid or hydroxyl rhodamine green, it is possible to improve color reproducibility by compensating for the purple to blue-green wavelengths where the output of the illumination light source is low. Also, when the fluorescent substance is talaporfin sodium polymer, it is possible to compensate for the orange to red wavelengths close to those of blood, making it possible to grasp the condition of the affected area more accurately.
(Control Unit)
The control unit controls the timing of emission of light from the illumination light source and the excitation light source, the intensity and wavelength of the light, etc. For example, in one embodiment, when the multiple illumination light sources constituting the illumination light source are a blue light source, a green light source, and a red light source, and the excitation light has a wavelength between the blue light and the green light, the control unit controls so as to lower the intensity of the blue light and the green light having wavelengths adjacent to both sides of the wavelength of the excitation light when the illumination light and the excitation light are simultaneously irradiated onto the subject, compared to when only the illumination light is irradiated onto the subject.

Alternatively, in another embodiment, when the multiple light sources constituting the illumination light source are a blue light source, a green light source, and a red light source, and the excitation light has a wavelength between the blue light and the green light, the control unit controls the wavelengths of the blue light and the green light to be farther away from the wavelength of the excitation light when the illumination light and the excitation light are simultaneously irradiated onto the subject, compared to when only the illumination light is irradiated onto the subject.

Furthermore, when adjusting the intensity or wavelength of the blue and green light based on the wavelength of the excitation light in this manner, the intensity of the red light, which is not adjacent to the wavelength of the excitation light, may be left unchanged and remain the same when only the illumination light is irradiated onto the subject.

In one embodiment, the control unit may be configured to have an illumination light observation mode in which only illumination light is irradiated and a mode in which illumination light and excitation light are irradiated simultaneously, and an excitation light observation mode in which only excitation light is irradiated, and to be able to select between these modes. In this case, the control unit is capable of controlling the intensity of the excitation light in the mode in which illumination light and excitation light are irradiated simultaneously to be lower than the intensity of the excitation light irradiated in the excitation light observation mode.

Furthermore, the control unit adjusts at least one of the intensity and wavelength of the illumination light so that the color reproducibility of the mixed light of the illumination light and the excitation light is higher than the color reproducibility of the illumination light alone. Color reproducibility is evaluated using the average color rendering index Ra, which is commonly used in the lighting field.

It is preferable that the control unit is configured so that the color reproducibility of the mixed light of the illumination light and the excitation light is improved by about 10 or more in terms of general color rendering index Ra compared to the color reproducibility of the illumination light alone.

Such an illumination light source device can be used in endoscopes, and when observing the surface of the inside of a subject's digestive tract, such as the large intestine or stomach, or the respiratory tract, using excitation light for fluorescence observation, and when observing using white light, the color reproducibility of the white light can be improved by simultaneously irradiating the excitation light and illumination light.

The present invention also provides a method for setting the wavelength of illumination light that is irradiated onto a subject simultaneously with excitation light that excites fluorescent substances in the subject, and this method for setting the wavelength of illumination light sets the wavelength of illumination light so that when illumination light and excitation light are irradiated onto a subject simultaneously, the spectral distribution of the mixed light of illumination light and excitation light is closer to the spectral distribution of natural light than when only illumination light is irradiated onto a subject, and other conditions for setting the wavelength of illumination light are not limited, and other conditions for setting the wavelength of illumination light are arbitrary.

In this way, the illumination light source device of the present invention is not particularly limited in other configurations as long as it adjusts at least one of the intensity and wavelength of the illumination light so that when illumination light and excitation light are simultaneously irradiated onto a subject, the spectral distribution of the mixed light of the illumination light and excitation light is closer to the spectral distribution of natural light than when only illumination light is irradiated onto a subject. In the following embodiments, however, a first embodiment is given in which the intensity of the illumination light is dynamically changed, and a second embodiment is given in which the intensity and wavelength of the illumination light are dynamically adjusted.

In addition, the illumination light source device of embodiment 1 uses light-emitting diodes for the blue light source, green light source, and red light source, which are the multiple illumination light sources in the illumination light source, and the illumination light source device of embodiment 2 uses laser diodes for the blue light source, green light source, and red light source, which are the multiple illumination light sources in the illumination light source, and the illumination light source devices of both embodiments use laser diodes as excitation light sources.

Below, an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 2 is a diagram showing a specific configuration of the illumination light source device 100 according to the first embodiment of the present invention.

The illumination light source device 100 of this embodiment 1 is used in an endoscope and can be applied to luminal tissues in general, such as the digestive tract, stomach, and respiratory tract of the human body. However, the illumination light source device of the present invention is not limited to observations using an endoscope, and can also be used in observations in an open abdominal position, etc.

This illumination light source device 100 includes an illumination light source 110 that irradiates the subject 101 with illumination light L10, an excitation light source 120 that irradiates excitation light L2 capable of exciting fluorescent substances contained in the subject 101, and a control unit 140a that controls the illumination light source 110 and the excitation light source 120.

The control unit 140a adjusts the intensity of the illumination light L10 and the excitation light L2 so that when the illumination light L10 and the excitation light L2 are simultaneously irradiated onto the subject 101, the spectral distribution of the mixed light L3 of the illumination light L10 and the excitation light L2 becomes closer to the spectral distribution of natural light than when only the illumination light L10 is irradiated onto the subject 101.

(Illumination Light Source 110)
Here, the illumination light source 110 has three color light sources for outputting white light, the three color light sources being a blue light source 111 , a green light source 112 , and a red light source 113 .

The blue light source (blue LED) 111 uses a blue light emitting diode that outputs blue light (wavelength approximately 440 nm) L11, the green light source (green LED) 112 uses a green light emitting diode that outputs green light L12 (wavelength approximately 540 nm), and the red light source (red LED) 113 uses a red light emitting diode that outputs red light (wavelength approximately 635 nm) L13. When the intensities of the three colors of illumination light L11 to L13 are the same, the color reproducibility of the white light obtained by mixing these three colors of illumination light L11 to L13 is Ra = 80 in terms of the average color rendering index Ra, which is an index that indicates color reproducibility compared to natural light (daytime sunlight). In the case of natural light, the average color rendering index Ra is Ra = 100.

The illumination light source 110 has an LED drive circuit 110 that drives the blue LED 111, the green LED 112, and the red LED 113 based on an illumination control signal Ct1 from the control unit 140a, and the LED drive circuit 110 is configured to supply a blue drive current D11, a green drive current D12, and a red drive current D13 to the blue LED 111, the green LED 112, and the red LED 113, respectively.

(Excitation Light Source 120)
The excitation light source 120 has a laser diode (excitation LD) 121 that outputs excitation light (wavelength: about 490 nm) L2, and an LD drive circuit 120a that drives the excitation LD 121 based on an excitation control signal Ct2 from the control unit 140a, and the LD drive circuit 120a is configured to supply an excitation drive current D2 to the excitation LD 121. As described above, the excitation light L2 has a wavelength between the blue light L11 and the green light L12.

(Mixer 30)
The illumination light source device 100 also has a mixer 130 that mixes blue light L11 from the blue LED 111, green light L12 from the green LED 112, red light L13 from the red LED 113, and excitation light L2 from the excitation LD 121, and outputs mixed light L31 as white light.

Needless to say, when only blue light L11, green light L12, and red light L13 are output, the mixer 130 mixes the blue light L11, green light L12, and red light L13 to produce mixed light L31, and irradiates only the illumination light L10 onto the subject 101. When only the excitation light L2 is output, the mixer 130 irradiates only the excitation light L2 onto the subject 101.

(Light guiding member)
A light guide member (not shown) may be provided to guide the mixed light L31 mixed in the mixer 30 to the periphery of the subject 101.

The light-guiding member may have any shape. In one embodiment, the light-guiding member is an optical fiber, but is not limited to this. For example, in addition to optical fibers that utilize the refractive index difference of glass, it can also be applied to hollow fibers with air or inert gas as the core, liquid fibers with liquid as the core, and non-deforming waveguides made of processed glass or resin.

(Control unit 140a)
Furthermore, the control unit 140a has, as illumination light observation modes, a first operation mode in which only illumination light L10 is irradiated, and a second operation mode in which illumination light L10 and excitation light L2 are irradiated simultaneously, and a third operation mode in which only excitation light is irradiated, as excitation light observation modes.These operation modes are selected based on an operation signal Sm operated by an operator, and the control unit 140a is configured to control the LED driving circuit 110a and the LD driving circuit 120a according to the selected operation mode.

Here, when illumination light L1 and excitation light L2 are simultaneously irradiated onto subject 101, control unit 140a controls the intensities of blue light L11 and green light L12, which have wavelengths adjacent to both sides of the wavelength of excitation light L2, to be lower by a difference X1 (approximately 20% of the original intensity) compared to when only illumination light L10 is irradiated onto subject 101 (see FIG. 3(b)).

The control unit 140a also controls the excitation light source 120 in an operation mode in which illumination light and excitation light are irradiated simultaneously so that the intensity of the excitation light is lower than the intensity of the excitation light irradiated in the second operation mode (excitation light observation mode) by a difference X2 (approximately 90% of the original intensity) (see FIG. 3(a)). As a specific example, during excitation, the illuminance during illumination (410 [lm]) is reduced to 40 [lm]. However, the intensity of the excitation light varies greatly depending on the sensitivity of the fluorescent material.

Next, the operation of the illumination light source device 100 of embodiment 1 will be described.

The following describes the switching of operating modes in the illumination light source device 100 that occurs when the tip of an endoscope including the illumination light source device 100 is inserted into a subject's lumen and moved to a target site to observe the surface of the target site.

FIG. 3 shows the operation of the illumination light source device 100 shown in FIG. 2, where FIG. 3(a) shows dynamic switching of the intensity of the excitation light L2, FIG. 3(b) shows dynamic switching of the intensity of the illumination light L10 (blue light L11 and green light L12), and FIG. 3(c) shows the superimposed spectral distributions of the illumination light L10 (blue light L1, green light L2, red light L13) and the excitation light L2 that are irradiated simultaneously.

(First Operation Mode)
First, the operator operates an operation unit (not shown) to select a mode (first operation mode) in which the illumination light L10 is irradiated solely onto the subject 101 until the endoscope is moved inside the lumen of the subject 101 and reaches the target site. This is because, when the endoscope is moved inside the lumen, it is not necessary to illuminate the illumination range particularly brightly.

At this time, when an operation signal Sm from an operation unit (not shown) is input to the control unit 140a, the control unit 140a controls the LED drive circuit 110a and the LD drive circuit 120a with the illumination control signal Ct1 and the excitation control signal Ct2, respectively. As a result, the blue LED 111, the green LED 112, and the red LED 113 output blue light L11, green light L12, and red light L13 of the determined optimal intensity (see the spectral distribution on the left side of Figure 3 (b)). In this case, the blue light L11, the green light L12, and the red light L13 have the same intensity. Also, the excitation light source 120 does not output the excitation light L2. The color reproducibility of the illumination light L10 at this time, expressed in terms of the average color rendering index Ra, was Ra = 80.

(Second Operation Mode)
In addition, when performing natural light observation after the endoscope has reached the target site within the lumen of the subject 101, the operator selects a mode (second operating mode) in which illumination light L10 and excitation light L2 are irradiated simultaneously by operating the operation unit (not shown).

At this time, when the control unit 140a receives an operation signal Sm from an operation unit (not shown) and outputs a lighting control signal Ct1 and an excitation control signal Ct2 to the LED drive circuit 110a and the LD drive circuit 120a, the blue LED 111, the green LED 112 and the red LED 113 output blue light L11, green light L12 and red light L13, respectively, and the excitation LD 121 outputs excitation light L2.

In this case, the blue LED 111 and the green LED 112 respectively reduce the intensity of the blue light L11 and the green light L12 to about 0.8 times the intensity of the red light L13 (see the spectral distribution on the right side of FIG. 3(b)). In other words, the intensity of the blue light L11 and the green light L12 is reduced by a difference X1 (about 20% of the original intensity) compared to the case where the illumination light is irradiated alone.

This is because the excitation light L2, which has a wavelength between the blue light L11 and the green light L12, is mixed with the blue light L11, the green light L12, and the red light L13, increasing the intensity of the light having wavelengths close to the wavelengths of the blue light L11 and the green light L12, and preventing the overall spectral distribution of the mixed light L31 from becoming farther away from the spectral distribution of natural light.

In the above case, the intensities of the blue light L11 and green light L12 adjacent to the excitation light L2 are adjusted, but instead of adjusting the intensities of the blue light L11 and green light L12, the intensity of the excitation light L2 may be adjusted. Specifically, the excitation LD 121 may reduce the intensity of the excitation light L2 to about 0.1 times that in the case of irradiation of the excitation light L2 alone (see FIG. 3(a)).

The intensity of the excitation light in excitation light observation is often set high to excite fluorescent substances. By lowering the intensity of the excitation light when irradiating it at the same time, it is possible to minimize the effects on the subject, such as temperature rise.

Note that FIG. 3(c) shows the superimposed spectral distributions of the illumination light L1 and the excitation light L2 when they are irradiated simultaneously, with the intensities of the blue light L11 and the green light L12 reduced compared to when illumination light L10 is irradiated alone, and with the intensity of the excitation light L2 reduced compared to when excitation light L2 is irradiated alone.

In this way, when illumination light L1 and excitation light L2 are irradiated simultaneously, the intensity of blue light L11 and green light L12, which have wavelengths adjacent to both sides of the wavelength of excitation light L2 contained in illumination light L10, is reduced compared to when illumination light L1 is irradiated alone, so that the spectral distribution of mixed light L3 of illumination light L1 and excitation light L2 approaches the spectral distribution of natural light, and it is possible to improve the color reproducibility of mixed light L31 to approach that of natural light. The color reproducibility of illumination light L10 at this time, expressed in terms of average color rendering index Ra, was Ra = 90.

In this way, you can observe the subject with improved color reproduction, making it possible to find the area you want to observe accurately and efficiently.

In the above embodiment 1, when the illumination light L10 and the excitation light L2 are irradiated simultaneously, the adverse effect on the spectral distribution of the illumination light L10 caused by the excitation light L2 being mixed into the illumination light L10 is suppressed by reducing the intensity of the blue light L11 and the green light L12, which have wavelengths adjacent to the wavelength of the excitation light L2, and further reducing the intensity of the mixed excitation light L2. However, the method of suppressing the adverse effect of the mixing of the excitation light L2 into the illumination light L1 is not limited to the method of dynamically reducing the intensity of the blue light L11 and the green light L12, and further the excitation light L2, shown in embodiment 1, and other methods may be used in combination. In the following modified example 1 of embodiment 1, a case will be described in which a method of previously adjusting the wavelengths of the blue light L11 and the green light L12, which have wavelengths adjacent to the wavelength of the excitation light L2 mixed into the illumination light L10, is also used in combination.

(Third Operation Mode)
Next, when excitation light observation is to be performed with the endoscope having reached the target site within the lumen of the subject 101, the operator operates the operation unit (not shown) to select a mode (third operating mode) in which excitation light L2 is irradiated solely onto the subject 101.

At this time, when an operation signal Sm from an operation unit (not shown) is input to the control unit 140a, the LED drive circuit 110a and the LD drive circuit 120a are controlled by the illumination control signal Ct1 and the excitation control signal Ct2 from the control unit 140a. As a result, the blue LED 111, the green LED 112, and the red LED 113 stop their light output, and the excitation LD 121 outputs excitation light L2 of the determined optimal intensity (see the spectral distribution on the left side of Figure 3(a)).

(First Modification of First Embodiment)
FIG. 4 is a diagram showing a first modified example of the illumination light source device 100 shown in FIG. 2, and shows a case in which the wavelengths of the blue light L11 and the green light L12 in the illumination light L10 are changed in advance to match the wavelength of the excitation light L2 that is irradiated simultaneously with the illumination light L10, and then the intensities of the blue light L11 and the green light L12 are dynamically switched as in the first embodiment.

In particular, FIG. 4(a) shows a specific wavelength change of blue light L11 and green light L12 taking into account the wavelength of excitation light L2, FIG. 4(b) shows dynamic switching of the intensity of excitation light L2, FIG. 4(c) shows dynamic switching of the intensity of blue light L11 and green light L12, and FIG. 4(d) shows the superimposed spectral distributions of blue light L11, green light L12, red light L13, and excitation light L2 that are irradiated simultaneously.

In the illumination light source device of this variation 1 of embodiment 1, the composition of the semiconductor material constituting the blue LED 111 and green LED 112 mounted as the illumination light source 110 in the illumination light source device 100 of embodiment 1 is adjusted to distance the wavelengths of the blue light L11 and green light L12 from the wavelength of the excitation light L2 mixed into the illumination light L1.

Specifically, in this modified example 1 of embodiment 1, the wavelength of the blue light L11 is about 430 nm, which is about 10 nm away from the wavelength of the blue light L11 (about 440 nm) in embodiment 1, taking into account the wavelength of the excitation light L2 (about 490 nm) (FIG. 4(a)). Also, in modified example 1 of embodiment 1, the wavelength of the green light L12 is about 550 nm (FIG. 4(a)), which is about 10 nm away from the wavelength of the excitation light L2 (about 540 nm) in embodiment 1, taking into account the wavelength of the excitation light L2 (about 490 nm) (FIG. 4(a)).

In this first modified example of the first embodiment, the wavelengths of the blue light L11 and the green light L12 out of the three colors of RGB in the illumination light L10 are adjusted taking into consideration the wavelength of the excitation light L2 irradiated simultaneously with the illumination light L10, and then, similar to the illumination light source device 100 of the first embodiment described above, light irradiation operations are performed in which only the illumination light L10 is irradiated (first operation mode), only the excitation light L2 is irradiated (third operation mode), and the illumination light L1 and the excitation light L2 are irradiated simultaneously (second operation mode).

In other words, in this modified example 1, in order to reduce the adverse effects of mixing the excitation light L2 with the illumination light L10, the wavelength of the excitation light L2 is taken into consideration and blue light L11 and green light L12 having wavelengths farther away from the wavelength of the excitation light L2 are used than when the illumination light L10 is irradiated alone, and furthermore, when the illumination light L10 and the excitation light L2 are irradiated simultaneously, the intensities of the blue light L11 and green light L12 having wavelengths adjacent to the wavelength of the excitation light L2 are dynamically reduced compared to when the illumination light L10 is irradiated alone (FIG. 4(c)). Furthermore, in the case of the above simultaneous irradiation, the intensity of the excitation light L2 is dynamically reduced compared to when the excitation light L2 is irradiated alone (FIG. 4(b)).

Note that FIG. 4(d) shows the superimposed spectral distributions of blue light L11, green light L12, red light L13, and excitation light L2 when illumination light L1 and excitation light L2 are simultaneously irradiated onto the subject 101.

As a result, in this first variant of the first embodiment, when the illumination light L10 and the excitation light L2 are irradiated simultaneously, the adverse effects caused by the excitation light L2 being mixed into the illumination light L10 can be effectively suppressed.

The color reproducibility of the mixed light of the illumination light L10 and the excitation light L2 at this time, expressed as an average color rendering index Ra, was Ra = 92.

However, the wavelengths of the blue light L11, green light L12, and red light L13 are changed compared to when illumination light L10 is irradiated alone so as to reduce the adverse effects of the excitation light L2 being mixed in, and so there is a risk that the spectral distribution when illumination light L10 is irradiated alone may deteriorate. Therefore, the wavelength adjustment of the blue light L11 and green light L12 taking into account the wavelength of excitation light L2 must be performed depending on whether color reproducibility is prioritized when illumination light L10 is irradiated alone or when illumination light L10 and excitation light L2 are irradiated simultaneously.

In the above-mentioned embodiment 1 and its modified example 1, the blue light source, green light source, and red light source included in the illumination light source 110 are shown to use light emitting diodes, blue LED 111, green LED 112, and red LED 113, respectively. However, laser diodes can also be used instead of light emitting diodes for these three color light sources. Below, an illumination light source device using laser diodes instead of light emitting diodes in embodiment 1 will be described as modified example 2 of embodiment 1, and an illumination light source device using laser diodes instead of light emitting diodes in modified example 1 of embodiment 1 will be described as modified example 3 of embodiment 1.

(Modification 2 of the First Embodiment)
FIG. 5 is a diagram showing a second modification of the first embodiment shown in FIG. 2, in which a laser diode (LD) is used instead of the light emitting diode (LED) in the illumination light source 110 of the first embodiment.

In particular, FIG. 5(a) shows the spectral distributions of blue, green, and red light sources using LDs in comparison with the case where LEDs are used as the light sources for the three colors, FIG. 5(b) shows dynamic switching of the intensity of excitation light L2, FIG. 5(c) shows dynamic switching of the intensity of blue light L11a and green light L12a output by the LD, and FIG. 5(d) shows the superimposed spectral distributions of blue light L11a, green light L12a, red light L13a, and excitation light L2 simultaneously irradiated from the LD.

In the blue light source, green light source, and red light source using laser diodes as semiconductor light-emitting elements, the wavelengths of blue light L11a, green light L12a, and red light L13a are 470 nm, 530 nm, and 640 nm, respectively, which are slightly different from the wavelengths of blue light L11, green light L12, and red light L13b (440 nm, 540 nm, 635 nm) when light-emitting diodes are used (see Figure 5(a)).

However, in the case of simultaneous irradiation of the illumination light and the excitation light L2, the intensities of the blue light L11a and the green light L12a are reduced as in the first embodiment compared to the case of irradiation of the illumination light alone (see FIG. 5(c)). The specific degree of reduction X5 is about 10%, unlike the approximately 20% in the case of using a light-emitting diode, and in the case of simultaneous irradiation, the intensities of the blue light L11a and the green light L12a are reduced to about 0.9 times the intensity of the red light L13a. The spectral distributions of the blue light L11a, the green light L12a, the red light L13a, and the excitation light L2 contained in the mixed light of the illumination light and the excitation light at this time are as shown in FIG. 5(d), and the color reproducibility of the mixed light L31, expressed in terms of the average color rendering index Ra, was Ra = 75.

Furthermore, in some cases, the intensity of the excitation light L2 during simultaneous irradiation is also reduced compared to the case of irradiation with the excitation light alone, as in the first embodiment (FIG. 5(b)). The specific degree of reduction X4 is about 90%.

(Variation 3 of the First Embodiment)
FIG. 6 is a diagram showing a third modification of the illumination light source device 100 shown in FIG. 2, in which a laser diode (LD) is used instead of the light emitting diode (LED) in the illumination light source of the first modification of the first embodiment.

In other words, FIG. 6 shows a case where the wavelengths of the blue light L11a and green light L12a output by the LD are changed in advance to match the wavelength of the excitation light L2 that is irradiated simultaneously with the illumination light, and then the intensities of the blue light L11a and green light L12a are dynamically switched as in Variation 1 of Embodiment 1.

In particular, FIG. 6(a) shows a specific wavelength change of blue light L11a and green light L12a taking into account the wavelength of excitation light L2, FIG. 6(b) shows dynamic switching of the intensity of excitation light L2, FIG. 6(c) shows dynamic switching of the intensity of blue light L11a and green light L12a, and FIG. 6(d) shows the superimposed spectral distributions of blue light L11a, green light L12a, red light L13a, and excitation light L2 that are simultaneously irradiated from the LD.

The illumination light source device of this variation 3 of embodiment 1 is obtained by adjusting the composition of the semiconductor material that constitutes the blue LD and green LD mounted as the illumination light source in the illumination light source device of variation 2 of embodiment 1, so that the wavelengths of the blue light L11a and green light L12a contained in the illumination light are made farther away from the wavelength of the excitation light L2 mixed into the illumination light.

Specifically, in this modified example 3 of embodiment 1, the wavelength of the blue light L11a is about 430 nm, which is about 40 nm away from the wavelength of the blue light L11a (about 470 nm) in modified example 2 of embodiment 1, taking into account the wavelength of the excitation light L2 (about 490 nm) (FIG. 6(a)). Also, in modified example 3 of embodiment 1, the wavelength of the green light L12a is about 550 nm, which is about 20 nm away from the wavelength of the green light L12a (about 530 nm) in modified example 2 of embodiment 1, taking into account the wavelength of the excitation light L2 (about 490 nm) (FIG. 6(a)).

In this third variant of the first embodiment, the wavelengths of the blue light L11a and the green light L12a of the three colors of laser light contained in the illumination light are adjusted in consideration of the wavelength of the excitation light L2 that is irradiated simultaneously with the illumination light, and then, as in the second variant of the first embodiment described above, light irradiation operations are performed in which only the illumination light is irradiated (first operation mode), only the excitation light L2 is irradiated (second operation mode), and the illumination light and the excitation light L2 are irradiated simultaneously (second operation mode).

In this modification 3, in order to reduce the adverse effects of mixing the excitation light L2 with the illumination light, the wavelength of the excitation light L2 is taken into consideration and blue light L11a and green light L12a having wavelengths farther away from the wavelength of the excitation light L2 are used compared to the case of irradiation of the illumination light alone. Furthermore, when the illumination light and the excitation light L2 are irradiated simultaneously, the intensity of the blue light L11a and green light L12a having wavelengths adjacent to the wavelength of the excitation light L2 is dynamically reduced compared to the case of irradiation of the illumination light L1 alone (FIG. 6(c)). The degree of reduction in intensity X5 at this time is about 10% of the original intensity. Furthermore, in the case of the above simultaneous irradiation, the intensity of the excitation light L2 is dynamically reduced compared to the case of irradiation of the excitation light L2 alone (FIG. 6(b)). The degree of reduction in intensity X5 at this time is about 10% of the original intensity.

Note that FIG. 6(d) shows the superimposed spectral distributions of blue light L11a, green light L12a, red light L13a, and excitation light L2 when illumination light and excitation light L2 are simultaneously irradiated onto the subject 101.

As a result, in Variation 3 of Embodiment 1, in which a laser diode (LD) is used instead of the light-emitting diode (LED) of Variation 1 of Embodiment 1, similar to Variation 1 of Embodiment 1, in which a light-emitting diode is used as the semiconductor light-emitting element, it is possible to effectively suppress the adverse effects caused by the excitation light L2 being mixed into the illumination light when the illumination light and the excitation light L2 are irradiated simultaneously.

The color reproducibility of the mixed light of the illumination light and the excitation light at this time, expressed as an average color rendering index Ra, was Ra = 80.

However, the wavelengths of the blue light L11a and the green light L12a are changed compared to when illumination light is irradiated alone so as to reduce the adverse effects of the mixing of excitation light L2. As in the case of variant 1 of embodiment 1, there is a risk that the spectral distribution may deteriorate when illumination light is irradiated alone. Therefore, the wavelength adjustment of the blue light L11a and the green light L12a taking into account the wavelength of the excitation light L2 must be performed depending on whether color reproducibility is prioritized when illumination light is irradiated alone or when illumination light and excitation light L2 are irradiated simultaneously.

In the second embodiment, therefore, an illumination light source device is described that can independently set the spectral distribution of illumination light when illumination light is irradiated alone and when illumination light and excitation light L2 are irradiated simultaneously, and that dynamically changes both the intensity and wavelength of illumination light when illumination light is irradiated alone and when illumination light and excitation light are irradiated simultaneously.

(Embodiment 2)
FIG. 7 is a diagram showing a configuration of an illumination light source device 200 according to a second embodiment of the present invention.

In place of the illumination light source 110 in the illumination light source device 100 of embodiment 1, the illumination light source device 200 of embodiment 2 is provided with an illumination light source 210 capable of dynamically adjusting the intensity and wavelength of the emitted illumination light L20, and when the illumination light L20 and the excitation light L2 are simultaneously irradiated onto the subject 101, the intensity and wavelength of the illumination light L20 are changed so that the spectral distribution of the mixed light L32 of the illumination light L20 and the excitation light L2 becomes closer to the spectral distribution of natural light than when the illumination light L20 is irradiated alone.

Therefore, unlike the control unit 140a of the illumination light source device 100 of embodiment 1, the control unit 240 of this illumination light source device 200 is configured to be able to control not only the intensity but also the wavelength of the illumination light L20 from the illumination light source 210.

Note that the excitation light source 120 and the mixer 130 are the same as those in the illumination light source device 100 of embodiment 1, and the illumination light source 210 and the control unit 240 will be described in detail below.

(Illumination Light Source 210)
The illumination light source 210 has a blue light source 211, a green light source 212, and a red light source 213, similar to the illumination light source 110 of the first embodiment. However, in this second embodiment, the blue and green light sources are each made of a wavelength-variable laser diode, and the red light source is made of a wavelength-fixed laser diode.

Therefore, the blue light source (blue LD) 211 is capable of adjusting the wavelength of the output blue light L21 within a predetermined wavelength range (e.g., at least in the range of about 470 nm to about 430 nm). The green light source (green LD) 212 is capable of adjusting the wavelength of the output green light L22 within a predetermined wavelength range (e.g., at least in the range of about 530 nm to about 550 nm). The red light source (red LD) 213 outputs red light L23 with a fixed wavelength of about 640 nm.

However, the blue light source (blue LD) 211 may be capable of switching the wavelength of the blue light L21 output between approximately 470 nm and approximately 430 nm, and the green light source (green LD) 212 may be capable of switching the wavelength of the green light L22 output between approximately 530 nm and approximately 550 nm. Here, the wavelength of approximately 470 nm of the blue light L21 and the wavelength of approximately 530 nm of the green light L22 are wavelengths for obtaining good color reproducibility in the case of single irradiation of the illumination light L20, and the wavelength of approximately 430 nm of the blue light L21 and the wavelength of approximately 550 nm of the green light L22 are wavelengths for obtaining good color reproducibility in the case of simultaneous irradiation of the illumination light L20 and the excitation light L2. In this embodiment, the blue light source and the green light source are wavelength-variable, but the red light source may also be wavelength-variable, or one or more of the blue light source, the green light source, and the red light source may be wavelength-variable.

(Control unit 240)
In this illumination light source device 200, the control unit 240 is configured to output an illumination control signal Ct1 to the illumination light source 210 based on an operation signal Sm from an operation unit (not shown), output an excitation control signal Ct2 to the excitation light source 120, and further output a blue wavelength control signal C21 and a green wavelength control signal C22 to the illumination light source 210.

The illumination light source 210 has an LD drive circuit 210a that drives the blue LD 211, the green LD 212, and the red LD 213 based on an illumination control signal Ct1 from the control unit 240. Specifically, the LD drive circuit 210a is configured to supply a blue drive current D21, a green drive current D22, and a red drive current D23 to the blue LD 211, the green LD 212, and the red LD 213, respectively, based on the illumination control signal Ct1 from the control unit 240. The control unit 240 is configured to change the intensity of the blue light L21 from the blue LD 211 and the intensity of the green light L22 from the green LD 212 by adjusting the blue drive current D21 to the blue LD 211 and the green drive current D22 to the green LD 212 in the case of single irradiation of the illumination light L20 and the case of simultaneous irradiation of the illumination light L20 and the excitation light L2.

The control unit 240 also outputs a blue wavelength control signal C21 to the blue LD 211 and a green wavelength control signal C22 to the green LD 212, thereby switching the wavelengths of the blue light L21 and the green light L22 between the case of irradiation with the illumination light L20 alone and the case of simultaneous irradiation with the illumination light L20 and the excitation light L2.

The control unit 240 is also configured to change the intensity of the excitation light L2 from the excitation LD 121 by adjusting the excitation drive current D2 output to the excitation LD 121 when the illumination light L20 is irradiated alone and when the illumination light L20 and the excitation light L2 are irradiated simultaneously.

Next, the operation of the illumination light source device 200 of this embodiment 2 will be described.

FIG. 8 shows the operation of the illumination light source device 200 of embodiment 2 shown in FIG. 7, where FIG. 8(a) shows dynamic switching of the intensity of the excitation light L2, FIG. 8(b) shows dynamic switching of the intensity and wavelength of the blue light L21 and the green light L22, and FIG. 8(c) shows the superimposed spectral distributions of the blue light L21, the green light L22, the red light L23, and the excitation light L2 that are irradiated simultaneously.

In the illumination light source device 200 configured as above, when the illumination light L20 is irradiated solely onto the subject 101, the control unit 240 receives an operation signal Sm from an operation unit (not shown) and outputs an illumination control signal Ct1 from the control unit 240 to the LD drive circuit 210a of the illumination light source 210, and the LD drive circuit 210a drives the blue LD 211, the green LD 212, and the red LD 213 based on the illumination control signal Ct1. As a result, the blue LD 211, the green LD 212, and the red LD 213 output blue light L21, green light L22, and red light L23 of the same intensity such that the wavelength of the blue light L21 is about 470 nm, the wavelength of the green light L22 is about 530 nm, and the wavelength of the red light L23 is about 640 nm. At this time, the excitation light source 120 is not operated, and the subject 101 is not irradiated with the excitation light L2.

When the subject 101 is irradiated with the excitation light L2 alone, the control unit 240 receives an operation signal Sm from an operation unit (not shown) and outputs an excitation control signal Ct2 to the excitation light source 120. The LD drive circuit 122 of the excitation light source 120 drives the excitation LD 121 based on the excitation control signal Ct2. As a result, the excitation LD 121 outputs the excitation light L2 so that its wavelength is approximately 490 nm. At this time, the illumination light source 210 does not operate, and the illumination light L20 is not irradiated to the subject 101.

When illumination light L20 and excitation light L2 are irradiated simultaneously onto the subject 101, the control unit 240 receives an operation signal Sm from an operation unit (not shown) and outputs a blue wavelength control signal C21 and a green wavelength control signal C22 along with an illumination control signal Ct1 to the illumination light source 210. At this time, the control unit 240 also simultaneously outputs an excitation control signal Ct2 to the excitation light source 120.

In the illumination light source 210, the LD drive circuit 210a drives the blue LD 21, the green LD 22, and the red LD 23 based on the illumination control signal Ct1 so that the intensity of the blue light L21 and the green light L22 is approximately 0.9 times the intensity of the red light L23 (see the spectral distribution in the upper right corner of Figure 8 (b)). Note that while the embodiment describes a device that uses a light-guiding member made of optical fiber to observe the inside of the body, it goes without saying that the illumination light source device of the present invention can also be applied to devices in which a light source directly irradiates an affected area, such as in surgery or laparotomy.

In addition, at this time, the blue LD21 adjusts the wavelength of the blue light L21 it outputs from the wavelength (approximately 470 nm) when the illumination light L20 is irradiated alone to approximately 430 nm, away from the wavelength of the excitation light L2 (approximately 490 nm), based on the blue wavelength control signal C21. At the same time, the green LD22 adjusts the wavelength of the green light L22 it outputs from the wavelength (approximately 530 nm) when the illumination light L20 is irradiated alone to approximately 550 nm, away from the wavelength of the excitation light L2 (approximately 490 nm) (see the spectral distribution at the bottom left of Figure 8(b)).

As a result, when illumination light source 210 is irradiated simultaneously with illumination light L1 and excitation light L2, blue light L21 and green light L22 are output whose wavelengths are changed to be farther away from the wavelength of excitation light L2 and whose intensity is reduced to approximately 0.9 times that of red light L23, compared to when illumination light L10 is irradiated alone (see the spectral distribution in the upper left of FIG. 8(b)). At this time, the wavelength and intensity of red light L23 are unchanged from when illumination light L20 is irradiated alone (see the spectral distribution in the lower right of FIG. 8(b)).

As described above, the color reproducibility of the white light obtained by mixing the three colors of illumination light L21 to L23 is such that, when the intensities of the three colors of illumination light L21 to L23 are the same and their respective wavelengths are approximately 470 nm, approximately 530 nm, and approximately 640 nm, the color reproducibility (Ra) is Ra = 50 in terms of the average color rendering index Ra, which is an index that indicates a comparison with natural light (daytime sunlight).

On the other hand, the color reproducibility of the white light obtained by mixing these three colors of illumination light L21 to L23 and the excitation light L2 is such that the wavelengths of the blue light L21 and the green light L22 are the same as the wavelength of the excitation light L2 (about 490 nm).
By moving the wavelengths of the blue light L21 and the green light L22, which have wavelengths adjacent to the wavelength of the excitation light L2, away from the center of the optical axis, to approximately 430 nm and approximately 550 nm, respectively, and further by weakening the intensities of the blue light L21 and the green light L22, which have wavelengths adjacent to the wavelength of the excitation light L2, below the intensity of the red light L23, it was possible to achieve an average color rendering index Ra, which is an index showing the color reproducibility of the mixed light in comparison with natural light (daytime sunlight), of Ra = 80.

In the second embodiment, a laser diode is used as the wavelength-variable light-emitting element, but a fixed-wavelength light-emitting diode may be used as the light-emitting element, and the wavelength may be changed using a wavelength conversion element.

In the above-mentioned first and second embodiments, an illumination light source device is shown that adjusts at least one of the intensity and wavelength of the illumination light, as well as the intensity of the excitation light, so that when illumination light and excitation light are irradiated simultaneously on a subject, the spectral distribution of the mixed light of illumination light and excitation light becomes closer to the spectral distribution of natural light than when only illumination light is irradiated on a subject. However, when illumination light and excitation light are irradiated simultaneously on a subject, the illumination light source device of the present invention may adjust at least one of the intensity and wavelength of only the excitation light, rather than adjusting the intensity and wavelength of the illumination light, or may adjust both the illumination light and the excitation light separately.

As described above, the present invention has been illustrated using a preferred embodiment of the present invention, but the present invention should not be interpreted as being limited to this embodiment. It is understood that the scope of the present invention should be interpreted only by the claims. It is understood that a person skilled in the art can implement an equivalent scope based on the description of the specific preferred embodiments of the present invention and common technical knowledge from the description of the present invention. It is understood that the contents of the documents cited in this specification should be incorporated by reference into this specification in the same manner as if the contents themselves were specifically described in this specification.

The present invention is useful for obtaining an illumination light source device that can bring the color reproducibility of the mixed light of the illumination light and the excitation light closer to that of natural light when the subject is simultaneously irradiated with excitation light capable of exciting fluorescent substances contained in the subject together with the illumination light.

100 Illumination light source device 101 Subject 110 Illumination light source 110a LED drive circuit 111 Blue light source (blue LED)
112 Green light source (green LED)
113 Red light source (red LED)
120 Excitation light source 120a, 210a LD driving circuit 121 Excitation light emitting element (excitation LD)
130 Mixer 140, 140a, 240 Control unit 211 Blue light source (blue LD)
212 Green light source (green LD)
213 Red light source (red LD)
C21 Blue wavelength control signal C22 Green wavelength control signal Ct1 Illumination control signal Ct2 Excitation control signal D11, D21 Blue drive current D12, D22 Green drive current D13, D23 Red drive current D2 Excitation drive current L10, L20 Illumination light L11, L11a Blue Light (B)
L12, L12a Green light (G)
L13, L13a Red light (R)
L2 Excitation light (E)
L3, L31, L32 Mixed light Sm Operation signal

Claims (16)

an illumination light source that irradiates an object with illumination light;
an excitation light source that irradiates excitation light capable of exciting a fluorescent substance contained in the subject;
a control unit for controlling the illumination light source and the excitation light source,
the control unit adjusts at least one of the intensity and the wavelength of the illumination light or the excitation light so that, when the illumination light and the excitation light are simultaneously irradiated onto the subject, a spectral distribution of a mixture of the illumination light and the excitation light becomes closer to a spectral distribution of natural light than when only the illumination light is irradiated onto the subject. The illumination light source device according to claim 1, wherein the control unit adjusts the intensity and wavelength of the illumination light when the illumination light and the excitation light are simultaneously irradiated onto the subject. The illumination light source device according to claim 1, wherein the control unit adjusts the intensity and wavelength of the excitation light when the illumination light and the excitation light are irradiated simultaneously onto the subject. the illumination light source includes a plurality of illumination light sources outputting illumination light of different wavelengths;
The illumination light source device according to claim 1 , wherein a wavelength of the excitation light is different from a wavelength of the illumination light emitted from the plurality of illumination light sources. The illumination light source device according to claim 4, wherein the control unit controls the intensity of light from the illumination light source having a wavelength adjacent to the wavelength of the excitation light when the illumination light and the excitation light are simultaneously irradiated onto the subject, to be lowered compared to when only the illumination light is irradiated onto the subject. The illumination light source device according to claim 4 or 5, wherein the control unit controls the wavelength of light from the illumination light source having a wavelength adjacent to the wavelength of the excitation light to be farther away from the wavelength of the excitation light when the illumination light and the excitation light are simultaneously irradiated onto the subject, compared to when only the illumination light is irradiated onto the subject. The illumination light source device according to claim 5, wherein the control unit does not change the intensity of light from the illumination light source that is not adjacent to the wavelength of the excitation light when the illumination light and the excitation light are irradiated simultaneously to the subject. the illumination light source includes a blue light source, a green light source, and a red light source;
5. The illumination light source device according to claim 4, wherein the wavelength of the excitation light source is between the wavelength of the light from the blue light source and the wavelength of the light from the green light source. The illumination light source device according to claim 8, wherein the control unit controls the intensity of the light from the blue light source and the light from the green light source, which have wavelengths adjacent to both sides of the wavelength of the excitation light, to be lowered when the illumination light and the excitation light are simultaneously irradiated onto the subject, compared to when only the illumination light is irradiated onto the subject. The illumination light source device according to claim 8 or 9, wherein the control unit controls the wavelengths of the light from the blue light source and the light from the green light source to be farther away from the wavelength of the light from the excitation light source when the illumination light and the excitation light are simultaneously irradiated onto the subject, compared to when only the illumination light is irradiated onto the subject. The illumination light source device according to claim 9, wherein the control unit does not change the intensity of light from the red light source that is not adjacent to the wavelength of the excitation light when the illumination light and the excitation light are irradiated simultaneously to the subject. The control unit has an illumination light observation mode in which only the illumination light is irradiated and a mode in which the illumination light and the excitation light are irradiated simultaneously, and an excitation light observation mode in which only the excitation light is irradiated, and is configured to be able to select between these modes, and in the mode in which the illumination light and the excitation light are irradiated simultaneously, the control unit controls the intensity of light from the excitation light source to be lower than the intensity of light from the excitation light source irradiated in the excitation light observation mode. The illumination light source device according to claim 1. The illumination light source device according to claim 1, wherein the control unit adjusts at least one of the intensity and wavelength of the illumination light so that the color reproducibility of the mixed light of the illumination light and the excitation light is improved by about 10 to about 30 in average color rendering index Ra compared to the color reproducibility of the illumination light alone. An endoscope equipped with the illumination light source device according to claim 1. A light-guiding member equipped with the illumination light source device according to claim 1. A method for setting a wavelength of an illumination light that is irradiated onto an object simultaneously with an excitation light that excites a fluorescent substance in the object, comprising:
a wavelength of the illumination light being set so that, when the illumination light and the excitation light are simultaneously irradiated onto the subject, a spectral distribution of a mixture of the illumination light and the excitation light is closer to a spectral distribution of natural light than when only the illumination light is irradiated onto the subject.

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