JP7546204B2 - Light emitting device and endoscope system - Google Patents

Description

The present invention relates to a light emitting device and an endoscope system.

In endoscope observation, normal observation is performed by irradiating white light, and special observation is performed by irradiating light of a specific wavelength. Special observation includes observation using a narrow band of light called NBI (Narrow Band Imaging). For example, Patent Documents 1 and 2 disclose light source devices that can selectively emit white light and light for special observation.

JP 2009-291347 A JP 2017-225861 A

In addition to NBI, special observations also include ICG (indocyanine green) fluorescence imaging. Since the wavelength of light to be irradiated differs depending on the type of special observation, there is a demand for light-emitting devices that can irradiate light with wavelengths appropriate for each type of observation.

The present invention aims to provide a light-emitting device and an endoscope system that can switch between multiple lights that can be used for multiple types of special observation.

A light emitting device according to one aspect of the present invention includes a first light source that emits a first light, a second light source that emits a second light having a wavelength different from that of the first light, and a wavelength conversion unit including a first phosphor and a second phosphor, the first phosphor absorbs a part of the first light and emits a third light having a wavelength different from that of both the first light and the second light, the second phosphor absorbs another part of the first light and emits a fourth light having a wavelength different from that of both the first light, the second light, and the third light, the wavelength conversion unit is disposed on the optical path of the first light, and when the first light is incident, the wavelength conversion unit emits the other part of the first light, the third light, and the fourth light, and the fourth light has a peak wavelength in a wavelength band of 700 nm or more.

An endoscope system according to one aspect of the present invention includes a light-emitting device according to the above aspect.

The present invention makes it possible to switch between multiple lights that can be used for multiple types of special observation.

FIG. 1 is a diagram showing the configuration of a light emitting device and an endoscope system according to the first embodiment. FIG. 2 is a diagram showing emission spectra of light emitted by the light source and phosphor of the light emitting device according to the first embodiment. FIG. 3A is a diagram showing a modification of the light emitting device according to the first embodiment. FIG. 3B is a diagram showing another modified example of the light emitting device according to embodiment 1. In FIG. FIG. 4 is a diagram showing an example of the operation of the light emitting device according to the first embodiment. FIG. 5 is a diagram illustrating a modification of the wavelength conversion unit according to the first embodiment. FIG. 6 is a diagram showing the configuration of a light emitting device and an endoscope system according to the second embodiment. FIG. 7 is a diagram showing emission spectra of light emitted by a light source and a phosphor of the light emitting device according to the second embodiment. FIG. 8 is a diagram showing an example of the operation of the light emitting device according to the second embodiment. FIG. 9 is a diagram showing the configuration of a light emitting device and an endoscope system according to the third embodiment. FIG. 10 is a diagram showing the emission spectrum of light emitted by the light source and the phosphor of the light emitting device according to the third embodiment. FIG. 11 is a diagram showing an example of the operation of the light emitting device according to the third embodiment. FIG. 12 is a diagram showing the configuration of a light-emitting device and an endoscope system according to the fourth embodiment. FIG. 13 is a diagram showing emission spectra of light emitted by a light source and a phosphor of the light emitting device according to the fourth embodiment. FIG. 14 is a diagram showing an example of the operation of the light emitting device according to the fourth embodiment.

The following describes in detail the light-emitting device and endoscope system according to the embodiments of the present invention with reference to the drawings. Note that each of the embodiments described below shows a specific example of the present invention. Therefore, the numerical values, shapes, materials, components, arrangement and connection of the components, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components that are not described in the independent claims are described as optional components.

In addition, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, for example, the scales of each figure do not necessarily match. In addition, in each figure, substantially the same configuration is given the same reference numerals, and duplicate explanations are omitted or simplified.

In addition, in this specification, terms indicating relationships between elements, such as "parallel," terms indicating the shapes of elements, and numerical ranges are not expressions that express only strict meanings, but are expressions that include substantially equivalent ranges, for example, differences of about a few percent.

In addition, in this specification, the "peak wavelength" refers to the wavelength at which the emission intensity is maximum within a specified wavelength band. The intensity at the peak wavelength is referred to as the "peak intensity." The peak intensity does not have to be the maximum intensity in the entire wavelength band. In other words, a peak with an intensity higher than the peak intensity within a specified wavelength band may exist in a band other than the specified wavelength band.

In addition, in this specification, ordinal numbers such as "first" and "second" do not refer to the number or order of components, unless otherwise specified, but are used for the purpose of avoiding confusion and distinguishing between components of the same type.

(Embodiment 1)
[composition]
First, the configuration of a light emitting device and an endoscope system according to the present embodiment will be described with reference to FIG.

Fig. 1 is a diagram showing the configuration of a light-emitting device 2 and an endoscope system 1 according to this embodiment. The endoscope system 1 shown in Fig. 1 is used to observe the inside of a subject's body. The subject is a living body such as a human body or an animal body. The endoscope system 1 is used for normal observation and several types of special observation.

As shown in FIG. 1, the endoscope system 1 includes a light emitting device 2, a rod lens 3, an optical fiber 4, and an objective lens 5.

The light-emitting device 2 is a device that emits the emitted light L. The specific configuration of the light-emitting device 2 will be described later.

The rod lens 3 is an optical component that homogenizes the illuminance distribution of the emitted light L emitted from the light emitting device 2. The emitted light L passes through the rod lens 3, whereby the illuminance distribution is homogenized, and then enters one end of the optical fiber 4.

At least a portion of the optical fiber 4 is inserted into the subject's body and guides the emitted light L into the subject's body. The emitted light L enters one end (base end) of the optical fiber 4 and exits from the other end (tip end).

The objective lens 5 irradiates the emitted light L emitted from the tip of the optical fiber 4 into the subject's body.

The optical fiber 4 and the objective lens 5 are held by a tubular member (not shown). The rod lens 3 and the objective lens 5 are not essential components of the endoscope system 1.

Although not shown in FIG. 1, the endoscope system 1 also includes a light receiving unit that receives reflected light of the emitted light L irradiated inside the body. The light receiving unit can extract only a specific wavelength from the reflected light and convert the intensity into an electrical signal. For example, the light receiving unit includes a filter that passes the specific wavelength, and an image sensor that photoelectrically converts the light that passes through the filter. The image sensor includes a plurality of pixels arranged two-dimensionally, and each pixel includes sub-pixels corresponding to, for example, R (red), G (green), B (blue), and IR (near infrared), but is not limited to this. The light receiving unit is disposed, for example, near the tip of the optical fiber 4.

Next, the configuration and light spectrum of the light emitting device 2 will be described with reference to Figures 1 and 2. Figure 2 shows the emission spectrum of light emitted by the light source and phosphor of the light emitting device 2 according to this embodiment.

As shown in FIG. 1, the light-emitting device 2 includes a first light source 10, a second light source 20, a wavelength conversion unit 30, and a control circuit 40.

The first light source 10 emits the first light L1. The first light source 10 is a laser light source. In this embodiment, as shown in FIG. 2, the first light L1 is blue light having a peak wavelength in a wavelength band of 430 nm or more and 495 nm or less. The first light L1 is narrowband light. Specifically, the half-width of the first light L1 is 20 nm or less, but may be 10 nm or less, or may be 5 nm or less. For example, the first light source 10 is a blue laser light source having a peak wavelength of 455 nm. The first light L1 may be purple light having a peak wavelength in a wavelength band of 380 nm or more and less than 430 nm.

The second light source 20 emits a second light L2 having a wavelength different from that of the first light L1. The second light source 20 is a laser light source. In this embodiment, as shown in FIG. 2, the peak wavelength of the second light L2 is shorter than the peak wavelength of the first light L1. Specifically, the second light L2 is a purple light having a peak wavelength in a wavelength band of 380 nm or more and less than 430 nm. The second light L2 is a narrowband light. Specifically, the half-width of the second light L2 is 20 nm or less, but may be 10 nm or less, or may be 5 nm or less. For example, the second light source 20 is a purple laser light source having a peak wavelength of 415 nm. The second light L2 may be a green light having a peak wavelength in a wavelength band of 510 nm or more and 550 nm or less.

In this embodiment, the first light source 10 and the second light source 20 are arranged side by side so that their optical axes are parallel to each other. The optical axis of the light source is the center of the light emitted from the light source and coincides with the direction of light emission. For example, the first light source 10 and the second light source 20 are provided on the same substrate. The first light L1 emitted from the first light source 10 and the second light L2 emitted from the second light source 20 both enter the wavelength conversion unit 30 without entering other optical elements (lenses, mirrors, etc.).

The first light source 10 and the second light source 20 may be provided on separate substrates. At least one of the first light L1 emitted from the first light source 10 and the second light L2 emitted from the second light source 20 may be incident on the wavelength conversion unit 30 via other optical elements (lenses, mirrors, etc.), for example, as in the light emitting device 2A shown in FIG. 3A. The light emitting device 2A includes a dichroic mirror 50 and a mirror 51. The dichroic mirror 50 is disposed between the first light source 10 and the wavelength conversion unit 30, and passes the first light L1 emitted from the first light source 10 and causes it to enter the wavelength conversion unit 30. The dichroic mirror 50 also reflects the second light L2 emitted from the second light source 20 and reflected by the mirror 51, and causes it to enter the wavelength conversion unit 30. This configuration makes it possible to uniformize the energy distribution of the first light L1 and the second light L2, and to align the irradiation positions of the first light L1 and the second light L2 in the wavelength conversion section 30, thereby providing a light-emitting device with less unevenness in the output light.

Furthermore, as long as the optical axes of the first light L1 and the second light L2 incident on the wavelength conversion unit 30 are parallel, the first light source 10 and the second light source 20 do not have to be arranged side by side so that their optical axes are parallel, as in the light-emitting device 2B shown in FIG. 3B. The light-emitting device 2B includes a dichroic mirror 50. The dichroic mirror 50 receives the second light L2 emitted from the second light source 20 directly, reflects the incident second light L2, and makes it incident on the wavelength conversion unit 30. This configuration increases the design freedom of the light-emitting device.

As shown in FIG. 1, the wavelength conversion unit 30 includes a first phosphor 31 and a second phosphor 32. In FIG. 1, a part of the wavelength conversion unit 30 is shown enlarged and schematic in a rectangular area surrounded by a dashed line. For example, both the first phosphor 31 and the second phosphor 32 are particulate matter.

For example, the wavelength conversion unit 30 has a plate-shaped resin base material (not shown), in which a plurality of first phosphors 31 and a plurality of second phosphors 32 are mixed and dispersed. Alternatively, the wavelength conversion unit 30 may have a transparent plate material, in which a plurality of first phosphors 31 and a plurality of second phosphors 32 are mixed and dispersed in a transparent resin applied to the surface of the plate material. Furthermore, the wavelength conversion unit 30 may be an aggregate (e.g., a ceramic sintered body) in which a plurality of first phosphors 31 and a plurality of second phosphors 32 are aggregated.

The first phosphor 31 absorbs a part of the first light L1 and emits a third light L3 having a wavelength different from both the first light L1 and the second light L2. That is, the first light L1 functions as an excitation light for the first phosphor 31. In this embodiment, as shown in FIG. 2, the peak wavelength of the third light L3 is longer than the peak wavelength of the first light L1. Specifically, the third light L3 is a yellow light having a peak wavelength in a wavelength band of 525 nm to 600 nm. The third light L3 has an intensity equal to or greater than a predetermined ratio of the peak intensity over a wavelength band of 500 nm to 600 nm. The predetermined ratio is, for example, 5%, but may be 3%, 10%, or 20%. That is, the third light L3 is a light having a larger half-width and a broader intensity than each of the first light L1 and the second light L2. For example, the first phosphor 31 is a _{Y3Al5O12 :} Ce3 ⁺ phosphor (YAG:Ce3 ⁺ ) having an excitation wavelength of 455 nm and a peak wavelength of 545 _nm . Note that the first phosphor 31 may be any phosphor having a fluorescence spectrum equivalent to that of YAG: ^{Ce3 +} , and other yellow phosphors may be used instead of or in addition to YAG:Ce3 ⁺ .

The second phosphor 32 absorbs the other part of the first light L1 (i.e., the light not absorbed by the first phosphor 31) and emits a fourth light L4 having a wavelength different from any of the first light L1, the second light L2, and the third light L3. That is, the first light L1 functions as an excitation light for the second phosphor 32. In this embodiment, as shown in FIG. 2, the peak wavelength of the fourth light L4 is longer than the peak wavelengths of the first light L1 and the third light L3. Specifically, the fourth light L4 is near-infrared light having a peak wavelength in a wavelength band of 700 nm or more. The fourth light L4 has an intensity equal to or greater than a predetermined ratio of the peak intensity over a wavelength band of 700 nm or more and 800 nm or less. The predetermined ratio is, for example, 5%, but may be 3%, 10%, or 20%. That is, the fourth light L4 is a light having a larger half-width and a broader intensity than each of the first light L1 and the second light L2. For example, the second phosphor 32 is _a ( _{Gd0.8La0.2 ) 3} ( _{Ga0.47Sc0.50Cr0.03 )2Ga5O12 phosphor} (GGG) having an excitation wavelength of 455 nm and a peak wavelength of 765 _nm . Note that the second phosphor 32 may be _any phosphor having a fluorescence spectrum equivalent to that of GGG, and other near-infrared phosphors may be used instead of or in addition to GGG.

The wavelength conversion unit 30 is disposed on the optical path of the first light L1 and on the optical path of the second light L2. Specifically, when viewed from the light L emission side, the wavelength conversion unit 30 overlaps both the first light source 10 and the second light source 20. When the first light L1 is incident on the wavelength conversion unit 30, it emits another part of the first light L1 (i.e., the light not absorbed by each phosphor), a third light L3, and a fourth light L4.

When the second light L2 is incident on the wavelength conversion unit 30, the wavelength conversion unit 30 emits at least a portion of the second light L2. Note that a portion of the second light L2 may be absorbed by at least one of the first phosphor 31 and the second phosphor 32. In other words, the second light L2 may function as excitation light for at least one of the first phosphor 31 and the second phosphor 32. In this case, when the second light L2 is incident on the wavelength conversion unit 30, the wavelength conversion unit 30 emits another portion of the second light L2 and at least one of the third light L3 and the fourth light L4.

The control circuit 40 controls the first light source 10 and the second light source 20. The control circuit 40 controls the emission and stopping of each of the first light source 10 and the second light source 20. For example, the control circuit 40 causes a light source suitable for performing a desired observation to emit light based on an operational input from a user.

The control circuit 40 is realized, for example, by an LSI (Large Scale Integration) which is an integrated circuit (IC). The integrated circuit is not limited to an LSI, and may be a dedicated circuit or a general-purpose processor. For example, the control circuit 40 may be a microcontroller. The microcontroller includes, for example, a non-volatile memory in which a program is stored, a volatile memory which is a temporary storage area for executing the program, an input/output port, and a processor for executing the program. The control circuit 40 may also be a programmable FPGA (Field Programmable Gate Array) or a reconfigurable processor in which the connections and settings of the circuit cells in the LSI can be reconfigured. The functions executed by the control circuit 40 may be realized by software or hardware.

[Action]
Next, a specific example of the operation of the light emitting device 2 according to the present embodiment and observation using the endoscope system 1 will be described with reference to FIG.

Figure 4 is a diagram showing an example of the operation of the light-emitting device 2 according to this embodiment. As shown in Figure 4, the endoscope system 1 equipped with the light-emitting device 2 is used for normal observation and special observation. Special observation includes NBI and ICG fluorescence imaging.

Normal observation involves obtaining visible light images of the inside of the body using white light. When performing normal observation, the control circuit 40 causes the first light source 10 to emit light and stops the second light source 20 from emitting light. Note that in FIG. 4, the light source is indicated as "ON" when it emits light, and the stop of light emission is indicated as "OFF." This notation is the same in FIG. 8, FIG. 11, and FIG. 14, which will be described later.

When the first light source 10 emits the first light L1, the first phosphor 31 and the second phosphor 32 are excited, respectively, and emit the third light L3 and the fourth light L4. As a result, the wavelength conversion unit 30 emits a composite light of the first light L1 (blue light), the third light L3 (yellow light), and the fourth light L4 (near-infrared light) as the emitted light L. In normal observation, the first light L1 (blue light) and the third light L3 (yellow light) of the emitted light L are used. Specifically, a visible light image suitable for normal observation can be obtained based on the electrical signals generated by each of the R, G, and B sub-pixels included in each pixel of the image sensor. In addition, a filter that removes the fourth light L4 may be arranged on the light receiving surface of the image sensor.

NBI uses two narrow bands of light with different wavelengths to obtain an image that highlights a specific object. The specific object is, for example, the blood vessels of the subject. When performing NBI, the control circuit 40 causes both the first light source 10 and the second light source 20 to emit light.

Compared to normal observation, the second light source 20 emits the second light L2, and the wavelength conversion unit 30 emits a composite light of the first light L1 (blue light), the second light L2 (purple light), the third light L3 (yellow light), and the fourth light L4 (near-infrared light) as the emitted light L. In NBI, the first light L1 (blue light) and the second light (purple light) of the emitted light L are used.

Hemoglobin contained in blood flowing through blood vessels strongly absorbs blue, violet, and green light. Blue light is used to observe capillaries on the surface of the mucous membrane. Green and violet light are used to observe larger blood vessels deep inside and to emphasize the contrast with the capillaries. By processing the electrical signals according to the respective intensities of blue and violet light, an image in which the blood vessels are emphasized can be obtained.

The electrical signals corresponding to the intensities of the blue light and the purple light can be obtained, for example, by using an image sensor having a plurality of pixels, each of which includes a sub-pixel sensitive to each of the blue light and the purple light. Alternatively, an image sensor having a plurality of pixels sensitive to a wavelength band including at least the blue light and the purple light may be used. By alternately emitting light from the first light source 10 and the second light source 20, an electrical signal corresponding to the intensity of the blue light and an electrical signal corresponding to the intensity of the purple light can be obtained. In addition, a filter that removes light other than blue light and a filter that removes light other than purple light may be arranged on the light receiving surface of the image sensor.

ICG fluorescence imaging uses near-infrared light to obtain an image that highlights a specific object. The specific object is, for example, a tumor or lymph node of a subject. Specifically, when ICG is administered to a subject and the administered ICG is irradiated with near-infrared light, the ICG emits near-infrared fluorescence with a longer wavelength than the irradiated near-infrared light. By receiving this near-infrared fluorescence, it becomes possible to observe objects that are difficult to observe using normal observation.

In ICG fluorescence imaging, as in normal observation, the control circuit 40 causes the first light source 10 to emit light and stops the second light source 20 from emitting light. As a result, a composite light of the first light L1 (blue light), the third light L3 (yellow light), and the fourth light L4 (near-infrared light) is emitted from the wavelength conversion unit 30 as the emitted light L. In ICG fluorescence imaging, the fourth light L4 (near-infrared light) of the emitted light L is used. Specifically, a near-infrared light image can be obtained based on an electrical signal generated by an IR sub-pixel included in each pixel of the image sensor. A filter that removes visible light may be placed on the light receiving surface of the image sensor.

In addition, in normal observation and ICG fluorescence imaging, the control circuit 40 may cause the second light source 20 to emit light. In other words, the control circuit 40 may integrally control the emission and stopping of the first light source 10 and the second light source 20. In this case, the second light L2 (violet light) that is unnecessary for each observation will be included in the emitted light L, but each observation can be performed appropriately by removing the second light L2 using a filter, for example.

[Effects, etc.]
As described above, the light emitting device 2 according to the present embodiment includes the first light source 10 that emits the first light L1, the second light source 20 that emits the second light L2 that has a different wavelength from the first light L1, and the wavelength conversion unit 30 that includes the first phosphor 31 and the second phosphor 32. The first phosphor 31 absorbs a part of the first light L1 and emits the third light L3 that has a different wavelength from both the first light L1 and the second light L2. The second phosphor 32 absorbs another part of the first light L1 and emits the fourth light L4 that has a different wavelength from both the first light L1, the second light L2, and the third light L3. The wavelength conversion unit 30 is disposed on the optical path of the first light L1, and when the first light L1 is incident, it emits the other part of the first light L1, the third light L3, and the fourth light L4. The fourth light L4 has a peak wavelength in a wavelength band of 700 nm or more.

This allows multiple lights that can be used for multiple types of special observation to be switched and emitted, thereby improving the versatility of the light-emitting device 2 and the endoscope system 1.

For example, the first light source 10 and the second light source 20 are arranged side by side so that their optical axes are parallel to each other. The wavelength conversion unit 30 is arranged on the optical path of the second light L2, and when the second light L2 is incident, it emits at least a portion of the second light L2.

This allows the first light source 10 and the second light source 20 to be placed close to each other. Also, like the first light L1, the second light L2 can be passed through the wavelength conversion unit 30 and guided to the optical fiber 4, so there is no need to provide optical components for adjusting the optical path of the second light L2. As a result, the light emitting device 2 can be made smaller.

Also, for example, the fourth light L4 has an intensity of 5% or more of the peak wavelength intensity over a wavelength band of 700 nm or more and 800 nm or less.

This allows the emission of the fourth light L4, which is near-infrared light having sufficient intensity over a wide wavelength band, making it easy to accommodate variations in the characteristics of drugs such as ICG. In other words, the light-emitting device 2 can be effectively used for ICG fluorescence imaging.

For example, the first light L1 has a peak wavelength in a wavelength band of 430 nm or more and 495 nm or less. The second light L2 has a peak wavelength in a wavelength band of 380 nm or more and less than 430 nm. The third light L3 has a peak wavelength in a wavelength band of 525 nm or more and 600 nm or less.

This allows the light-emitting device 2 to be used for normal observations as well as special observations such as NBI and ICG fluorescence imaging.

For example, the half-width of each of the first light L1 and the second light L2 is 20 nm or less.

This reduces unnecessary wavelength components (noise) and improves the accuracy of each observation.

Furthermore, for example, the first light source 10 and the second light source 20 are each a laser light source.

This allows unnecessary wavelength components (noise) to be reduced and stronger light to be emitted, improving the accuracy of each observation.

The endoscope system 1 according to this embodiment also includes a light-emitting device 2.

This allows for normal observations as well as multiple types of special observations, such as NBI and ICG fluorescence imaging.

[Modification]
Next, a modified example of the wavelength conversion unit of the light emitting device according to the embodiment will be described with reference to Fig. 5. Fig. 5 is a diagram showing a modified example of the wavelength conversion unit according to the embodiment.

The wavelength conversion unit 130 shown in FIG. 5 includes a first portion 131 and a second portion 132 that is different from the first portion 131.

The first portion 131 contains the first phosphor 31. For example, the first portion 131 has a plate-shaped resin base material, and a plurality of the first phosphors 31 are dispersed within the resin base material. The first portion 131 does not contain the second phosphor 32. The first portion 131 may be an aggregate in which a plurality of the first phosphors 31 are aggregated.

The second portion 132 contains the second phosphor 32. For example, the second portion 132 has a plate-shaped resin base material, and the second phosphor 32 is dispersed in the resin base material. The second portion 132 does not contain the first phosphor 31. The second portion 132 may be an aggregate of a plurality of second phosphors 32.

The first portion 131 is located closer to the incident side of the first light L1 than the second portion 132. That is, the first light L1 is incident on the first portion 131, then incident on the second portion 132, and is emitted from the second portion 132. When the first light L1 is incident on the first portion 131, a portion of the first light L1 is absorbed, and a third light L3 is emitted.

In the second portion 132, a part of the first light L1 that passed through the first portion 131 is incident, a part of the first light L1 is absorbed, and a fourth light L4 is emitted. In addition, the third light L3 emitted from the first portion 131 also enters the second portion 132. The third light L3 passes through the second portion 132.

As described above, in the light emitting device according to this modified example, the wavelength conversion section 130 includes a first portion 131 and a second portion 132 different from the first portion 131. The first portion 131 is located closer to the incident side of the first light L1 than the second portion 132. The first phosphor 31 is included in the first portion 131. The second phosphor 32 is included in the second portion 132.

This allows for switching between multiple lights that can be used for multiple types of special observations.

The first part 131 and the second part 132 may be separate. In other words, the first part 131 and the second part 132 may be spaced apart from each other without contacting each other.

(Embodiment 2)
Next, a description will be given of embodiment 2. In embodiment 2, the light emitting device is different from embodiment 1 in that it includes a third light source. In the following, the description will be centered on the differences from embodiment 1, and the description of the commonalities will be omitted or simplified.

[composition]
First, the configurations of a light emitting device and an endoscope system according to the present embodiment will be described with reference to FIGS. 6 and 7. FIG.

Figure 6 is a diagram showing the configuration of the light-emitting device 202 and the endoscope system 201 according to this embodiment. Figure 7 is a diagram showing the emission spectrum of the light emitted by the light source and phosphor of the light-emitting device 202 according to this embodiment.

As shown in FIG. 6, the endoscope system 201 includes a light-emitting device 202 instead of the light-emitting device 2 in the endoscope system 1 according to the first embodiment. The light-emitting device 202 further includes a third light source 250 in the endoscope system 1 according to the first embodiment. The light-emitting device 202 also includes a control circuit 240 instead of the control circuit 40.

The third light source 250 emits a fifth light L5. The third light source 250 is a laser light source. In this embodiment, as shown in FIG. 6, the fifth light L5 is red light having a peak wavelength in a wavelength band of 620 nm or more and 750 nm or less. The fifth light L5 is narrowband light. Specifically, the half-width of the fifth light L5 is 20 nm or less, but may be 10 nm or less, or may be 5 nm or less. For example, the third light source 250 is a red laser light source with a peak wavelength of 660 nm.

The second phosphor 32 absorbs a portion of the fifth light L5 and emits the fourth light L4. That is, the fifth light L5 functions as excitation light for the second phosphor 32.

In this embodiment, the first light source 10, the second light source 20, and the third light source 250 are arranged side by side so that their optical axes are parallel to each other. For example, the first light source 10, the second light source 20, and the third light source 250 are provided on the same substrate. The first light L1 emitted from the first light source 10, the second light L2 emitted from the second light source 20, and the fifth light L5 emitted from the third light source 250 all enter the wavelength conversion unit 30 without entering other optical elements (lenses, mirrors, etc.). In other words, the wavelength conversion unit 30 is arranged on the optical path of the fifth light L5.

The first light source 10, the second light source 20, and the third light source 250 may each be provided on a different substrate. At least one of the first light L1 emitted from the first light source 10, the second light L2 emitted from the second light source 20, and the fifth light L5 emitted from the third light source 250 may be incident on the wavelength conversion unit 30 via other optical elements (lenses, mirrors, etc.). For example, a plurality of dichroic mirrors 50 or mirrors 51 shown in FIG. 3A may be arranged. With this configuration, it is possible to uniformize the energy distribution of the first light L1, the second light L2, and the fifth light L5, and to align the irradiation positions of the first light L1, the second light L2, and the fifth light L5 in the wavelength conversion unit 30, thereby providing a light-emitting device with less unevenness in the output light. Furthermore, if the optical axes of the first light L1, the second light L2, and the fifth light L5 incident on the wavelength conversion unit 30 are parallel, the first light source 10, the second light source 20, and the third light source 250 do not have to be arranged side by side so that their optical axes are parallel. For example, multiple dichroic mirrors 50 shown in FIG. 3B may be arranged, or other optical elements such as a mirror 51 may be further combined and arranged. Such a configuration can increase the design freedom of the light emitting device.

When the fifth light L5 is incident on the wavelength conversion unit 30, the wavelength conversion unit 30 emits another part of the fifth light L5 and the fourth light L4.

The control circuit 240 controls the first light source 10, the second light source 20, and the third light source 250. The control circuit 240 controls the emission and stopping of each of the first light source 10, the second light source 20, and the third light source 250. For example, the control circuit 240 causes a light source suitable for performing a desired observation to emit light based on an operational input from a user.

[Action]
Next, the operation of the light emitting device 202 according to this embodiment and a specific example of observation using the endoscope system 201 will be described with reference to FIG.

Figure 8 is a diagram showing an example of the operation of the light-emitting device 202 according to this embodiment. As shown in Figure 8, the endoscope system 201 equipped with the light-emitting device 202 is used for normal observation, special observation, and photodynamic therapy (PDT). In other words, the endoscope system 201 is used not only for observing the inside of a subject, but also for treating the subject.

PDT is performed using red light. Specifically, an appropriate drug (photosensitizer) is administered to the subject according to the purpose of treatment. The subject is made to wait in a dark room until the drug accumulates in the pathological tissue, and then the light emitting device 202 (endoscopic system 201) irradiates the affected area with red light. Specifically, the control circuit 240 causes the third light source 250 to emit light, thereby emitting the fifth light L5 (red light). The drug excited by the red light reacts with oxygen, generating reactive oxygen species with high oxidizing power. This makes it possible to eliminate the harmful tissue.

As shown in FIG. 8, when PDT is performed, the control circuit 240 stops the emission of light from the first light source 10 and the second light source 20. This makes it possible to prevent the irradiation of light unnecessary for PDT, which also contributes to reducing power consumption.

The third light source 250 can also be used for ICG fluorescence imaging in addition to PDT. As shown in FIG. 8, in the endoscope system 201, in the case of ICG fluorescence imaging, the control circuit 240 causes not only the first light source 10 but also the third light source 250 to emit light. When the fifth light L5 emitted from the third light source 250 enters the wavelength conversion unit 30, it excites the second phosphor 32. As a result, another part of the fifth light L5 (red light) and the fourth light L4 (near-infrared light) are emitted from the wavelength conversion unit 30. This increases the amount of near-infrared light, thereby improving the accuracy of ICG fluorescence imaging.

In the endoscope system 201, normal observation and NBI are performed in the same manner as in the endoscope system 1 according to embodiment 1.

[Effects, etc.]
As described above, in the endoscope system 201 according to the present embodiment, the light emitting device 202 includes the third light source 250 that emits the fifth light L5 having a wavelength different from the wavelengths of the first light L1 and the second light L2. The fifth light L5 has a peak wavelength in a wavelength band of 620 nm or more and 750 nm or less.

This allows the light-emitting device 202 and the endoscope system 201 to be used not only for normal observation and special observation, but also for treatment such as PDT. This increases the versatility of the light-emitting device 202 and the endoscope system 201.

Also, for example, the second phosphor 32 absorbs a portion of the fifth light L5 and emits a fourth light L4. The first light source 10 and the third light source 250 are arranged side by side so that their optical axes are parallel to each other. The wavelength conversion unit 30 is arranged on the optical path of the fifth light L5, and when the fifth light L5 is incident, it emits another portion of the fifth light L5 and the fourth light L4.

This allows the fourth light L4 (near-infrared light) to be efficiently emitted by the fifth light L5 emitted by the third light source 250.

(Embodiment 3)
Next, a description will be given of embodiment 3. In embodiment 3, the wavelength conversion unit includes a third phosphor, which is different from embodiment 1. In the following, the differences from embodiment 1 will be mainly described, and the description of the commonalities will be omitted or simplified.

[composition]
First, a light emitting device and an endoscope system according to the present embodiment will be described with reference to FIGS.

Figure 9 is a diagram showing the configuration of the light-emitting device 302 and endoscope system 301 according to this embodiment. Figure 10 is a diagram showing the emission spectrum of the light emitted by the light source and phosphor of the light-emitting device 302 according to this embodiment.

As shown in FIG. 9, the endoscope system 301 includes a light emitting device 302 instead of the light emitting device 2 in the endoscope system 1 according to the first embodiment. The light emitting device 302 includes a wavelength conversion unit 330 instead of the wavelength conversion unit 30 in the light emitting device 2 according to the first embodiment. The wavelength conversion unit 330 further includes a third phosphor 333.

The wavelength conversion section 330 has a plate-shaped resin base material (not shown), in which a plurality of first phosphors 31, a plurality of second phosphors 32, and a plurality of third phosphors 333 are mixed and dispersed. Alternatively, the wavelength conversion section 330 may include a third section in which only a plurality of third phosphors 333 are dispersed, in addition to the first section 131 and the second section 132, as in the wavelength conversion section 130 according to the modified example of the first embodiment. The third section is, for example, disposed closer to the light incident side than the first section 131, but is not limited thereto. Alternatively, the plurality of third phosphors 333 may be mixed and dispersed with the first phosphor 31 or the second phosphor 32 in at least one of the first section 131 and the second section 132.

The third phosphor 333 absorbs a part of the first light L1 and emits a sixth light L6 having a wavelength different from any of the first light L1, the second light L2, the third light L3, and the fourth light L4. That is, the first light L1 functions as an excitation light for the third phosphor 333. In this embodiment, as shown in FIG. 10, the peak wavelength of the sixth light L6 is longer than the peak wavelengths of the first light L1 and the second light L2, and shorter than the peak wavelengths of the third light L3 and the fourth light L4. Specifically, the sixth light L6 is green light having a peak wavelength in a wavelength band of 505 nm or more and less than 525 nm. The sixth light L6 has an intensity equal to or greater than a predetermined ratio of the peak intensity over a wavelength band of 500 nm or more and 600 nm or less. The predetermined ratio is, for example, 5%, but may be 3%, 10%, or 20%. That is, the sixth light L6 is a broad light having a larger half-width than each of the first light _L1 and the second light L2. For example, the third phosphor 333 is a _Lu3Al5O12 :Ce3 ⁺ phosphor (LuAG:Ce3 ⁺ ) having an excitation wavelength of 455 nm and a peak wavelength of 512 _nm . Note that the third phosphor 333 may be any phosphor having a fluorescence spectrum equivalent to that of LuAG: ^{Ce3+ ,} and other green phosphors may be used instead of or in addition to LuAG:Ce3 ⁺ . Other green phosphors that can be used include Ca ₃ Sc ₂ Si ₃ O ₁₂ :Ce ³⁺ , Ca(Sc,Lu) ₂ O ₄ :Ce ³⁺ , β-SiAlON:Eu ²⁺ , and BaMgAl ₁₀ O ₁₇ :Eu ²⁺ ,Mn ²⁺ .

[Action]
Next, a specific example of the operation of the light emitting device 302 according to this embodiment and observation using the endoscope system 301 will be described with reference to FIG.

Figure 11 is a diagram showing an example of the operation of the light-emitting device 302 according to this embodiment. As shown in Figure 11, an endoscope system 301 equipped with the light-emitting device 302 is used for normal observation, special observation, and PDT.

In this embodiment, PDT is performed using green light instead of red light. The drug used is one that is excited by green light.

When performing PDT, the control circuit 40 causes the first light source 10 to emit light and stops the second light source 20 from emitting light. As a result, a composite light of the first light L1 (blue light), the sixth light L6 (green light), the third light L3 (yellow light), and the fourth light L4 (near-infrared light) is emitted from the wavelength conversion unit 330 as the emitted light L. Of these, the sixth light L6 (green light) can be used to perform PDT. Note that a movable filter that removes light other than green light may be placed on the optical path from the wavelength conversion unit 330 to the objective lens 5.

In the endoscope system 301, normal observation and special observation are performed in the same manner as in the endoscope system 1 according to embodiment 1. By including green light, the accuracy of normal observation can also be improved.

[Effects, etc.]
As described above, in the endoscope system 301 according to the present embodiment, the wavelength converting unit 330 further includes the third phosphor 333. The third phosphor 333 absorbs another part of the first light L1 and emits the sixth light L6 having a wavelength different from any of the first light L1, the second light L2, the third light L3, and the fourth light L4. The sixth light L6 has a peak wavelength in a wavelength band of 505 nm or more and less than 525 nm.

This allows for normal and special observations as well as PDT using green light.

The third phosphor 333 may absorb another part of the second light L2 and emit a sixth light L6. That is, the second light L2 may function as excitation light for the third phosphor 333. In this case, the control circuit 40 causes the second light source 20 to emit more light when performing PDT. This makes it possible to increase the intensity of the green light, thereby making it possible to perform PDT more efficiently.

(Embodiment 4)
Next, a fourth embodiment will be described. In the fourth embodiment, the wavelength of the light emitted by the second light source is different from that in the first embodiment. In the following, the differences from the first embodiment will be mainly described, and the description of the commonalities will be omitted or simplified.

[composition]
First, a light emitting device and an endoscope system according to the present embodiment will be described with reference to FIGS.

Figure 12 is a diagram showing the configuration of the light-emitting device 402 and endoscope system 401 according to this embodiment. Figure 13 is a diagram showing the emission spectrum of light emitted by the light source and phosphor of the light-emitting device 402 according to this embodiment.

As shown in FIG. 12, the endoscope system 401 includes a light-emitting device 402 instead of the light-emitting device 2 in the endoscope system 1 according to the first embodiment. The light-emitting device 402 includes a second light source 420 instead of the second light source 20 in the light-emitting device 2 according to the first embodiment.

The second light source 420 emits a second light L7 having a different wavelength from the first light L1. The second light source 420 is a laser light source. In this embodiment, as shown in FIG. 13, the peak wavelength of the second light L7 is longer than the peak wavelength of the first light L1. Specifically, the second light L7 is green light having a peak wavelength in a wavelength band of 505 nm or more and less than 525 nm. The second light L7 is narrowband light. Specifically, the half-width of the second light L7 is 20 nm or less, but may be 10 nm or less, or may be 5 nm or less. For example, the second light source 420 is a green laser light source having a peak wavelength of 515 nm.

[Action]
Next, the operation of the light emitting device 402 according to this embodiment and a specific example of observation using the endoscope system 401 will be described with reference to FIG.

Figure 14 is a diagram showing an example of the operation of the light-emitting device 402 according to this embodiment. As shown in Figure 14, an endoscope system 401 equipped with the light-emitting device 402 is used for normal observation, special observation, and PDT.

In this embodiment, NBI uses blue light and green light. When performing NBI, the control circuit 40 causes both the first light source 10 and the second light source 20 to emit light. Since purple light is not used, NBI can be easily performed by an image sensor that includes general RGB sub-pixels.

In addition, PDT is performed using green light instead of red light. The drug used is one that is excited by green light. When performing PDT, the control circuit 40 causes the second light source 20 to emit light and stops the first light source 10 from emitting light. This causes the wavelength conversion unit 30 to emit second light L7 (green light) as the emitted light L. Therefore, PDT can be performed using the second light L7 (green light). Note that a movable filter that removes light other than green light may be placed on the optical path from the wavelength conversion unit 30 to the objective lens 5.

In the endoscope system 401, normal observation and ICG fluorescence imaging are performed in the same manner as in the endoscope system 1 according to embodiment 1.

[Effects, etc.]
As described above, in the endoscope system 401 according to the present embodiment, the first light L1 has a peak wavelength in a wavelength band of 430 nm or more and 495 nm or less, the second light L2 has a peak wavelength in a wavelength band of 505 nm or more and less than 525 nm, and the third light L3 has a peak wavelength in a wavelength band of 525 nm or more and 600 nm or less.

This allows for normal observation and ICG fluorescence imaging, as well as NBI using blue and green light, and PDT using green light.

(others)
Although the light emitting device and the endoscope system according to the present invention have been described based on the above-mentioned embodiment, the present invention is not limited to the above-mentioned embodiment.

For example, at least one of the first light source, the second light source, and the third light source may be an LED (Light Emitting Diode).

In addition, an optical element such as a mirror or a lens may be arranged on the optical path between at least one of the first light source, the second light source, and the third light source and the wavelength conversion unit. For example, the optical path of each light can be bent by a mirror, which increases the degree of freedom in arranging each element within the light emitting device.

The wavelength conversion unit does not have to be disposed on the optical path of the second light emitted by the second light source. The wavelength conversion unit does not have to be disposed on the optical path of the fifth light emitted by the third light source. In other words, the second light and the fifth light do not have to be incident on the wavelength conversion unit.

Furthermore, the fifth light emitted by the third light source does not have to function as excitation light for the second phosphor.

In addition, the present invention also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art may conceive, and forms realized by arbitrarily combining the components and functions of each embodiment within the scope of the spirit of the present invention.

1, 201, 301, 401 Endoscope system 2, 2A, 2B, 202, 302, 402 Light emitting device 10 First light source 20, 420 Second light source 30, 130, 330 Wavelength conversion section 31 First phosphor 32 Second phosphor 131 First portion 132 Second portion 250 Third light source 333 Third phosphor L Emitted light L1 First light L2, L7 Second light L3 Third light L4 Fourth light L5 Fifth light L6 Sixth light

Claims (11)

a first light source that emits a first light;
a second light source that emits a second light having a wavelength different from that of the first light;
A wavelength conversion unit including a first phosphor and a second phosphor;
a control circuit that controls the first light source and the second light source,
the first phosphor absorbs a portion of the first light and emits a third light having a wavelength different from both the first light and the second light;
the second phosphor absorbs another part of the first light and emits a fourth light having a wavelength different from any of the first light, the second light, and the third light;
the wavelength conversion unit is disposed on an optical path of the first light, and when the first light is incident thereon, the wavelength conversion unit emits another part of the first light, the third light, and the fourth light;
the first light has a peak wavelength in a wavelength band of 430 nm or more and 495 nm or less,
the second light has a peak wavelength in a wavelength band of 380 nm or more and less than 430 nm,
the third light has a peak wavelength in a wavelength band of 525 nm or more and 600 nm or less,
the fourth light has a peak wavelength in a wavelength band of 700 nm or more,
The control circuit includes:
When performing normal observation, the first light source is caused to emit light and the second light source is stopped from emitting light;
When performing NBI (Narrow Band Imaging), both the first light source and the second light source are caused to emit light;
When performing ICG (indocyanine green) fluorescence imaging, the first light source is caused to emit light and the second light source is stopped from emitting light.
Light emitting device. the first light source and the second light source are arranged side by side such that their optical axes are parallel to each other;
the wavelength conversion unit is disposed on an optical path of the second light, and when the second light is incident thereon, the wavelength conversion unit emits at least a portion of the second light.
The light emitting device according to claim 1 . The fourth light has an intensity of 5% or more of the intensity of the peak wavelength over a wavelength band of 700 nm or more and 800 nm or less.
3. A light emitting device according to claim 1 or 2. Further, a third light source is provided that emits a fifth light having a wavelength different from that of the first light and the second light,
The fifth light has a peak wavelength in a wavelength band of 620 nm or more and 750 nm or less.
The light emitting device according to any one of claims 1 to 3 . the second phosphor absorbs a portion of the fifth light and emits the fourth light;
the first light source and the third light source are arranged side by side such that their optical axes are parallel to each other;
the wavelength conversion unit is disposed on an optical path of the fifth light, and when the fifth light is incident thereon, the wavelength conversion unit emits another part of the fifth light and the fourth light.
The light emitting device according to claim 4 . The wavelength converting unit further includes a third phosphor,
the third phosphor absorbs another part of the first light and emits a sixth light having a wavelength different from any of the first light, the second light, the third light, and the fourth light;
The sixth light has a peak wavelength in a wavelength band of 505 nm or more and less than 525 nm.
The light emitting device according to any one of claims 1 to 3 . the first light has a peak wavelength in a wavelength band of 430 nm or more and 495 nm or less,
the second light has a peak wavelength in a wavelength band of 505 nm or more and less than 525 nm,
The third light has a peak wavelength in a wavelength band of 525 nm or more and 600 nm or less.
The light emitting device according to any one of claims 1 to 3. The wavelength converting portion is
A first portion; and
a second portion different from the first portion;
the first portion is located closer to a side where the first light is incident than the second portion,
the first phosphor is included in the first portion;
The second phosphor is contained in the second portion.
The light emitting device according to any one of claims 1 to 7 . The half width of each of the first light and the second light is 20 nm or less.
The light emitting device according to any one of claims 1 to 8 . each of the first light source and the second light source is a laser light source;
The light emitting device according to any one of claims 1 to 9 . The light emitting device according to any one of claims 1 to 10 is provided.
Endoscopy system.

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