Medical control device and medical observation system

Abstract

A medical control device 9 comprises: a light source control unit 941 that executes first control for emitting first light from a light source device 3 and second control for emitting excitation light from the light source device 3; an imaging control unit 942 that controls the operation of a first imaging element 531 for imaging light including at least a portion of the visible light wavelength band in return light from an observation target OB, and the operation of a second imaging element 532 for imaging light including at least a portion of the wavelength band of observation target fluorescence in the return light; and a mode switching unit 943. The light source control unit 941 sets, in a first mode, a control value for the first control to a control value equal to or smaller than a control threshold, and sets, in a second mode, the control value for the first control to a control value greater than the control threshold. The control threshold is a maximum value of the control value at which a signal value based on the observation target fluorescence becomes greater than a signal value based on unnecessary light that is captured by the second imaging element 532 and is generated due to at least the first light.

Description

Medical control device and medical observation system

[0001] The present disclosure relates to a medical control device and a medical observation system.

[0002] Conventionally, a medical observation system has been known that irradiates an observation target (a subject such as a human) with a first light including visible light, such as narrow-band excitation light or broad-band white light, emitted from a light source device, and observes the fluorescence (hereinafter referred to as "observation target fluorescence") emitted from a substance contained in the observation target by the irradiation of the excitation light (see, for example, Patent Document 1). This type of fluorescence observation makes it possible to grasp tissue conditions that are difficult to recognize through the observation target fluorescence. Therefore, fluorescence observation can be used for various purposes and applications, such as identifying lesions.

[0003] Japanese Patent Application Laid-Open No. 2021-132695

[0004] A medical observation system has an observation optical path including a first optical path along which first light propagates from a light source device to an observation object, and a second optical path along which second light propagates, the second light being return light (including observation object fluorescence) of the first light from the observation object irradiated with the first light. As the first and second lights propagate through the observation optical path, the first and second lights irradiate optical elements constituting the observation optical path, causing autofluorescence to be generated from the optical elements. Such autofluorescence has a wavelength band that includes the wavelength band of the observation object fluorescence that is the target of fluorescence observation, and causes noise in the fluorescence observation. Therefore, there is a demand for technology that enables satisfactory fluorescence observation.

[0005] The present disclosure has been made in view of the above, and has an object to provide a medical control device and a medical observation system that are capable of performing satisfactory fluorescence observation.

[0006] In order to solve the above-mentioned problems and achieve the object, a medical control device according to the present disclosure includes a light source control unit that executes a first control for causing a light source device to emit first light including at least a part of a visible light wavelength band, and a second control for causing the light source device to emit excitation light that excites a substance included in an observation object; a first image sensor that captures light including at least a part of a visible light wavelength band among the first light and second light that is return light of the excitation light from the observation object; and a second image sensor that captures light including at least a part of a wavelength band of observation object fluorescence emitted from the observation object by irradiation with the excitation light among the second light. The apparatus includes an imaging control unit that controls the operation of a second imaging element that captures light, and a mode switching unit that switches between a first mode and a second mode, wherein the light source control unit, when in the first mode, sets the control value in the first control to a control value that is equal to or less than a control threshold, and when in the second mode, sets the control value in the first control to a control value that is greater than the control threshold, and the control threshold is the maximum value of the control value at which a signal value based on the fluorescence of the object of observation, which is imaged by the second imaging element, is greater than a signal value based on unwanted light generated due to at least the first light.

[0007] Furthermore, a medical control device according to the present disclosure includes a light source control unit that executes a first control for causing a light source device to emit first light including at least a part of a visible light wavelength band and a second control for causing the light source device to emit excitation light that excites a substance included in an observation object; an imaging control unit that controls the operation of a first image sensor that captures light including at least a part of the visible light wavelength band among second light that is the first light and return light of the excitation light from the observation object; and a second image sensor that captures light including at least a part of the wavelength band of observation object fluorescence emitted from the observation object by irradiation with the excitation light among the second light. The image capturing apparatus includes a mode switching unit that switches between a first mode and a second mode, and a brightness control unit that adjusts the brightness of an image based on pixel signals output from the first imaging element, wherein the light source control unit, when in the first mode, sets the control value in the first control to a control value that is equal to or less than a control threshold, and when in the second mode, sets the control value in the first control to a control value that is greater than the control threshold, and when in the first mode, the brightness control unit adjusts the brightness of the image based on the pixel signals output from the first imaging element to approach the brightness of the image in the second mode.

[0008] The medical control device according to the present disclosure includes a light source control unit that executes a first control for causing a light source device to emit first light including at least a part of a visible light wavelength band and a second control for causing the light source device to emit excitation light that excites a substance included in an observation object; an imaging control unit that controls the operation of a first image sensor that captures light including at least a part of a visible light wavelength band among second light, which is the first light from the observation object and return light of the excitation light, and a second image sensor that captures light including at least a part of a wavelength band of observation object fluorescence emitted from the observation object by irradiation with the excitation light among the second light; a mode switching unit that switches between a first mode and a second mode; and a pixel signal output from the first image sensor. and a brightness control unit that adjusts the brightness of an image based on a pixel signal output from the first image sensor, wherein the light source control unit sets a control value for the first control to a control value equal to or less than a control threshold when in the first mode, and sets the control value for the first control to a control value greater than the control threshold when in the second mode, and the brightness control unit sets a parameter to a value greater than the parameter in the second mode when in the first mode, and the parameter is at least one of an exposure time of the first image sensor, an analog gain that adjusts the brightness of an image based on a pixel signal output from the first image sensor, and a digital gain that adjusts the brightness of an image based on a pixel signal output from the first image sensor.

[0009] Further, a medical observation system according to the present disclosure includes a light source device that emits first light including at least a part of a visible light wavelength band and excitation light that excites a substance included in an observation object, an imaging device including a first image sensor that captures light including at least a part of the visible light wavelength band among second light that is return light of the first light and the excitation light from the observation object, and a second image sensor that captures light including at least a part of the wavelength band of observation object fluorescence emitted from the observation object by irradiation with the excitation light among the visible light and the return light of the excitation light, and a medical control device that controls the operations of the light source device and the imaging device, respectively, and the medical control device controls the operation of the light source device and the imaging device, and the medical control device controls the operation of the first light from the light source device. The imaging device includes a light source control unit that executes a first control for emitting light and a second control for emitting the excitation light from the light source device, an imaging control unit that controls the operation of the imaging device, and a mode switching unit that switches between a first mode and a second mode, wherein the light source control unit, when in the first mode, sets the control value for the first control to a control value that is equal to or less than a control threshold, and, when in the second mode, sets the control value for the first control to a control value that is greater than the control threshold, and the control threshold is the maximum value of the control value at which a signal value based on the fluorescence of the object of observation, which is imaged by the second imaging element, is greater than a signal value based on unwanted light generated due to at least the first light.

[0010] Further, a medical observation system according to the present disclosure includes a light source device that emits first light including at least a part of a visible light wavelength band and excitation light that excites a substance contained in an observation object, an imaging device including a first image sensor that captures light including at least a part of the visible light wavelength band among second light that is return light of the first light and the excitation light from the observation object, and a second image sensor that captures light including at least a part of the wavelength band of observation object fluorescence emitted from the observation object by irradiation with the excitation light among the visible light and the return light of the excitation light, and a medical control device that controls the operations of the light source device and the imaging device, respectively, and the medical control device controls a first control that causes the light source device to emit the first light, and a second control that controls the light source device the light source control unit performs a first control to emit the excitation light from the first image sensor, an imaging control unit controls the operation of the imaging device, a mode switching unit switches between a first mode and a second mode, and a brightness control unit adjusts the brightness of an image based on a pixel signal output from the first image sensor, wherein the light source control unit sets a control value for the first control to a control value equal to or less than a control threshold when in the first mode, and sets the control value for the first control to a control value greater than the control threshold when in the second mode, and the brightness control unit adjusts the brightness of an image based on the pixel signal output from the first image sensor when in the first mode so that the brightness approaches the brightness of the image in the second mode.

[0011] Further, a medical observation system according to the present disclosure includes a light source device that emits first light including at least a part of a visible light wavelength band and excitation light that excites a substance included in an observation object; an imaging device including a first image sensor that captures light including at least a part of a visible light wavelength band among second light that is return light of the first light and the excitation light from the observation object; and a second image sensor that captures light including at least a part of a wavelength band of observation object fluorescence emitted from the observation object by irradiation with the excitation light among the visible light and the return light of the excitation light; and a medical control device that controls the operations of the light source device and the imaging device, respectively, wherein the medical control device includes a light source control unit that executes first control to cause the light source device to emit the first light and second control to cause the light source device to emit the excitation light, respectively, and an imaging unit that controls the operation of the imaging device. The image capturing apparatus includes a control unit, a mode switching unit that switches between a first mode and a second mode, and a brightness control unit that adjusts the brightness of an image based on pixel signals output from the first image sensor, wherein the light source control unit, when in the first mode, sets the control value for the first control to a control value that is equal to or less than a control threshold, and, when in the second mode, sets the control value for the first control to a control value that is greater than the control threshold, and the brightness control unit, when in the first mode, sets a parameter to a value that is greater than the parameter in the second mode, and the parameter is at least one of an exposure time of the first image sensor, an analog gain that adjusts the brightness of an image based on pixel signals output from the first image sensor, and a digital gain that adjusts the brightness of an image based on pixel signals output from the first image sensor.

[0012] The medical control device and medical observation system according to the present disclosure enable good fluorescence observation.

[0013] FIG. 1 is a diagram illustrating the configuration of a medical observation system according to a first embodiment. FIG. 2 is a block diagram illustrating the configuration of a camera head and a control device. FIG. 3 is a diagram illustrating the functions of a light source control unit and an imaging control unit. FIG. 4 is a diagram illustrating the functions of a light source control unit and an imaging control unit. FIG. 5 is a diagram illustrating the functions of a light source control unit and an imaging control unit. FIG. 6 is a diagram illustrating the functions of a light source control unit and an imaging control unit. FIG. 7 is a diagram illustrating a method for setting the lighting period of a first light source in the third light source control. FIG. 8 is a diagram illustrating a method for setting the lighting period of a first light source in the third light source control. FIG. 9 is a diagram illustrating a method for setting the lighting period of a first light source in the third light source control. FIG. 10 is a diagram illustrating a method for setting the lighting period of a first light source in the third light source control. FIG. 11 is a diagram illustrating a method for calculating an S / N ratio. FIG. 12 is a diagram illustrating the configuration of a medical observation system according to a second embodiment. FIG. 13 is a diagram illustrating a modified example 2-1 of the second embodiment. FIG. 14 is a diagram illustrating a modified example 2-2 of the second embodiment. FIG. 15 is a diagram illustrating a modified example 2-7 of the second embodiment. FIG. 16 is a diagram illustrating a modified example 2-7 of the second embodiment. FIG. 17 is a diagram illustrating a modified example 2-9 of the second embodiment. FIG. 18 is a diagram illustrating a modified example 3-1 of the first and second embodiments. FIG. 19 is a diagram illustrating a modified example 3-2 of the first and second embodiments. FIG. 20 is a diagram illustrating a modified example 3-3 of the first and second embodiments. FIG. 21 is a diagram illustrating a modified example 3-3 of the first and second embodiments.

[0014] Hereinafter, modes for carrying out the present disclosure (hereinafter, referred to as embodiments) will be described with reference to the drawings. Note that the present disclosure is not limited to the embodiments described below. Furthermore, in the description of the drawings, the same parts are assigned the same reference numerals.

[0015] (Embodiment 1) [Configuration of Medical Observation System] Fig. 1 is a diagram showing the configuration of a medical observation system 1 according to embodiment 1. In this embodiment 1, the medical observation system 1 is a medical endoscope system that uses an endoscope to observe an observation object OB (inside a living organism). As shown in Fig. 1, this medical observation system 1 includes an insertion section 2, a light source device 3, a light guide 4, a camera head 5, a first transmission cable 6, a display device 7, a second transmission cable 8, a control device 9, and a third transmission cable 10.

[0016] The insertion section 2 corresponds to an optical endoscope according to the present disclosure. In the first embodiment, the insertion section 2 is configured as a rigid endoscope. That is, the insertion section 2 has an elongated shape that is rigid as a whole or has a soft portion and a rigid portion, and is inserted into the observation object OB. The insertion section 2 includes an optical system configured using one or more lenses that focuses second light (subject image) from the observation object OB, which will be described later.

[0017] An excitation light cut filter 22 ( FIG. 1 ) that partially, substantially, or completely suppresses excitation light, which will be described later, contained in the collected second light (subject image), is disposed at the proximal end (eyepiece 21) of the insertion portion 2. The excitation light cut filter 22 is not limited to being disposed in the insertion portion 2, and may be disposed in the camera head 5.

[0018] One end of the light guide 4 is connected to the light source device 3. The light source device 3 supplies light to the one end of the light guide 4 under the control of the control device 9. As shown in FIG. 1 , the light source device 3 includes a first light source 31 and a second light source 32.

[0019] The first light source 31 emits first light (broadband light such as white light or narrowband light such as red light, green light, or blue light) including at least a portion of the visible light wavelength band. Examples of the configuration of the first light source 31 include a configuration including a white LED (Light Emitting Diode) and a configuration including three light sources that respectively emit red light, green light, and blue light, and an optical element that combines the red light, green light, and blue light. The first light source 31 may be configured using an LED or a semiconductor laser. The number of first light sources 31 may be one or more.

[0020] The second light source 32 emits excitation light that excites substances contained in the observation object OB. The second light source 32 may be configured with an LED or a semiconductor laser. The number of second light sources 32 may be one or more. Furthermore, the second light source 32 may emit, for example, infrared light or ultraviolet light.

[0021] Here, examples of substances contained in the observation object OB that are excited by the excitation light include drugs or fluorescent dyes attached to the observation object OB, or fluorescent substances derived from the observation object OB that constitute the observation object OB itself.

[0022] Examples of the above-mentioned drugs administered to the observation subject OB include "5-ALA (PP-IX)", "ADS780WS", "ADS830WS", "aggregation-induced emission dots allophycocyanin (APC)", "boron-dipyrromethane (BODIPY)", "CLR 1502", "Flavins", "fluorescamine", "Fluorescein", "fluoro-gold", "green fluorescence protein", "ICG (indocyanine green)", "IRDye 78", "IR-PEG nanoparticles", "Isothiocyanate", "rose Bengal", "SGM-101", and "trypan blue".

[0023] The above-mentioned fluorescent dyes applied to the observation target OB include "coumarine," "Cy3," "DyLight547," "GE3126," "metal nanoclusters," "oxacarbocyanine," "rhodamine," "riboflavin," "fluorescein," "AlexaFluor660," "AlexaFluor680," "AlexaFluor700," "Cy5," "Cy5.5," "Dy677," "Dy682," "Dy752," "DyLight647," "HiLyte Fluor 647," "HiLyte Fluor 680," "IRDye 700DX," "methylene blue," "Porphyrins," "Porphysomes," "VivoTag-680," "VivoTag-S680," "AlexaFluor750," "AlexaFluor790," "carbocyanine," "conjugated copolymers," "CW800-CA," "Cy7," "Cy7.5," "cyanine dyes," "Dy780," and "HiLyte Fluor 750," "Indocarbocyanine," "IR-786," ​​"IRDye 800CW," "IRDye 800RS," "IRDye 800BK," "Nervelight," "OTL-38 (Pafolacianine)," "Polymethine," "VivoTag-S750," "Xanthene," and "LUM-015" can be cited as examples.

[0024] Furthermore, examples of fluorescent substances derived from the observation object OB that constitute the observation object OB itself include "collagen," "elastin," and "NADH."

[0025] In this embodiment 1, the light source device 3 is configured as a separate entity from the control device 9, but this is not limited to this, and a configuration in which the light source device 3 and the control device 9 are provided in the same housing may also be adopted.

[0026] One end of the light guide 4 is detachably connected to the light source device 3. The other end of the light guide 4 is detachably connected to the insertion section 2. The light guide 4 transmits light (first light or excitation light) supplied from the light source device 3 from one end to the other end, and supplies the light to the insertion section 2. The light (first light or excitation light) supplied to the insertion section 2 is emitted from the tip of the insertion section 2 and irradiated onto the observation object OB. When the observation object OB is irradiated with the first light, return light of the first light (reflected light of the first light) from the observation object OB is collected by the optical system within the insertion section 2. When the observation object OB is irradiated with excitation light, return light of the excitation light from the observation object OB is collected by the optical system within the insertion section 2. The return light of the excitation light includes not only the excitation light reflected by the observation target OB, but also fluorescence emitted from a substance contained in the observation target OB when the excitation light is irradiated onto the observation target OB and the substance is excited (hereinafter referred to as observation target fluorescence). For convenience of explanation, the return light of the first light from the observation target OB and the return light of the excitation light from the observation target OB will be referred to as second light below.

[0027] The camera head 5 corresponds to the imaging device according to the present disclosure. The camera head 5 is detachably connected to the eyepiece 21 of the insertion section 2. Under the control of the control device 9, the camera head 5 captures an image of the second light collected by the insertion section 2 to generate a pixel signal. Hereinafter, for convenience of explanation, the pixel signal may be referred to as a captured image. The detailed configuration of the camera head 5 will be described later in the section "Configuration of the Camera Head."

[0028] One end of the first transmission cable 6 is detachably connected to the control device 9 via a connector CN1 (FIG. 1). The other end of the first transmission cable 6 is detachably connected to the camera head 5 via a connector CN2 (FIG. 1). The first transmission cable 6 transmits captured images and other signals output from the camera head 5 to the control device 9, and also transmits control signals, synchronization signals, clocks, power, and other signals output from the control device 9 to the camera head 5.

[0029] The captured images and the like transmitted from the camera head 5 to the control device 9 via the first transmission cable 6 may be transmitted as optical signals or as electrical signals. The same applies to the transmission of control signals, synchronization signals, and clocks from the control device 9 to the camera head 5 via the first transmission cable 6.

[0030] The display device 7 is configured with a display using a liquid crystal or organic EL (Electro Luminescence) display, etc., and displays an image based on a video signal from the control device 9 under the control of the control device 9 .

[0031] One end of the second transmission cable 8 is detachably connected to the display device 7. The other end of the second transmission cable 8 is detachably connected to the control device 9. The second transmission cable 8 transmits the video signal processed by the control device 9 to the display device 7.

[0032] The control device 9 corresponds to a medical control device according to the present disclosure. The control device 9 is configured with a CPU (Central Processing Unit), FPGA (Field-Programmable Gate Array), etc., and comprehensively controls the operations of the light source device 3, camera head 5, and display device 7. The detailed configuration of the control device 9 will be described later in the section "Configuration of the Control Device."

[0033] One end of the third transmission cable 10 is detachably connected to the light source device 3. The other end of the third transmission cable 10 is detachably connected to the control device 9. The third transmission cable 10 transmits a control signal from the control device 9 to the light source device 3.

[0034] [Configuration of Camera Head] Next, a description will be given of the configuration of the camera head 5. Fig. 2 is a block diagram showing the configuration of the camera head 5 and the control device 9. As shown in Fig. 2, the camera head 5 includes a lens unit 51, a prism 52, an imaging unit 53, and a communication unit 54.

[0035] The lens unit 51 is configured using one or more lenses and forms an image of the second light (subject image) collected by the insertion portion 2 on the imaging surfaces of the first and second imaging elements 531 and 532, respectively.

[0036] The prism 52 separates the second light (subject image) transmitted through the lens unit 51 into light of first and second wavelength bands that are different from each other. The light of the first wavelength band is light of a wavelength band that excludes at least a portion of the wavelength band of the fluorescence of the object of observation and includes at least a portion of the wavelength band of visible light. Hereinafter, the light of the first wavelength band will be referred to as the first subject image. The light of the second wavelength band is light of a wavelength band that excludes at least a portion of the wavelength band of visible light and includes at least a portion of the wavelength band of the fluorescence of the object of observation. Hereinafter, the light of the second wavelength band will be referred to as the second subject image. The prism 52 then causes the first subject image to travel toward the first image sensor 531. The prism 52 also causes the second subject image to travel toward the second image sensor 532.

[0037] The imaging unit 53 captures an image of the observation object OB under the control of the control device 9. As shown in FIG. 2 , the imaging unit 53 includes a first imaging element 531, a second imaging element 532, and a signal processing unit 533.

[0038] The first and second image sensors 531 and 532 receive a subject image and convert it into an electrical signal (analog signal). In the first embodiment, the first and second image sensors 531 and 532 are each configured as a CMOS (Complementary Metal Oxide Semiconductor) imaging device that is a rolling shutter type imaging device in which a plurality of pixels are two-dimensionally arranged in horizontal line units.

[0039] Although not specifically shown, the first image sensor 531 is made up of an invalid area where the output signal is not used to generate a captured image, an optical black area (OB area), and an effective pixel area where the first subject image formed by the lens unit 51 is converted into pixel signals and output. Similarly, the second image sensor 532 is made up of an invalid area, an optical black area (OB area), and an effective pixel area.

[0040] The first image sensor 531 then captures a first subject image via the prism 52 under the control of the control device 9. That is, the first image sensor 531 captures light that includes at least a part of the wavelength band of visible light. For ease of explanation, the captured image generated by capturing the first subject image with the first image sensor 531 will be referred to as a normal light image below.

[0041] Furthermore, the second image sensor 532 captures a second subject image via the prism 52 under the control of the control device 9. That is, the second image sensor 532 captures light that includes at least a part of the wavelength band of the fluorescence of the object of observation. For ease of explanation, the captured image generated by capturing the second subject image with the second image sensor 532 will be referred to as a fluorescence image below.

[0042] The number of pixels in the normal light image and the number of pixels in the fluorescent light image may be different or the same.

[0043] The signal processing unit 533 performs signal processing on the captured images (analog signals) generated by the first and second image sensors 531 and 532, and outputs the captured images (digital signals), under the control of the control device 9. For example, the signal processing unit 533 performs signal processing on the captured images (analog signals) generated by the first and second image sensors 531 and 532, such as processing to remove reset noise, processing to multiply the analog signals by an analog gain that amplifies the analog signals, and A / D conversion.

[0044] The communication unit 54 functions as a transmitter that transmits the captured images sequentially output from the imaging unit 53 to the control device 9 via the first transmission cable 6. The communication unit 54 is configured, for example, with a high-speed serial interface that communicates captured images with the control device 9 via the first transmission cable 6 at a transmission rate of 1 Gbps or more.

[0045] The communication unit 54 may alternately transmit the normal light image and the fluorescent light image to the control device 9, or may transmit them simultaneously.

[0046] [Configuration of Control Device] Next, the configuration of the control device 9 will be described with reference to Fig. 2. As shown in Fig. 2, the control device 9 includes a communication unit 91, an image memory 92, a processing module 93, a control unit 94, an input unit 95, an output unit 96, and a storage unit 97.

[0047] The communication unit 91 functions as a receiver that receives captured images sequentially transmitted from the camera head 5 (communication unit 54) via the first transmission cable 6. The communication unit 91 is configured, for example, with a high-speed serial interface that communicates captured images with the communication unit 54 at a transmission rate of 1 Gbps or more.

[0048] The image memory 92 is configured by, for example, a dynamic random access memory (DRAM), etc. The image memory 92 is capable of temporarily storing multiple frames of captured images sequentially output from the camera head 5 (communication unit 54).

[0049] Under the control of the control unit 94, the processing module 93 processes the captured images sequentially transmitted from the camera head 5 (communication unit 54) and received by the communication unit 91. As shown in FIG. 2 , the processing module 93 includes a memory controller 931, a first image processing unit 932, a second image processing unit 933, and a display control unit 934.

[0050] The memory controller 931 controls the writing of captured images to the image memory 92 and the reading of the captured images from the image memory 92. More specifically, the memory controller 931 writes normal light images received by the communication unit 91 to the image memory 92, reads the normal light images from the image memory 92 at specific times, and inputs them to the first image processing unit 932. The memory controller 931 also writes fluorescent light images received by the communication unit 91 to the image memory 92, and reads the fluorescent light images from the image memory 92 at specific times, and inputs them to the second image processing unit 933.

[0051] The first image processing unit 932 performs first image processing on the input normal light image, such as optical black subtraction (clamping), white balance adjustment, demosaic processing, color correction matrix processing, gamma correction, YC processing for converting RGB signals into luminance color difference signals (Y, Cb / Cr signals), digital gain adjustment for multiplying by digital gain, noise removal, and filtering for enhancing structure.

[0052] The second image processing unit 933 performs second image processing on the input fluorescence image. Examples of the second image processing include optical black subtraction (clamping), white balance adjustment, demosaic processing, color correction matrix processing, gamma correction, YC processing for converting RGB signals into luminance color difference signals (Y, Cb / Cr signals), digital gain adjustment for multiplying by a digital gain, noise removal, and filtering for structural enhancement. The first and second image processing may be different from each other or may be the same.

[0053] Under the control of the control unit 94, the display control unit 934 generates video signals for displaying the normal light image after the first image processing has been performed by the first image processing unit 932 and the fluorescent light image after the second image processing has been performed by the second image processing unit 933. Then, the display control unit 934 outputs the video signals to the display device 7 via the second transmission cable 8.

[0054] The control unit 94 is realized by a controller such as a CPU or an MPU (Micro Processing Unit) executing various programs stored in the storage unit 97, and controls the operations of the light source device 3, the camera head 5, and the display device 7, as well as the operation of the entire control device 9. Note that the control unit 94 is not limited to a CPU or an MPU, and may be configured using an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA. As shown in FIG. 2 , the control unit 94 has the functions of a light source control unit 941 and an imaging control unit 942.

[0055] The functions of the light source control unit 941 and the imaging control unit 942 will be described later in the section "Functions of the Light Source Control Unit and the Imaging Control Unit."

[0056] The input unit 95 corresponds to an operation receiving unit according to the present disclosure. The input unit 95 is configured using operation devices such as a mouse, a keyboard, and a touch panel, and receives user operations from a user such as a surgeon. The input unit 95 then outputs an operation signal corresponding to the user operation to the control unit 94.

[0057] The output unit 96 is configured using a speaker, a printer, etc., and outputs various information.

[0058] The storage unit 97 stores programs executed by the control unit 94, information necessary for the processing of the control unit 94, and the like.

[0059] [Functions of the Light Source Control Unit and the Imaging Control Unit] Next, the functions of the light source control unit 941 and the imaging control unit 942 will be described. FIGS. 3 to 6 are diagrams illustrating the functions of the light source control unit 941 and the imaging control unit 942. Specifically, FIG. 3 is a diagram illustrating first light source control and first imaging control. FIGS. 4 and 5 are diagrams illustrating second light source control and second imaging control. FIG. 6 is a diagram illustrating third light source control and third imaging control. Here, FIGS. 3(a), 4(a), 5(a), and 6(a) are diagrams illustrating imaging control of the first imaging element 531, with the vertical axis representing the horizontal line of the first imaging element 531 (the top row represents the highest horizontal line (the first horizontal line) and the bottom row represents the lowest horizontal line (the last line)), and the horizontal axis representing time. The parallelogram region is the region that contributes to generating a normal light image in one field. 3(b), 4(b), 5(b), and 6(b) are diagrams illustrating dimming control, with the vertical axis representing the power value [W] supplied to the first light source 31 and the horizontal axis representing time (the supply time of power supplied to the first light source 31). In the first embodiment, the voltage value supplied to the first light source 31 is fixed, and therefore, in FIGS. 3(b), 4(b), 5(b), and 6(b), the vertical axis corresponds to the current value supplied to the first light source 31. FIGS. 3(c), 4(c), 5(c), and 6(c) are diagrams illustrating imaging control of the second image sensor 532, with the vertical axis representing the horizontal line of the second image sensor 532 (the top row represents the uppermost horizontal line (the first horizontal line), and the bottom row represents the lowermost horizontal line (the final line)), and the horizontal axis representing time. The parallelogram region is the region that contributes to the generation of a fluorescence image in one field. Figures 3(d), 4(d), 5(d), and 6(d) are diagrams illustrating dimming control, with the vertical axis representing the power value [W] supplied to the second light source 32 and the horizontal axis representing time (the duration of power supply to the second light source 32). In the first embodiment, the voltage value supplied to the second light source 32 is fixed, and therefore, in Figures 3(d), 4(d), 5(d), and 6(d), the vertical axis corresponds to the current value supplied to the second light source 32.

[0060] The light source control unit 941 is capable of executing first to third light source controls, respectively. The imaging control unit 942 is capable of executing first to third imaging controls, respectively. Below, the "first light source control and first imaging control," "second light source control and second imaging control," and "third light source control and third imaging control" will be described in order.

[0061] [First Light Source Control and First Imaging Control] First, the first light source control and the first imaging control will be described with reference to Fig. 3. The imaging control unit 942 performs first imaging control using a so-called rolling shutter system, in which exposure of the first and second imaging elements 531 and 532 in one field period is started sequentially for each horizontal line, and readout is performed sequentially for each horizontal line after a predetermined period (so-called shutter speed) has elapsed since the start of exposure. Furthermore, in the first imaging control, in the case of the NTSC system, one field is set to 1 / 60 [s] (Fig. 3(a) and Fig. 3(c)).

[0062] The light source control unit 941 executes first light source control, which controls the operation of the first and second light sources 31 and 32. Here, the first light source control includes a first control for steadily lighting (continuously lighting) the first light source 31 and a second control for steadily lighting the second light source 32 (see FIGS. 3B and 3D). The first light source control also adjusts the current value supplied to the first light source 31 based on the brightness (average luminance value, etc.) of a specific region (detection region) in the normal light image to adjust the normal light image to a reference brightness. Furthermore, the first light source control also executes dimming control to maintain the light intensity ratio shown below. That is, the light source control unit 941 adjusts the brightness of the normal light image as described above, and also adjusts the brightness of the fluorescent image by referring to ratio information indicating the light intensity ratio stored in the storage unit 97. Specifically, the light source control unit 941 refers to the ratio information and adjusts the current value supplied to the second light source 32 in accordance with the adjustment of the current value supplied to the first light source 31 so that the ratio between the amount of first light emitted from the first light source 31 and the amount of excitation light emitted from the second light source 32 is maintained at a specific ratio.

[0063] [Regarding the Second Light Source Control and the Second Imaging Control] Next, the second light source control and the second imaging control will be described with reference to Figures 4 and 5. Incidentally, in a fluorescence image, the observation object fluorescence from the observation object OB is weak, and the signal value based on the observation object fluorescence is very low. To increase the signal value, it is conceivable to perform long-time exposure in which multiple fields are treated as a single pseudo-field (Figures 4(a) and 4(c)). In the examples of Figures 4(a) and 4(c), two fields are treated as a single pseudo-field, and the single field is set to 1 / 30 [s].

[0064] However, when the above-described long-time exposure and dimming control that maintains the light intensity ratio are used in combination, the following problem may arise. That is, when long-time exposure is performed, not only the signal level in the fluorescence image but also the signal level in the normal light image increases (by approximately two times in the example of FIG. 4 ). In other words, since the brightness of the normal light image increases, when dimming control that maintains the light intensity ratio is performed, the amount of the first light is reduced to adjust the brightness of the normal light image to a reference brightness, and the amount of the excitation light is also reduced in accordance with the reduction in the amount of the first light. This results in a first problem: the brightness of the fluorescence image is reduced.

[0065] Therefore, the following method can be considered to solve the first problem. As shown in FIG. 4B, instead of the originally assumed power of N [W] to be supplied to the first light source 31, half the power, N / 2 [W], is supplied to the first light source 31. In this way, the normal light image will not be brighter than necessary, and even when dimming control is performed to maintain the light intensity ratio, the brightness of the fluorescent light image will not decrease. However, this method has the second problem described below.

[0066] This significantly reduces the amount of first light emitted from the first light source 31, thereby reducing the margin of the current value (margin from the lower drive limit Th) for adjusting the amount of first light emitted from the first light source 31. Furthermore, in dimming control that maintains the light amount ratio, the amount of excitation light is adjusted in accordance with the amount of first light, so the margin of the current value (margin from the lower drive limit Th) for adjusting the amount of excitation light emitted from the second light source 32 is also reduced.

[0067] The second light source control and the second imaging control are methods for solving the second problem. The second imaging control is a control for discarding image information generated by the first imaging element 531 in response to light received during a portion of the exposure period of the first imaging element 531. In the first embodiment, the second imaging control is a control for adjusting the aperture value of the electronic shutter of the first imaging element 531. That is, in the first embodiment, the image information corresponds to the charge accumulated for each pixel by the first imaging element 531. In the example of FIG. 5 , the imaging control unit 942 fixes the aperture value of the electronic shutter of the first imaging element 531 to 1 / 60 [s]. Note that in FIG. 5A, the dotted area Ar1 indicates the area where charge is discarded by the electronic shutter. Furthermore, the shaded area Ar2 indicates the area where the exposure period is valid. Note that the second light source control is the same as the first light source control described above.

[0068] [Regarding the Third Light Source Control and the Third Imaging Control] Hereinafter, the optical path of the first light and the excitation light that travels from the light source device 3 to the light guide 4 to the insertion section 2 to the observation object OB will be referred to as the first optical path P1 ( FIG. 1 ). Furthermore, the optical path of the second light that travels from the observation object OB to the insertion section 2 to the first imaging element 531 will be referred to as the second optical path P2 ( FIG. 1 ). Furthermore, the first and second optical paths P1 and P2 will be collectively referred to as the observation optical path P0 ( FIG. 1 ). When the first light and the excitation light propagate through the first optical path P1, and when the second light propagates through the second optical path P2, the first light, the excitation light, and the second light are irradiated onto a component (hereinafter referred to as the autofluorescence generating component) that forms the observation optical path P0, causing autofluorescence (hereinafter referred to as the unwanted light) to be generated from the autofluorescence generating component. Examples of such autofluorescence-generating materials include components contained in multi-component glasses such as lenses, organic material components contained in color filters, adhesives that bond lenses together, and oils attached to optical elements such as lenses. Such unwanted light has a wavelength band that includes the wavelength band of the observation target fluorescence, which is the light that is the object of observation in fluorescence observation, and becomes noise in the fluorescence observation. Note that such unwanted light is also generated when the observation target OB is irradiated with the first light or excitation light.

[0069] If the observation target fluorescence from the observation target OB is weak, in order to separate the observation target fluorescence from the unnecessary light described above and perform good fluorescence observation, it is necessary to adjust the signal value based on the observation target fluorescence imaged by the second image sensor 532. However, adjusting the signal value based on the observation target fluorescence is difficult due to the influence of the following factors (1) to (4).

[0070] (1) Drugs Generally, the intensity of the fluorescence emitted from the observation object OB varies depending on the type and dosage of the drug. The type of drug administered to the observation object OB is selected according to the observation object OB (cancer, blood, lymph, etc.). Furthermore, in order to image the fluorescence emitted from the drug in the medical observation system 1, drugs are selected that can separate the wavelength of the excitation light that excites the drug from the wavelength of the fluorescence emitted from the drug. Drugs selected in this manner emit different intensities of fluorescence from the observation object. Furthermore, while the intensity of fluorescence from the observation object can be adjusted by the dosage of the drug, it is difficult to increase the dosage more than necessary to achieve minimally invasive treatment. In other words, it is difficult to adjust the intensity of fluorescence from the observation object by selecting the type of drug and adjusting the dosage. As a result, it is difficult to adjust the signal value based on the fluorescence from the observation object imaged by the second image sensor 532 by selecting the type of drug and adjusting the dosage.

[0071] (2) Observation Object The amount of observation object fluorescence emitted from the observation object OB varies depending on the location and condition of the observation object OB. Specifically, if the observation object OB is located in a location or condition where the drug is likely to remain, the amount of observation object fluorescence emitted from the observation object OB increases. On the other hand, if the observation object OB is located in a location or condition where the drug is likely to flow and not remain, the amount of observation object fluorescence emitted from the observation object OB decreases and the afterglow time also becomes shorter. Furthermore, if the observation object OB is a tumor, the amount of observation object fluorescence received by the second image sensor 532 changes depending on its spread, size, and depth. In other words, it is difficult to adjust the amount of observation object fluorescence depending on the type and condition of the observation object OB. As a result, it is difficult to adjust the signal value based on the observation object fluorescence imaged by the second image sensor 532 depending on the type and condition of the observation object OB.

[0072] (3) Light Source Device The intensity of the fluorescence emitted from the observation object varies depending on the intensity of the excitation light emitted from the light source device 3. Increasing the intensity of the excitation light may require adjusting the power supplied to the light source device 3. However, the power that can be supplied to the light source device 3 is limited by the upper limit of the power required to operate the entire medical observation system 1. Furthermore, the intensity of the excitation light must be adjusted taking into account factors such as heat generation in components constituting the optical path of the excitation light (e.g., heat generation between the light guide 4 and the insertion section 2), compatibility with the laser class, the amount of light energy received by the observation object OB and surrounding living tissue (high light energy levels pose a risk of burns), and the rate of fading of the fluorescence emitted from the drug. Furthermore, the intensity of the excitation light can also be adjusted by changing the number of excitation light sources installed in the light source device 3. However, the number of light sources may affect the size of the light source device 3. The size of the light source device 3 may be limited by the size of a cart used to transport the light source device 3. In other words, it is difficult to adjust the intensity of the fluorescence emitted from the observation object by adjusting the intensity of the excitation light. As a result, it is difficult to adjust the signal value based on the fluorescence of the object of observation imaged by the second image sensor 532 by adjusting the amount of excitation light.

[0073] (4) Imager The signal value based on the observation target fluorescence generated by the second imager 532 varies depending on the amount of observation target fluorescence received by the second imager 532. To adjust the signal value based on the observation target fluorescence, it is desirable to select a second imager 532 with optimal sensitivity, configuration, etc. for imaging the observation target fluorescence. However, the second imager 532 may be required not only to output an image for fluorescence observation based on receiving observation target fluorescence in a predetermined wavelength band, but also to output an image for normal light observation based on receiving visible light, such as white light. Furthermore, the second imager 532 may be required to output an image for fluorescence observation corresponding to a wide wavelength band or multiple wavelength bands within a wavelength band including visible light and invisible light. Furthermore, the amount of observation target fluorescence may change depending on the procedure or the observation target OB, even when the same drug is used. Therefore, the second imager 532 may be required to output an image for fluorescence observation that corresponds to such changes in the amount of observation target fluorescence. In this case, an element compatible with such observations must be selected for the second imaging element 532, and it may not be possible to use an imaging element with optimal characteristics for imaging fluorescence in a predetermined wavelength band. Furthermore, although the second imaging element 532 is disposed within the camera head 5, the size and weight of the camera head 5 must be appropriate for the observation, which may limit the type of the second imaging element 532, including its size. Even when the second imaging element 532 is disposed at the tip of a rigid endoscope or a flexible endoscope, rather than being disposed within the camera head 5, the size and weight must be appropriate for the observation, which may limit the type of the second imaging element 532, including its size. In other words, it is difficult to adjust the signal value based on the fluorescence of the observation target imaged by the second imaging element 532 by selecting the type of second imaging element 532.

[0074] As described above, the signal value based on the fluorescence from the object of observation captured by the second image capturing element 532 is determined within the above-mentioned constraints, and therefore cannot be easily adjusted.

[0075] In the above-described "first light source control and first imaging control" and "second light source control and second imaging control," unnecessary light is likely to be generated because the first and second light sources 31 and 32 are constantly lit. On the other hand, the third light source control and third imaging control are controls that partially, substantially, or completely suppress unnecessary light.

[0076] As shown in Figures 6A and 6C, the third imaging control is a control in which the aperture value of the electronic shutter is not adjusted in the second imaging control, i.e., the third imaging control is a control in which only long-time exposure is performed.

[0077] The third light source control includes a second control ((d) of FIG. 6 ) in which the second light source 32 is constantly lit, and a first control in which the first light source 31 is lit only during the full-line exposure period TE (1 / 60 [s] in the example of FIG. 6 ) of the first image sensor 531. In the example of FIG. 6 , the lighting period of the first light source 31 in the first control is 1 / 60 [s], but it may be other periods, for example, 1 / 120 [s]. That is, by shortening the period during which the first light is emitted in the first control, the generated unnecessary light is partially, substantially, or completely suppressed. Here, shortening the period during which the first light is emitted reduces the brightness of the normal light image, but the brightness is increased by the first image processing (digital gain adjustment, etc.) by the first image processing unit 932. That is, the first and second light source controls have the advantage of being able to increase the brightness of the normal light image without digital gain adjustment. In the third light source control, similar to the first and second light source controls, dimming control is performed to maintain the light amount ratio.

[0078] [Method for Setting the On-state Period of the First Light Source 31 in the Third Light Source Control] Next, a method for setting the on-state period of the first light source 31 in the third light source control will be described. FIGS. 7 to 10 are diagrams for explaining a method for setting the on-state period of the first light source 31 in the third light source control. Specifically, FIG. 7 corresponds to FIG. 1 and shows an ideal state in which no unwanted light that becomes noise is generated. FIG. 8 corresponds to FIG. 7 and shows an actual state in which unwanted light that becomes noise is generated. FIG. 9 is a diagram showing a case in which the third light source control and the third imaging control are executed in the state of FIG. 8. FIG. 10 is a diagram for explaining the second image processing (clamping processing and digital gain adjustment) by the second image processing unit 933.

[0079] 7 to 9, the first light source 31 is configured to emit red light, green light, and blue light, respectively. The red light is designated as "R," the green light as "G," and the blue light as "B."

[0080] First, an ideal state in which unnecessary light that becomes noise is not generated will be described with reference to Fig. 7. As shown in Fig. 7(a), the light source device 3 emits first light (R, G, B) and excitation light. For convenience of explanation, Fig. 7 shows that the intensity of the first light (R, G, B) emitted from the light source device 3 is the same as the intensity of the excitation light.

[0081] When the first light (R, G, B) and the excitation light are irradiated onto the observation object OB via the first optical path P1, the excitation light excites a substance contained in the observation object OB, causing the substance to emit observation object fluorescence, as shown in (b) of Fig. 7. Note that in Fig. 7, for the sake of convenience, the intensity of the observation object fluorescence is set to about half the intensity of the first light (R, G, B) and the intensity of the excitation light, but the actual intensity is about 1 / 20 for a drug that emits bright observation object fluorescence and about 1 / 500 for a drug that emits dark observation object fluorescence.

[0082] When the first light (R, G, B) from the observation object OB and the second light (the first light (R, G, B), excitation light, and observation object fluorescence), which is the return light of the excitation light, propagate through the second optical path P2, the excitation light contained in the second light is partially, substantially, or completely suppressed by the excitation light cut filter 22, as shown in (c) of Figure 7.

[0083] Furthermore, the second light (first light (R, G, B) and the fluorescence of the object to be observed) that has passed through the excitation light cut filter 22 is separated by the prism 52 into a first subject image containing the first light (R, G, B) and a second subject image ((e) of FIG. 7) containing the fluorescence of the object to be observed, as shown in (d) of FIG. 7. The first image sensor 531 then captures the first subject image to generate a normal light image. Meanwhile, the second image sensor 532 captures the second subject image to generate a fluorescence image.

[0084] Then, by performing second image processing on the fluorescence image in the second image processing unit 933, the signal value based on the fluorescence of the object of observation is increased by digital gain adjustment. Furthermore, by performing second image processing on the fluorescence image, positions where the intensity of the fluorescence of the object of observation is relatively strong are colored with, for example, a pseudo-green color. Furthermore, the display control unit 934 may generate a superimposed image by superimposing the normal light image after the first image processing in the first image processing unit 932 and the fluorescence image after the second image processing in the second image processing unit 933, and generate a video signal for displaying the superimposed image.

[0085] Next, referring to FIG. 8 , an actual state in which unwanted light that becomes noise is generated will be described. When the first light (R, G, B), excitation light, and second light propagate through the observation optical path P0, unwanted light is generated from the autofluorescence generating component. Note that in FIG. 8 , the symbol "L1" indicates unwanted light. As shown in FIG. 8(b), this unwanted light is light with a wide wavelength range that includes the wavelength band of the fluorescence of the object of observation. For this reason, as shown in FIG. 8(e), the second subject image contains not only the fluorescence of the object of observation but also the unwanted light L1. This makes it difficult to separate the fluorescence of the object of observation from the unwanted light L1 in the fluorescence image.

[0086] Next, with reference to FIG. 9 , a case where the third light source control and the third imaging control are executed will be described. When the third light source control is executed, as shown in FIG. 9A , the intensity of the first light (R, G, B) is reduced compared to FIG. 8A . As a result, as shown in FIG. 9B to FIG. 9E , the intensity of the unwanted light L1 is reduced compared to FIG. 8B to FIG. 8E . In the first embodiment, the light source control unit 941 executes the first control (control to turn on the first light source 31) in the third light source control so that the signal value based on the observation object fluorescence imaged by the second imaging element 532 is greater than the signal value based on the unwanted light L1. In other words, the light source control unit 941 executes the first control so that the S / N ratio of the signal value based on the observation object fluorescence imaged by the second imaging element 532 is greater than 1. The method of calculating the S / N ratio will be described later in the "Method of Calculating the S / N Ratio" section.

[0087] For example, if the S / N ratio of the signal value based on the fluorescence of the object of observation imaged by the second image sensor 532 is greater than 1, the signal value based on the fluorescence of the object of observation can be further amplified by second image processing by the second image processing unit 933, and the signal value based on the fluorescence of the object of observation and the signal value based on the unwanted light L1 can be separated, as shown in Fig. 10. Note that in Fig. 10, the unwanted light is referred to as unwanted light L1, and the fluorescence of the object of observation is referred to as observation fluorescence L2.

[0088] Specifically, in the clamping process, the second image processing unit 933 separates the signal value based on the unwanted light L1 from the signal value based on the fluorescence L2 under observation by raising the black cutoff level (clamp value), as shown in (a) to (c) of Figure 10.

[0089] However, as shown in FIG. 10(c), the signal level of the signal after the clamp value is increased is lower than the original level.

[0090] Therefore, the second image processing unit 933 increases the signal level of the signal shown in FIG. 10(c) by digital gain adjustment, as shown in FIG. 10(d).

[0091] The light source control unit 941 then sets a control value for the first control or a control value for the second control based on a predetermined value according to the present disclosure. In the first embodiment, the predetermined value according to the present disclosure is the control value for the first control itself. In the first embodiment, the control value for the first control according to the present disclosure is the lighting period of the first light source 31 (the emission period of the first light), but is not limited to this. The control value for the first control according to the present disclosure is not limited to the lighting period of the first light source 31, and may be the current value supplied to the first light source 31, or the like, as long as it is the luminous energy of the first light emitted from the first light source 31. Furthermore, the control threshold according to the present disclosure is the maximum control value for the first control at which the S / N ratio of the signal value based on the observation object fluorescence L2 imaged by the second image sensor 532 is greater than 1. In the first embodiment, the light source control unit 941 then sets the control value for the first control of the third light source control to a control value equal to or less than the control threshold. In the first embodiment, the control threshold is a period equal to or shorter than the all-line exposure period TE.

[0092] In the first embodiment, the predetermined value according to the present disclosure is the lighting period of the first light source 31, and is a fixed value determined in advance at the design stage so that the S / N ratio of the signal value based on the observation target fluorescence L2 imaged by the second image sensor 532 is greater than 1.

[0093] As described above, the light source control unit 941 executes the first control so as to suppress the signal value based on the unwanted light L1 captured by the second image sensor 532, and executes the second control for a period that overlaps with at least a portion of the period during which the first control is executed and is longer than the period during which the first control is executed. Note that the control by the light source control unit 941 is not limited to the above. Conversely, the light source control unit 941 may execute the first control for a period that overlaps with at least a portion of the period during which the second control is executed and is shorter than the period during which the second control is executed, and execute the second control so that the signal value based on the unwanted light L1 captured by the second image sensor 532 is smaller than the signal value based on the observation target fluorescence L2. In other words, the light source control unit 941 executes at least one of the first control and the second control so that the signal value based on the observation target fluorescence L2 is larger than the signal value based on the unwanted light L1 captured by the second image sensor 532. In addition, the light source control unit 941 performs at least one of the first control and the second control so as to increase the difference between the signal value based on the unwanted light L1 captured by the second imaging element 532 and the signal value based on the fluorescence L2 to be observed.

[0094] [Method of calculating S / N ratio] Fig. 11 is a diagram for explaining a method of calculating the S / N ratio. Specifically, Fig. 11 is a diagram corresponding to Fig. 1. The method of calculating the S / N ratio according to this embodiment is a method that refers to "2.D.8. Excitation light crosstalk" and "3.G. Excitation light crosstalk" in the title "Performance test methods for near-infrared fluorescence imaging" of the following document A. (Document A) "MEDICAL PHYSICS" Volume 47, Issue 8, August 2020, Pages 3389-3401

[0095] In the method for calculating the S / N ratio, first and second objects (phantoms) F1 and F2 are used, as shown in Fig. 11. The first object F1 is a phantom that does not contain any drug and contains only scattering particles. The second object F2 is a phantom that contains a drug at a concentration appropriate for the living body to be observed.

[0096] The S / N ratio is calculated by the following formula (1): S / N ratio=((c)-(a)) / ((b)-(a)) (1)

[0097] Here, (a) in equation (1) is the luminance level based on the pixel signal output from the second image sensor 532 in a state in which no external light enters the camera head 5 and the first and second light sources 31 and 32 are turned off in the medical observation system 1 shown in Fig. 11. Note that (a) may also be the luminance level based on the pixel signal output from the second image sensor 532 in a state in which a mechanical shutter is provided between the camera head 5 and the eyepiece 21 and the mechanical shutter prevents light from entering the camera head 5. Furthermore, (b) is the luminance level based on the pixel signal output from the second image sensor 532 when the first and second light sources 31 and 32 are turned on, the first subject F1 is irradiated with the first light and excitation light, and the second light is imaged by the second image sensor 532 in the medical observation system 1 shown in Fig. 11. Furthermore, (c) is the luminance level based on the pixel signal output from the second image sensor 532 when the first and second light sources 31, 32 are turned on, the first light and excitation light are irradiated onto the second subject F2, and the second light is imaged by the second image sensor 532 in the medical observation system 1 shown in FIG. 11 .

[0098] The predetermined value according to the present disclosure is preferably a value that results in an S / N ratio greater than 1 when calculated using equation (1) using pixel signals (RAW signals (pre-processed pixel signals according to the present invention)) output from the second image sensor 532 before image processing (first image processing or second image processing) is performed on the pixel signals. Furthermore, the predetermined value according to the present disclosure is preferably a value that results in an S / N ratio greater than 4 when calculated using equation (1) using pixel signals (post-processed pixel signals according to the present invention) output from the second image sensor 532 after image processing (first image processing or second image processing) is performed on the pixel signals.

[0099] The first embodiment described above has the following advantages. The control device 9 according to the first embodiment executes at least one of the first control and the second control so that the signal value based on the observation object fluorescence L2, which is imaged by the second image sensor 532, is greater than the signal value based on the unwanted light L1 generated due to at least the first light. In other words, the control device 9 executes at least one of the first control and the second control so that the S / N ratio of the signal value based on the observation object fluorescence L2 imaged by the second image sensor 532 is greater than 1. This makes it possible for the control device 9 to generate an image that makes it easy for the user to distinguish between the observation object fluorescence L2 and the unwanted light L1. Therefore, the control device 9 according to the first embodiment enables satisfactory fluorescence observation.

[0100] In particular, the control device 9 sets the control value in the first control to the lighting period of the first light source 31, and by adjusting this control value, the unnecessary light L1 is partially, substantially, or completely suppressed, and the S / N ratio of the signal value based on the observation object fluorescence L2 imaged by the second image sensor 532 is made greater than 1. Therefore, good fluorescence observation can be performed with simple processing.

[0101] (Modification 1-1 of First Embodiment) In the first embodiment described above, fixed values ​​determined in advance at the design stage are used as the predetermined values ​​according to the present disclosure, but the present disclosure is not limited to this.

[0102] For example, the light source control unit 941 causes only the first light source 31 in the light source device 3 to emit the first light at the timing of executing the white balance adjustment process before starting observation of the observation object OB. Then, the light source control unit 941 may set a predetermined value according to the present disclosure that makes the S / N ratio of the signal value based on the observation object fluorescence L2 imaged by the second image sensor 532 greater than 1, based on the signal value of the pixel signal output from the first image sensor 531 or the second image sensor 532. For example, the light source control unit 941 reduces the predetermined value according to the present disclosure because it is predicted that the greater the signal value of the pixel signal, the more unwanted light L1 is generated.

[0103] Even when the configuration of the present modified example 1-1 described above is adopted, the same effects as those of the first embodiment described above can be achieved.

[0104] (Modification 1-2 of First Embodiment) In the first embodiment described above, fixed values ​​determined in advance at the design stage are used as the predetermined values ​​according to the present disclosure, but the present disclosure is not limited to this.

[0105] For example, the light source control unit 941 may set the predetermined value according to the present disclosure based on the brightness (average luminance value, etc.) of a specific region (detection region) in the normal light image so that the S / N ratio of the signal value based on the observation target fluorescence L2 imaged by the second image sensor 532 is greater than 1. In other words, the light source control unit 941 sets the predetermined value according to the present disclosure based on the signal value of the pixel signal output from the first image sensor 531. For example, the light source control unit 941 reduces the predetermined value according to the present disclosure because it is predicted that the brighter the brightness of the specific region (detection region) in the normal light image, the more unwanted light L1 is generated.

[0106] Even when the configuration of the present modified example 1-2 described above is adopted, the same effects as those of the first embodiment described above can be achieved.

[0107] (Modification 1-3 of First Embodiment) In the first embodiment described above, fixed values ​​determined in advance at the design stage are used as the predetermined values ​​according to the present disclosure, but the present disclosure is not limited to this.

[0108] For example, the light source control unit 941 may set the predetermined value according to the present disclosure based on the brightness (average luminance value, etc.) of a specific region (detection region) in the fluorescence image so that the S / N ratio of the signal value based on the observation target fluorescence L2 imaged by the second image sensor 532 is greater than 1. In other words, the light source control unit 941 sets the predetermined value according to the present disclosure based on the signal value of the pixel signal output from the second image sensor 532. For example, the light source control unit 941 reduces the predetermined value according to the present disclosure because it is predicted that the brighter the brightness of the specific region (detection region) in the fluorescence image, the more unwanted light L1 is generated.

[0109] The above-described Modification 1-3 achieves the same effects as those of the first embodiment, as well as the following effects. According to Modification 1-3, the light source control unit 941 can estimate the type of drug being used based on the brightness (e.g., average luminance value) of a specific region (detection region) in the fluorescence image. That is, when a drug that emits bright observation target fluorescence L2 is used, the predetermined value according to the present disclosure is increased, whereas when a drug that emits dim observation target fluorescence L2 is used, the predetermined value according to the present disclosure is decreased, thereby sufficiently reducing the unwanted light L1. Furthermore, even for the same drug, the drug accumulation level varies depending on the subject (medical department) being observed, so the signal value based on the observation target fluorescence L2 varies depending on the observed region, even for the same drug. For example, when observing blood flow in the large intestine, the drug (ICG) flows with the blood flow, resulting in a dark signal value based on the observation target fluorescence L2. On the other hand, when observing the bile duct, the drug accumulates, resulting in a bright signal value based on the observation target fluorescence L2. In this way, the predetermined value according to the present disclosure can be changed based on the signal value (brightness (average luminance value, etc.) of a specific region (detection region) in the fluorescence image) based on the observation target fluorescence L2.

[0110] (Modification 1-4 of First Embodiment) In the first embodiment described above, fixed values ​​determined in advance at the design stage are used as the predetermined values ​​according to the present disclosure, but the present disclosure is not limited to this.

[0111] For example, the above-mentioned fixed value (predetermined value according to the present disclosure) may be changed in response to a user operation on the input unit 95 .

[0112] Even when the configuration of the present modified example 1-4 described above is adopted, the same effects as those of the first embodiment described above can be achieved.

[0113] (Modification 1-5 of First Embodiment) In the first embodiment described above, fixed values ​​determined in advance at the design stage are used as the predetermined values ​​according to the present disclosure, but the present disclosure is not limited to this.

[0114] For example, the light source control unit 941 may set the predetermined value according to the present disclosure based on the fading time of the signal value based on the observation object fluorescence L2 imaged by the second image sensor 532. In other words, the light source control unit 941 determines the type of drug being used and sets the predetermined value according to the type of drug. For example, the light source control unit 941 sets the predetermined value according to the present disclosure to a smaller value when it is determined that the observation object fluorescence L2 emitted by the drug is dark than when it is determined that the observation object fluorescence L2 emitted by the drug is bright.

[0115] Even when the configuration of the present modified example 1-5 described above is adopted, the same effects as those of the first embodiment described above can be achieved.

[0116] (Embodiment 2) Next, embodiment 2 will be described. In the following, the same components as those in embodiment 1 described above will be given the same reference numerals, and detailed descriptions thereof will be omitted or simplified. In the following, the same components as those in embodiment 1 described above will be given the same reference numerals, and detailed descriptions thereof will be omitted or simplified. Fig. 12 is a diagram showing the configuration of a medical observation system 1A according to embodiment 2. Specifically, Fig. 12 is a diagram corresponding to Fig. 2. The medical observation system 1A according to embodiment 2 differs from the medical observation system 1 described in embodiment 1 above in that a mode switching unit 943 is added to the control unit 94, as shown in Fig. 12.

[0117] The mode switching unit 943 switches the medical observation system 1A between the first mode and the second mode in response to a user operation on the input unit 95 .

[0118] The first mode is a mode in which the unnecessary light L1 is partially, substantially, or completely suppressed. In the first mode, the light source control unit 941 executes a third light source control. In addition, the imaging control unit 942 executes a third imaging control.

[0119] The second mode is a mode in which the unnecessary light L1 is not partially, substantially, or completely suppressed. In the second mode, the light source control unit 941 executes the first light source control or the second light source control. Furthermore, the imaging control unit 942 executes the first imaging control or the second imaging control. That is, in the second mode, the light source control unit 941 sets the control value in the first control of the third light source control to a control value greater than the control threshold. Note that the second mode may be a mode in which the unnecessary light L1 is partially, substantially, or completely suppressed, similar to the first mode. That is, the light source control unit 941 may execute the third light source control in the second mode. Furthermore, the imaging control unit 942 may execute the third imaging control in the second mode. In this case, the second mode is a mode in which the amount of suppression of the unnecessary light L1 is less than in the first mode. That is, in the second mode, the control value in the first control of the third light source control is greater than the control value in the first mode.

[0120] The second embodiment described above achieves the same effects as the first embodiment. While control that partially, substantially, or completely suppresses the unwanted light L1 has the effect of preventing the observation target fluorescence L2 from being obscured by the unwanted light L1, it also darkens the brightness of the normal light image, resulting in increased noise even when the brightness of the normal light image is adjusted by digital gain adjustment. Furthermore, some drugs emit sufficiently bright observation target fluorescence L2 that observation is possible without partially, substantially, or completely suppressing the unwanted light L1.

[0121] The control device 9 according to the second embodiment switches between the first mode and the second mode described above. Therefore, the first mode can be selected when it is necessary to partially, substantially, or completely suppress the unwanted light L1, and the second mode can be selected when it is not necessary to partially, substantially, or completely suppress the unwanted light L1, thereby improving convenience.

[0122] (Modification 2-1 of Embodiment 2) Fig. 13 is a diagram illustrating Modification 2-1 of Embodiment 2. In the above-described Embodiment 2, the mode switching unit 943 switches the medical observation system 1A between the first mode and the second mode in response to a user operation on the input unit 95, but this is not limiting.

[0123] 13, the mode switching unit 943 according to the present modification 2-1 reads out an endoscope ID (identifier) ​​stored in the memory 23 provided in the insertion unit 2, and switches the medical observation system 1A between the first mode and the second mode based on the endoscope ID. The endoscope ID is identification information unique to the insertion unit 2, and varies depending on the diameter of the insertion unit 2, the type of excitation light cutoff filter 22, the glass material of the lenses that make up the optical system within the insertion unit 2, and so on.

[0124] The above-described modified example 2-1 provides the same effects as those of the second embodiment, as well as the following effects. The amount of unwanted light L1 generated varies depending on the diameter of the insertion section 2, the type of excitation light cut filter 22, and the glass material of the lenses that make up the optical system within the insertion section 2. The control device 9 according to the modified example 2-1 switches the medical observation system 1A between the first mode and the second mode based on the endoscope ID. This makes it possible to switch between the first mode and the second mode appropriately depending on the type of the insertion section 2.

[0125] In the above-described first embodiment, the predetermined value according to the present disclosure may be set based on the endoscope ID, as in Modification 2-1. For example, the light source control unit 941 sets the predetermined value according to the present disclosure to a smaller value when an insertion unit 2 (endoscope ID) that generates a large amount of unwanted light L1 is connected than when an insertion unit 2 (endoscope ID) that generates a small amount of unwanted light L1 is connected.

[0126] (Modification 2-2 of Embodiment 2) Fig. 14 is a diagram illustrating Modification 2-2 of Embodiment 2. In the above-described Embodiment 2, the mode switching unit 943 switches the medical observation system 1A between the first mode and the second mode in response to a user operation on the input unit 95, but this is not limiting.

[0127] 14, an endoscopic observation device 100 and an open field observation device 200 can be connected to the control device 9 according to Modification 2-2. The endoscopic observation device 100 is an apparatus that uses an endoscope and includes the insertion section 2 and camera head 5 described in the above-mentioned second embodiment. On the other hand, the open field observation device 200 is an apparatus used in open surgery.

[0128] Then, the mode switching unit 943 according to the present modification 2-2 reads out the device ID stored in the memory 101 provided in the endoscopic observation device 100 connected to the control device 9, or the device ID stored in the memory 201 provided in the open field observation device 200 connected to the control device 9. The device ID is identification information indicating whether it is an endoscopic observation device or an open field observation device. Then, when the mode switching unit 943 determines that the connected device is the open field observation device 200 based on the read-out device ID, it switches the medical observation system 1A to the second mode. On the other hand, when the mode switching unit 943 determines that the connected device is the endoscopic observation device 100 based on the read-out device ID, it switches the medical observation system 1A to the first mode.

[0129] According to the modified example 2-2 described above, in addition to the same effects as those of the second embodiment described above, the following effects are achieved. However, when using the open field observation device 200, if the device switches to the first mode in which the first light flashes, the user will see the flashing first light directly, which is undesirable. The control device 9 according to the modified example 2-2 switches the medical observation system 1A between the first mode and the second mode based on the device ID. This makes it possible to avoid switching to the first mode when using the open field observation device 200, thereby improving convenience.

[0130] In the above-described first embodiment, the predetermined value according to the present disclosure may be set based on the device ID, as in Modification 2-2. For example, the light source control unit 941 sets the predetermined value according to the present disclosure to a larger value when the open field observation device 200 is connected than when the endoscopic observation device 100 is connected.

[0131] (Variation 2-3 of Embodiment 2) In the above-described embodiment 2, the mode switching unit 943 switches the medical observation system 1A between the first mode and the second mode in response to a user operation on the input unit 95, but this is not limited to this.

[0132] For example, the light source control unit 941 causes the first light source 31 in the light source device 3 to emit only the first light at the timing of performing white balance adjustment processing before starting observation of the observation object OB. The mode switching unit 943 may switch the medical observation system 1A between the first mode and the second mode based on the signal value of the pixel signal output from the first image sensor 531 or the second image sensor 532. For example, if the signal value of the pixel signal is greater than a predetermined threshold, the mode switching unit 943 predicts that a large amount of unwanted light L1 is being generated, and switches the medical observation system 1A to the first mode. On the other hand, if the signal value of the pixel signal is equal to or less than the predetermined threshold, the mode switching unit 943 switches the medical observation system 1A to the second mode.

[0133] Even when the configuration of the present modified example 2-3 described above is adopted, the same effects as those of the second embodiment described above can be achieved.

[0134] (Variation 2-4 of Embodiment 2) In the above-described embodiment 2, the mode switching unit 943 switches the medical observation system 1A between the first mode and the second mode in response to a user operation on the input unit 95, but this is not limited to this.

[0135] For example, the mode switching unit 943 may switch the medical observation system 1A between the first mode and the second mode based on the brightness (average luminance value, etc.) of a specific region (detection region) in the normal light image. In other words, the light source control unit 941 may switch the medical observation system 1A between the first mode and the second mode based on the signal value of the pixel signal output from the first image sensor 531. For example, if the brightness of the specific region (detection region) in the normal light image is brighter than a predetermined threshold (brightness), the mode switching unit 943 predicts that a large amount of unwanted light L1 is being generated, and switches the medical observation system 1A to the first mode. On the other hand, if the brightness of the specific region (detection region) in the normal light image is equal to or less than the predetermined threshold, the mode switching unit 943 switches the medical observation system 1A to the second mode.

[0136] Even when the configuration of the present modified example 2-4 described above is adopted, the same effects as those of the above-described second embodiment are achieved.

[0137] (Variation 2-5 of Embodiment 2) In the above-described embodiment 2, the mode switching unit 943 switches the medical observation system 1A between the first mode and the second mode in response to a user operation on the input unit 95, but this is not limited to this.

[0138] For example, the mode switching unit 943 may switch the medical observation system 1A between the first mode and the second mode based on the brightness (average luminance value, etc.) of a specific region (detection region) in the fluorescence image. In other words, the mode switching unit 943 may switch the medical observation system 1A between the first mode and the second mode based on the signal value of the pixel signal output from the second image sensor 532. For example, if the brightness of the specific region (detection region) in the fluorescence image is brighter than a predetermined threshold (brightness), the mode switching unit 943 predicts that a large amount of unwanted light L1 is being generated, and switches the medical observation system 1A to the first mode. On the other hand, if the brightness of the specific region (detection region) in the fluorescence image is equal to or less than the predetermined threshold, the mode switching unit 943 switches the medical observation system 1A to the second mode.

[0139] Even when the configuration of the present modified example 2-5 described above is adopted, the same effects as those of the above-described second embodiment can be achieved.

[0140] (Variation 2-6 of Embodiment 2) In the above-described embodiment 2, the mode switching unit 943 switches the medical observation system 1A between the first mode and the second mode in response to a user operation on the input unit 95, but this is not limited to this.

[0141] For example, the mode switching unit 943 may switch the medical observation system 1A between the first mode and the second mode based on the fading time of the signal value based on the observation object fluorescence L2 imaged by the second image sensor 532. In other words, the mode switching unit 943 determines the type of drug being used and switches the medical observation system 1A between the first mode and the second mode depending on the type of drug. For example, if the light source control unit 941 determines that the observation object fluorescence L2 emitted is a bright drug, it switches the medical observation system 1A to the second mode. On the other hand, if the light source control unit 941 determines that the observation object fluorescence L2 emitted is a dark drug, it switches the medical observation system 1A to the first mode.

[0142] Even when the configuration of the present modified example 2-6 described above is adopted, the same effects as those of the second embodiment described above can be achieved.

[0143] (Variation 2-7 of Embodiment 2) Figures 15 and 16 are diagrams for explaining Variation 2-7 of Embodiment 2. Specifically, Figures 15 and 16 are diagrams corresponding to Figure 1. The configuration described in the above-mentioned Embodiment 2 may be applied to surgery using multiple drugs as shown in Table 1 below. In Table 1, drugs that are used are marked with "◯" and drugs that are not used are marked with "X".

[0144]

[0145] Here, when fluorescein is irradiated with excitation light in a wavelength band of approximately 470 to 480 nm, it emits fluorescence L2 of approximately 520 nm. When ALM-488 is irradiated with excitation light in a wavelength band of approximately 488 nm, it emits fluorescence L2 of approximately 530 nm. When LUM-015 is irradiated with excitation light in a wavelength band of approximately 650 nm, it emits fluorescence L2 of approximately 675 nm. When 5-ALA is irradiated with excitation light in a wavelength band of approximately 405 nm, it emits fluorescence L2 of approximately 530 to 630 nm. When ICG is irradiated with excitation light in a wavelength band of approximately 805 nm, it emits fluorescence L2 of approximately 830 nm.

[0146] For example, when performing lymph node dissection during lobectomy for lung cancer, ALM-488 and ICG are used, as shown in Table 1. Specifically, ALM-488 is used to visualize the left recurrent laryngeal nerve, and ICG is used to visualize the lymph nodes. Visualizing the left recurrent laryngeal nerve and lymph nodes in this manner allows for differentiation between the left recurrent laryngeal nerve and lymph nodes, thereby reducing recurrent laryngeal nerve paralysis during lobectomy. Because two drugs, ALM-488 and ICG, are used in this procedure, the medical observation system 1A must be configured with a second light source 32 that emits excitation light to excite one of the two drugs, as well as a third light source 33 that emits excitation light to excite the other drug, as shown in FIG. 15 . The second and third light sources 32 and 33 correspond to the second light source according to the present disclosure. Furthermore, the medical observation system 1A switches to the first mode when using one of the two drugs, ALM-488 and ICG, which produces a weak fluorescence L2 (corresponding to the first drug according to the present disclosure), and switches to the second mode when using the other drug (corresponding to the second drug according to the present disclosure).The physician performing the lobectomy can determine the location of either the left recurrent laryngeal nerve or the lymph nodes from the image displayed on the display device 7 in the first mode, and can determine the location of the other of the left recurrent laryngeal nerve and the lymph nodes from the image displayed on the display device 7 in the second mode.

[0147] Furthermore, for example, when performing lateral lymph node dissection in rectal resection for colorectal cancer, ALM-488 and ICG are used, as shown in Table 1. Specifically, ALM-488 is used to visualize the neurovascular bundle, and ICG is used to visualize the lymph nodes. Visualizing the neurovascular bundle and lymph nodes in this manner allows differentiation between the neurovascular bundle and lymph nodes, thereby reducing urinary disorders, defecation disorders, male sexual dysfunction, and motor dysfunction due to nerve damage during rectal resection. Because two drugs, ALM-488 and ICG, are used in this case, a medical observation system 1A must be configured with a second light source 32 that emits excitation light to excite one of the two drugs, as well as a third light source 33 that emits excitation light to excite the other drug, as shown in FIG. 15 . The second and third light sources 32 and 33 correspond to the second light source according to the present disclosure. Furthermore, the medical observation system 1A switches to the first mode when one of the two drugs, ALM-488 and ICG, that produces weak fluorescence L2 (corresponding to the first drug according to the present disclosure) is used, and switches to the second mode when the other drug (corresponding to the second drug according to the present disclosure) is used. The physician performing the rectal resection can determine the position of one of the nerve bundle vascular bundle and lymph node from the image displayed on the display device 7 in the first mode, and can determine the position of the other of the nerve bundle vascular bundle and lymph node from the image displayed on the display device 7 in the second mode.

[0148] Furthermore, for example, in pediatric brain tumor resection, ALM-488 and ICG are used when performing malignant tumor resection, as shown in Table 1. Specifically, ALM-488 is used to visualize nerves, and ICG is used to visualize blood vessels (blood flow). Visualizing nerves and blood vessels in this manner allows for differentiation between malignant tumors, nerves, and blood vessels, preventing cancer recurrence after malignant tumor resection, and preventing damage to nerves and blood vessels during malignant tumor resection. Because two drugs, ALM-488 and ICG, are used in this procedure, a medical observation system 1A must be configured with a second light source 32 that emits excitation light to excite one of the two drugs, and a third light source 33 that emits excitation light to excite the other drug, as shown in FIG. 15 . The second and third light sources 32 and 33 correspond to the second light source in the present disclosure. Furthermore, the medical observation system 1A switches to the first mode when one of the two drugs, ALM-488 and ICG, that produces weak fluorescence L2 (corresponding to the first drug according to the present disclosure) is used, and switches to the second mode when the other drug (corresponding to the second drug according to the present disclosure) is used. A physician performing malignant tumor resection surgery can determine the position of one of the nerves and blood vessels from the image displayed on the display device 7 in the first mode, and can determine the position of the other of the nerves and blood vessels from the image displayed on the display device 7 in the second mode.

[0149] For example, in mastectomy for breast cancer, when removing a malignant tumor and performing axillary lymph node dissection, ALM-488, LUM-015, and ICG are used, as shown in Table 1. That is, nerves such as the intercostobrachial nerves and thoracodorsal nerves are visualized using ALM-488, the malignant tumor is visualized using LUM-015, and the lymph nodes are visualized using ICG. Visualization of nerves, malignant tumors, and lymph nodes in this way makes it possible to distinguish between malignant tumors, nerves, and lymph nodes, thereby reducing nerve damage during mastectomy. In this case, because three drugs, ALM-488, LUM-015, and ICG, are used, the medical observation system 1A must be configured with a second light source 32 that emits excitation light to excite one of the three drugs, a third light source 33 that emits excitation light to excite one of the other two drugs, and a fourth light source 34 that emits excitation light to excite the other of the other two drugs, as shown in Figure 16. Note that the second to fourth light sources 32 to 34 correspond to the second light source according to the present disclosure. Furthermore, the medical observation system 1A switches to the first mode when using one of the three drugs, ALM-488, LUM-015, and ICG, that produces weak observation target fluorescence L2 (corresponding to the first drug according to the present disclosure), and switches to the second mode when using the other drug (corresponding to the second drug according to the present disclosure). The doctor performing the mastectomy can determine the location of at least one of the nerves, malignant tumors, and lymph nodes from the image displayed on the display device 7 in the first mode, and can determine the locations of the other nerves, malignant tumors, and lymph nodes from the image displayed on the display device 7 in the second mode.

[0150] Furthermore, for example, when treating brain tumors using photodynamic diagnosis (PDD), ALM-488 and 5-ALA (5-aminolevulinic acid) are used, as shown in Table 1. Specifically, the tumor vicinity is visualized using fluorescein, the fluorescent dye of ALM-488, and tumor cells are visualized using protoporphyrin (PpIX), which is biosynthesized from 5-ALA. Visualizing tumor cells, including those near the tumor, in this manner allows for safe tumor removal while preventing damage during brain tumor treatment. Because two drugs, ALM-488 and 5-ALA, are used in this case, a medical observation system 1A is required, as shown in FIG. 15 , which includes a second light source 32 that emits excitation light to excite one of the two drugs, and a third light source 33 that emits excitation light to excite the other drug. The second and third light sources 32 and 33 correspond to the second light source in the present disclosure. Furthermore, the medical observation system 1A switches to the first mode when using 5-ALA (corresponding to the first drug according to the present disclosure), which of the two drugs, ALM-488 and 5-ALA, produces a weak fluorescence L2, and switches to the second mode when using ALM-488 (corresponding to the second drug according to the present disclosure).The physician treating the brain tumor can determine the location of tumor cells from the image displayed on the display device 7 in the first mode, and can determine the location of the area near the tumor from the image displayed on the display device 7 in the second mode.

[0151] Furthermore, for example, when performing transurethral cystectomy in the surgical treatment of superficial urothelial cell carcinoma using photodynamic diagnosis, fluorescein and 5-ALA are used, as shown in Table 1. Specifically, tumors are visualized using PpIX, which is biosynthesized from 5-ALA. However, PpIX has the drawback of visualizing not only tumors but also hypermetabolic inflammatory tissue present in the bladder. Therefore, false positives due to PpIX in hypermetabolic inflammatory tissue are reduced by using fluorescein. In this case, because two drugs, fluorescein and 5-ALA, are used, a medical observation system 1A must be configured with a second light source 32 that emits excitation light to excite one of the two drugs, as well as a third light source 33 that emits excitation light to excite the other drug, as shown in FIG. 15 . The second and third light sources 32 and 33 correspond to the second light source in the present disclosure. Furthermore, the medical observation system 1A switches to the first mode when using 5-ALA (corresponding to the first drug according to the present disclosure), which of the two drugs, fluorescein and 5-ALA, produces a weak fluorescence L2 as the observation target, and switches to the second mode when using fluorescein (corresponding to the second drug according to the present disclosure). The physician performing the transurethral cystectomy identifies the location of the tumor from the image displayed on the display device 7 in the first mode, and identifies false positives due to hypermetabolic inflammatory tissue caused by PpIX from the image displayed on the display device 7 in the second mode.

[0152] Even when the configuration of the present modified example 2-7 described above is adopted, the same effects as those of the above-described second embodiment can be achieved.

[0153] (Variation 2-8 of Embodiment 2) The configuration described in the above-mentioned Embodiment 2 may be applied to the following first to sixth scenes. Note that, although ICG is used as the drug in the following first to sixth scenes, other drugs may also be used in the scenes.

[0154] [First Scene] An example of a scene in which the observation target fluorescence L2 is weak when using ICG is a scene in which a pediatric patient is undergoing surgery. The amount of ICG administered per session must be set according to the patient's weight. Therefore, compared to adult patients, when administering ICG to a pediatric patient, the amount of ICG must be reduced in proportion to the patient's weight. That is, when ICG is administered to a pediatric patient, the ICG concentration may be low, resulting in weak observation target fluorescence L2. The medical observation system 1A switches to the first mode when performing surgery on a pediatric patient (corresponding to the first surgical scene in the present disclosure) and switches to the second mode when performing surgery on an adult patient (corresponding to the second surgical scene in the present disclosure).

[0155] [Second Scene] An example of a scene in which the observation target fluorescence L2 is weak when using ICG is a scene in which intrabronchial injection is performed. Intrabronchial injection is a technique for identifying lung segments during lung segmental resection. Specifically, with intrabronchial injection, ICG is sprayed into the segmental bronchi using a bronchoscope, and the lung segment to be resected is identified through fluorescence observation. That is, with intrabronchial injection, it is more difficult to achieve a high ICG concentration than when identifying the lung segment to be resected using intravenous ICG injection, in which ICG is intravenously injected, and the observation target fluorescence L2 may be weak. The medical observation system 1A switches to the first mode when identifying the lung segment using intrabronchial injection (corresponding to the first surgical scene in the present disclosure) and switches to the second mode when identifying the lung segment using intravenous ICG injection (corresponding to the second surgical scene in the present disclosure).

[0156] [Third Scene] A scene in which the fluorescence L2 of the observation target is weak when ICG is used includes a scene in which a thin-diameter endoscope with a narrower outer diameter of the insertion section 2 is used. As fluorescence observation using ICG in the lower gastrointestinal tract becomes more common, there is a growing need for less invasive surgery. Furthermore, in cases with spatial constraints, such as transanal total mesorectal excision and single-port surgery, thin-diameter endoscopes are often used to improve the operability of forceps and other instruments. However, compared to standard endoscopes or wide-diameter endoscopes with a wider outer diameter of the insertion section 2, the thin-diameter endoscope has a narrower light guide path for the excitation light. This reduces the energy of the emitted excitation light, which can result in weak fluorescence L2 of the observation target. The medical observation system 1A switches to the first mode when a thin-diameter endoscope is used (corresponding to the first surgical scene in the present disclosure) and to the second mode when a standard endoscope or wide-diameter endoscope is used (corresponding to the second surgical scene in the present disclosure).

[0157] [Scene 4] When using ICG, the fluorescence intensity L2 of the target object becomes weak. For example, when identifying lung regions through multiple fluorescence observations using intravenous ICG injection, a low concentration of ICG is used for the first observation. A challenge with intravenous ICG injection is that once ICG is intravenously injected, it continues to glow as it travels through the bloodstream, making it impossible to observe again until it is metabolized by the liver. For example, if the entire lung glows during lobectomy due to incorrect hemostasis or loose ligation, it becomes extremely difficult to identify the region again using intravenous ICG injection. Furthermore, due to the upper limit on the adult dosage, it is also difficult to identify the region again using intravenous ICG injection after ICG has been metabolized. Therefore, when identifying lung regions for the first time, a low concentration of ICG (e.g., 1 / 10 of the normal concentration) is intravenously injected, and fluorescence observation is performed. If the appropriate area cannot be identified through the fluorescence observation, the ICG concentration is adjusted to the normal concentration, the ICG is intravenously injected again, and fluorescence observation is performed. When identifying the lung area for the first time, the ICG concentration is set to a low concentration, which may result in the observation target fluorescence L2 being weaker than when the ICG concentration is set to a normal concentration. The medical observation system 1A then switches to the first mode when performing fluorescence observation with a low ICG concentration (corresponding to the first surgical scene in the present disclosure), and switches to the second mode when performing fluorescence observation with a normal ICG concentration (corresponding to the second surgical scene in the present disclosure). In this way, performing fluorescence observation multiple times on the same area allows for more accurate identification of the lung area.

[0158] [Scene 5] An example of a scene in which the fluorescence L2 of the observation target becomes weak when using ICG is when blood flow in an intestinal anastomotic failure is confirmed by multiple fluorescence observations using intravenous ICG injection, for example, using a low concentration of ICG the first time. When confirming blood flow in an intestinal anastomotic failure by fluorescence observation, if the blood flow cannot be properly confirmed due to incorrect instrument settings or the subject being buried in tissue such as fat, it takes time for the ICG to be metabolized, making it difficult to confirm the blood flow again by ICG injection. Therefore, as in the fourth scene described above, when confirming blood flow for the first time, ICG is intravenously injected at a low concentration (e.g., 1 / 10 of the normal concentration) and then fluorescence observation is performed. If blood flow cannot be properly confirmed by the fluorescence observation, ICG is intravenously injected again at the normal concentration, and then fluorescence observation is performed. When blood flow is checked for the first time, the ICG concentration is set to a low concentration, and the observation target fluorescence L2 may be weaker than when the ICG concentration is set to a normal concentration. The medical observation system 1A switches to the first mode when performing fluorescence observation with a low ICG concentration (corresponding to the first surgical scene in the present disclosure), and switches to the second mode when performing fluorescence observation with a normal ICG concentration (corresponding to the second surgical scene in the present disclosure). In this way, performing fluorescence observation multiple times at the same site can reduce complications such as peritonitis due to anastomotic failure.

[0159] [Sixth Scene] When using ICG, the fluorescence L2 of the observation object may be weak when a fluorescent image is converted into a 3D image (hereinafter referred to as 3D fluorescence observation). When performing 3D fluorescence observation, a twin-lens relay scope may be used as the insertion section 2. In this twin-lens relay scope, two parallel optical paths are arranged within the scope. Each of the two optical paths is provided with an optical system. The twin-lens relay scope captures and emits observation light for the right and left eyes, each with a parallax between them (see, for example, Japanese Patent Application Laid-Open No. 6-160731). In this twin-lens relay scope, as with the thin-diameter endoscope described in the third scene above, the two optical paths narrow the light guide path of the excitation light compared to a standard endoscope. This reduces the energy of the emitted excitation light, which may result in weak fluorescence L2 of the observation object. Furthermore, when performing 3D fluorescence observation, two image capturing elements, one for capturing observation light for the right eye and one for the left eye, may be used as the second image capturing element 532. When two image capturing elements are used as the second image capturing element 532, the size is smaller than when a single image capturing element is used. Therefore, the received light energy of the observation target fluorescence L2 may be lower, and the signal value based on the observation target fluorescence L2 may be weak. While the above example illustrates the use of a rigid endoscope for 3D fluorescence observation, the observation target fluorescence L2 and the signal value based on the observation target fluorescence L2 may also be weak when a flexible endoscope for 3D fluorescence observation is used. The medical observation system 1A switches to the first mode when performing surgery using an endoscope for 3D fluorescence observation (corresponding to the first surgical scene according to the present disclosure), and switches to the second mode when performing surgery using an endoscope for fluorescence observation of 2D fluorescence images (corresponding to the second surgical scene according to the present disclosure).

[0160] In the first to sixth scenes described above, the mode switching unit 943 may switch the medical observation system 1A between the first mode and the second mode in response to a user operation on the input unit 95, as in the second embodiment described above. However, the mode switching unit 943 may also switch the mode as follows. For example, the mode switching unit 943 acquires patient information about the patient, surgery information about the type of surgery, or endoscope type information about the type of endoscope. Then, the mode switching unit 943 switches the medical observation system 1A between the first mode and the second mode based on the patient information, surgery information, or endoscope type information. Furthermore, for example, the mode switching unit 943 estimates the patient, the type of surgery, or the type of endoscope by image recognition using a trained model generated by machine learning, for example. The trained model is, for example, a learned model obtained after a learning process is repeatedly performed on the learned model using multiple sets of medical information and images, each set consisting of medical information and an image. The medical information is at least one of the patient's age, medical department, surgical site, surgical status, drug type, drug dosage, and imaging device (diameter of the rigid endoscope, or whether the rigid endoscope or ring light is used), etc. The mode switching unit 943 switches the medical observation system 1A between the first mode and the second mode based on the estimated patient, type of surgery, or type of endoscope.

[0161] Furthermore, an imaging element is provided in the connected endoscope or camera head 5, but the range of fluorescence intensity that can be imaged varies depending on the sensitivity of the imaging element and the system configuration. However, even in such observations, similar to the above, equivalent observation performance can be ensured by switching the medical observation system 1A between the first mode and the second mode.

[0162] Even when the configuration of the present modified example 2-8 described above is adopted, the same effects as those of the second embodiment described above can be achieved.

[0163] (Variation 2-9 of Embodiment 2) FIG. 17 is a diagram illustrating Variation 2-9 of Embodiment 2. Specifically, FIG. 17 is a diagram corresponding to FIG. 12. In the above-described Embodiment 2, the first mode may be the fluorescence observation mode, and the second mode may be the normal light observation mode. The fluorescence observation mode (first mode) is a mode in which a display image is generated based on pixel signals output from the first and second image sensors 531 and 532. The display image is an image in which a normal light image and a fluorescence image are superimposed, with the normal light image serving as the background image (hereinafter referred to as a superimposed image). The normal light observation mode (second mode) is a mode in which a display image is generated based on pixel signals output from only the first image sensor 531 of the first and second image sensors 531 and 532. The display image is a normal light image.

[0164] A user such as a doctor switches between the normal light observation mode (second mode) and the fluorescence observation mode (first mode) and observes the normal light image in the normal light observation mode and the superimposed image in the fluorescence observation mode. If the brightness of the normal light image in the normal light observation mode differs from that of the normal light image serving as the background image in the superimposed image in the fluorescence observation mode, the doctor or other user may feel uncomfortable. The aforementioned phenomenon may occur because the brightness of the normal light image serving as the background image in the superimposed image is reduced due to the shorter period of emission of the first light in the first mode (fluorescence observation mode).

[0165] Therefore, in this modification 2-9, a configuration is adopted in which, in the first mode (fluorescence observation mode), the brightness of an image based on pixel signals output from the first image sensor 531 is adjusted to approach the brightness of the image in the second mode (normal light observation mode). Furthermore, in this modification 2-9, a configuration is adopted in which, in the first mode (fluorescence observation mode), the digital gain is set to a value greater than the digital gain in the second mode (normal light observation mode). Specifically, in this modification 2-9, as shown in FIG. 17 , a digital gain control unit 944 is added to the control unit 94 in addition to the configuration described in the second embodiment. The digital gain control unit 944 corresponds to a brightness adjustment unit according to the present disclosure.

[0166] For example, if the period during which the first light is emitted in the first mode (fluorescence observation mode) is half that in the second mode (normal light observation mode), the signal value of the pixel signal output from the first image sensor 531 will be half that in the second mode. As a result, the brightness of the normal light image, which is the background image in the superimposed image, will also be half that of the normal light image in the second mode (normal light observation mode). Therefore, the digital gain control unit 944 sets the digital gain in the first mode (fluorescence observation mode) to a value greater than the digital gain in the second mode (normal light observation mode) (e.g., twice as large). This allows the brightness of the normal light image, which is the background image in the superimposed image in the first mode, to approach the brightness of the normal light image in the second mode (normal light observation mode).

[0167] In the first mode (fluorescence observation mode), the brightness of the image based on the pixel signals output from the first image sensor 531 can be adjusted to approach the brightness of the image in the second mode (normal light observation mode) by using not only the digital gain control unit 944 but also the imaging control unit 942. In this case, the imaging control unit 942 corresponds to the brightness adjustment unit according to the present disclosure.

[0168] Specifically, in the first mode (fluorescence observation mode), the imaging control unit 942 sets the analog gain to a value greater than the analog gain in the second mode (normal light observation mode). Alternatively, in the first mode (fluorescence observation mode), the imaging control unit 942 sets the exposure time (opening amount of the electronic shutter) of the second image sensor 532 to a value greater than the exposure time in the second mode (normal light observation mode). This makes it possible, in the first mode, to bring the brightness of the normal light image, which is the background image in the superimposed image, closer to the brightness of the normal light image in the second mode (normal light observation mode).

[0169] Even when the configuration of Modification 2-9 described above is adopted, the same effects as those of the above-described Embodiment 2 are achieved. Note that the normal light image, which is the background image in the superimposed image, may be an image generated based on at least one of the pixel signals output from the R (red) pixels, G (green) pixels, and B (blue) pixels of the first imaging element 531. Specifically, the normal light image, which is the background image in the superimposed image, may be a color image, a pseudo-color image using only some colors, or a monochrome image having only brightness information.

[0170] (Variation 2-10 of Embodiment 2) The configuration of Variation 2-9 described above may be combined with the configuration of Variation 2-7 described above, which uses multiple drugs. Specifically, in Variation 2-7 described above, if the images generated in the first and second modes are the superimposed images described in Variation 2-9 described above, a phenomenon similar to that of Variation 2-9 described above may occur. That is, a phenomenon may occur in which the brightness of the normal light image that is the background image in the superimposed image in the first mode using the first drug differs from the brightness of the normal light image that is the background image in the superimposed image in the second mode using the second drug.

[0171] Therefore, in the above-described Variation 2-7, similar to the above-described Variation 2-9, a configuration is adopted in which, in the first mode, the brightness of the image based on the pixel signal output from the first image sensor 531 is adjusted to approach the brightness of the image in the second mode. Also, similar to the above-described Variation 2-9, in the above-described Variation 2-7, a configuration is adopted in which, in the first mode, a parameter is set to a value greater than the parameter in the second mode (normal light observation mode). The parameter is at least one of the exposure time (opening amount of the electronic shutter) of the second image sensor 532, the analog gain, and the digital gain. This allows the brightness of the normal light image, which is the background image in the superimposed image in the first mode using the first drug, to approach the brightness of the normal light image, which is the background image in the superimposed image in the second mode using the second drug, even when multiple drugs are used.

[0172] Even when the configuration of the present modified example 2-10 described above is adopted, the same effects as those of the second embodiment and modified examples 2-7 and 2-9 described above can be achieved.

[0173] (Variation 2-11 of Embodiment 2) The configuration of Variation 2-8 described above, which is applied to the first to sixth scenes, may be combined with the configuration of Variation 2-9 described above. Specifically, in Variation 2-8 described above, if the images generated in the first and second modes are the superimposed images described in Variation 2-9 described above, a phenomenon similar to that of Variation 2-9 described above may occur. That is, a phenomenon may occur in which the brightness of the normal light image serving as the background image in the superimposed image generated in the first surgical scene (first mode) differs from the brightness of the normal light image serving as the background image in the superimposed image generated in the second surgical scene (second mode).

[0174] Therefore, in the above-described Variation 2-8, similar to the above-described Variation 2-9, a configuration is adopted in which, in the first mode, the brightness of the image based on the pixel signal output from the first image sensor 531 is adjusted so as to approach the brightness of the image in the second mode. Also, similar to the above-described Variation 2-9, the above-described Variation 2-8 adopts a configuration in which, in the first mode, a parameter is set to a value greater than the parameter in the second mode (normal light observation mode). The parameter is at least one of the exposure time (opening amount of the electronic shutter) of the second image sensor 532, the analog gain, and the digital gain. This allows the brightness of the normal light image, which is the background image in the superimposed image generated in the first surgical scene (first mode), to approach the brightness of the normal light image, which is the background image in the superimposed image in the second surgical scene (second mode).

[0175] Even when the configuration of the present modified example 2-11 described above is adopted, the same effects as those of the second embodiment and modified examples 2-7 and 2-9 described above can be achieved.

[0176] Other Embodiments While the embodiments for carrying out the present disclosure have been described above, the present disclosure should not be limited to the above-described embodiments. In the above-described first and second embodiments, the first and second image sensors 531 and 532 are configured by CMOS, but this is not a limitation and they may be configured by CCDs (Charge Coupled Devices).

[0177] In the first and second embodiments described above, the NTSC system is exemplified and 1 / 60 [s] is used as the reference, but this is not limited thereto. In the case of the PAL system, 1 / 50 [s] may be used as the reference, or a high-speed imaging operation (e.g., 1 / 240 [s]) may be used as the reference. Furthermore, the readout timing of each field at the first imaging element 531 and the second imaging element 532 may be the same or may be shifted. For example, in the case of the NTSC system, the readout timing of each field at the first imaging element 531 and the second imaging element 532 may be shifted by 1 / 120 [s]. Furthermore, in the first and second embodiments described above, the first imaging element 531 reads at 1 / 60 [s] and the second imaging element 532 reads at 1 / 120 [s], but the readout speeds of the first and second imaging elements 531 and 532 are not limited thereto. That is, the readout speeds of the first and second image sensors 531 and 532 may be the same or different. For example, in the case of the NTSC system, both the first and second image sensors 531 and 532 may read out at 1 / 120 [s].

[0178] In the first mode of the second embodiment described above, the predetermined value (control value in the first control) according to the present disclosure may be changed, similar to the above-described modified examples 1-1 to 1-5.

[0179] In the first and second embodiments described above, the light source controller 941 adjusts the brightness of the normal light image based on the brightness of a specific region (detection region) in the normal light image. The light source controller 941 then references the ratio information stored in the storage unit 97 and performs dimming control to maintain a specific ratio between the intensity of the first light and the intensity of the excitation light. However, the light source controller 941 is not limited to performing dimming control to maintain such a light intensity ratio. The light source controller 941 may also perform dimming control to maintain a specific ratio between the intensity of the first light and the intensity of the excitation light. For example, the light source controller 941 may adjust the intensity of the excitation light independently of the adjustment of the intensity of the first light, based on the brightness of a specific region (detection region) in the fluorescence image, to adjust the fluorescence image to a reference brightness. Furthermore, for example, the light source controller 941 may control the operation of the second light source 32 so that the intensity of the excitation light is a fixed value (constant value). In this case, the fixed value may be changeable in response to a user operation on the input unit 95.

[0180] In the above-described first and second embodiments, the following modified examples 3-1 and 3-2 may be adopted.

[0181] (Variation 3-1) The medical observation system according to Variation 3-1 is a medical observation system that uses a so-called videoscope (flexible endoscope) that has an imaging unit at the tip of an insertion section. For ease of explanation, the medical observation system 1 according to Variation 3-1 will be referred to as medical observation system 1B below.

[0182] Fig. 18 is a diagram showing a modified example 3-1 of Embodiments 1 and 2. As shown in Fig. 18, the medical observation system 1B includes an endoscope 300B that captures in-vivo images of an observation site by inserting an insertion section 2B into a living body and outputs the captured images, a light source device 3 that emits first light and excitation light from the tip of the endoscope 300B, a control device 9 that processes the captured images output from the endoscope 300B, and a display device 7 that is connected to the control device 9 via a second transmission cable 8 and displays an image based on a video signal processed by the control device 9.

[0183] 18, the endoscope 300B includes a flexible, elongated insertion section 2B, an operation section 301 connected to the base end side of the insertion section 2B and accepting various operations, and a universal cord 302 extending from the operation section 301 in a direction different from the direction in which the insertion section 2B extends and incorporating various cables connecting to the light source device 3 and the control device 9. As shown in Fig. 19, the insertion section 2B includes a tip section 24, a freely bendable bending section 25 connected to the base end side of the tip section 24 and made up of a plurality of bending pieces, and a flexible, long flexible tube section 26 connected to the base end side of the bending section 25.

[0184] Although not specifically shown in the drawings, the tip unit 24 has a built-in configuration that is substantially the same as that of the camera head 5 described in the above-mentioned embodiments 1 and 2. An image captured by the tip unit 24 (image pickup element) is output to the control device 9 via the operation unit 301 and the universal cord 302.

[0185] Even when the configuration of the present modified example 3-1 described above is adopted, the same effects as those of the first and second embodiments described above can be achieved.

[0186] (Variation 3-2) The medical observation system according to Variation 3-2 is a medical observation system that uses a surgical microscope to magnify and capture images of a predetermined field of view of the inside of a subject (inside a living body) or the surface of a subject (surface of a living body), which is the observation target. For ease of explanation, the medical observation system 1 according to Variation 3 will be referred to as medical observation system 1C below.

[0187] Fig. 19 is a diagram showing a modified example 3-2 of embodiments 1 and 2. As shown in Fig. 19, the medical observation system 1C comprises a surgical microscope 12 that captures images for observing a subject and outputs the captured images, a control device 9 that processes the captured images output from the surgical microscope 12, and a display device 7 that is connected to the control device 9 via a second transmission cable 8 and displays images based on video signals processed by the control device 9.

[0188] As shown in Fig. 19 , the surgical microscope 12 includes a microscope unit 121 that magnifies and captures a minute portion of a subject and outputs the captured image, a support unit 122 that is connected to the base end of the microscope unit 121 and includes an arm that rotatably supports the microscope unit 121, and a base unit 123 that rotatably holds the base end of the support unit 122 and is movable on the floor. The control device 9 is mounted on the base unit 123 as shown in Fig. 19 . Although not specifically shown, the light source device 3 that emits first light and excitation light from the surgical microscope 12 to the observation target is also mounted on the base unit 123. The base unit 123 may be configured to support the support unit 122 by being fixed to a ceiling, wall, or the like, rather than being movable on the floor.

[0189] Although not specifically shown in the drawings, the microscope unit 121 has a built-in configuration that is substantially the same as that of the camera head 5 described in the above-mentioned Embodiments 1 and 2. The image captured by the microscope unit 121 (image capture element) is output to the control device 9 via a first transmission cable 6 wired along the support unit 122.

[0190] Even when the configuration of the present modified example 3-2 described above is adopted, the same effects as those of the first and second embodiments described above can be achieved.

[0191] (Variation 3-3) Figures 20 and 21 are diagrams illustrating Variation 3-3 of the embodiment. Specifically, Figure 20 is a view of the ring light 15 as seen from the side. Figure 21 is a view of the ring light 15 as seen from the front side (left side in Figure 20). In this Variation 4, in addition to the insertion section 2 described in the above-mentioned embodiments 1 and 2, the ring light 15 shown in Figures 20 and 21 is detachably connected to the camera head 5. That is, depending on the usage state of the user, as shown in Figure 20, there are cases where the insertion section 2 is connected to the camera head 5, and cases where the ring light 15 is connected.

[0192] The ring light 15 is not inserted into the observation object OB like the insertion section 2, but supplies the first light and excitation light to the surgical site and captures the second light (subject image) which is the return light of the first light and excitation light from the surgical site. As shown in Figures 20 and 21, the ring light 15 includes an illumination section 151 and a subject image capture section 152 that captures the subject image.

[0193] 20 and 21 , the illumination unit 151 includes a housing 1511 and a plurality of illumination lenses 1512. The housing 1511 has an annular shape centered on the optical axis Ax. The other end of the light guide 4 is detachably connected to the housing 1511.

[0194] 21 , the multiple illumination lenses 1512 are arranged at predetermined intervals along the circumferential direction centered on the optical axis Ax on the front end surface of the housing 1511. The multiple illumination lenses 1512 each irradiate the first light, which is supplied from the light source device 3 and introduced into the housing 1511 via the light guide 4, toward the surgical site.

[0195] The subject image capture unit 152 extends along the optical axis Ax. An optical system configured with one or more lenses is provided within the subject image capture unit 152, and focuses second light (subject image) emitted from the multiple illumination lenses 1512 and transmitted through the surgical site. A connector 1521 is provided at the end on the proximal side (right side in FIG. 20 ) of the subject image capture unit 152. This connector 1521 has a design (shape) compatible with the eyepiece 21 of the insertion unit 2, and is detachably connected to the camera head 5.

[0196] Even when the configuration of the present modified example 3-3 described above is adopted, the same effects as those of the first and second embodiments described above can be achieved.

[0197] The following configurations also fall within the technical scope of the present disclosure. (1) A medical control device includes: a light source control unit that executes a first control to cause a light source device to emit first light including at least a part of a visible light wavelength band; and a second control to cause the light source device to emit excitation light that excites a substance contained in an observation object; an imaging control unit that controls the operation of a first image sensor that captures light including at least a part of the visible light wavelength band from the first light and second light that is return light of the excitation light from the observation object; and a second image sensor that captures light including at least a part of the wavelength band of observation object fluorescence emitted from the observation object by irradiation with the excitation light from the second light; and a mode switching unit that switches between a first mode and a second mode, wherein the light source control unit sets a control value in the first control to a control value that is equal to or less than a control threshold value when in the first mode, and sets a control value in the first control to a control value that is greater than the control threshold value when in the second mode, and the control threshold value is the maximum control value at which a signal value based on the observation object fluorescence, imaged by the second image sensor, is greater than a signal value based on unwanted light generated at least due to the first light. (2) The medical control device according to (1), wherein the control value in the first control includes at least one of an emission period of the first light from the light source device and a current value supplied to the light source device to emit the first light. (3) The medical control device according to (1) or (2), further comprising an operation receiving unit that receives a user operation, wherein the mode switching unit switches between the first mode and the second mode in response to the user operation. (4) The medical control device according to (1) or (2), wherein the mode switching unit switches between the first mode and the second mode based on a type of endoscope connected to the medical control device. (5) The medical control device according to (1) or (2), wherein the medical control device is configured to be connectable to an open field observation device or an endoscopic observation device, and wherein the mode switching unit switches to the second mode when the open field observation device is connected to the medical control device, and switches to the first mode when the endoscopic observation device is connected to the medical control device.(6) The medical control device according to (1) or (2), wherein the mode switching unit switches between the first mode and the second mode based on a signal value of a pixel signal output from the first imaging element. (7) The medical control device according to (1) or (2), wherein the mode switching unit switches between the first mode and the second mode based on a signal value of a pixel signal output from the second imaging element. (8) The medical control device according to (1) or (2), wherein the mode switching unit switches between the first mode and the second mode based on a type of substance contained in the observation target that is excited by the excitation light. (9) The medical control device according to any one of (1) to (8), wherein the control value in the first control is an emission period of the first light from the light source device, and the control threshold is a period equal to or shorter than a full-line exposure period of the first imaging element. (10) The medical control device according to any one of (1) to (9), wherein the light source control unit, in the first mode, executes the first control so that a signal value based on unwanted light captured by the second image sensor and generated due to at least the first light is smaller than a signal value based on the unwanted light in the second mode. (11) The medical control device according to any one of (1) to (10), wherein the first mode is a fluorescence observation mode in which a display image is generated based on pixel signals output from the first image sensor and the second image sensor, and the second mode is a normal light observation mode in which a display image is generated based on pixel signals output from only the first image sensor out of the first image sensor and the second image sensor. (12) The medical control device according to any one of (1) to (10), wherein the first mode is a mode corresponding to a first drug that emits the observation object fluorescence when irradiated with the excitation light, and the second mode is a mode corresponding to a second drug that is different from the first drug and emits the observation object fluorescence when irradiated with the excitation light. (13) The medical control device according to (12), wherein the intensity of the observation object fluorescence caused by the first drug is smaller than the intensity of the observation object fluorescence caused by the second drug.(14) The medical control device according to any one of (1) to (10), wherein the first mode is a mode corresponding to a first surgical scene, and the second mode is a mode corresponding to a second surgical scene different from the first surgical scene. (15) The medical control device according to (14), wherein the intensity of the observation object fluorescence in the first surgical scene is smaller than the intensity of the observation object fluorescence in the second surgical scene. (16) The medical control device according to (14), comprising: a light source control unit that executes a first control to cause a light source device to emit first light including at least a part of a visible light wavelength band, and a second control to cause the light source device to emit excitation light that excites a substance included in the observation object; an imaging control unit that controls the operation of a first image sensor that captures light including at least a part of a visible light wavelength band among second light that is the first light and return light of the excitation light from the observation object, and a second image sensor that captures light including at least a part of the wavelength band of the observation object fluorescence emitted from the observation object by irradiation with the excitation light among the second light; and a brightness control unit that adjusts the brightness of an image based on pixel signals output from the first imaging element when in the first mode, wherein the light source control unit sets a control value for the first control to a control value that is equal to or less than a control threshold when in the first mode, and sets the control value for the first control to a control value that is greater than the control threshold when in the second mode, and the brightness control unit adjusts the brightness of an image based on pixel signals output from the first imaging element when in the first mode so that the brightness approaches the brightness of the image when in the second mode.(17) A light source control unit that executes a first control to cause a light source device to emit first light including at least a part of a visible light wavelength band and a second control to cause the light source device to emit excitation light that excites a substance included in an observation target; an imaging control unit that controls the operation of a first imaging element that captures light including at least a part of a visible light wavelength band among second light that is the first light from the observation target and return light of the excitation light, and a second imaging element that captures light including at least a part of a wavelength band of observation target fluorescence emitted from the observation target by irradiation with the excitation light among the second light; a mode switching unit that switches between a first mode and a second mode; and a brightness control unit that controls the brightness of an image based on a pixel signal output from the first imaging element. and a brightness control unit that adjusts a brightness of an image based on a pixel signal output from the first imaging element, wherein the light source control unit sets a control value for the first control to a control value that is equal to or less than a control threshold when in the first mode, and sets the control value for the first control to a control value that is greater than the control threshold when in the second mode, and the brightness control unit sets a parameter to a value that is greater than the parameter in the second mode when in the first mode, and the parameter is at least one of an exposure time of the first imaging element, an analog gain that adjusts the brightness of an image based on a pixel signal output from the first imaging element, and a digital gain that adjusts the brightness of an image based on a pixel signal output from the first imaging element.(18) A medical imaging device includes a light source device that emits first light including at least a part of a visible light wavelength band and excitation light that excites a substance included in an observation target, an imaging device including a first image sensor that captures light including at least a part of a visible light wavelength band among second light that is return light of the first light and the excitation light from the observation target, and a second image sensor that captures light including at least a part of a wavelength band of observation target fluorescence emitted from the observation target by irradiation with the excitation light among the visible light and the return light of the excitation light, and a medical control device that controls the operations of the light source device and the imaging device, respectively, and the medical control device is configured to control the first control of the light source device to emit the first light. a light source controller that executes a first control and a second control that causes the light source device to emit the excitation light, an imaging controller that controls the operation of the imaging device, and a mode switching unit that switches between a first mode and a second mode, wherein the light source controller sets a control value for the first control to a control value equal to or less than a control threshold when in the first mode, and sets the control value for the first control to a control value greater than the control threshold when in the second mode, the control threshold being the maximum control value at which a signal value based on the fluorescence of the object of observation, imaged by the second imaging element, is greater than a signal value based on unwanted light generated at least due to the first light. (19) The medical observation system according to (18), wherein the first light is broadband light or narrowband light. (20) The medical observation system according to (18) or (19), wherein the light source device includes a first light source that emits the first light, and the first light source is composed of one or more light sources. (21) The medical observation system according to any one of (18) to (20), wherein the light source device includes a first light source that emits the first light, and the first light source is configured with an LED or a semiconductor laser. (22) The medical observation system according to any one of (18) to (21), wherein the excitation light is narrowband light. (23) The medical observation system according to any one of (18) to (22), wherein the light source device includes a second light source that emits the excitation light, and the second light source is configured with one or more light sources.(24) The medical observation system according to any one of (18) to (23), wherein the light source device includes a second light source that emits the excitation light, and the second light source is configured as an LED or a semiconductor laser. (25) The medical observation system includes a light source device that respectively emits first light including at least a part of a visible light wavelength band and excitation light that excites a substance contained in an observation object, an imaging device including a first image sensor that captures light including at least a part of the visible light wavelength band among the first light and second light that is return light of the excitation light from the observation object, and a second image sensor that captures light including at least a part of the wavelength band of observation object fluorescence emitted from the observation object by irradiation with the excitation light among the visible light and return light of the excitation light, and a medical control device that controls the operations of the light source device and the imaging device, respectively, and the medical control device controls a first control that causes the light source device to emit the first light, and a second control that causes the light source device to emit the excitation light. a light source control unit that performs a first control and a second control, an imaging control unit that controls the operation of the imaging device, a mode switching unit that switches between a first mode and a second mode, and a brightness control unit that adjusts the brightness of an image based on pixel signals output from the first imaging element, wherein the light source control unit, when in the first mode, sets a control value for the first control to a control value that is equal to or less than a control threshold, and, when in the second mode, sets the control value for the first control to a control value that is greater than the control threshold, and the brightness control unit, when in the first mode, adjusts the brightness of the image based on the pixel signals output from the first imaging element to approach the brightness of the image in the second mode.(26) A medical imaging device includes a light source device that emits first light including at least a part of a visible light wavelength band and excitation light that excites a substance contained in an observation object, an imaging device including a first image sensor that captures light including at least a part of a visible light wavelength band among second light that is return light of the first light and the excitation light from the observation object, and a second image sensor that captures light including at least a part of a wavelength band of observation object fluorescence emitted from the observation object by irradiation with the excitation light among the visible light and the return light of the excitation light, and a medical control device that controls the operations of the light source device and the imaging device, respectively, wherein the medical control device includes a light source control unit that executes first control to cause the light source device to emit the first light and second control to cause the light source device to emit the excitation light, an imaging control unit that controls the operation of the imaging device, and a first mode or and a brightness control unit that adjusts the brightness of an image based on pixel signals output from the first image sensor, wherein the light source control unit, when in the first mode, sets a control value for the first control to a control value that is equal to or less than a control threshold, and, when in the second mode, sets the control value for the first control to a control value that is greater than the control threshold; and the brightness control unit, when in the first mode, sets a parameter to a value that is greater than the parameter in the second mode, and the parameter is at least one of an exposure time of the first image sensor, an analog gain that adjusts the brightness of an image based on pixel signals output from the first image sensor, and a digital gain that adjusts the brightness of an image based on pixel signals output from the first image sensor.

[0198] DESCRIPTION OF SYMBOLS 1, 1A to 1C Medical observation system 2, 2B Insertion section 3 Light source device 4 Light guide 5 Camera head 6 First transmission cable 7 Display device 8 Second transmission cable 9 Control device 10 Third transmission cable 12 Surgical microscope 15 Ring light 21 Eyepiece section 22 Excitation light cut filter 23 Memory 24 Tip section 25 Bending section 26 Flexible tube section 31 First light source 32 Second light source 33 Third light source 34 Fourth light source 51 Lens unit 52 Prism 53 Imaging section 54 Communication section 91 Communication section 92 Image memory 93 Processing module 94 Control section 95 Input section 96 Output section 97 Storage section 100 Endoscopic observation device 101 Memory 121 Microscope section 122 Support section 123 Base section DESCRIPTION OF SYMBOLS 151 Illumination unit 152 Subject image capture unit 200 Open field observation device 201 Memory 300B Endoscope 301 Operation unit 302 Universal cord 531 First image capture element 532 Second image capture element 533 Signal processing unit 931 Memory controller 932 First image processing unit 933 Second image processing unit 934 Display control unit 941 Light source control unit 942 Imaging control unit 943 Mode switching unit 944 Digital gain control unit 1511 Housing 1512 Illumination lens 1521 Connection unit Ar1, Ar2 Area Ax Optical axis CN1, CN2 Connector F1 First subject F2 Second subject L1 Unwanted light L2 Observation subject fluorescence OB Observation subject P0 Observation optical path P1 First optical path P2 Second optical path TE All line exposure period

Claims

1. A light source control unit that executes a first control for causing a light source device to emit a first light including at least a part of a visible light wavelength band, and a second control for causing the light source device to emit excitation light for exciting a substance included in an object of observation, an imaging control unit that controls the operation of a first imaging element that captures light including at least a part of a visible light wavelength band among the first light and second light which is return light of the excitation light from the object of observation, and a second imaging element that captures light including at least a part of the wavelength band of the object of observation fluorescence emitted from the object of observation by irradiation with the excitation light among the second light, and a mode switching unit that switches between a first mode and a second mode, wherein the light source control unit sets a control value in the first control to a control value equal to or lower than a control threshold value when in the first mode, and sets a control value in the first control to a control value greater than the control threshold value when in the second mode, and the control threshold value is A medical control device, wherein the control value is a maximum value at which a signal value based on the fluorescence of the object to be observed, which is imaged by the second imaging element, is greater than a signal value based on unwanted light generated at least due to the first light.

2. A medical control device as described in claim 1, wherein the control value in the first control includes at least one of a period during which the first light is emitted from the light source device and a current value supplied to the light source device to emit the first light.

3. A medical control device as described in claim 1, further comprising an operation receiving unit that receives user operation, wherein the mode switching unit switches between the first mode and the second mode in response to the user operation.

4. A medical control device as described in claim 1, wherein the mode switching unit switches between the first mode and the second mode based on the type of endoscope connected to the medical control device.

5. A medical control device as described in claim 1, wherein the medical control device is configured to be connectable to an open field observation device or an endoscopic observation device, and the mode switching unit switches to the second mode when the open field observation device is connected to the medical control device, and switches to the first mode when the endoscopic observation device is connected to the medical control device.

6. The medical control device according to claim 1, wherein the mode switching unit switches between the first mode and the second mode based on a signal value of a pixel signal output from the first imaging element.

7. The medical control device according to claim 1, wherein the mode switching unit switches between the first mode and the second mode based on a signal value of a pixel signal output from the second imaging element.

8. A medical control device as described in claim 1, wherein the mode switching unit switches between the first mode and the second mode based on the type of substance contained in the object of observation that is excited by the excitation light.

9. A medical control device as described in claim 1, wherein the control value in the first control is the emission period of the first light from the light source device, and the control threshold is a period less than or equal to the total line exposure period of the first imaging element.

10. The medical control device of claim 1, wherein the light source control unit executes the first control so that, in the first mode, a signal value based on unwanted light captured by the second imaging element and generated due to at least the first light is smaller than the signal value based on the unwanted light in the second mode.

11. A medical control device as described in claim 1, wherein the first mode is a fluorescence observation mode in which an image for display is generated based on pixel signals output from the first imaging element and the second imaging element, respectively, and the second mode is a normal light observation mode in which an image for display is generated based on pixel signals output from only the first imaging element of the first imaging element and the second imaging element.

12. A medical control device as described in claim 1, wherein the first mode is a mode corresponding to a first drug that emits the fluorescence of the object to be observed when irradiated with the excitation light, and the second mode is a mode corresponding to a second drug that is different from the first drug and emits the fluorescence of the object to be observed when irradiated with the excitation light.

13. The medical control device according to claim 12, wherein the intensity of the fluorescence of the object to be observed due to the first drug is smaller than the intensity of the fluorescence of the object to be observed due to the second drug.

14. A medical control device as described in claim 1, wherein the first mode is a mode corresponding to a first surgical scene, and the second mode is a mode corresponding to a second surgical scene different from the first surgical scene.

15. The medical control device according to claim 14, wherein the intensity of the fluorescence of the object being observed in the first surgical scene is smaller than the intensity of the fluorescence of the object being observed in the second surgical scene.

16. A light source control unit that executes a first control for emitting first light including at least a part of a visible light wavelength band from a light source device, and a second control for emitting excitation light for exciting a substance contained in an object of observation from the light source device; an imaging control unit that controls the operation of a first imaging element that captures light including at least a part of a visible light wavelength band among the first light and second light which is return light of the excitation light from the object of observation, and a second imaging element that captures light including at least a part of the wavelength band of the object of observation fluorescence emitted from the object of observation by irradiation with the excitation light among the second light; a mode switching unit that switches between a first mode and a second mode; and a brightness control unit that adjusts the brightness of an image based on a pixel signal output from the first imaging element, wherein the light source control unit sets the control value in the first control to a control value equal to or lower than a control threshold value when in the first mode, and sets the control value in the first control to a control value greater than the control threshold value when in the second mode, and the brightness control unit A medical control device that, when in the first mode, adjusts the brightness of an image based on a pixel signal output from the first imaging element so that it approaches the brightness of the image in the second mode.

17. A light source control unit that executes a first control for emitting first light including at least a part of a visible light wavelength band from a light source device, and a second control for emitting excitation light for exciting a substance contained in an object of observation from the light source device; an imaging control unit that controls the operation of a first imaging element that captures light including at least a part of a visible light wavelength band among the first light and second light which is return light of the excitation light from the object of observation, and a second imaging element that captures light including at least a part of the wavelength band of the object of observation fluorescence emitted from the object of observation by irradiation with the excitation light among the second light; a mode switching unit that switches between a first mode and a second mode; and a brightness control unit that adjusts the brightness of an image based on a pixel signal output from the first imaging element, wherein the light source control unit: when in the first mode, sets a control value in the first control to a control value equal to or lower than a control threshold value; and when in the second mode, sets a control value in the first control to a control value greater than the control threshold value; and the brightness control unit: A medical control device that, when in the first mode, sets a parameter to a value greater than the parameter in the second mode, the parameter being at least one of an exposure time of the first imaging element, an analog gain that adjusts the brightness of an image based on a pixel signal output from the first imaging element, and a digital gain that adjusts the brightness of an image based on a pixel signal output from the first imaging element.

18. A medical imaging device comprising: a light source device which respectively emits first light including at least a part of the visible light wavelength band and excitation light for exciting a substance contained in an object of observation; an imaging device including a first imaging element which images light including at least a part of the visible light wavelength band among second light which is the first light and return light of the excitation light from the object of observation, and a second imaging element which images light including at least a part of the wavelength band of the object of observation fluorescence emitted from the object of observation by irradiation with the excitation light among the visible light and the return light of the excitation light; and a medical control device which controls the operation of the light source device and the imaging device, respectively, the medical control device comprising: a light source control unit which respectively executes a first control for causing the light source device to emit the first light and a second control for causing the light source device to emit the excitation light; an imaging control unit which controls the operation of the imaging device; and a mode switching unit which switches between a first mode and a second mode, the light source control unit setting a control value in the first control to a control value equal to or lower than a control threshold value when in the first mode, a medical observation system in which, in the second mode, a control value in the first control is set to a control value greater than the control threshold value, and the control threshold value is a maximum control value at which a signal value based on the fluorescence of the object of observation, which is imaged by the second image sensor, is greater than a signal value based on unwanted light generated due to at least the first light.

19. The medical observation system according to claim 18, wherein the first light is broadband light or narrowband light.

20. The medical observation system according to claim 18, wherein the light source device includes a first light source that emits the first light, and the first light source is composed of one or more light sources.

21. The medical observation system according to claim 18, wherein the light source device includes a first light source that emits the first light, and the first light source is configured with an LED or a semiconductor laser.

22. The medical observation system according to claim 18, wherein the excitation light is narrowband light.

23. The medical observation system according to claim 18, wherein the light source device includes a second light source that emits the excitation light, and the second light source is composed of one or more light sources.

24. The medical observation system according to claim 18, wherein the light source device includes a second light source that emits the excitation light, and the second light source is configured with an LED or a semiconductor laser.

25. A medical imaging device comprising: a light source device which respectively emits first light including at least a part of the visible light wavelength band and excitation light for exciting a substance contained in an object of observation; an imaging device including a first imaging element which images light including at least a part of the visible light wavelength band among the first light and second light which is return light of the excitation light from the object of observation, and a second imaging element which images light including at least a part of the wavelength band of the fluorescence of the object of observation emitted from the object of observation by irradiation with the excitation light among the visible light and the return light of the excitation light; and a medical control device which controls the operation of the light source device and the imaging device, respectively, the medical control device comprising: a light source control unit which respectively executes a first control for causing the light source device to emit the first light, and a second control for causing the light source device to emit the excitation light; an imaging control unit which controls the operation of the imaging device; a mode switching unit which switches between a first mode and a second mode; and a brightness control unit which adjusts the brightness of an image based on a pixel signal output from the first imaging element, the light source control unit comprising: A medical observation system in which, when in the first mode, a control value in the first control is set to a control value equal to or lower than a control threshold, and, when in the second mode, a control value in the first control is set to a control value greater than the control threshold, and the brightness control unit adjusts, when in the first mode, the brightness of an image based on a pixel signal output from the first imaging element so as to approach the brightness of the image in the second mode.

26. A medical imaging device comprising: a light source device which respectively emits first light including at least a part of the visible light wavelength band and excitation light for exciting a substance contained in an object of observation; an imaging device including a first imaging element which images light including at least a part of the visible light wavelength band among the first light and second light which is return light of the excitation light from the object of observation, and a second imaging element which images light including at least a part of the wavelength band of the object of observation fluorescence emitted from the object of observation by irradiation with the excitation light among the visible light and the return light of the excitation light; and a medical control device which controls the operation of the light source device and the imaging device, respectively, the medical control device comprising: a light source control unit which respectively executes a first control for causing the light source device to emit the first light and a second control for causing the light source device to emit the excitation light; an imaging control unit which controls the operation of the imaging device; a mode switching unit which switches between a first mode and a second mode; and a brightness control unit which adjusts the brightness of an image based on a pixel signal output from the first imaging element, the light source control unit comprising: A medical observation system in which, when in the first mode, a control value in the first control is set to a control value equal to or lower than a control threshold, and, when in the second mode, a control value in the first control is set to a control value greater than the control threshold, and the brightness control unit, when in the first mode, sets a parameter to a value greater than the parameter in the second mode, the parameter being at least one of an exposure time of the first imaging element, an analog gain that adjusts the brightness of an image based on a pixel signal output from the first imaging element, and a digital gain that adjusts the brightness of an image based on a pixel signal output from the first imaging element.

Images