Medical control device and medical observation system

Abstract

To generate an image suitable for observation.SOLUTION: A medical control device 9 includes an imaging control unit 943 for causing an image pick-up device to image first return light from an observation object irradiated with first light, which is narrow band light, and second return light from an observation object irradiated with second light respectively. The imaging control unit 943 includes a shutter control part for changing a signal value related to a first image generated by the image pick-up device by the imaging of the first return light by controlling an opening amount of a shutter for imaging. When the ratio of the signal value related to the first image to a signal value related to a second image generated by the image pick-up device by the imaging of the second return light when an opening amount of the shutter is a first opening amount is represented as a first ratio, the shutter control part changes the ratio of the signal value related to the first image to the signal value related to the second image to a second ratio smaller than the first ratio by changing the opening amount of the shutter from the first opening amount to a second opening amount smaller than the first opening amount.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, a medical observation system has been known in which excitation light, which is narrow-band light emitted from a light source device, is irradiated onto an observation object (a subject such as a human being) and fluorescence emitted from a substance contained in the observation object due to the irradiation of the excitation light is observed (see, for example, Patent Document 1). Such fluorescence observation makes it possible to grasp tissue conditions that are difficult to recognize through fluorescence, and therefore can be used for various purposes and applications, such as identifying lesions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-119524 Summary of the Invention [Problem to be solved by the invention]

[0004] The intensity of fluorescence during fluorescence observation varies depending on the conditions for the observation. For example, drugs administered to the observation subject can be a first drug that emits weak fluorescence and a second drug that emits strong fluorescence. When the first drug is used, the intensity of the fluorescence can be increased (the image captured from the fluorescence can be made brighter) by signal processing (increasing the analog gain or digital gain). On the other hand, when the second drug is used, the signal value of the image becomes saturated when the fluorescence is captured, and the gradation of the image is lost even if signal processing (reducing the analog gain or digital gain) is simply performed. Therefore, there is a demand for a technology that can generate an image suitable for observation.

[0005] The present disclosure has been made in view of the above, and aims to provide a medical control device and a medical observation system that are capable of generating images suitable for observation. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the medical control device of the present disclosure includes an imaging control unit that controls the operation of an imaging element and causes the imaging element to capture first return light from an object of observation irradiated with first light, which is narrowband light, and second return light from the object of observation irradiated with second light having a wavelength band different from the narrowband light, respectively. The imaging control unit includes a shutter control unit that changes a signal value related to a first image generated by the imaging element when the first return light is captured by controlling the opening amount of an imaging shutter. When the ratio of the signal value related to the first image to the signal value related to a second image generated by the imaging element when the second return light is captured when the opening amount of the shutter is a first opening amount, the shutter control unit changes the opening amount of the shutter from the first opening amount to a second opening amount that is smaller than the first opening amount, thereby changing the ratio of the signal value related to the first image to the signal value related to the second image to a second ratio that is smaller than the first ratio.

[0007] In addition, the medical control device according to the present disclosure includes an imaging control unit that controls the operation of an imaging element and causes the imaging element to capture return light from an object of observation irradiated with narrowband light, and the imaging control unit includes a shutter control unit that changes a signal value related to an image generated by the imaging element by capturing the return light by controlling the opening amount of an imaging shutter, and when the signal value becomes saturated when the opening amount of the shutter is set to a first opening amount, the shutter control unit desaturates the signal value by setting the opening amount of the shutter to a second opening amount that is smaller than the first opening amount.

[0008] Furthermore, a medical observation system according to the present disclosure includes an image sensor that captures first return light from an observation object irradiated with first light, which is narrowband light, and second return light from the observation object irradiated with second light having a wavelength band different from that of the narrowband light, and an image sensor that controls the operation of the image sensor. The image sensor includes a shutter controller that controls an opening amount of an image sensor to change a signal value associated with a first image generated by the image sensor when the first return light is captured. When a ratio of a signal value associated with the first image to a signal value associated with a second image generated by the image sensor when the second return light is captured when the shutter opening amount is a first opening amount, the shutter controller changes the opening amount of the shutter from the first opening amount to a second opening amount that is smaller than the first opening amount, thereby changing the ratio of the signal value associated with the first image to the signal value associated with the second image to a second ratio that is smaller than the first ratio.

[0009] Furthermore, a medical observation system according to the present disclosure includes an image sensor that captures an image of return light from an observation object irradiated with narrowband light, and an image sensor control unit that controls the operation of the image sensor, wherein the image sensor control unit includes a shutter control unit that changes a signal value associated with an image generated by the image sensor by capturing the return light by controlling an opening amount of an image capturing shutter, and when the signal value becomes saturated when the opening amount of the shutter is set to a first opening amount, the shutter control unit desaturates the signal value by setting the opening amount of the shutter to a second opening amount that is smaller than the first opening amount. [Effects of the Invention]

[0010] The medical control device and medical observation system according to the present disclosure can generate images suitable for observation. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing the configuration of a medical observation system according to an embodiment. [Figure 2]FIG. 2 is a block diagram showing the configuration of the camera head and the control device. [Figure 3] FIG. 3 is a diagram illustrating the problems encountered in the conventional technology. [Figure 4] FIG. 4 is a diagram illustrating gain control, light source control, and electronic shutter control according to the embodiment. [Figure 5] FIG. 5 is a diagram showing the fluorescence gain set by the user. [Figure 6] FIG. 6 is a diagram illustrating a first modification of the embodiment. [Figure 7] FIG. 7 is a diagram illustrating a first modification of the embodiment. [Figure 8] FIG. 8 is a diagram illustrating a first modification of the embodiment. [Figure 9] FIG. 9 is a diagram illustrating a first modification of the embodiment. [Figure 10] FIG. 10 is a diagram illustrating a first modification of the embodiment. [Figure 11] FIG. 11 is a diagram illustrating a first modification of the embodiment. [Figure 12] FIG. 12 is a diagram illustrating a second modification of the embodiment. [Figure 13] FIG. 13 is a diagram illustrating a third modification of the embodiment. [Figure 14] FIG. 14 is a diagram illustrating a fourth modification of the embodiment. [Figure 15] FIG. 15 is a diagram illustrating a fourth modification of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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 drawings, the same parts are denoted by the same reference numerals.

[0013] [Configuration of medical observation system] FIG. 1 is a diagram showing the configuration of a medical observation system 1 according to an embodiment. In this embodiment, the medical observation system 1 is a medical endoscope system that uses an endoscope to observe an observation target (inside a living body). 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.

[0014] In this embodiment, the insertion section 2 is configured as a rigid endoscope. That is, the insertion section 2 has an elongated shape that is entirely rigid or has a soft portion and a rigid portion, and is inserted into an observation object. The insertion section 2 includes an optical system configured using one or more lenses that focuses return light (subject image) from the observation object.

[0015] The light source device 3 is connected to one end of the light guide 4 and includes a first light source 31 (FIG. 1) that supplies a first light to the one end of the light guide 4 under the control of the control device 9, and a second light source 32 (FIG. 1) that supplies a second light to the one end of the light guide 4. In this embodiment, the first light is excitation light, which is narrow-band light. The first light may be visible light or invisible light. The second light is white light including a visible wavelength band. The first light source 31 may be configured with an LED (Light Emitting Diode) or a semiconductor laser. The second light source 32 may also be configured with an LED or a semiconductor laser. The number of first light sources 31 that emit the first light may be one or more. The number of second light sources 32 that emit the second light may also be one or more.

[0016] Here, examples of substances contained in the object of observation that are excited by the first light include drugs or fluorescent dyes that are applied to the object of observation, or fluorescent substances derived from the object of observation that constitute the object of observation itself.

[0017] Examples of the above-mentioned drugs that are administered to the subject of observation 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."

[0018] The above-mentioned fluorescent dyes that can be applied to the object of observation include "coumarine," "Cy3," "DyLight547," "GE3126," "metal nanoclusters," "oxacarbocyanine," "rhodamine," "riboflavin," "fluorescein," "AlexaFluor 488," "AlexaFluor 660," "AlexaFluor 680," "AlexaFluor 700," "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 Examples include "Fluor 750", "Indocarbocyanine", "IR-786", "IRDye 800CW", "IRDye 800RS", "IRDye 800BK", "Nervelight", "OTL-38", "Polymethine", "VivoTag-S750", "ASP5354", and "Xanthene".

[0019] Furthermore, examples of fluorescent substances derived from the observation target that constitute the observation target itself include "collagen," "elastin," and "NADH."

[0020] In this embodiment, the light source device 3 is configured as a separate entity from the control device 9, but this is not limiting, 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.

[0021] One end of the light guide 4 is detachably connected to the light source device 3, and the other end is detachably connected to the insertion section 2. The light guide 4 propagates the first and second light beams supplied from the light source device 3 (first and second light sources 31 and 32) from one end to the other end, supplying them to the insertion section 2. The first and second light beams supplied to the insertion section 2 are emitted from the tip of the insertion section 2 and irradiated onto the observation object. The first and second light beams irradiated onto the observation object and returned from the observation object (subject image) are collected by an optical system within the insertion section 2. The returned light of the first light (hereinafter referred to as the first returned light) includes not only the first light reflected from the observation object, but also fluorescence emitted from the substance when the first light is irradiated onto the observation object and the substance is excited. The returned light of the second light (hereinafter referred to as the second returned light) is the second light reflected from the observation object.

[0022] The camera head 5 is detachably connected to the proximal end (eyepiece 21 (FIG. 1)) of the insertion section 2. Under the control of the control device 9, the camera head 5 captures the first and second return light beams collected by the insertion section 2 and generates pixel signals. For ease of explanation, the pixel signal generated by capturing the first return light beam will be referred to as a fluorescence image below. This fluorescence image corresponds to the first image according to the present disclosure. Furthermore, the pixel signal generated by capturing the second return light beam will be referred to as a normal light image. This normal light image corresponds to the second image according to the present disclosure. Furthermore, the fluorescence image and the normal light image will be collectively referred to as captured images. The detailed configuration of the camera head 5 will be explained later in the section "Configuration of the Camera Head."

[0023] One end CN1 of the first transmission cable 6 is detachably connected to the control device 9, and the other end CN2 is detachably connected to the camera head 5. The other end CN2 is not limited to being detachably connected to the camera head 5, but may also be fixed to the camera head 5. The first transmission cable 6 transmits captured images output from the camera head 5 to the control device 9, and also transmits control signals, synchronization signals, clocks, power, and the like sent from the control device 9 to the camera head 5.

[0024] The captured images and the like may be transmitted as optical signals or electrical signals from the camera head 5 to the control device 9 via the first transmission cable 6. 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.

[0025] The display device 7 is configured with a display using liquid crystal or organic EL (Electro Luminescence) or the like, and displays an image based on a video signal from the control device 9 under the control of the control device 9.

[0026] One end of the second transmission cable 8 is detachably connected to the display device 7, and the other end 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.

[0027] The control device 9 corresponds to the medical control device according to the present disclosure. The control device 9 includes a controller such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and comprehensively controls the operations of the light source device 3, the camera head 5, and the display device 7. The control device 9 is not limited to a CPU or an MPU, and may include an integrated circuit such as an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit). The detailed configuration of the control device 9 will be explained later in the section "Configuration of the Control Device."

[0028] One end of the third transmission cable 10 is detachably connected to the light source device 3, and the other end 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.

[0029] [Camera head configuration] Next, the configuration of the camera head 5 will be described. FIG. 2 is a block diagram showing the configuration of the camera head 5 and the control device 9. As shown in FIG. 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 .

[0030] The lens unit 51 is configured using one or more lenses. The lens unit 51 forms an image of the first return light (excitation light and fluorescence) collected by the insertion portion 2 on the imaging surface of the first image sensor 531 (FIG. 2), and forms an image of the second return light (white light) collected by the insertion portion 2 on the imaging surface of the second image sensor 532 (FIG. 2).

[0031] The prism 52 separates the first return light (excitation light and fluorescence) and the second return light (white light) that have passed through the lens unit 51. The prism 52 then causes the first return light (excitation light and fluorescence) to travel toward the first image sensor 531. The prism 52 also causes the second return light (white light) to travel toward the second image sensor 532.

[0032] The imaging unit 53 captures images of the inside of a living body under the control of the control device 9. The imaging unit 53 includes a first imaging element 531, a second imaging element 532, and a signal processing unit 533, as shown in FIG.

[0033] The first and second image sensors 531 and 532 receive the first and second return light beams and convert them into electrical signals (analog signals). In this embodiment, the first and second image sensors 531 and 532 are each configured with a CMOS (Complementary Metal Oxide Semiconductor), which is a rolling shutter type image sensor in which a plurality of pixels are two-dimensionally arranged in horizontal line units.

[0034] Although not specifically shown, the first imaging element 531 is made up of an invalid area that is not electrically guaranteed, an optical black area (OB area), and an effective pixel area that converts the first return light formed into an image by the lens unit 51 into an imaging signal and outputs it. Similarly, the second imaging element 532 is made up of an invalid area, an optical black area (OB area), and an effective pixel area.

[0035] Then, the first image capturing element 531 captures an image of the first return light (excitation light and fluorescence) that has passed through the prism 52 under the control of the control device 9. An excitation light cut filter that removes only at least a part of the first light (excitation light) directed toward the first image sensor 531 may be disposed on the upstream side of the optical path of the first image sensor 531.

[0036] Further, the second image pickup element 532, under the control of the control device 9, picks up an image of the second return light (white light) that has passed through the prism 52. The number of pixels in the fluorescent light image and the number of pixels in the normal light image may be different or the same.

[0037] Under the control of the control device 9, 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). For example, the signal processing unit 533 performs signal processing such as removing reset noise from the captured images (analog signals) generated by the first and second image sensors 531 and 532, multiplying the analog signals by an analog gain to amplify the analog signals, and A / D conversion.

[0038] 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.

[0039] The communication unit 54 may alternately transmit the fluorescent light image and the normal light image to the control device 9, or may transmit them simultaneously.

[0040] [Configuration of the control device] Next, the configuration of the control device 9 will be described with reference to FIG. 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.

[0041] 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. This 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.

[0042] The image memory 92 is configured by, for example, a DRAM (Dynamic Random Access Memory), etc. This image memory 92 is capable of temporarily storing multiple frames of captured images sequentially output from the camera head 5 (communication unit 54).

[0043] Under the control of the control unit 94, the processing module 93 processes the captured images that are 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.

[0044] 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 the fluorescence image received by the communication unit 91 to the image memory 92, reads the fluorescence image from the image memory 92 at a specific timing, and inputs it to the first image processing unit 932. The memory controller 931 also writes the normal light image received by the communication unit 91 to the image memory 92, and reads the normal light image from the image memory 92 at a specific timing and inputs it to the second image processing unit 933.

[0045] The first image processing unit 932 performs first image processing on the input fluorescence image. Examples of the first image processing include optical black subtraction processing, white balance adjustment processing, demosaic processing, color correction matrix processing, gamma correction processing, YC processing that converts RGB signals into luminance color difference signals (Y, Cb / Cr signals), digital gain adjustment that multiplies by digital gain, noise removal, and filter processing that emphasizes structure.

[0046] The second image processing unit 933 performs second image processing on the input normal light image. Examples of the second image processing include optical black subtraction processing, white balance adjustment processing, demosaic processing, color correction matrix processing, gamma correction processing, YC processing that converts RGB signals into luminance color difference signals (Y, Cb / Cr signals), digital gain adjustment, noise removal, and filter processing that enhances structure. The first and second image processing may be different from each other, or may be the same.

[0047] Under the control of the control unit 94, the display control unit 934 generates video signals for displaying the fluorescence image after the first image processing has been performed by the first image processing unit 932 and the normal 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.

[0048] The control unit 94 is realized by a controller such as a CPU or an MPU (Micro Processing Unit) executing various programs stored in a 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. 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 functions as a mode switching unit 941, a light source control unit 942, and an imaging control unit 943.

[0049] The mode switching unit 941 switches the mode of the medical observation system 1 between the normal observation mode and the fluorescent observation mode in response to a user operation on the input unit 95.

[0050] The normal observation mode is a mode in which, of the fluorescent image and the normal light image, only the normal light image is generated and displayed on the display device 7. In this normal observation mode, the control unit 94 turns on only the second light source 32 of the first and second light sources 31, 32. The communication unit 54 sequentially transmits the normal light images generated by the imaging unit 53 to the communication unit 91. The processing module 93 then performs second image processing on the normal light images received by the communication unit 91, generates a video signal for displaying the normal light image after the second image processing, and outputs the video signal to the display device 7. As a result, the normal light image is displayed on the display device 7.

[0051] The fluorescence observation mode is a mode in which a fluorescence image and a normal light image are generated and the fluorescence image and the normal light image (or a superimposed image in which the fluorescence image and the normal light image are superimposed) are displayed on the display device 7. In this fluorescence observation mode, the control unit 94 simultaneously turns on the first and second light sources 31, 32. Furthermore, the communication unit 54 transmits the fluorescence image and the normal light image generated by the imaging unit 53 to the communication unit 91. Furthermore, the processing module 93 performs image processing on each of the fluorescence image and the normal light image received by the communication unit 91, generates a video signal for displaying the fluorescence image and the normal light image (or a superimposed image in which the fluorescence image and the normal light image are superimposed) after the image processing has been performed, and outputs the video signal to the display device 7. As a result, the fluorescence image and the normal light image (or a superimposed image in which the fluorescence image and the normal light image are superimposed) are displayed on the display device 7.

[0052] The functions of the light source control unit 942 and the imaging control unit 943 will be explained in the sections "Regarding conventional problems" and "Regarding gain control, light source control, and electronic shutter control" below.

[0053] The input unit 95 corresponds to an operation reception 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 by 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. Note that the operation reception unit according to the present disclosure is not limited to a configuration provided in the control device 9 like the input unit 95, and may also be provided in another configuration, for example, the camera head 5.

[0054] The output unit 96 is configured using a speaker, a printer, etc., and outputs various information.

[0055] 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.

[0056] Generally, in the medical observation system 1, adjusting the signal value of the fluorescence image generated by the first image sensor 531 that receives the first return light (excitation light and fluorescence) is difficult due to the influence of the following factors (1) to (4):

[0057] (1) Drugs In general, the amount of fluorescent light varies depending on the type and dosage of the drug. The type of drug to be administered to the observation target is selected according to the target (cancer, blood, lymph, etc.). Furthermore, in order to image the fluorescence emitted from the drug in the medical observation system 1, a drug is selected that allows the wavelength of the excitation light that excites the drug to be separated from the wavelength of the fluorescence emitted from the drug. The drugs selected in this way each have a different amount of fluorescent light. Furthermore, although the amount of fluorescent light can be adjusted by the amount of drug administered, it is difficult to increase the amount more than necessary to achieve minimally invasive treatment. In other words, it is difficult to adjust the amount of fluorescent light by selecting the type of drug and adjusting the dosage, and as a result, it is difficult to adjust the signal value related to the fluorescent image generated by the first image sensor 531 of the medical observation system 1 by selecting the type of drug and adjusting the dosage.

[0058] (2) Observation subject The amount of fluorescent light varies depending on the part and condition of the object being observed. Specifically, in areas and conditions where the drug is likely to remain, the amount of fluorescent light increases. On the other hand, in areas and conditions where the drug is likely to flow and not remain, the amount of fluorescent light decreases and the afterglow time becomes shorter. Furthermore, if the observation target is a tumor, the amount of fluorescent light received by the first image sensor 531 of the medical observation system 1 changes depending on its spread, size, and depth. That is, it is difficult to adjust the amount of fluorescent light depending on the type and situation of the observation object, and as a result, it is difficult to adjust the signal value related to the fluorescent image generated by the first image sensor 531 of the medical observation system 1 depending on the type and situation of the observation object.

[0059] (3) Light source device The amount of fluorescent light varies depending on the amount of first light (excitation light) emitted from the light source device 3. To increase the intensity of the excitation light, it may be necessary to adjust 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, adjustment of the intensity of the excitation light must be performed taking into consideration factors such as heat generation in components that make up 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 subject or surrounding living organisms (high light energy levels pose a risk of burns), and the rate of fading of the fluorescent agent. Furthermore, adjustment of the intensity of the excitation light can also be achieved by changing the number of excitation light sources installed in the light source device 3. However, the number of light sources affects the size of the light source device 3, which 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 amount of fluorescent light by adjusting the amount of excitation light, and as a result, it is difficult to adjust the signal value related to the fluorescent image generated by the first image sensor 531 of the medical observation system 1 by adjusting the amount of excitation light.

[0060] (4) Image sensor Depending on the amount of fluorescent light received by the first image capturing element 531, the signal value of the fluorescent image generated by the first image capturing element 531 varies. To adjust the signal values ​​related to the fluorescence image, it is desirable to select a first imaging element 531 with optimal sensitivity and configuration for fluorescence imaging. However, the first imaging element 531 may be required to output not only an image for fluorescence observation based on received fluorescence light, but also an image for normal light observation based on received visible light, such as white light. In such cases, the first imaging element 531 must be capable of both fluorescence observation and normal light observation, and it may not be possible to use an imaging element with optimal characteristics for fluorescence imaging. Furthermore, the first imaging element 531 is disposed within the camera head 5, and the size and weight of the camera head 5 required for observation may limit the type of first imaging element 531, including its size. That is, it is difficult to adjust the signal values ​​related to the fluorescent image generated by the first image sensor 531 of the medical observation system 1 by selecting the type of the first image sensor 531.

[0061] As described above, the signal values ​​related to the fluorescent image generated by the first image sensor 531 are determined within the above constraints, and therefore are not easy to adjust.

[0062] [Regarding conventional issues] FIG. 3 is a diagram illustrating the problems of the related art. (a) of FIG. 3 shows the subject brightness (brightness level) of a normal light image. In FIG. 3, the subject brightness increases toward the right side and decreases toward the left side. (b) and (c) of FIG. 3 show gain control (adjustment of analog gain and digital gain), which is signal processing. More specifically, (b) of FIG. 3 shows gain control for a normal light image. (c) of FIG. 3 shows gain control for a fluorescence image. (d) and (e) of FIG. 3 show control of the light intensity of the first and second light beams directed to the object of observation in the light source device 3 (light source control (current dimming)). More specifically, (d) of FIG. 3 shows light source control (current dimming) of the second light source 32. (e) of FIG. 3 shows light source control (current dimming) of the first light source 31. (f) and (g) of Fig. 3 show electronic shutter control in the first and second image pickup elements 531 and 532. More specifically, (f) of Fig. 3 shows electronic shutter control in the second image pickup element 532. (g) of Fig. 3 shows electronic shutter control in the first image pickup element 531.

[0063] The control unit 94 calculates the subject luminance (average luminance) within the detection region based on the luminance signal (Y signal) within the detection region, which is at least a portion of the entire image region of the normal light image, out of the luminance and color difference signals (Y, Cb / Cr signals) that are the normal light image after YC processing has been performed by the first image processing unit 932 or the second image processing unit 933. Then, based on the calculated subject luminance, the control unit 94 executes dimming control to adjust the captured image to a reference brightness.

[0064] Specifically, as shown in Figures 3(b) and 3(c), when the calculated subject brightness is darker than a specific reference subject brightness (the subject brightness indicated by the arrow Ar in Figure 3), the control unit 94 brightens the subject brightness by gain control (adjustment of analog gain and digital gain by the imaging control unit (gain control unit) 943), which is signal processing. Also, as shown in Figures 3(d) and 3(e), when the calculated subject brightness is brighter than the specific reference subject brightness, the control unit 94 first reduces the current values ​​supplied to the first and second light sources 31 and 32 to reduce the amounts of first and second light emitted from the first and second light sources 31 and 32 (light source control (current dimming) by the light source control unit 942), and then reduces the opening amounts of the electronic shutters of the first image sensor 531 and the second image sensor 532, respectively (electronic shutter control by the imaging control unit (shutter control unit) 943).

[0065] Here, in conventional gain control, light source control (current dimming), and electronic shutter control, the same amount of gain (analog gain and digital gain) is multiplied in the white field (the field that generates a normal light image) and the fluorescent field (the field that generates a fluorescent image), the amount of light of the first and second light is adjusted at the same ratio, and further the opening amount of the electronic shutter in the first image sensor 531 and the opening amount of the electronic shutter in the second image sensor 532 are adjusted at the same ratio.

[0066] As mentioned above, various types of drugs can be administered to an observation subject, ranging from those that emit bright fluorescence to those that emit only dim fluorescence. Furthermore, depending on the region of the observation subject, there are various regions, from areas where the drug accumulates and emits bright light to areas where the drug concentration is low due to perfusion or metabolism of the observation subject, resulting in weak fluorescence. Therefore, users performing fluorescence observation require a function to adjust brightness. While this function is generally implemented using gain control, when a high-sensitivity imager is used as the first imaging element 531, the image may become bright even without multiplication by gain (analog gain and digital gain). In this case, signal processing involves multiplication by a negative gain, which poses a problem: if the signal value of the fluorescence image is saturated, the gradation of the signal value cannot be restored.

[0067] In this embodiment, in order to address the above-mentioned problems, mainly the electronic shutter control is different from the conventional control. Details of the electronic shutter control will be explained in "Gain control, light source control, and electronic shutter control."

[0068] [Gain control, light source control, electronic shutter control] Fig. 4 is a diagram illustrating gain control, light source control, and electronic shutter control according to an embodiment. Specifically, Fig. 4(a) to Fig. 4(g) are diagrams corresponding to Fig. 3(a) to Fig. 3(g), respectively. Fig. 5 is a diagram showing the fluorescence gain set by the user. The control unit 94 calculates the subject luminance (average luminance) within the detection region based on the luminance signal (Y signal) within the detection region, which is at least a portion of the entire image region of the normal light image, out of the luminance and color difference signals (Y, Cb / Cr signals) that are the normal light image after YC processing has been performed by the first image processing unit 932 or the second image processing unit 933. Then, based on the calculated subject luminance, the control unit 94 executes dimming control to adjust the captured image to a reference brightness.

[0069] Specifically, as shown in Figures 4(b) and 4(c), when the calculated subject brightness is darker than a specific reference subject brightness (the subject brightness indicated by the arrow Ar in Figure 4), the control unit 94 brightens the subject brightness by gain control (adjustment of analog gain and digital gain by the imaging control unit (gain control unit) 943), which is signal processing. Also, as shown in Figures 4(d) and 4(e), when the calculated subject brightness is brighter than the specific reference subject brightness, the control unit 94 first reduces the current values ​​supplied to the first and second light sources 31 and 32 to reduce the amounts of first and second light emitted from the first and second light sources 31 and 32 (light source control (current dimming) by the light source control unit 942), and then reduces the opening amounts of the electronic shutters of the first image sensor 531 and the second image sensor 532, respectively (electronic shutter control by the imaging control unit (shutter control unit) 943).

[0070] Here, in the gain control of this embodiment, the white field and the fluorescent field are not multiplied by the same gain (analog gain and digital gain). More specifically, the imaging control unit (gain control unit) 943 multiplies the gain (analog gain and digital gain) for the white field as in the conventional method (see the above-mentioned "Regarding the Conventional Problems"). On the other hand, for the fluorescent field, the imaging control unit (gain control unit) 943 sets the gain (analog gain and digital gain) corresponding to the fluorescent gain selected by a user operation on the input unit 95 ( FIG. 5 ) as a minimum value and adjusts the gain. As shown in FIG. 5 , the fluorescent gain is information in which the gain (analog gain and digital gain) is associated with the opening amount of the electronic shutter of the first image sensor 531 according to a numerical value (+3 to −3), and is stored in the storage unit 97. For example, if a fluorescent gain of +2 is selected by a user operation, the imaging control unit (gain control unit) 943 sets the gain (analog gain and digital gain) four times the reference gain (analog gain and digital gain) as a minimum value and adjusts the gain.

[0071] Furthermore, in the light source control (current dimming) in this embodiment, the light intensities of the first and second light are adjusted at the same ratio, as in the conventional case (see "Regarding the problems of the conventional case" above).

[0072] Furthermore, in the electronic shutter control of this embodiment, the opening amount of the electronic shutter at the first image sensor 531 and the opening amount of the electronic shutter at the second image sensor 532 are not adjusted at the same ratio. More specifically, for white fields, the imaging control unit (shutter control unit) 943 adjusts the opening amount of the electronic shutter at the second image sensor 532, as in the conventional technique (see the above-mentioned "Regarding Conventional Problems"). On the other hand, for fluorescent fields, the imaging control unit (shutter control unit) 943 sets the opening amount according to the fluorescent gain ( FIG. 5 ) selected by a user operation on the input unit 95 to the maximum value, and adjusts the opening amount of the electronic shutter at the first image sensor 531. For example, if a fluorescent gain of −2 is selected by a user operation, the imaging control unit (shutter control unit) 943 sets the maximum value to ¼ of the reference opening amount (reference exposure shown in FIG. 5 ).

[0073] That is, in this embodiment, when the ratio of the signal value related to the fluorescent image to the signal value related to the normal light image when the opening amount of the electronic shutter of the first image sensor 531 is a first opening amount (for example, a reference opening amount (reference exposure shown in FIG. 5)) is set to a first ratio, the imaging control unit (shutter control unit) 943 changes the opening amount of the electronic shutter of the first image sensor 531 from the first opening amount to a second opening amount smaller than the first opening amount (for example, 1 / 4 of the reference opening amount (reference exposure shown in FIG. 5)), thereby changing the ratio of the signal value related to the fluorescent image to the signal value related to the normal light image to a second ratio smaller than the first ratio.

[0074] Furthermore, in this embodiment, when the brightness of the fluorescent image is darker than the reference brightness (the subject brightness indicated by the arrow Ar in FIG. 4), the imaging control unit (gain control unit) 943 uses a gain (analog gain and digital gain) that is greater than the gain reference value (the reference shown in FIG. 5). Furthermore, when the brightness of the fluorescent image is brighter than the reference brightness, the imaging control unit (shutter control unit) 943 sets the opening amount of the electronic shutter of the first image sensor 531 to an opening amount that is smaller than the opening amount reference value (the reference exposure shown in FIG. 5).

[0075] Furthermore, in this embodiment, the first return light is a first fluorescence based on a first fluorescent agent. The imaging control unit (shutter control unit) 943 is configured to set the opening amount of the electronic shutter to a first opening amount when imaging the first return light, and to set the opening amount of the electronic shutter from the first opening amount to a second opening amount when imaging second fluorescence based on a second fluorescent agent that emits weaker fluorescence than the first fluorescence.

[0076] According to the present embodiment described above, the following effects are achieved. In the control device 9 of this embodiment, when the ratio of the signal value related to the fluorescent image to the signal value related to the normal light image when the opening amount of the electronic shutter of the first image sensor 531 is a first opening amount (for example, a reference opening amount (reference exposure shown in Figure 5)) is set to a first ratio, the imaging control unit (shutter control unit) 943 changes the opening amount of the electronic shutter of the first image sensor 531 from the first opening amount to a second opening amount smaller than the first opening amount (for example, 1 / 4 of the reference opening amount (reference exposure shown in Figure 5)), thereby changing the ratio of the signal value related to the fluorescent image to the signal value related to the normal light image to a second ratio smaller than the first ratio. Therefore, even in cases where the signal value of the fluorescence image would become saturated if an electronic shutter were not used, for example, when a drug that emits bright fluorescence is used, the brightness of the fluorescence image can be adjusted to an appropriate brightness without losing the gradation of the fluorescence image. Therefore, the control device 9 according to this embodiment can generate a fluorescent image suitable for observation.

[0077] (Other embodiments) Although the embodiments for carrying out the present disclosure have been described above, the present disclosure should not be limited to only the above-described embodiments. In the above-described embodiment, a configuration capable of executing only the fluorescence observation mode may be adopted. That is, the second image sensor 532, the second light source 32, and the second image processing unit 933 may be omitted. In such a configuration, if the signal value related to the fluorescence image becomes saturated when the opening amount of the electronic shutter of the first image sensor 531 is set to the first opening amount, the image sensor control unit (shutter control unit) 943 desaturates the signal value by setting the opening amount to a second opening amount that is smaller than the first opening amount.

[0078] In the above-described embodiment, the number of fluorescence observation modes is not limited to one, and multiple modes may be provided, for example, for each type of drug administered to the observation subject. In this case, the fluorescence gain (FIG. 5) stored in the memory unit 97 is also prepared for each fluorescence observation mode. That is, the imaging control unit (shutter control unit) 943 refers to the fluorescence gain corresponding to the fluorescence observation mode switched by the mode switching unit 941, and changes the opening amount of the electronic shutter of the first image sensor 531 to correspond to the fluorescence gain.

[0079] In the above-described embodiment, the imaging control unit (shutter control unit) 943 controls the electronic shutter of the first imaging element 531, but this is not limited to this, and a configuration may be adopted in which a mechanical shutter corresponding to the first imaging element 531 is controlled.

[0080] In the above-described embodiment, the following modifications 1 to 4 may be adopted.

[0081] (Variation 1) 6 to 11 are diagrams illustrating a first modified example of the embodiment. Specifically, (a) to (e) of FIG. 6 correspond to (a) to (e) of FIG. 4, respectively. (f) and (g) of FIG. 6 illustrate control of the light amounts of the first and second lights to the observation object in the light source device 3 (light source control (PWM dimming)). More specifically, (f) of FIG. 6 illustrates light source control (PWM dimming) of the second light source 32. (g) of FIG. 6 illustrates light source control (PWM dimming) of the first light source 31. (h) and (i) of FIG. 6 correspond to (f) and (g) of FIG. 4, respectively. FIGS. 7 and 8 are diagrams illustrating issues that arise when PWM dimming is used. More specifically, in (a) of FIG. 7 and (a) of FIG. 8, the vertical axis indicates the horizontal line of the first image sensor 531 (the top row indicates the highest horizontal line (the first horizontal line) and the bottom row indicates the lowest horizontal line (the final line)), and the horizontal axis indicates time. The parallelogram area is the area that contributes to the generation of a fluorescence image in one field. (b) of FIG. 7 and (b) of FIG. 8 indicate the current value supplied to the first light source 31 on the vertical axis, and the horizontal axis indicates time (the supply time of the current supplied to the first light source 31). (c) of FIG. 8 is a schematic diagram showing the generated fluorescence image FG. (9) and (10) are diagrams explaining control that solves the problems that arise when PWM dimming is used. More specifically, (a) of FIG. 9 and (a) of FIG. 10 correspond to (a) of FIG. 7 and (a) of FIG. 8, respectively. Figure 9(b) and Figure 10(b) are diagrams corresponding to Figure 7(b) and Figure 8(b), respectively. Figure 10(c) is a diagram corresponding to Figure 8(c). Figure 11 is a diagram corresponding to Figure 5, showing the fluorescence gain set by the user.

[0082] In the above-described embodiment, as a method for reducing the brightness of the captured image in the time direction, PWM dimming for adjusting the light emission times of the first and second light emitted from the first and second light sources 31 and 32 may be adopted.

[0083] Specifically, as shown in (b) and (c) of Figure 6, if the calculated subject brightness is darker than a specific reference subject brightness (the subject brightness indicated by the arrow Ar in Figure 6), the imaging control unit (gain control unit) 943 brightens it by gain control (adjusting the analog gain and digital gain), which is signal processing, as in the above-mentioned embodiment.

[0084] Furthermore, as shown in (d) of Figure 6, (e) of Figure 6, (b) of Figure 7, and (b) of Figure 9, when the calculated subject brightness is brighter than a specific reference subject brightness, the light source control unit 942 reduces the amount of light of the first and second light emitted from the first and second light sources 31, 32 by reducing the current value supplied to the first and second light sources 31, 32, as in the above-mentioned embodiment (current dimming).

[0085] Then, as shown in (f) of Figure 6, (g) of Figure 6, (b) of Figure 7, and (b) of Figure 9, if the subject brightness needs to be further darkened after the current value supplied to the first and second light sources 31 and 32 has decreased to the drive limit value TH, the light source control unit 942 reduces the supply time of the current supplied to the first and second light sources 31 and 32 and reduces the emission time of the first and second light (PWM dimming).

[0086] In the electronic shutter control of Modification 1, as shown in FIGS. 6(h) and 6(i), the opening amounts of the electronic shutters of the first and second image sensors 531 and 532 are fixed. More specifically, the opening amount of the electronic shutter of the first image sensor 531 is fixed to an opening amount of the electronic shutter corresponding to a fluorescent light gain (FIG. 11) selected by a user operation on the input unit 95. As shown in FIG. 11, the fluorescent light gain is information that associates gains (analog gain and digital gain), the opening amount of the electronic shutter of the first image sensor 531, and the minimum multiplication of the PWM pulse (first light) according to a numerical value (+3 to −3), and is stored in the storage unit 97. For example, when a fluorescent light gain of −1 is selected by a user operation, the opening amount of the electronic shutter of the first image sensor 531 is fixed to ½ of the reference opening amount (reference exposure shown in FIG. 11).

[0087] Here, for example, as shown in Figures 7(a) and 8(a), if PWM dimming is performed with the opening amount of the electronic shutter of the first image sensor 531 fixed to half the reference opening amount (reference exposure shown in Figure 11), the following problem occurs. Note that in Figures 7(a) and 8(a), the hatched parallelogram regions indicate the regions where charge is swept away by the electronic shutter. Also, the unhatched parallelogram regions indicate the regions where exposure is effective.

[0088] Specifically, as shown in Fig. 8, when the emission time of the first light is reduced by PWM dimming, the first light does not strike the upper and lower horizontal lines of the first image sensor 531 within the region indicating the effective exposure period (the region of the unshaded parallelogram). Therefore, as shown in Fig. 8(c), the generated fluorescence image FG has dark upper and lower portions, resulting in an image with uneven brightness.

[0089] Therefore, in this first modification, as shown in FIGS. 9 and 10 , when performing PWM dimming, the light source control unit 942 intermittently lights the first light emitted from the first light source 31 for each fluorescence field at a predetermined cycle obtained by dividing the period of the fluorescence field. As a result, as shown in FIG. 10 , the first light is incident on the entire area indicating the effective exposure period (the area of ​​the unhatched parallelogram), and brightness does not vary in the generated fluorescence image FG ( FIG. 10 (c)). Note that FIGS. 9 and 10 illustrate an example of a four-fold multiplication, in which the period of the fluorescence field is divided into four. The multiplication is performed at a rate corresponding to the fluorescence gain selected by the user ( FIG. 11 ). The minimum multiplication of the PWM pulse shown in FIG. 11 is merely an example, and a value greater than the stated multiplication value may be used.

[0090] (Variation 2) The medical observation system according to Modification 2 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 Modification 2 will be referred to as medical observation system 1B below.

[0091] FIG. 12 is a diagram illustrating a second modification of the embodiment. As shown in FIG. 12, the medical observation system 1B includes an endoscope 300B that captures an in-vivo image of an observation site by inserting an insertion portion 2B into a living body and outputs the captured image, a light source device 3 that emits first and second light from the tip of the endoscope 300B, a control device 9 that processes the captured image 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.

[0092] As shown in FIG. 12, the endoscope 300B includes a flexible, elongated insertion section 2B, an operation section 301 connected to the base end 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. 12, 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 composed of a plurality of bending pieces, and a long flexible tube section 26 connected to the base end side of the bending section 25 and having flexibility.

[0093] Although not specifically shown in the drawings, the tip portion 24 has a built-in configuration substantially similar to that of the camera head 5 described in the above-described embodiment. Images captured by the tip portion 24 (first and second image pickup elements 531, 532) are output to the control device 9 via the operation unit 301 and the universal cord 302.

[0094] Even when the configuration of the present modified example 2 described above is adopted, the same effects as those of the above-described embodiment are achieved.

[0095] (Variation 3) The medical observation system according to Modification 3 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 Modification 3 will be referred to as medical observation system 1C below.

[0096] FIG. 13 is a diagram illustrating a third modification of the embodiment. As shown in FIG. 13, the medical observation system 1C includes 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.

[0097] As shown in Figure 13, the surgical microscope 12 comprises a microscope unit 121 that magnifies and captures images of minute areas of the subject and outputs the captured images, 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. 13, the control device 9 is mounted on a base 123. Although not specifically shown, the base 123 also has mounted thereon a light source device 3 that emits first and second light beams from the surgical microscope 12 to an object to be observed. The base portion 123 may be configured to support the support portion 122 by being fixed to a ceiling or a wall surface, rather than being provided so as to be movable on the floor surface.

[0098] 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-described embodiment. Images captured by the microscope unit 121 (first and second image capture elements 531, 532) are output to the control device 9 via a first transmission cable 6 wired along the support unit 122.

[0099] Even when the configuration of the third modified example described above is adopted, the same effects as those of the above-described embodiment are achieved.

[0100] (Variation 4) 14 and 15 are diagrams illustrating a fourth modified example of the embodiment. Specifically, Fig. 14 is a diagram of the ring light 15 as seen from the side. Fig. 15 is a diagram of the ring light 15 as seen from the front side (left side in Fig. 14). In this fourth modification, in addition to the insertion section 2 described in the above embodiment, a ring light 15 shown in Fig. 14 and Fig. 15 is detachably connected to the camera head 5. That is, depending on the state of use by the user, the insertion section 2 or the ring light 15 may be connected to the camera head 5 as shown in Fig. 14 .

[0101] The ring light 15 is not inserted into the observation target like the insertion section 2, but supplies the first and second lights to the surgical site and captures the return light of the first and second lights from the surgical site. As shown in Figures 14 and 15, the ring light 15 includes an illumination section 151 and a subject image capture section 152 that captures a subject image.

[0102] As shown in FIGS. 14 and 15, the illumination unit 151 includes a housing 1511 and a plurality of illumination lenses 1512. The housing 1511 has a circular ring shape centered on the optical axis Ax. The other end of the light guide 4 is detachably connected to the housing 1511.

[0103] 15, 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 irradiate the first and second light beams, which are supplied from the light source device 3 and introduced into the housing 1511 via the light guide 4, toward the operative area.

[0104] The subject image capture unit 152 extends along the optical axis Ax. An optical system configured using one or more lenses is provided within the subject image capture unit 152, and focuses the first and second return light beams irradiated from multiple illumination lenses 1512 and passing through the surgical site. Furthermore, a connector 1521 is provided at the end on the proximal side (right side in FIG. 14) of the subject image capture unit 152. This connector 1521 has a design (shape) compatible with the eyepiece unit 21 of the insertion unit 2, and is detachably connected to the camera head 5.

[0105] Even when the configuration of the fourth modification described above is adopted, the same effects as those of the above-described embodiment are achieved.

[0106] The following configurations also fall within the technical scope of the present disclosure. (1) A medical control device comprising an imaging control unit that controls the operation of an imaging element and causes the imaging element to capture first return light from an object of observation irradiated with first light, which is narrowband light, and second return light from the object of observation irradiated with second light having a wavelength band different from the narrowband light, respectively; the imaging control unit comprises a shutter control unit that changes a signal value related to a first image generated by the imaging element when the first return light is captured by controlling the opening amount of an imaging shutter; and the shutter control unit, when a ratio of a signal value related to the first image to a signal value related to a second image generated by the imaging element when the second return light is captured when the opening amount of the shutter is a first opening amount, changes the opening amount of the shutter from the first opening amount to a second opening amount that is smaller than the first opening amount, thereby changing the ratio of the signal value related to the first image to the signal value related to the second image to a second ratio that is smaller than the first ratio. (2) The medical control device according to (1), wherein the second light is white light including a visible wavelength band. (3) A medical control device as described in (1) or (2), further comprising a mode switching unit that switches the observation mode, and the shutter control unit changes the opening amount of the shutter according to the observation mode switched by the mode switching unit. (4) The imaging control unit further includes a gain control unit that adjusts at least one of an analog gain and a digital gain to adjust the brightness of the first image, and the gain control unit uses a gain greater than a gain reference value as at least one of the gains when the brightness of the first image is darker than a reference brightness, and the shutter control unit sets the opening amount of the shutter to an opening amount smaller than the opening amount reference value when the brightness of the first image is brighter than the reference brightness.The medical control device described in any one of (1) to (3). (5) A medical control device described in any one of (1) to (4), further comprising a light source control unit that controls the operation of a light source device that emits the first light and the second light, wherein the light source control unit intermittently lights the first light emitted from the light source device at a predetermined cycle that divides the period of the field for each field that forms the first image. (6) The medical control device according to any one of (1) to (5), wherein the first return light is a first fluorescence based on a first fluorescent agent, and the shutter control unit is configured to set the opening amount of the shutter to a first opening amount when imaging the first return light, and to set the opening amount of the shutter to the second opening amount when imaging second fluorescence based on a second fluorescent agent that emits fluorescence weaker than the first fluorescence. (7) The medical control device according to any one of (1) to (6), further comprising an operation receiving unit that receives a user operation for setting the opening amount of the shutter. (8) The medical control device according to any one of (1) to (7), wherein the shutter control unit controls the opening amount of an electronic shutter of the imaging element. (9) A medical control device comprising an imaging control unit that controls the operation of an imaging element and causes the imaging element to capture returning light from an object of observation illuminated with narrowband light, wherein the imaging control unit comprises a shutter control unit that changes a signal value related to an image generated by the imaging element by capturing the returning light by controlling the opening amount of an imaging shutter, and wherein the shutter control unit desaturates the signal value by setting the opening amount of the shutter to a second opening amount that is smaller than the first opening amount when the signal value is saturated when the opening amount of the shutter is set to a first opening amount. (10) A medical observation system comprising: an imaging element that captures first return light from an observation object irradiated with first light, which is narrowband light; and second return light from the observation object irradiated with second light having a wavelength band different from that of the narrowband light; and an imaging control unit that controls the operation of the imaging element, wherein the imaging control unit comprises a shutter control unit that changes a signal value related to a first image generated by the imaging element when the first return light is captured by controlling an opening amount of an imaging shutter, and the shutter control unit changes the ratio of the signal value related to the first image to the signal value related to the second image when the opening amount of the shutter is a first opening amount, by changing the opening amount of the shutter from the first opening amount to a second opening amount that is smaller than the first opening amount. (11) A medical observation system comprising an imaging element that captures returning light from an observation object irradiated with narrowband light, and an imaging control unit that controls the operation of the imaging element, wherein the imaging control unit comprises a shutter control unit that changes a signal value related to an image generated by the imaging element by capturing the returning light by controlling the opening amount of an imaging shutter, and wherein the shutter control unit desaturates the signal value by setting the opening amount of the shutter to a second opening amount that is smaller than the first opening amount when the signal value is saturated when the opening amount of the shutter is set to a first opening amount. [Explanation of symbols]

[0107] 1,1B,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 24 Tip 25 Curved section 26 Flexible tube section 31 First Light Source 32 Second Light Source 51 Lens unit 52 Prism 53 Imaging unit 54 Communications Department 91 Communications Department 92 Image Memory 93 Processing Module 94 Control Unit 95 Input section 96 Output section 97 Memory section 121 Microscope Section 122 Support part 123 Base 151 Lighting Department 152 Subject image capture unit 300B Endoscope 301 Operation section 302 Universal Code 531 First imaging element 532 Second imaging element 533 Signal Processing Unit 931 Memory Controller 932 First image processing unit 933 Second Image Processing Section 934 Display control unit 941 Mode switching unit 942 Light source control unit 943 Imaging control unit 1511 Case 1512 Lighting lens 1521 Connection Arrow Ax optical axis CN1 one end CN2 other end TH drive limit value

Claims

1. an imaging control unit that controls the operation of the imaging element and causes the imaging element to capture first return light from an observation object irradiated with first light that is narrow band light and second return light from the observation object irradiated with second light having a wavelength band different from that of the narrow band light, The imaging control unit a shutter control unit that changes a signal value related to a first image generated by the image sensor by capturing the first returned light by controlling an opening amount of an image capturing shutter, The shutter control unit includes: A medical control device that, when the ratio of the signal value of the first image to the signal value of the second image generated by the imaging element when the second return light is captured when the shutter opening amount is a first opening amount, sets the ratio of the signal value of the first image to the signal value of the second image to a second ratio smaller than the first ratio by changing the shutter opening amount from the first opening amount to a second opening amount smaller than the first opening amount.

2. The second light is 2. The medical control device according to claim 1, wherein the light is white light including a visible wavelength band.

3. further comprising a mode switching unit for switching between observation modes; The shutter control unit includes: The medical control device according to claim 1 , wherein the opening amount of the shutter is changed in accordance with the observation mode switched by the mode switching unit.

4. The imaging control unit a gain control unit that adjusts at least one of an analog gain and a digital gain to adjust brightness of the first image; The gain control unit When the brightness of the first image is darker than a reference brightness, a gain greater than a reference gain value is used as at least one of the gains; The shutter control unit includes:

2. The medical control device according to claim 1, wherein when the brightness of the first image is brighter than a reference brightness, the opening amount of the shutter is set to an opening amount smaller than a reference opening amount value.

5. a light source control unit that controls the operation of a light source device that emits the first light and the second light, The light source control unit 2. The medical control device according to claim 1, wherein the first light emitted from the light source device is intermittently turned on for each field forming the first image at a predetermined cycle obtained by dividing the period of the field.

6. The first return light is a first fluorescence based on a first fluorescent agent; The shutter control unit includes:

2. The medical control device according to claim 1, wherein the opening amount of the shutter is set to a first opening amount when imaging the first return light, and is configured to be able to set the opening amount of the shutter to the second opening amount when imaging second fluorescence based on a second fluorescent agent that emits fluorescence weaker than the first fluorescence.

7. The medical control device according to claim 1 , further comprising an operation receiving unit that receives a user operation to set the opening amount of the shutter.

8. The shutter control unit includes: The medical control device according to claim 1 , wherein the opening amount of the electronic shutter of the image pickup device is controlled.

9. an imaging control unit that controls the operation of the imaging element and causes the imaging element to capture an image of return light from an observation object irradiated with narrow band light; The imaging control unit a shutter control unit that controls an opening amount of an imaging shutter to change a signal value related to an image generated by the imaging element by capturing the returned light; The shutter control unit includes: A medical control device that, when the signal value saturates when the shutter opening amount is set to a first opening amount, desaturates the signal value by setting the shutter opening amount to a second opening amount that is smaller than the first opening amount.

10. an image sensor configured to capture images of first return light from an object of observation illuminated with first light, which is narrowband light, and second return light from the object of observation illuminated with second light having a wavelength band different from that of the narrowband light; an imaging control unit that controls the operation of the imaging element; The imaging control unit a shutter control unit that changes a signal value related to a first image generated by the image sensor by capturing the first returned light by controlling an opening amount of an image capturing shutter, The shutter control unit includes: a medical observation system in which, when a ratio of a signal value related to the first image to a signal value related to a second image generated by the imaging element in capturing the second returned light when the opening amount of the shutter is a first opening amount is set to a first ratio, the ratio of the signal value related to the first image to the signal value related to the second image is set to a second ratio smaller than the first ratio by changing the opening amount of the shutter from the first opening amount to a second opening amount smaller than the first opening amount.

11. an imaging element that captures an image of return light from an object to be observed that is irradiated with narrowband light; an imaging control unit that controls the operation of the imaging element; The imaging control unit a shutter control unit that controls an opening amount of an imaging shutter to change a signal value related to an image generated by the imaging element by capturing the returned light; The shutter control unit includes: A medical observation system in which, when the signal value is saturated when the opening amount of the shutter is set to a first opening amount, the signal value is desaturated by setting the opening amount of the shutter to a second opening amount that is smaller than the first opening amount.

Images