Medical observation system and light source control device

Abstract

To generate an image suitable for observation.SOLUTION: A medical observation system 1 comprises: a light source device 3 which emits first and second light respectively toward an observation target; an imaging device 5 which captures return light of the first and second light from the observation target, and in which the number of horizontal lines simultaneously exposed by at least one of the return light of the first light and the return light of the second light varies; and a light source control unit 941 which adjusts emission periods of the first and second light so that energy of the light exposing the return light of the first light in the imaging device 5 and energy of the light exposing the return light of the second light in the imaging device 5 have a predetermined ratio.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Conventionally, a medical observation system is known that uses a CMOS (Complementary Metal Oxide Semiconductor), which is a rolling shutter type image sensor, to image an observation target such as inside a living body and observes the observation target (see, for example, Patent Document 1).

[0003] In the medical observation system described in Patent Document 1, a normal light image and a fluorescence image are generated. Specifically, the normal light image is an image obtained by irradiating an observation target with normal light in a visible wavelength band from a light source device and imaging the normal light transmitted through the observation target. The fluorescence image is an image obtained by irradiating the observation target with excitation light from the light source device and imaging the fluorescence from the observation target excited by the excitation light.

[0004] Here, in the medical observation system described in Patent Document 1, in order to generate a bright fluorescence image, excitation light is emitted even outside the all-line exposure period in which all horizontal lines of the effective pixel region in the image sensor are simultaneously exposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the medical observation system described in Patent Document 1, when PWM control is performed to control the operation of the light source device, the emission period of the normal light changes within the entire line exposure period, while the emission period of the excitation light changes even outside the entire line exposure period. For this reason, when the emission period of the excitation light is changed at the same ratio as the change in the emission period of the normal light, the ratio between the brightness of the normal light image and the brightness of the fluorescence image changes, and the brightness balance deteriorates. That is, there is a problem that it is difficult to generate an image suitable for observation.

[0007] The present disclosure has been made in view of the above, and an object thereof is to provide a medical observation system and a light source control device capable of generating an image suitable for observation.

Means for Solving the Problems

[0008] In order to solve the above-described problems and achieve the object, a medical observation system according to the present disclosure includes a light source device that emits first light and second light to an observation target, and the first light and the second light from the observation target. An imaging device that images each of the return lights, and a light source control unit that adjusts the emission periods of the first light and the second light so that the energy of the light that exposes the return light of the first light in the imaging device and the energy of the light that exposes the return light of the second light in the imaging device are in a predetermined ratio.

[0009] Further, a medical observation system according to the present disclosure includes a light source device that emits light to an observation target, an imaging device that images the return light of the light from the observation target, and the horizontal line number that is simultaneously exposed by the return light of the light changes. And a light source control unit that adjusts the emission period of the light based on an energy index value that is an index of a target value of the energy of the return light exposed in the imaging device.

[0010] In addition, the light source control device according to the present disclosure includes a light source control unit that controls the operation of the light source device and emits first light and second light from the light source device to an observation target, and each of the return lights of the first light and the second light from the observation target is imaged by an imaging device in which the number of horizontal lines simultaneously exposed by at least one of the return light of the first light and the return light of the second light changes. The light source control unit adjusts the light emission periods of the first light and the second light so that the energy of the light that exposes the return light of the first light in the imaging device and the energy of the light that exposes the return light of the second light in the imaging device are in a predetermined ratio.

[0011] In addition, the light source control device according to the present disclosure includes a light source control unit that controls the operation of the light source device and emits light from the light source device to an observation target, and the return light of the light from the observation target is imaged by an imaging device in which the number of horizontal lines simultaneously exposed by the return light changes. The light source control unit adjusts the light emission period of the light based on an energy index value that is an index of a target value of the energy of the return light exposed in the imaging device.

Advantages of the Invention

[0012] According to the medical observation system and the light source control device according to the present disclosure, an image suitable for observation can be generated.

Brief Description of the Drawings

[0013]

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Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments 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 by the embodiments described below. Further, in the description of the drawings, the same parts are denoted by the same reference numerals.

[0015] 〔Configuration of Medical Observation System〕 Figure 1 is a diagram showing the configuration of a medical observation system 1 according to the embodiment. In this embodiment, the medical observation system 1 is a medical endoscope system that observes an observation target (inside the living body) using an endoscope. As shown in FIG. 1, this medical observation system 1 includes an insertion portion 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] In this embodiment, the insertion portion 2 is configured as a rigid endoscope. That is, the insertion portion 2 has an elongated shape that is entirely rigid or partially soft and the other parts are rigid, and is inserted into the observation target (inside the living body). Inside this insertion portion 2, an optical system is provided that is configured using one or more lenses and condenses light from the observation target.

[0017] One end of the light guide 4 is connected to the light source device 3, and the light source device 3 supplies light to one end of the light guide 4 under the control of the control device 9. As shown in FIG. 1, this light source device 3 includes a first light source 31 and a second light source 32.

[0018] The first light source 31 emits a first light (broadband light such as white light or narrowband light such as red light, green light, or blue light) that includes at least a part 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 synthesizes the red light, the green light, and the blue light. Note that the first light source 31 may be configured by an LED or may be configured by a semiconductor laser. Also, the number of the first light sources 31 may be one or more.

[0019] The second light source 32 emits excitation light that excites substances contained in the observation target. The excitation light corresponds to the second light according to the present disclosure. Note that the second light source 32 may be constituted by an LED or may be constituted by a semiconductor laser. Further, the number of the second light sources 32 may be one or plural. Furthermore, the second light source 32 may emit, for example, infrared light or ultraviolet light.

[0020] Here, examples of the substances contained in the observation target that are excited by the excitation light include drugs or fluorescent dyes applied to the observation target, or fluorescent substances derived from the observation target that constitute the observation target itself.

[0021] Examples of the above-described drugs applied to the observation target 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".

[0022] In addition, examples of the above-described fluorescent dyes to be applied to the observation target 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", "HiLyte Fluor 750", "Indocarbocyanine", "IR-786", "IRDye 800CW", "IRDye 800RS", "IRDye 800BK", "Nervelight", "OTL-38", "Polymethine", "VivoTag-S750", "ASP5354", and "Xanthene".

[0023] Furthermore, examples of the fluorescent substances derived from the observation target that constitute the observation target itself include "collagen", "elastin", and "NADH".

[0024] In the present embodiment, the light source device 3 is configured separately from the control device 9, but it is not limited thereto, and a configuration provided in the same housing as the control device 9 may be adopted.

[0025] The light guide 4 has one end detachably connected to the light source device 3 and the other end detachably connected to the insertion part 2. Then, the light guide 4 transmits the light (the first light or the excitation light) supplied from the light source device 3 from one end to the other end and supplies it to the insertion part 2. The light (the first light or the excitation light) supplied to the insertion part 2 is emitted from the tip of the insertion part 2 and irradiates the observation target. When the observation target is irradiated with the first light, the return light (the reflected light of the first light) of the first light from the observation target is condensed by the optical system in the insertion part 2. Further, when the observation target is irradiated with the excitation light, the return light of the excitation light from the observation target is condensed by the optical system in the insertion part 2. The return light of the excitation light includes, in addition to the excitation light reflected by the observation target, fluorescence emitted from the substance when the excitation light irradiates the observation target and the substance contained in the observation target is excited. Hereinafter, for convenience of explanation, the return light of the first light from the above-described observation target is referred to as the first return light, and the return light of the excitation light from the observation target is referred to as the second return light.

[0026] The camera head 5 corresponds to the imaging device according to the present disclosure. This camera head 5 is detachably connected to the eyepiece part 21 of the insertion part 2. Then, the camera head 5 captures the first and second return lights condensed by the insertion part 2 under the control of the control device 9 and generates a pixel signal. Hereinafter, for convenience of explanation, the pixel signal is referred to as a captured image. The detailed configuration of the camera head 5 will be described in the "Configuration of Camera Head" described later.

[0027] One end of the first transmission cable 6 is detachably connected to the control device 9 via the connector CN1 (FIG. 1), and the other end is detachably connected to the camera head 5 via the connector CN2 (FIG. 1). Then, the first transmission cable 6 transmits the captured image and the like output from the camera head 5 to the control device 9, and transmits the control signal, the synchronization signal, the clock, the power, and the like output from the control device 9 to the camera head 5, respectively.

[0028] Note that the transmission of imaging images and the like from the camera head 5 to the control device 9 via the first transmission cable 6 may be performed by transmitting the imaging images and the like as optical signals, or may be transmitted 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.

[0029] The display device 7 is composed of a display using liquid crystal or organic EL (Electro Luminescence) or the like, and displays an image based on the video signal from the control device 9 under the control of the control device 9.

[0030] 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. Then, the second transmission cable 8 transmits the video signal processed by the control device 9 to the display device 7.

[0031] The control device 9 corresponds to the light source control device according to the present disclosure. This control device 9 is composed of a CPU (Central Processing Unit), an FPGA (Field-Programmable Gate Array), etc., and comprehensively controls the operations of the light source device 3, the camera head 5, and the display device 7. Note that the detailed configuration of the control device 9 will be described in the "Configuration of the Control Device" described later.

[0032] 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. Then, the third transmission cable 10 transmits the control signal from the control device 9 to the light source device 3.

[0033] 〔Configuration of the Camera Head〕 Next, the configuration of the camera head 5 will be described. FIG. 2 is a block diagram showing the configurations 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.

[0034] The lens unit 51 is composed of one or more lenses. The lens unit 51 forms the first and second return lights (subject images) condensed by the insertion unit 2 on the imaging surfaces of the first and second imaging elements 531 and 532, respectively.

[0035] The prism 52 separates the first and second return lights (subject images) passing through the lens unit 51 into lights in different first and second wavelength bands. The light in the first wavelength band is light in a wavelength band excluding the wavelength band of the second return light and including the wavelength band of visible light that is the first return light. Hereinafter, the light in the first wavelength band is referred to as the first subject image. The light in the second wavelength band is light in a wavelength band excluding the wavelength band of visible light and including the wavelength band of the second return light. Hereinafter, the light in the second wavelength band is referred to as the second subject image. Then, the prism 52 causes the first subject image (first return light) to travel toward the first imaging element 531. The prism 52 also causes the second subject image (second return light) to travel toward the second imaging element 532.

[0036] The imaging unit 53 images an observation target 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.

[0037] The first and second imaging elements 531 and 532 receive a subject image and convert it into an electrical signal (analog signal). In the present embodiment, the first and second imaging elements 531 and 532 are each composed of a CMOS, which is a rolling shutter type imaging element in which a plurality of pixels are two-dimensionally arranged in horizontal line units.

[0038] Here, although not specifically illustrated, the first imaging element 531 is composed of an invalid region that is not electrically guaranteed, an optical black region (OB region), and an effective pixel region that converts the first subject image imaged by the lens unit 51 into a pixel signal and outputs it. Note that the second imaging element 532 is similarly composed of an invalid region, an optical black region (OB region), and an effective pixel region.

[0039] Then, under the control of the control device 9, the first imaging element 531 captures the first subject image (first return light) via the prism 52. That is, the first imaging element 531 captures light including at least a part of the visible light wavelength band. Hereinafter, for convenience of explanation, the captured image generated by capturing the first subject image with the first imaging element 531 is referred to as a normal light image.

[0040] Also, under the control of the control device 9, the second imaging element 532 captures the second subject image via the prism 52. That is, the second imaging element 532 captures light including at least a part of the invisible light wavelength band. Hereinafter, for convenience of explanation, the captured image generated by capturing the second subject image with the second imaging element 532 is referred to as a fluorescence image.

[0041] Note that the number of pixels of the normal light image and the number of pixels of the fluorescence image may be different or may be the same.

[0042] The signal processing unit 533 performs signal processing on the captured images (analog signals) generated by the first and second imaging elements 531 and 532 under the control of the control device 9 and outputs the captured images (digital signals). For example, the signal processing unit 533 performs signal processing such as a process of removing reset noise, a process of multiplying an analog gain for amplifying the analog signal, and A / D conversion on the captured images (analog signals) generated by the first and second imaging elements 531 and 532.

[0043] 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. This communication unit 54 is configured by, for example, a high-speed serial interface that performs communication of the captured images at a transmission rate of 1 Gbps or more with the control device 9 via the first transmission cable 6.

[0044] Note that the communication unit 54 may alternately transmit the normal light image and the fluorescence image to the control device 9, or may transmit them simultaneously.

[0045] 〔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.

[0046] The communication unit 91 functions as a receiver that receives the 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 the captured images at a transmission rate of 1 Gbps or more with the communication unit 54.

[0047] The image memory 92 is configured, for example, with a DRAM (Dynamic Random Access Memory) or the like. This image memory 92 can temporarily store a plurality of frames of the captured images sequentially output from the camera head 5 (communication unit 54).

[0048] 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 under the control of the control unit 94. As shown in FIG. 2, this 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.

[0049] The memory controller 931 controls the writing of the captured image to the image memory 92 and the reading of the captured image from the image memory 92. More specifically, the memory controller 931 writes the normal light image received by the communication unit 91 to the image memory 92, reads the normal light image from the image memory 92 at a specific timing, and inputs it to the first image processing unit 932. Further, 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 second image processing unit 933.

[0050] The first image processing unit 932 executes the first image processing on the input normal light image. Examples of the first image processing include optical black subtraction processing (clamp processing), white balance adjustment processing, demosaic processing, color correction matrix processing, gamma correction processing, YC processing for converting RGB signals into luminance chrominance signals (Y, Cb / Cr signals), gain adjustment, noise removal, and filter processing for enhancing structure.

[0051] The second image processing unit 933 executes the second image processing on the input fluorescence image. Examples of the second image processing include optical black subtraction processing (clamp processing), white balance adjustment processing, demosaic processing, color correction matrix processing, gamma correction processing, YC processing for converting RGB signals into luminance chrominance signals (Y, Cb / Cr signals), gain adjustment, noise removal, and filter processing for enhancing structure. Note that the first and second image processings may be different from each other or may be the same image processing.

[0052] The display control unit 934 generates a video signal for displaying the normal light image after the first image processing is executed by the first image processing unit 932 or the fluorescence image after the second image processing is executed by the second image processing unit 933 under the control of the control unit 94. Then, the display control unit 934 outputs the video signal to the display device 7 via the second transmission cable 8.

[0053] The control unit 94 is realized by executing various programs stored in the storage unit 97 by a controller such as a CPU or an MPU (Micro Processing Unit). It controls the operations of the light source device 3, the camera head 5, and the display device 7, and also controls the overall operation of the control device 9. Note that the control unit 94 may be constituted by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA, not limited to a CPU or an MPU. As shown in FIG. 2, this control unit 94 has functions as a light source control unit 941 and an imaging control unit 942. Note that the light source control unit 941 may adopt a configuration provided in the light source device 3, not limited to the configuration provided in the control device 9.

[0054] Note that the function of the imaging control unit 942 will be described in "Problems of the Present Disclosure" which will be described later. Also, the function of the light source control unit 941 will be described in "Problems of the Present Disclosure" and "Function of the Light Source Control Unit" which will be described later.

[0055] The input unit 95 is configured using an operation device such as a mouse, a keyboard, and a touch panel, and receives user operations by a user such as an operator. Then, the input unit 95 outputs an operation signal corresponding to the user operation to the control unit 94.

[0056] The output unit 96 is configured using a speaker, a printer, etc., and outputs various information.

[0057] 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.

[0058] 〔Problems of the Present Disclosure〕 Before explaining the operation of the control device 9, the problems of the present disclosure will be explained. Figs. 3 to 8 are diagrams for explaining the problems of the present disclosure. Specifically, (b) of Fig. 3 shows the horizontal lines of the rolling shutter type imaging elements (the first and second imaging elements 531 and 532) on the vertical axis (the uppermost line shows the uppermost horizontal line (the first horizontal line), and the lowermost line shows the lowermost horizontal line (the last line)), and the horizontal axis shows time. The parallelogram region is the region that contributes to the generation of the captured image in one field (one frame). (a) of Fig. 3 is a diagram showing the light emission period (light emission width) vd of the light emitted from the light sources (the first and second light sources 31 and 32). Fig. 4 is a diagram showing the relationship between the exposure area S in the imaging element and the light emission period vd (exposure period) of the light emitted from the light sources (the first and second light sources 31 and 32). Here, the exposure area S corresponds to the "energy index value" according to the present disclosure, and is a value obtained by summing the exposure periods for each exposed horizontal line. Fig. 5 is a diagram corresponding to Fig. 4, and shows the relationship between the exposure area S (hereinafter referred to as exposure area S1) in the first imaging element 531 and the light emission period vd (hereinafter referred to as light emission period vd1) of the first light emitted from the first light source 31. Fig. 6 is a diagram corresponding to Fig. 4, and shows the relationship between the exposure area S (hereinafter referred to as exposure area S2) in the second imaging element 532 and the light emission period vd (hereinafter referred to as light emission period vd2) of the excitation light emitted from the second light source 32. In Fig. 7, the parallelograms shown by the broken line and the solid line are diagrams corresponding to (b) of Fig. 3. Also, in Fig. 7, the rectangle shown by the dashed-dotted line indicates the light (pulse light) emitted from the light sources (the first and second light sources 31 and 32). Fig. 8 is a diagram corresponding to (b) of Fig. 3. The white parallelogram indicates one field (one frame) that contributes to the generation of the normal light image. The hatched parallelogram indicates one field (one frame) that contributes to the generation of the fluorescence image. That is, the upper part of (a) of Fig. 8 shows one field (one frame) that contributes to the generation of the normal light image by the first imaging element 531. Also, the lower part of (a) of Fig. 8 shows one field (one frame) that contributes to the generation of the fluorescence image by the second imaging element 532. Fig. 9 shows one field (one frame) that contributes to the generation of the normal light image and the fluorescence image when only one imaging element according to the present disclosure is provided.

[0059] The imaging control unit 942 performs imaging control by a so-called rolling shutter method in which the exposure of the first and second imaging elements 531 and 532 during one field period is sequentially started for each horizontal line, and the reading is sequentially performed for each horizontal line after a predetermined period (so-called shutter speed) has elapsed since the start of the exposure.

[0060] Here, when a rolling shutter method imaging element is adopted, if the light emission period vd of the light is changed within the total line exposure period a, as shown in FIG. 4, the relationship between the exposure area S and the light emission period vd is linear. On the other hand, if the light emission period vd of the light is changed outside the total line exposure period a, the relationship between the exposure area S and the light emission period vd becomes non-linear. The non-linearity means that the number of horizontal lines exposed simultaneously changes. In the present embodiment, as described above, since the first and second imaging elements 531 and 532 are rolling shutter method imaging elements, there is a region where the relationship between the exposure area S and the light emission period vd is non-linear.

[0061] In the present embodiment, for the first light source 31, the light source control unit 941 executes PWM control to change the light emission period vd1 of the first light in a state where the maximum light emission period vd_max (hereinafter referred to as the maximum light emission period vd1_max) of the first light is within the total line exposure period a (hereinafter referred to as the total line exposure period a1) in the first imaging element 531. On the other hand, for the second light source 32, the light source control unit 941 executes PWM control to change the light emission period vd2 of the excitation light in a state where the maximum light emission period vd_max (hereinafter referred to as the maximum light emission period vd2_max) of the excitation light is larger than the total line exposure period a (hereinafter referred to as the total line exposure period a2) in the second imaging element 532.

[0062] That is, for the first light, the light source control unit 941 changes it only in the region where the relationship between the exposure area S1 in the first imaging element 531 and the emission period vd1 of the first light is linear. On the other hand, for the excitation light, the light source control unit 941 may change it in the region where the relationship between the exposure area S2 in the second imaging element 532 and the emission period vd2 of the excitation light is non-linear. Note that the exposure area S1 corresponds to the first energy index value according to the present disclosure. Also, the exposure area S2 corresponds to the second energy index value according to the present disclosure.

[0063] For this reason, there are the following problems. Here, assume a case where the target duty x0 calculated from the brightness of the target light source is 80%. The duty is the ratio (%) obtained by dividing the emission period by the maximum emission period.

[0064] As described above, for the first light, the relationship between the exposure area S1 in the first imaging element 531 and the emission period vd1 of the first light changes only in the linear region. Therefore, when the emission period vd1 of the first light is specified as the emission period 0.8 * vd1_max corresponding to the target duty x0 (80%) and emitted, as shown in FIG. 5, the exposure area S1 also becomes 80% of the maximum.

[0065] On the other hand, as described above, for the excitation light, the relationship between the exposure area S2 in the second imaging element 532 and the emission period vd2 of the excitation light may change in the non-linear region. Therefore, when the emission period vd2 of the excitation light is specified as the emission period 0.8 * vd2_max corresponding to the target duty x0 (80%) and emitted, as shown in FIG. 6, the exposure area S2 does not become 80% of the maximum.

[0066] Here, the exposure areas S1 and S2 correspond to the brightness of the captured image. For this reason, there is a problem that the ratio between the brightness of the normal light image and the brightness of the fluorescence image changes, and the brightness balance deteriorates.

[0067] Therefore, the light source control unit 941 according to the present disclosure executes the following control in order to maintain the ratio between the brightness of the normal light image and the brightness of the fluorescence image and generate an image suitable for observation with a good balance between the brightness of the normal light image and the fluorescence image.

[0068] Here, as shown in FIG. 7, assume a case where imaging is continuously performed (the fields (frames) are continuous). In this case, if the emission timing of the pulsed light is adjusted to the imaging timing, exposure will also occur in the preceding and succeeding fields (frames), so the above-described problems will not occur. More specifically, focusing on the field (frame) indicated by the solid line in FIG. 7, the reduction in the upper and lower exposure areas Ar1 is compensated by the addition of the exposure area Ar2 by the preceding and succeeding pulsed lights. That is, due to the presence of the exposure area Ar1, a region where the relationship between the emission period and the exposure area becomes non-linear does not occur, and the above-described problems do not occur.

[0069] In the present embodiment, as shown in FIG. 8(a), the first image sensor 531 generates a normal light image intermittently rather than continuously, and the second image sensor 532 generates a fluorescence image intermittently rather than continuously. Since the state described in FIG. 7 is not achieved, the above-described problems occur.

[0070] Also, as shown in FIG. 8(b), even when only one image sensor according to the present disclosure is configured, the normal light image is generated intermittently rather than continuously, and the fluorescence image is generated intermittently rather than continuously. Therefore, the state described in FIG. 7 is not achieved, and the above-described problems occur. This state corresponds to Modifications 7 and 11 described later in which only one image sensor according to the present disclosure is configured.

[0071] Note that, not limited to the case of intermittently generating a normal light image and a fluorescence image as described above, the above-described problems also occur when the timing of light (pulsed light) emitted from the light sources (the first and second light sources 31 and 32) is shifted. And according to the following control by the light source control unit 941 according to the present disclosure, it is also possible to solve the above-described problems caused by the shift in the timing of light (pulsed light) emitted from the light sources (the first and second light sources 31 and 32).

[0072] [Regarding the functions of the light source control unit] FIG. 9 is a diagram for explaining the calculation formula of the exposure area S1(vd1) in the first image sensor 531. Specifically, FIG. 9 is a diagram corresponding to FIG. 3. FIG. 10 is a diagram for explaining the calculation formula of the exposure area S2(vd2) in the second image sensor 532. Specifically, FIG. 10 is a diagram corresponding to FIG. 3. Here, the exposure areas S1(vd1) and S2(vd2) in the first and second image sensors 531 and 532 can be calculated as follows.

[0073] Note that, hereinafter, for the convenience of calculation, when considering the exposure areas S1(vd1) and S2(vd2), the height (corresponding to the current value supplied to the first and second light sources 31 and 32) is set to 1.

[0074] First, with reference to FIG. 9, the calculation formula of the exposure area S1(vd1) in the first image sensor 531 will be described. The exposure area S1(vd1) is a function of the light emission period vd1. As described above, the maximum light emission period vd1_max of the first light is within the entire line exposure period a1. Therefore, the exposure area S1(vd1) can be calculated by the following formula (1).

[0075] (Equation 1) S1(vd1)=vd1*1 ···(1)

[0076] When expressing the target brightness of the first light source 31 as a duty x1 with respect to the maximum brightness, x1 = S1(vd1) / S1(vd1_max). Here, S1(vd1_max) is the exposure area during the maximum emission period vd1_max.

[0077] Next, while referring to FIG. 10, the calculation formula for the exposure area S2(vd2) in the second image sensor 532 will be described. The exposure area S2(vd2) is a function of the emission period vd2. As described above, the maximum emission period vd2_max of the excitation light is larger than the full line exposure period a2. More specifically, the maximum emission period vd2_max of the excitation light is larger than the full line exposure period a2 and smaller than the total exposure period (the period obtained by adding the full line exposure period a2 and the two readout periods b2) in the second image sensor 532 for constructing a fluorescence image of one field (one frame). That is, in the present embodiment, there is a part of the period (the blackened period in FIG. 10) in the total exposure period of the second image sensor 532 where the emission period vd2 of the excitation light cannot be adjusted. Hereinafter, let t2 = a2 + 2*b2 - vd2 (FIG. 10).

[0078] And the exposure area S2(vd2) can be calculated by the following formula (2) in the region where vd2 ≤ a2.

[0079] (Equation 2) S2(vd2) = vd2 * 1 ···(2)

[0080] Also, the exposure area S2(vd2) can be calculated by the following formula (3) in the region where a2 < vd2 < a2 + 2*b2.

[0081] (Equation 3) S2(vd2) = a2 * 1 + 2((b2 / 2) - ((t2 / 2)*(t2 / 2) / b2) / 2) = a2 * b2 - (a2 + b2 - vd2)*(a2 + b2 - vd2) / (4*b2) ···(3)

[0082] When expressing the target brightness of the second light source 32 as a duty x2 with respect to the maximum brightness, x2 = S2(vd1) / S2(vd2_max). S2(vd2_max) is the exposure area during the maximum light emission period vd2_max.

[0083] Then, the light source control unit 941 adjusts the light emission periods vd1 and vd2 as follows. First, the light source control unit 941 calculates a target duty x0 from the target brightness of the light source. Note that the target brightness of the light source may be specified through the input unit 95 (manual dimming) or calculated by the control unit 94 through arithmetic operations (automatic dimming). Even in this automatic dimming, fine adjustments corresponding to EV correction in photography are possible, and such fine adjustments are specified through the input unit 95.

[0084] Next, the light source control unit 941 calculates a duty x1 in the first light source 31 using the calculated target duty x0 in the following formula (4).

[0085] (Equation 4) x0 = x1 ···(4)

[0086] Next, the light source control unit 941 calculates a target exposure area S2_tgt using the calculated target duty x0 and the maximum exposure area S2(vd2_max) in the following formula (5).

[0087] (Equation 5) S2_tgt = S2(vd2_max) * x0 ···(5)

[0088] Next, the light source control unit 941 calculates a corrected light emission period vd2_revised using the calculated target exposure area S2_tgt and the inverse function of the exposure area S2(vd2) in the following formula (6).

[0089] (Equation 6) vd2_revised = inverse function of S2(vd2) (target exposure area S2_tgt) ···(6)

[0090] Here, when the target exposure area S2_tgt is an exposure area within the entire line exposure period a2, the light source control unit 941 uses the inverse function of S2(vd2) shown in Equation (2) in Equation (6). On the other hand, when the target exposure area S2_tgt is an exposure area exceeding the entire line exposure period a2, the light source control unit 941 uses the inverse function of S2(vd2) shown in Equation (3) in Equation (6).

[0091] Next, the light source control unit 941 calculates the corrected duty x2_revised using the calculated emission period vd2_revised and the maximum emission period vd2_max in the following Equation (7).

[0092] (Equation 7) x2_revised = vd2_revised / vd2_max ···(7)

[0093] That is, the above-mentioned problem that occurs when x2 = x1 is corrected by calculation to obtain x2_revised. In other words, the light source control unit 941 adjusts the emission periods vd1 and vd2 so that the ratio of the exposure area S1 to the exposure area S2 becomes a predetermined ratio. That is, the light source control unit 941 adjusts the emission periods vd1 and vd2 so that the energy of the first return light exposed by the first image sensor 531 and the energy of the light exposed by the second return light in the second image sensor 532 become a predetermined ratio. When the emission periods vd1 and vd2 are adjusted in this way, in the non-linear region shown in FIG. 6, the ratio of the change in the emission period vd1 of the first light and the ratio of the change in the emission period vd2 of the excitation light may be different.

[0094] Then, the light source control unit 941 controls the first light source 31 with the duty x1, so that the first light source 31 emits the first light with a light emission period vd1 corresponding to the duty x1. Further, the light source control unit 941 controls the second light source 32 with the corrected duty x2, so that the second light source 32 emits the excitation light with a corrected light emission period vd2_revised. That is, the light source control unit 941 alternately and sequentially turns on the first and second light sources 31 and 32.

[0095] According to the embodiment described above, the following effects can be obtained. In the control device 9 according to the present embodiment, the light source control unit 941 can adjust the light emission period vd2 of the excitation light to be larger than the entire line exposure period a2, and adjusts the light emission periods vd1 and vd2 so that the ratio of the exposure area S1 to the exposure area S2 becomes a predetermined ratio. That is, the light emission periods vd1 and vd2 are adjusted while maintaining the ratio of the brightness of the normal light image to the brightness of the fluorescence image. Therefore, according to the control device 9 according to the present embodiment, it is possible to maintain the ratio of the brightness of the normal light image to the brightness of the fluorescence image, and generate an image suitable for observation with a good balance of the brightness of the normal light image and the fluorescence image.

[0096] Further, the light source control unit 941 calculates the duties x1 and x2 using the arithmetic expressions (4), (5) to (7) from the target duty x0. Therefore, the light emission periods vd1 and vd2 can be adjusted by simple processing.

[0097] Further, in the formula (6), the light source control unit 941 uses different arithmetic expressions depending on whether the target exposure area S2_tgt is an exposure area within the entire line exposure period a2 or an exposure area exceeding the entire line exposure period a2. Therefore, the effect of "maintaining the ratio of the brightness of the normal light image to the brightness of the fluorescence image and generating an image suitable for observation with a good balance of the brightness of the normal light image and the fluorescence image" described above can be preferably realized.

[0098] (Other embodiments) So far, the embodiments for implementing the present disclosure have been described. However, the present disclosure should not be limited only by the above-described embodiments. In the above-described embodiments, the following modification examples 1 to 12 may be adopted.

[0099] (Modification Example 1) In the above-described embodiments, if at least one of the first and second imaging elements 531 and 532 has a region where the relationship between the exposure area and the emission period is non-linear, other configurations may be adopted.

[0100] For example, in the above-described embodiments, a CCD (Charge Coupled Device), which is a global shutter type imaging element, may be adopted for one of the first and second imaging elements 531 and 532.

[0101] Also, for example, in the above-described embodiments, the full-line exposure period of at least one of the first and second imaging elements 531 and 532 may be set to 0. That is, at least one of the first and second imaging elements 531 and 532 does not have a linear relationship between the exposure period S and the emission period vd, and has only a non-linear relationship.

[0102] Furthermore, for example, in the above-described embodiments, an imaging element different from the rolling shutter method and having a region where the relationship between the exposure area and the emission period is non-linear may be adopted for at least one of the first and second imaging elements 531 and 532.

[0103] (Modification Example 2) In the above-described embodiment, the maximum emission period vd1_max of the first light may be made larger than the entire line exposure period a1, similar to the maximum emission period vd2_max of the excitation light. More specifically, the maximum emission period vd1_max of the first light is larger than the entire line exposure period a1 and smaller than the entire exposure period (the period obtained by adding the entire line exposure period a1 and the two readout periods b1) in the first image sensor 531 for constituting a normal light image of one field (one frame). That is, in this modification, there is a part of the period (the blackened period in FIG. 9) in the entire exposure period in the first image sensor 531 where the emission period vd1 of the first light cannot be adjusted. Hereinafter, let t1 = a1 + 2 * b1 - vd1 (FIG. 9).

[0104] And the exposure area S1(vd1) can be calculated by the formula (1) in the region where vd1 ≦ a1.

[0105] Also, the exposure area S1(vd1) can be calculated by the following formula (8) in the region where a1 < vd1 < a1 + 2 * b1.

[0106] (Equation 8) S1(vd1)=a1*1+2((b1 / 2)-((t1 / 2)*(t1 / 2) / b1) / 2) =a1*b1-(a1+b1-vd1)*(a1+b1-vd1) / (4*b1) ···(8)

[0107] And the light source control unit 941 adjusts the emission period vd1 as shown below. The adjustment of the emission period vd2 is the same as that in the above-described embodiment.

[0108] First, the light source control unit 941 calculates the target exposure area S1_tgt by the following formula (9) using the calculated target duty x0 and the maximum exposure area S1(vd1_max).

[0109] (Equation 9) S1_tgt=S1(vd1_max)*x0 ···(9)

[0110] Next, the light source control unit 941 calculates a corrected emission period vd1_revised using the calculated target exposure area S1_tgt and the inverse function of the exposure area S1(vd1) by the following formula (10).

[0111] (Equation 10) vd1_revised = inverse function of S1(vd1) (target exposure area S1_tgt) ···(10)

[0112] Here, when the target exposure area S1_tgt is an exposure area within the full line exposure period a1, the light source control unit 941 uses the inverse function of S1(vd1) shown in Equation (1) in Equation (10). On the other hand, when the target exposure area S1_tgt is an exposure area exceeding the full line exposure period a1, the light source control unit 941 uses the inverse function of S1(vd1) shown in Equation (8) in Equation (10).

[0113] Next, the light source control unit 941 calculates a corrected duty x1_revised using the calculated emission period vd1_revised and the maximum emission period vd1_max by the following formula (11).

[0114] (Equation 11) x1_revised = vd1_revised / vd1_max ···(11)

[0115] Then, the light source control unit 941 controls the first light source 31 with the corrected duty x1_revised to emit the first light from the first light source 31 for the corrected emission period vd1_revised.

[0116] (Modification Example 3) In the above-described embodiment, the light source control unit 941 calculated the duties x1 and x2 from the target duty x0 using the arithmetic expressions (4), (5) to (7). However, the present invention is not limited to this, and the duties x1 and x2 corresponding to the target duty x0 may be specified with reference to a table. At this time, if the duties x1 and x2 corresponding to the target duty x0 are not in the table, the duties x1 and x2 may be calculated by interpolation.

[0117] (Modification Example 4) In the above-described embodiment, when calculating the exposure areas S1(vd1) and S2(vd2), the weights of the entire surface were all calculated to be the same. However, the present invention is not limited to this. That is, different weightings may be performed at the locations to be exposed to calculate the exposure areas S1(vd1) and S2(vd2).

[0118] For example, the exposure areas S1(vd1) and S2(vd2) may be calculated by reducing the weights of the upper, lower, left, and right portions of the exposure surface and emphasizing the brightness of the central portion.

[0119] Hereinafter, the exposure area S2(vd2) will be described as an example. FIG. 11 is a diagram for explaining Modification Example 4 of the embodiment. Specifically, FIG. 11 corresponds to FIG. 3(b). Note that the light emission period vd2 is common to all the parallelograms shown in FIG. 11. Also, the calculation functions of the respective exposure areas corresponding to the respective parallelograms shown in FIG. 11 become common by taking the full line exposure period and the readout period as arguments.

[0120] Here, let the original exposure area be the exposure area S20 (FIG. 11(a)). This exposure area S20 can be expressed as S20 = S(a20, b20, vd2) as a function of the full line exposure period a2 (hereinafter referred to as the full line exposure period a20), the readout period b2 (hereinafter referred to as the readout period b20), and the light emission period vd2.

[0121] Also, consider a parallelogram whose vertical and horizontal dimensions are reduced by a factor of z1 with respect to the exposure area S20 (Fig. 11(b)). Similarly, when this exposure area is denoted as the exposure area S21, it can be expressed as S21 = S(a21, b21, vd2) * z1.

[0122] Similarly, when the exposure area of the parallelogram that has been reduced by a factor of zn in the nth operation is denoted as the exposure area S2n (Fig. 11(c)), it can be expressed as S2n = S(a2n, b2n, Vd2) * zn. Note that vd2 > a2n + 2 * b2n.

[0123] Then, as shown in the following equation (12), let the sum of the above-described exposure areas be the exposure area S2(vd2) (Fig. 11(d)).

[0124]

Equation

[0125] (Modification Example 5) Fig. 12 is a diagram for explaining Modification Example 5 of the embodiment. Specifically, Fig. 12 corresponds to Fig. 2. In the above-described embodiment, two light sources, the first and second light sources 31 and 32, and two image pickup devices, the first and second image pickup devices 531 and 532, were employed, but it is not limited thereto. For example, three or more light sources and three or more image pickup devices may be employed.

[0126] Note that in Fig. 12, a configuration employing three light sources and three image pickup devices is illustrated. Specifically, in the medical observation system 1A according to this Modification Example 5, as shown in Fig. 12, in the imaging unit 53, in addition to the first and second image pickup devices 531 and 532, a third image pickup device, the third image pickup device 534, is added. Also, in the processing module 93, in addition to the first and second image processing units 932 and 933, a third image processing unit, the third image processing unit 935, is added. Further, in the light source device 3, in addition to the first and second light sources 31 and 32, a third light source, the third light source 33, is added.

[0127] For example, the first light source 31 emits first light such as white light, similar to the above-described embodiment. The second light source 32 emits infrared light. The third light source 33 emits ultraviolet light.

[0128] Here, the prism 52 separates the return light of the first light from the observation target, the return light of the infrared light from the observation target, and the return light of the ultraviolet light from the observation target. Then, the first imaging element 531 images the return light of the first light. The second imaging element 532 images the return light of the infrared light. The third imaging element 534 images the return light of the ultraviolet light. Hereinafter, the captured image generated by imaging with the first imaging element 531 is referred to as the first captured image. Also, the captured image generated by imaging with the second imaging element 532 is referred to as the second captured image. Further, the captured image generated by imaging with the third imaging element 534 is referred to as the third captured image.

[0129] Here, the memory controller 931 controls the writing of the captured image to the image memory 92 and the reading of the captured image from the image memory 92, thereby causing the first captured image to be input to the first image processing unit 932, the second captured image to be input to the second image processing unit 933, and the third captured image to be input to the third image processing unit 935. The first image processing unit 932 executes first image processing on the input first captured image. The second image processing unit 933 executes second image processing on the input second captured image. The third image processing unit 935 executes third image processing on the input third captured image. Then, the display control unit 934 generates a video signal for displaying at least any one of the first captured image after the first image processing is executed by the first image processing unit 932, the second captured image after the second image processing is executed by the second image processing unit 933, and the third captured image after the third image processing is executed by the third image processing unit 935 under the control of the control unit 94.

[0130] Note that, also in the fifth modification example, the first image pickup device 531 generates the first captured image intermittently instead of continuously. Further, the second image pickup device 532 generates the second captured image intermittently instead of continuously. Furthermore, the third image pickup device 533 generates the third captured image intermittently instead of continuously.

[0131] (Modification Example 6) In the above-described embodiments, the light source and the image pickup device are in a one-to-one correspondence, but it is not limited thereto. For example, a configuration in which a plurality of image pickup devices correspond to one light source may be adopted. As a specific example, one light source that emits xenon light is used, and imaging of white light and imaging of ultraviolet light are performed with two image pickup devices.

[0132] (Modification Example 7) FIGS. 13 and 14 are diagrams for explaining the seventh modification example of the embodiment. Specifically, FIG. 13 is a diagram corresponding to FIG. 2. FIG. 14(a) is a diagram corresponding to FIG. 3(b). FIG. 14(b) is a diagram corresponding to FIG. 9(a). FIG. 14(c) is a diagram corresponding to FIG. 10(a). In the above-described embodiments, the light source and the image pickup device are in a one-to-one correspondence, but it is not limited thereto. For example, a configuration in which one image pickup device corresponds to a plurality of light sources, and the one image pickup device is driven in a time-division manner to generate a plurality of captured images may be adopted.

[0133] Note that, in FIG. 13, a configuration adopting two light sources and one image pickup device is illustrated. Specifically, in the medical observation system 1B according to the seventh modification example, as shown in FIG. 13, in the camera head 5, the prism 52 is omitted. Further, in the imaging unit 53, the second image pickup device 532 is omitted.

[0134] Regarding the control of the first and second light sources 31 and 32 by the light source control unit 941, as shown in FIGS. 14(b) and 14(c), it is the same as that in the above-described embodiment.

[0135] Then, under the control of the imaging control unit 942, as shown in Fig. 14(a), the first imaging device 531 generates a normal light image and a fluorescence image in a time-division manner.

[0136] (Modification Example 8) In the above-described embodiment, the light source control unit 941 controls the first and second light sources 31 and 32 by the duties x1 and x2. However, the present invention is not limited to this, and the first and second light sources 31 and 32 may be controlled by the light emission periods vd1 and vd2_revised.

[0137] (Modification Example 9) In the above-described embodiment, the light source control unit 941 may change the parameters (a1, a2, b1, b2) of the arithmetic expressions (4), (5) to (7) for calculating the duties x1 and x2 from the target duty x0 according to the type of the vertical synchronization signal (for example, the vertical synchronization signal of the NTSC system, the vertical synchronization signal of the PAL system, etc.).

[0138] (Modification Example 10) In the above-described embodiment, the light source control unit 941 may switch the arithmetic expressions (4), (5) to (7) for calculating the duties x1 and x2 from the target duty x0 according to at least one of the type of the camera head 5 (the type of the imaging device and the operation control of the camera head 5 (for example, normal exposure, long-time exposure, etc.)) (for example, the difference in the length of the entire exposure period, the difference in the length of the entire line exposure period, normal exposure, long-time exposure, etc.). The same applies to Modification Example 3 using a table instead of the arithmetic expression.

[0139] (Modification Example 11) In the above-described embodiment, a configuration using one light source and one imaging device may be adopted. For example, in the above-described embodiment, the prism 52, the first light source 31, and the first imaging device 531 may be omitted.

[0140] That is, in the present Modification 11, the light source control unit 941 adjusts the light emission period vd2 of the excitation light based on the first energy index value (exposure area S2(vd2)), which is an energy index value serving as an index of the energy of the light obtained by exposing the second return light of the excitation light (corresponding to the first light according to the present disclosure) in the second imaging element 532.

[0141] (Modification 12) FIG. 15 is a diagram for explaining Modification 12 of the embodiment. The medical observation system 1C according to the present Modification 12 is a medical observation system using a so-called video scope (flexible endoscope) having an imaging unit on the distal end side of the insertion unit.

[0142] As shown in FIG. 15, the medical observation system 1C includes an endoscope 100 that captures an in-vivo image of an observation site by inserting the insertion unit 2C into the living body and outputs a captured image, a light source device 3 that emits the first light and the excitation light from the distal end of the endoscope 100, a control device 9 that processes the captured image output from the endoscope 100, 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 the video signal processed by the control device 9.

[0143] As shown in FIG. 15, the endoscope 100 includes an insertion unit 2C having an elongated flexible shape, an operation unit 101 connected to the proximal end side of the insertion unit 2C and receiving various operations, and a universal cord 102 that extends in a direction different from the direction in which the insertion unit 2C extends from the operation unit 101 and houses various cables connected to the light source device 3 and the control device 9.

[0144] As shown in FIG. 15, the insertion unit 2C includes a distal end portion 22, a bendable bending portion 23 connected to the proximal end side of the distal end portion 22 and formed of a plurality of bending members, and a flexible long flexible tube portion 24 connected to the proximal end side of the bending portion 23.

[0145] Although not shown in detail, the tip portion 22 has a configuration substantially the same as that of the camera head 5 described in the above embodiment. The captured image captured by the tip portion 22 (imaging element) is output to the control device 9 via the operation unit 101 and the universal code 102.

[0146] (Modification Example 13) FIG. 16 is a diagram for explaining Modification Example 13 of the embodiment. The medical observation system 1D according to this Modification Example 13 is a medical observation system using a surgical microscope that magnifies and images a predetermined visual field area inside the subject to be observed (inside the living body) or on the surface of the subject (living body surface).

[0147] As shown in FIG. 16, the medical observation system 1D includes a surgical microscope 12 that captures an image for observing a subject and outputs a captured image, a control device 9 that processes the captured image output from the surgical microscope 12, and a second transmission cable 8 connected to the control device 9 via the control device 9, and a display device 7 that displays an image based on the video signal processed by the control device 9.

[0148] As shown in FIG. 16, the surgical microscope 12 includes a microscope unit 121 that magnifies and images a minute part of the subject and outputs a 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 surface. And, as shown in FIG. 16, the control device 9 is installed on the base unit 123. Although not shown in detail, a light source device 3 that emits first light and excitation light from the surgical microscope 12 to the observation target is also installed on the base unit 123. Note that the base unit 123 may be configured to support the support unit 122 by being fixed to the ceiling, wall surface, etc. instead of being movably provided on the floor surface.

[0149] Although not specifically illustrated, the microscope unit 121 has a configuration substantially the same as that of the camera head 5 described in the above-described embodiment. The captured image captured by the microscope unit 121 (image sensor) is output to the control device 9 via the first transmission cable 6 wired along the support unit 122.

[0150] (Modification Example 14) FIGS. 17 and 18 are diagrams for explaining Modification Example 14 of the embodiment. Specifically, FIG. 17 is a side view of the ring light 15. FIG. 18 is a front view (left side in FIG. 17) of the ring light 15. In this Modification Example 14, the ring light 15 is detachably connected to the camera head 5 in addition to the insertion unit 2 described in the above-described embodiment. That is, depending on the usage state of the user, the insertion unit 2 may be connected as shown in FIG. 17, or the ring light 15 may be connected to the camera head 5.

[0151] The ring light 15 is not inserted into the observation target like the insertion unit 2, but supplies the first light and the excitation light to the surgical site and captures the return light of the first light and the excitation light from the surgical site. As shown in FIGS. 17 and 18, the ring light 15 includes an illumination unit 151 and a subject image capture unit 152 that captures a subject image.

[0152] As shown in FIGS. 17 and 18, 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.

[0153] As shown in FIG. 18, the plurality of illumination lenses 1512 are respectively arranged at predetermined intervals along the circumferential direction centered on the optical axis Ax on the front end surface of the housing 1511. The plurality of illumination lenses 1512 respectively irradiate the surgical site with the first light and the excitation light supplied from the light source device 3 and introduced into the housing 1511 via the light guide 4.

[0154] The subject image capturing unit 152 extends along the optical axis Ax. Further, inside the subject image capturing unit 152, an optical system is provided which is configured using one or a plurality of lenses, and which condenses the return light of the first light and the excitation light that have passed through the surgical site and have been irradiated from the plurality of illumination lenses 1512. Furthermore, a connection portion 1521 is provided at the end portion on the proximal end side (the right side in FIG. 17) of the subject image capturing unit 152. This connection portion 1521 has a design (shape) that is compatible with the eyepiece portion 21 in the insertion portion 2, and is detachably connected to the camera head 5.

[0155] Note that the following configurations also belong to the technical scope of the present disclosure. (1) A medical observation system comprising: a light source device that emits first light and second light to an observation target respectively; an imaging device that images each of the return lights of the first light and the second light from the observation target, and in which the number of horizontal lines simultaneously exposed by at least one of the return light of the first light and the return light of the second light changes; and a light source control unit that adjusts the emission periods of the first light and the second light so that the energy of the light that has exposed the return light of the first light in the imaging device and the energy of the light that has exposed the return light of the second light in the imaging device are in a predetermined ratio. (2) The medical observation system according to (1) above, wherein the imaging device intermittently images the return light of the first light and the return light of the second light. (3) When a value obtained by summing the exposure periods for each horizontal line in the imaging device is defined as an energy index value, the imaging device has a region where the relationship between the energy index value and the exposure period of light is non-linear, and the light source control unit adjusts the emission periods of the first light and the second light so that a first energy index value related to imaging of the return light of the first light and a second energy index value related to imaging of the return light of the second light are in a predetermined ratio. The medical observation system according to (1) or (2) above. (4) The light source control device according to any one of (1) to (3) above, wherein the light source control unit adjusts the emission periods of the first light and the second light using a predetermined arithmetic formula. (5) The imaging device is of a rolling shutter type in which a plurality of pixels are two-dimensionally arranged in horizontal line units, and includes an imaging element having an all-line exposure period during which all of the horizontal lines in the effective pixel region are simultaneously exposed. The light source control unit uses different arithmetic expressions when adjusting the emission period of at least one of the first light and the second light within the all-line exposure period and when adjusting the emission period of at least one of the first light and the second light outside the all-line exposure period. The light source control device according to (4) above. (6) The imaging device has a linear region and a non-linear region in which the relationship between the energy index value, which is an index of the energy of the exposed light, and the exposure period of the light is linear. The light source control unit uses different arithmetic expressions when adjusting the emission period of at least one of the first light and the second light in the linear region and when adjusting the emission period of at least one of the first light and the second light in the non-linear region. The light source control device according to (4) or (5) above. (7) The light source control unit makes it impossible to adjust the emission periods of the first light and the second light during a part of the total exposure period in the imaging device for constructing an image of one frame. The arithmetic expression is an arithmetic expression that does not take into account the part of the period during which the emission periods of the first light and the second light cannot be adjusted. The light source control device according to any one of (4) to (6) above. (8) The light source control unit changes the parameters of the arithmetic expression according to the type of vertical synchronization signal. The light source control device according to any one of (4) to (7) above. (9) The light source control unit switches the arithmetic expression according to at least one of the type of the imaging device and the operation control of the imaging device. The light source control device according to any one of (4) to (8) above. (10) The imaging device has a linear region and a non-linear region in the relationship between the energy index value serving as an index of the energy of the exposed light and the exposure period of the light. The first light is light including at least a part of the visible light wavelength band, the second light is excitation light for exciting a substance contained in the observation target, and the light source control unit adjusts the emission period of the first light in the linear region and enables adjustment of the emission period of the second light in the non-linear region. The light source control device according to any one of (1) to (9) above. (11) The light source control device according to any one of (1) to (10) above, wherein the ratio of change in the emission period of the first light and the ratio of change in the emission period of the second light may be different. (12) The light source control device according to any one of (1) to (3) above, wherein the light source control unit adjusts the emission periods of the first light and the second light using a predetermined table. (13) The light source control device according to (12) above, wherein the light source control unit switches the table according to at least one of the type of the imaging device and the operation control of the imaging device. (14) The light source control device according to (3) above, wherein the light source control unit performs different weightings at locations where at least one of the return light of the first light and the return light of the second light is exposed in the imaging device, and calculates at least one of the first energy index value and the second energy index value. (15) A medical observation system including a light source device that emits light to an observation target, an imaging device that images the return light of the light from the observation target and the number of horizontal lines simultaneously exposed by the return light of the light changes, and a light source control unit that adjusts the emission period of the light based on an energy index value serving as an index of a target value of the energy of the return light exposed in the imaging device. (16) The medical observation system according to any one of (1) to (15) above, wherein the light source device includes a plurality of light sources. (17) The medical observation system according to (16) above, wherein the imaging device includes only one imaging element. (18) The medical observation system according to any one of (1) to (16) above, wherein the imaging device includes a plurality of imaging elements. (19) The imaging device includes a second imaging element that images the return light of the second light, and the second imaging element has a non-linear relationship between a second energy index value that is an index of the light energy of the return light of the exposed second light and the exposure period of the second light, and has only a non-linear region. The medical observation system according to any one of (1) to (18) above. (20) The imaging device includes a first imaging element that images the return light of the first light and a second imaging element that images the return light of the second light, and both the first imaging element and the second imaging element have a non-linear region in the relationship between the energy index value that is an index of the energy of the exposed light and the exposure period of the light. The medical observation system according to any one of (1) to (19) above. (21) A light source control device that controls the operation of the light source device and emits the first light and the second light to the observation target from the light source device, and each of the return lights of the first light and the second light from the observation target is imaged by an imaging device in which the number of horizontal lines simultaneously exposed by at least one of the return light of the first light and the return light of the second light changes, and the light source control device adjusts the emission periods of the first light and the second light so that the energy of the light exposed by the return light of the first light in the imaging device and the energy of the light exposed by the return light of the second light in the imaging device are in a predetermined ratio. (22) A light source control device that controls the operation of the light source device and emits light to the observation target from the light source device, and the return light of the light from the observation target is imaged by an imaging device in which the number of horizontal lines simultaneously exposed by the return light changes, and the light source control device adjusts the emission period of the light based on an energy index value that is an index of a target value of the energy of the return light exposed in the imaging device.

Description of Reference Numerals

[0156] 1, 1A to 1D Medical observation system 2, 2C Insertion part 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 22 Tip 23 Bending part 24 Flexible tube part 31 First light source 32 Second light source 33 Third light source 51 Lens unit 52 Prism 53 Imaging unit 54 Communication unit 91 Communication unit 92 Image memory 93 Processing module 94 Control unit 95 Input unit 96 Output unit 97 Storage unit 100 Endoscope 101 Operation unit 102 Universal code 121 Microscope part 122 Support part 123 Base part 151 Lighting part 152 Subject image capture unit 531 First image sensor 532 Second image sensor 533 Signal processing unit 534 Third image sensor 931 Memory controller 932 First image processing unit 933 Second image processing unit 934 Display control unit 935 Third image processing unit 941 Light source control unit 942 Imaging control unit 1511 Housing 1512 Lighting lens 1521 Connection part Ax Optical axis CN1, CN2 Connectors

Claims

1. A light source device that emits first light and second light to an observation target respectively, an imaging device that images each of the return lights of the first light and the second light from the observation target, and the number of horizontal lines simultaneously exposed by at least one of the return light of the first light and the return light of the second light changes, a medical observation system comprising a light source control unit that adjusts the emission periods of the first light and the second light so that the energy of the light that exposes the return light of the first light in the imaging device and the energy of the light that exposes the return light of the second light in the imaging device are in a predetermined ratio.

2. The imaging device is the medical observation system according to claim 1, which intermittently images the return light of the first light and the return light of the second light.

3. When a value obtained by summing the exposure periods for each horizontal line in the imaging device is defined as an energy index value, the imaging device has a region where the relationship between the energy index value and the exposure period of light is non-linear, and the light source control unit is the medical observation system according to claim 1, which adjusts the emission periods of the first light and the second light so that a first energy index value related to imaging of the return light of the first light and a second energy index value related to imaging of the return light of the second light are in a predetermined ratio.

4. The light source control unit is the medical observation system according to claim 1, which adjusts the emission periods of the first light and the second light using a predetermined arithmetic formula.

5. The imaging device is a rolling shutter method in which a plurality of pixels are two-dimensionally arranged in horizontal line units, and includes an imaging element having an all-line exposure period in which all the horizontal lines in the effective pixel region are simultaneously exposed, and the light source control unit uses different arithmetic formulas when adjusting the emission period of at least one of the first light and the second light within the all-line exposure period and when adjusting the emission period of at least one of the first light and the second light outside the all-line exposure period, which is the medical observation system according to claim 4.

6. The imaging device has a linear region and a non-linear region in the relationship between the energy index value that is an index of the energy of the exposed light and the exposure period of the light, and the light source control unit The medical observation system according to claim 4, wherein different arithmetic expressions are used when adjusting the emission period of at least one of the first light and the second light in the linear region and when adjusting the emission period of the at least one light in the non-linear region.

7. The light source control unit makes it impossible to adjust the emission periods of the first light and the second light during a part of the total exposure period in the imaging device for constituting an image of one frame, The arithmetic expression is an arithmetic expression that does not take into account the part of the period during which the emission periods of the first light and the second light cannot be adjusted. The medical observation system according to claim 4.

8. The light source control unit changes the parameters of the arithmetic expression according to the type of vertical synchronization signal. The medical observation system according to claim 4.

9. The light source control unit switches the arithmetic expression according to at least one of the type of the imaging device and the operation control of the imaging device. The medical observation system according to claim 4.

10. The imaging device has a linear region and a non-linear region in the relationship between the energy index value serving as an index of the energy of the exposed light and the exposure period of the light, The first light is light including at least a part of the visible light wavelength band, The second light is excitation light for exciting a substance contained in the observation target, The light source control unit adjusts the emission period of the first light in the linear region and enables adjustment of the emission period of the second light in the non-linear region. The medical observation system according to claim 1.

11. There may be a case where the rate of change of the emission period of the first light is different from the rate of change of the emission period of the second light. The medical observation system according to claim 1.

12. The light source control unit adjusts the emission periods of the first light and the second light using a predetermined table. The medical observation system according to claim 1.

13. The light source control unit switches the table according to at least one of the type of the imaging device and the operation control of the imaging device. The medical observation system according to claim 12.

14. The light source control unit performs different weightings at locations where at least one of the return light of the first light and the return light of the second light is exposed in the imaging device, and calculates at least one of the first energy index value and the second energy index value. The medical observation system according to claim 3.

15. A light source device that emits light to an observation target, An imaging device that captures the return light of the light from the observation target, and the number of horizontal lines simultaneously exposed by the return light of the light changes; A medical observation system comprising a light source control unit that adjusts the light emission period of the light based on an energy index value that is an index of a target value of the energy of the return light exposed in the imaging device. **Claim 16** The light source device The medical observation system according to claim 1, comprising a plurality of light sources. **Claim 17** The imaging device The medical observation system according to claim 16, comprising only one imaging element. **Claim 18** The imaging device The medical observation system according to claim 1, comprising a plurality of imaging elements. **Claim 19** The imaging device Comprises a second imaging element that captures the return light of the second light, The second imaging element The medical observation system according to claim 1, wherein the relationship between the second energy index value that is an index of the energy of the return light of the exposed second light and the exposure period of the second light does not have a linear relationship and has only a non-linear region. **Claim 20** The imaging device A first imaging element that captures the return light of the first light, and A second imaging element that captures the return light of the second light, Both the first imaging element and the second imaging element The medical observation system according to claim 1, wherein the relationship between the energy index value that is an index of the energy of the exposed light and the exposure period of the light has a non-linear region respectively. **Claim 21** Comprises a light source control unit that controls the operation of the light source device and emits the first light and the second light to the observation target from the light source device, The return lights of the first light and the second light from the observation target Are respectively captured by an imaging device in which the number of horizontal lines simultaneously exposed by at least one of the return light of the first light and the return light of the second light changes, The light source control unit A light source control device that adjusts the light emission periods of the first light and the second light so that the energy of the light exposed by the return light of the first light in the imaging device and the energy of the light exposed by the return light of the second light in the imaging device are in a predetermined ratio. **Claim 22** Comprises a light source control unit that controls the operation of the light source device and emits light to the observation target from the light source device, The return light of the light from the observation target Is captured by an imaging device in which the number of horizontal lines simultaneously exposed by the return light changes, The light source control unit A light source control device that adjusts the light emission period based on an energy index value that serves as an index for the target value of the energy of the return light exposed in the imaging device.

Images