Medical observation system, medical light source control device, and medical light source control method

Abstract

To generate an image suitable for observation.SOLUTION: A light source control device 9 includes a light source controller 94. The light source controller 94 is configured to: cause a first light source 31 to emit light in a visible wavelength band in a first entire line exposure period, which is an entire line exposure period in which all horizontal lines in an effective pixel area in a rolling shutter type image sensor 522 in which multiple pixels are two-dimensionally arrayed in units of horizontal lines are simultaneously exposed; cause a second light source 32 to emit excitation light in a second entire line exposure period, which is different from the first entire line exposure period; and cause the excitation light to be emitted in an excitation light emission period including the second entire line exposure period and a period, which is adjacent to the second entire line exposure period and is at least a part of a readout period during which charges accumulated in the multiple pixels are read out, when controlling an operation of the second light source 32.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, there has been known a medical observation system that captures an image of an observation target, such as the inside of a living body, using a CMOS (Complementary Metal Oxide Semiconductor), which is a rolling shutter type imaging element, and observes the observation target (see, for example, Patent Document 1). The medical observation system described in Patent Document 1 generates normal light images and fluorescent images. Specifically, the normal light image is an image obtained by irradiating an observation target with normal light in the visible wavelength band and capturing an image of the normal light passing through the observation target. Meanwhile, the fluorescent image is an image obtained by irradiating an observation target with excitation light and capturing an image of the fluorescence from the observation target excited by the excitation light. In the medical observation system described in Patent Document 1, in order to suppress uneven brightness in normal light images and fluorescence images, normal light and excitation light are emitted only during a full-line exposure period in which all horizontal lines in the effective pixel area of ​​the image sensor are exposed simultaneously. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 170669 Summary of the Invention [Problem to be solved by the invention]

[0004] However, a fluorescent image has an extremely low signal level because the fluorescence from the object to be observed is very weak and the sensitivity of the image sensor in the wavelength band of the fluorescence is low, which makes it difficult to generate an image suitable for observation.

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

[0006] In order to solve the above-mentioned problems and achieve the object, the light source control device of the present disclosure includes a light source control unit that causes a first light source to emit light in a visible wavelength band in a first full-line exposure period, which is a full-line exposure period in which all horizontal lines of an effective pixel area of ​​a rolling shutter type image sensor in which a plurality of pixels are arranged two-dimensionally in horizontal line units are exposed simultaneously, and causes a second light source to emit excitation light in a second full-line exposure period, which is a full-line exposure period different from the first full-line exposure period, and when controlling the operation of the second light source, the light source control unit causes the excitation light to be emitted in an excitation light emission period that includes the second full-line exposure period and at least a portion of a readout period that is adjacent to the second full-line exposure period and in which charges accumulated in the plurality of pixels are read out.

[0007] Further, a medical observation system according to the present disclosure includes an imaging device including a rolling shutter type imaging element in which a plurality of pixels are two-dimensionally arranged in units of horizontal lines, a first light source emitting light in a visible wavelength band, a second light source emitting excitation light, and a light source control device controlling the first light source and the second light source, wherein the light source control device causes the first light source to emit light in the visible wavelength band in a first full line exposure period which is a full line exposure period in which all the horizontal lines of an effective pixel area of ​​the imaging element are simultaneously exposed, and a light source control unit causes the second light source to emit the excitation light in a second full line exposure period which is a full line exposure period different from the first full line exposure period, and when controlling the operation of the second light source, the light source control unit causes the excitation light to be emitted in an excitation light emission period which includes the second full line exposure period and at least a portion of a readout period which is adjacent to the second full line exposure period and in which charges accumulated in the plurality of pixels are read out. Effect of the Invention

[0008] According to the light source control device and medical observation system according to the present disclosure, an image suitable for observation can be generated. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of a medical observation system according to the first embodiment. [Diagram 2] FIG. 2 is a block diagram showing the configuration of the camera head and the control device. [Diagram 3] FIG. 3 is a diagram illustrating the operation of the control device. [Figure 4] FIG. 4 is a diagram illustrating the first excitation light emission control executed by the control unit according to the second embodiment. [Diagram 5] FIG. 5 is a diagram illustrating the second excitation light emission control executed by the control unit according to the second embodiment. [Figure 6] FIG. 6 is a diagram illustrating the third excitation light emission control executed by the control unit according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a mode for carrying out the present disclosure (hereinafter, referred to as an embodiment) will be described with reference to the drawings. Note that the present disclosure is not limited to the embodiment described below. Furthermore, in the description of the drawings, the same parts are given the same reference numerals.

[0011] (Embodiment 1) [Overview of medical observation system] FIG. 1 is a diagram showing the configuration of a medical observation system 1 according to the first embodiment. The medical observation system 1 is a system used in the medical field for capturing (observing) images of the inside of a living body (observation target) as a subject. As shown in Fig. 1, the 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.

[0012] In the first embodiment, the insertion section 2 is configured as a rigid endoscope. That is, the insertion section 2 has an elongated shape that is rigid as a whole or is partially flexible and other portions are rigid, and is inserted into a living body. The insertion section 2 includes an optical system that is configured using one or more lenses and that collects light from a subject.

[0013] The light source device 3 is connected to one end of the light guide 4, and supplies light to be irradiated into a living body to the one end of the light guide 4 under the control of the control device 9. As shown in FIG. 1, the light source device 3 includes a first light source 31 and a second light source 32. The first light source 31 emits (lights) normal light in the visible wavelength band. In the first embodiment, the first light source 31 is configured with an LED (Light Emitting Diode) that emits white light.

[0014] The second light source 32 emits (emits) excitation light in a wavelength band different from the wavelength band of the normal light. In the first embodiment, the second light source 32 is configured with a semiconductor laser or an LED that emits near-infrared excitation light in a near-infrared wavelength band (for example, a wavelength band of about 750 nm to 800 nm). The near-infrared excitation light is excitation light that excites fluorescent substances such as indocyanine green. When excited by the near-infrared excitation light, the fluorescent substance such as indocyanine green emits fluorescence in a wavelength band other than the visible range (for example, a wavelength band around 830 nm) having a central wavelength on the longer wavelength side than the central wavelength of the wavelength band of the near-infrared excitation light. The wavelength band of the near-infrared excitation light and the wavelength band of the fluorescence may be set so as to overlap partially, or may not overlap at all.

[0015] In the light source device 3 according to the first embodiment, the first light source 31 is driven in the first period of the alternately repeated first and second periods under the control of the control device 9. That is, in the first period, the light source device 3 emits normal light (white light). In the light source device 3, the second light source 32 is driven in the second period under the control of the control device 9. That is, in the second period, the light source device 3 emits near-infrared excitation light. In the first embodiment, the light source device 3 is configured as a separate entity from the control device 9, but the present invention is not limited to this, and a configuration in which the light source device 3 is provided inside the control device 9 may be adopted.

[0016] 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 transmits light (normal light or near-infrared excitation light) supplied from the light source device 3 from one end to the other end, and supplies the light to the insertion section 2. When normal light (white light) is irradiated into a living body, the normal light passing through the living body (normal light reflected within the living body) is collected by an optical system in the insertion section 2. When near-infrared excitation light is irradiated into a living body, the near-infrared excitation light passing through the living body (near-infrared excitation light reflected within the living body) and fluorescence emitted from a fluorescent substance such as indocyanine green that accumulates in a lesion in the living body and is excited by the near-infrared excitation light are collected by the optical system in the insertion section 2.

[0017] The camera head 5 corresponds to an imaging device according to the present disclosure. The camera head 5 is detachably connected to the base end (eyepiece 21 (FIG. 1)) of the insertion portion 2. Under the control of the control device 9, the camera head 5 captures light collected by the insertion portion 2 to generate a captured image. The detailed configuration of the camera head 5 will be described later in the section "Configuration of the Camera Head."

[0018] One end of the first transmission cable 6 is detachably connected to the control device 9 via a connector CN1 (FIG. 1), and the other end is detachably connected to the camera head 5 via a connector CN2 (FIG. 1). The first transmission cable 6 transmits captured images and the like output from the camera head 5 to the control device 9, and also transmits control signals, synchronization signals, clocks, power, and the like output from the control device 9 to the camera head 5. The captured image and the like may be transmitted as an optical signal or as an electrical signal when transmitted from the camera head 5 to the control device 9 via the first transmission cable 6. The same applies to the transmission of a control signal, a synchronization signal, and a clock from the control device 9 to the camera head 5 via the first transmission cable 6.

[0019] 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. 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.

[0020] The control device 9 corresponds to a light source control device according to the present disclosure. The control device 9 is composed of a CPU (Central Processing Unit), an FPGA (Field-Programmable Gate Array), etc., and controls the overall operations of the light source device 3, the camera head 5, and the display device 7. The detailed configuration of the control device 9 will be described later in the section "Configuration of the Control Device." 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.

[0021] [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, an imaging unit 52, and a communication unit 53. The lens unit 51 is configured using one or more lenses, and forms an image of the light (normal light, near-infrared excitation light, and fluorescent light) collected by the insertion portion 2 on the imaging surface of the imaging section 52 (imaging element 522).

[0022] The imaging section 52 captures images of the inside of a living body under the control of the control device 9. The imaging section 52 includes an excitation light cut filter 521, an imaging element 522, and a signal processing section 523, as shown in FIG.

[0023] The excitation light cut filter 521 is provided between the lens unit 51 and the image sensor 522, and is configured as a band-stop filter that removes a specific wavelength band. For ease of explanation, hereinafter, a wavelength band that is cut (removed) by the excitation light cut filter 521 is referred to as a cut band, a wavelength band that is shorter in wavelength than the cut band and transmits through the excitation light cut filter 521 is referred to as a short-wave transmission region, and a wavelength band that is longer in wavelength than the cut band and transmits through the excitation light cut filter 521 is referred to as a long-wave transmission region. Here, the cutoff band includes at least a part of the wavelength band of near-infrared excitation light. In the first embodiment, the cutoff band includes the entire wavelength band of near-infrared excitation light. The long-wave transmission band includes the wavelength band of fluorescent light. Furthermore, the short-wave transmission region includes the wavelength band of normal light (white light).

[0024] That is, the excitation light cut filter 521 transmits normal light (white light) traveling from the lens unit 51 to the image sensor 522. For ease of explanation, the normal light (white light) traveling through the excitation light cut filter 521 and traveling to the image sensor 522 is referred to as a subject image. On the other hand, with regard to the near-infrared excitation light and fluorescence traveling from the lens unit 51 to the image sensor 522, the excitation light cut filter 521 removes the near-infrared excitation light and transmits the fluorescence. For ease of explanation, the fluorescence traveling through the excitation light cut filter 521 and traveling to the image sensor 522 is referred to as a fluorescent image.

[0025] The image sensor 522 receives the subject image or fluorescent image transmitted through the excitation light cut filter 521 and converts it into an electrical signal (analog signal). In the first embodiment, the image sensor 522 is configured with a CMOS, which is a rolling shutter type image sensor in which a plurality of pixels are two-dimensionally arranged in horizontal line units. Here, although specific illustration is omitted, the image sensor 521 is composed of an invalid area that is not electrically guaranteed, an optical black area (OB area), and an effective pixel area that converts the subject image formed by the lens unit 51 into an image signal and outputs it. Then, under the control of the control device 9, the image sensor 522 captures images for each of the alternating first and second periods in synchronization with the light emission timing of the light source device 3. For ease of explanation, hereinafter, an image generated by the image sensor 522 capturing an image of a subject (normal light) in the first period will be referred to as a normal light image, and an image generated by the image sensor 522 capturing a fluorescent image (fluorescence) in the second period will be referred to as a fluorescent image. Moreover, the normal light image and the fluorescent image will be collectively referred to as a captured image. The signal processing unit 523 performs signal processing on the captured image generated by the image sensor 522 as an analog signal and outputs the captured image as a digital signal.

[0026] The communication unit 53 functions as a transmitter that transmits the captured image output from the imaging unit 52 to the control device 9 via the first transmission cable 6. The communication unit 53 is configured, for example, with a high-speed serial interface that communicates the captured image with the control device 9 via the first transmission cable 6 at a transmission rate of 1 Gbps or more.

[0027] [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, a memory 92, an observation image generating unit 93, a control unit 94, an input unit 95, an output unit 96, and a storage unit 97. The communication unit 91 functions as a receiver that receives captured images output from the camera head 5 (communication unit 53) 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 53 at a transmission rate of 1 Gbps or more. In other words, the communication unit 91 corresponds to an image acquisition unit according to the present disclosure. The memory 92 is configured, for example, with a dynamic random access memory (DRAM) etc. This memory 92 is capable of temporarily storing multiple frames of captured images sequentially output from the camera head 5 (communication unit 53).

[0028] Under the control of the control unit 94, the observation image generation unit 93 processes captured images that are sequentially output from the camera head 5 (communication unit 53) and received by the communication unit 91. As shown in FIG. 2, the observation image generation unit 93 includes a memory controller 931, a normal light image processing unit 932, a fluorescent light image processing unit 933, a superimposed image generation unit 934, and a display control unit 935.

[0029] The memory controller 931 controls the writing and reading of captured images to the memory 92. More specifically, the memory controller 931 sequentially writes captured images (normal light images and fluorescent images) that are sequentially output from the camera head 5 (communication unit 53) and received by the communication unit 91 to the memory 92. The memory controller 931 also reads out normal light images from the memory 92 at a specific timing, and inputs the read out normal light images to the normal light image processing unit 932. The memory controller 931 also reads out fluorescent images from the memory 92 at a specific timing, and inputs the read out fluorescent images to the fluorescent image processing unit 933.

[0030] The normal light image processing unit 932 executes a first image processing on the input normal light 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, and YC processing that converts an RGB signal (normal light image) into a luminance color difference signal (Y, Cb / Cr signal).

[0031] The fluorescent light image processing unit 933 executes a second image processing, which is different from the first image processing, on the input fluorescent light image. Examples of the second image processing, like the first image processing described above, include optical black subtraction processing, white balance adjustment processing, demosaic processing, color correction matrix processing, gamma correction processing, and YC processing that converts an RGB signal (fluorescence image) into a luminance color difference signal (Y, Cb / Cr signal).

[0032] The superimposed image generation unit 934 performs superimposition processing to generate a superimposed image by superimposing the fluorescent image after the second image processing has been performed by the fluorescent image processing unit 933 on the normal light image after the first image processing has been performed by the normal light image processing unit 932. Here, examples of the superimposition process include the first and second superimposition processes shown below. Note that, in the following, a region in a fluorescent image that is composed of pixels whose luminance value is equal to or greater than a specific threshold value is referred to as a fluorescent region. The first superimposition process is a process of replacing an area in the normal light image that is at the same pixel position as the fluorescent area with an image of the fluorescent area in the fluorescent image. The second superposition process is a process (so-called alpha blending process) that changes the brightness of the color indicating fluorescence applied to each pixel in an area that is at the same pixel position as the fluorescent area in the normal light image, depending on the luminance value of each pixel position in the fluorescent area of ​​the fluorescent image.

[0033] The display control unit 935, under the control of the control unit 94, generates a video signal for displaying the superimposed image generated by the superimposed image generation unit 934. Then, the display control unit 935 outputs the video signal to the display device 7 via the second transmission cable 8.

[0034] The control unit 94 is configured using, for example, a CPU, an FPGA, etc., 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 by outputting control signals via the first to third transmission cables 6, 8, and 10. This control unit 94 has a function as a light source control unit according to the present disclosure. The function of the light source control unit will be described later in "Operation of the control device".

[0035] 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 doctor. Then, the input unit 95 outputs an operation signal to the control unit 94 in response to the user operation. The output unit 96 is configured using a speaker, a printer, etc., and outputs various information. The storage unit 97 stores the programs executed by the control unit 94, information necessary for the processing of the control unit 94, and the like.

[0036] [Control device operation] Next, the operation of the above-mentioned control device 9 will be described. For ease of explanation, the following mainly describes the control of the image sensor 522 by the control unit 94 (hereinafter referred to as image capture control) and the control of the first and second light sources 31, 32 by the control unit 94 (hereinafter referred to as light source control). FIG. 3 is a diagram for explaining the operation of the control device 9. Specifically, FIG. 3(a) is a diagram showing the exposure timing of the image sensor 522, in which the vertical axis indicates the horizontal line of the image sensor 522 (the top row indicates the highest horizontal line (the first horizontal line), and the bottom row indicates the lowest horizontal line (the last line)), and the horizontal axis indicates time. In FIG. 3(a), the parallelogram region that contributes to the generation of the normal light image is described as a WLI (White Light Imaging) field, and the parallelogram region that contributes to the generation of the fluorescent image is described as an IR (Infra-Red) field. FIG. 3(b) is a diagram showing light source control, in which the vertical axis indicates the current value supplied to the first and second light sources 31 and 32, and the horizontal axis indicates time (the applied pulse width of the current supplied to the first and second light sources 31 and 32 (the current supply time)). In this light source control, the current value and the supply time of the current are actually changed based on the brightness (average luminance value, etc.) of a specific region (detection region) in the normal light image or the fluorescent image, but for convenience of explanation, Fig. 3(b) shows a case where the current value is maximized and the supply time of the current is maximized. Also, in Fig. 3(b), the emission of normal light is described as WLI and the emission of excitation light is described as IR.

[0037] First, the imaging control is as follows. The control unit 94 performs exposure control by a so-called rolling shutter method, in which exposure of the image sensor 522 in one frame period is started for each horizontal line in sequence, and reading is performed for each horizontal line after a predetermined period (so-called shutter speed) has elapsed since the start of exposure. In the first embodiment, the control unit 94 performs exposure control so that one frame period is composed of an all-line exposure period TE in which all horizontal lines in the effective pixel area of ​​the image sensor 522 are exposed simultaneously, and a readout period TR in which charges accumulated in multiple pixels of the image sensor 522 are read out, as shown in Fig. 3(a).

[0038] Next, the light source control is as follows. As shown in FIG. 3(b), the control unit 94 alternately controls the first light source 31 and the second light source 32 to emit light. Specifically, when operating the first light source 31, the control unit 94 causes the first light source 31 to emit light for the entire first period TE1' in the all-line exposure period TE1 in the WLI field among the alternating WLI and IR fields in order to suppress uneven brightness in the normal light image. Note that FIG. 3(b) shows a case in which the current supply time is maximized as described above, so the first period TE1' is the same period as the all-line exposure period TE1. The all-line exposure period TE1 corresponds to the first all-line exposure period according to the present disclosure.

[0039] On the other hand, when the control unit 94 operates the second light source 32, the control unit 94 causes the second light source 32 to emit light for the entire second period TIR' in the excitation light emission period TIR, which includes the all-line exposure period TE2 in the IR field of the alternating WLI fields and IR fields, at least a part of the period TRB' in the readout period TRB, and at least a part of the period TRA' in the readout period TRA. Note that, since FIG. 3(b) shows a case where the current supply time is maximized as described above, the second period TIR' is the same period as the excitation light emission period TIR. The all-line exposure period TE2 corresponds to the second all-line exposure period according to the present disclosure.

[0040] Here, the readout period TRB is adjacent to the all-line exposure period TE2 and is a readout period TR that precedes the all-line exposure period TE2 in terms of time series. In the first embodiment, the period TRB' is a period from timing P1', which is after timing P1 at which the central horizontal line among all horizontal lines of the image sensor 522 starts exposure, to the start timing of the all-line exposure period TE2. The readout period TRA is adjacent to the all-line exposure period TE2 and is a readout period TR that is chronologically subsequent to the all-line exposure period TE2. In the first embodiment, the period TRA' is a period from the end timing of the all-line exposure period TE2 to a timing P2' that precedes the timing P2 at which the exposure of the central horizontal line of all the horizontal lines of the image sensor 522 ends.

[0041] For example, when the image sensor 522 is an NTSC type image sensor, the total line exposure period TE is 8.0 ms. When the current supply time at the performance limit where the second light source 32 can continue to supply current at the maximum current value during overdrive driving is 12.0 ms, the periods TRB' and TRA' are each 2.0 ms. Note that overdrive driving is a method of instantaneously making lighting brighter by passing a current for a certain period of time that exceeds the current value that lighting such as LED passes during steady light emission. Also, for example, when the imaging element 522 is a PAL imaging element, the all-line exposure period TE is 10.0 ms. When the current supply time at the performance limit of the second light source 32 is 12.0 ms, the periods TRB' and TRA' are each 1.0 ms. When the imaging element 522 is a PAL imaging element, the maximum value of the first period TE1' may be a period (e.g., 8.0 ms) shorter than the all-line exposure period TE of 10.0 ms in order to match the balance of brightness between the normal light image and the fluorescent image with that of an NTSC imaging element.

[0042] According to the above-described first embodiment, the following effects are achieved. When controlling the operation of the second light source 32, the control device 9 according to the first embodiment causes the second light source 32 to emit light throughout the above-mentioned second period TIR'. That is, compared to the conventional technology in which the excitation light is emitted only within the all-line exposure period TE2, the amount of the excitation light can be increased. As a result, the luminance of the fluorescence associated with the excitation light can be increased, and the brightness of the fluorescence image can be sufficiently ensured. Here, the fluorescence associated with the excitation light from the second light source 32 leaks into the WLI field, but since the fluorescence is much darker than normal light, it has almost no effect on the image quality of the normal light image. Therefore, the control device 9 according to the first embodiment can generate images suitable for observation (normal light image and fluorescent image).

[0043] (Embodiment 2) Next, a second embodiment will be described. In the following description, the same components as those in the above-described first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted or simplified. In the second embodiment, when operating the second light source 32, the control unit 94 executes a control different from the light source control described in the first embodiment above.

[0044] The control unit 94 according to the second embodiment identifies the position of a fluorescent region in a fluorescent image that is made up of pixels whose pixel level is higher than a specific threshold. That is, the control unit 94 has a function as a region identification unit according to the present disclosure. Here, examples of the pixel level include a luminance value corresponding to a Y signal (luminance signal) and an RGB value (pixel value). In the second embodiment, the luminance value is adopted as the pixel level. The control unit 94 then executes one of the first to third excitation light emission controls based on the position of the fluorescent region. Specifically, when the fluorescent region is located at the top of the fluorescent image, the control unit 94 executes the first excitation light emission control. When the fluorescent region is located at the bottom of the fluorescent image, the control unit 94 executes the second excitation light emission control. Furthermore, when the fluorescent region is located in the top-bottom center of the fluorescent image, the control unit 94 executes the third excitation light emission control.

[0045] Fig. 4 is a diagram for explaining the first excitation light emission control executed by the control unit 94. Fig. 5 is a diagram for explaining the second excitation light emission control executed by the control unit 94. Fig. 6 is a diagram for explaining the third excitation light emission control executed by the control unit 94. Specifically, Figs. 4 to 6 correspond to Fig. 3. Note that, for convenience of explanation, Figs. 4 to 6 only show the IR field. Specifically, the first excitation light emission control is a control for making the second light source 32 emit light during the entire second period TIR' in the excitation light emission period TIR, which includes the all-line exposure period TE2 in the IR field and at least a part of the period TRB' of the readout period TRB, as shown in FIG. 4. Note that FIG. 4(b) shows a case where the current supply time is maximized, as in FIG. 3, so the second period TIR' is the same period as the excitation light emission period TIR. Also, FIG. 4(b) shows a current supply time at the performance limit of the second light source 32, so the period TRB' is a period obtained by adding the period TRB' and the period TRA' described in the first embodiment. Note that the period TRB' shown in FIG. 4(b) is a period from the timing P1' that is later than the timing P1 at which the horizontal line located at the center of all the horizontal lines of the image sensor 522 starts exposure to the start timing of the all-line exposure period TE2, as in the case of the period TRB' described in the first embodiment.

[0046] As shown in FIG. 5, the second excitation light emission control is a control for making the second light source 32 emit light during the entire second period TIR' in the excitation light emission period TIR, which includes the all-line exposure period TE2 in the IR field and at least a part of the period TRA' of the readout period TRA. Note that FIG. 5(b) shows a case where the current supply time is maximized, as in FIG. 3, so the second period TIR' is the same period as the excitation light emission period TIR. Note that FIG. 5(b) shows a current supply time at the performance limit of the second light source 32, so the period TRA' is the sum of the periods TRB' and TRA' described in the first embodiment. Note that the period TRA' shown in FIG. 5(b) is also a period from the end timing of the all-line exposure period TE2 to a timing P2' before the timing P2 at which the exposure of the horizontal line located at the center of all the horizontal lines of the image sensor 522 ends.

[0047] Furthermore, the third excitation light emission control is similar to the light source control explained in the above-mentioned first embodiment, as shown in FIG.

[0048] According to the above-described second embodiment, in addition to the same effects as those of the first embodiment, the following effects are achieved. The control device 9 according to the second embodiment executes any one of the first to third excitation light emission controls based on the position of the fluorescent region. That is, by executing the first excitation light emission control, it is possible to brighten the fluorescent region located at the top in the fluorescent image. Furthermore, by executing the second excitation light emission control, it is possible to brighten the fluorescent region located at the bottom in the fluorescent image. Furthermore, by executing the third excitation light emission control, it is possible to brighten the fluorescent region located in the vertical center in the fluorescent image. Therefore, according to the control device 9 according to the second embodiment, the fluorescent region can be made brighter, and a fluorescent image suitable for observation can be generated.

[0049] (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 first and second embodiments. In the above-described first embodiment, the excitation light emission period TIR (second period TIR') may be a period including the entire readout period TRB, the entire all-line exposure period TE2, and the entire readout period TRA. Similarly, in the above-mentioned second embodiment, the excitation light emission period TIR (second period TIR') in the first excitation light emission control may be a period including the entire readout period TRB and the entire all-line exposure period TE2. Also, the excitation light emission period TIR (second period TIR') in the second excitation light emission control may be a period including the entire all-line exposure period TE2 and the entire readout period TRA. In the above-mentioned first and second embodiments, the period TRB' and the period TRA' may be different periods. In the above-mentioned embodiment 1, the third excitation light emission control described in the above-mentioned embodiment 2 is executed, but this is not limited to this, and it is also acceptable to have a configuration that executes either the first or second excitation light emission control described in the above-mentioned embodiment 2. In the above-described second embodiment, any one of the first to third excitation light emission controls may be executed based on the brightness (average luminance value, etc.) of a specific region (detection region) in a normal light image or a fluorescent light image.

[0050] Incidentally, photodynamic diagnosis (PDD) has been known as one of the cancer diagnostic methods for detecting cancer cells. In the photodynamic diagnosis, a photosensitive substance such as 5-aminolevulinic acid (hereinafter, referred to as 5-ALA) is used. The 5-ALA is a natural amino acid originally contained in the living body of animals and plants. After administration to the body, the 5-ALA is taken up into cells and is biosynthesized into protoporphyrin in mitochondria. Then, the protoporphyrin is excessively accumulated in cancer cells. Furthermore, the protoporphyrin excessively accumulated in the cancer cells has photoactivity. Therefore, when the protoporphyrin is excited with excitation light (e.g., blue visible light in a wavelength band of 375 nm to 445 nm), it emits fluorescence (e.g., red fluorescence in a wavelength band of 600 nm to 740 nm). In this way, a cancer diagnosis method in which a photosensitive substance is used to make cancer cells emit fluorescence is called photodynamic diagnosis. In the above-mentioned first and second embodiments, the first light source 31 may be configured with an LED that emits white light, and the second light source 32 may be configured with a semiconductor laser that emits excitation light (e.g., blue visible light in a wavelength band of 375 nm to 445 nm) that excites protoporphyrin. Even in such a configuration, the same effects as those of the above-mentioned first and second embodiments can be achieved.

[0051] In the above-mentioned first and second embodiments, the first and second periods are set to alternately repeat, but this is not limited thereto. It is also acceptable to configure the first and second periods so that at least one of them is consecutive and the frequency ratio between the first and second periods is a ratio other than 1:1.

[0052] In the above-described first and second embodiments, the light source control device according to the present disclosure is mounted on the medical observation system 1 in which the insertion section 2 is configured with a rigid endoscope, but this is not limited thereto. For example, the light source control device according to the present disclosure may be mounted on a medical observation system in which the insertion section 2 is configured with a flexible endoscope. Furthermore, the light source control device according to the present disclosure may be mounted on a medical observation system such as a surgical microscope (see, for example, JP 2016-42981 A) that enlarges and observes a predetermined field of view area inside a subject (inside a living body) or on a subject's surface (surface of a living body). In the above-mentioned first and second embodiments, a part of the configuration of the camera head 5 and a part of the configuration of the control device 9 may be provided in, for example, the connector CN1 and the connector CN2.

[0053] Note that the following configurations also fall within the technical scope of the present disclosure. (1) A light source control unit is provided that causes a first light source to emit light in a visible wavelength band during a first full-line exposure period, which is a full-line exposure period in which all horizontal lines of an effective pixel area of ​​a rolling shutter type image sensor in which a plurality of pixels are arranged two-dimensionally in horizontal line units, are exposed simultaneously, and causes a second light source to emit excitation light during a second full-line exposure period, which is a full-line exposure period different from the first full-line exposure period, and when controlling the operation of the second light source, causes the light source control unit to emit the excitation light during an excitation light emission period that includes the second full-line exposure period and at least a portion of a readout period that is adjacent to the second full-line exposure period and in which electric charges accumulated in the plurality of pixels are read out. (2) The light source control device described in (1), wherein the excitation light emission period is a period including at least a portion of the readout period that chronologically precedes the second full line exposure period and the second full line exposure period. (3) The light source control device described in (2), wherein the excitation light emission period is a period from a timing later than the timing at which the central horizontal line among all the horizontal lines starts to be exposed to the timing at which the second full line exposure period ends. (4) The light source control device described in (1), wherein the excitation light emission period includes the second full line exposure period and at least a portion of the readout period that is chronologically subsequent to the second full line exposure period. (5) The light source control device described in (4), wherein the excitation light emission period is a period from the start timing of the second full line exposure period to a timing before the timing at which the exposure of the central horizontal line among all the horizontal lines ends. (6) The light source control device described in (1), wherein the excitation light emission period includes the second full line exposure period, at least a portion of the readout period that is chronologically before the second full line exposure period, and at least a portion of the readout period that is chronologically after the second full line exposure period. (7) The present invention further includes an image acquisition unit that acquires a fluorescence image in which an observation target is irradiated with the excitation light and fluorescence from the observation target excited by the excitation light is captured by an image capture unit, and a region identification unit that identifies a position of a fluorescence region composed of pixels whose pixel level according to the fluorescence is higher than a specific threshold value within an entire image region in the fluorescence image, wherein the light source control unit performs a first excitation light emission control that emits the excitation light during the excitation light emission period including the second entire line exposure period and at least a part of the readout period chronologically preceding the second entire line exposure period, based on the position of the fluorescence region, and The light source control device according to any one of (1) to (6), which executes either a second excitation light emission control that emits the excitation light in the excitation light emission period that includes a second full line exposure period and at least a portion of the readout period that is chronologically subsequent to the second full line exposure period, or a third excitation light emission control that emits the excitation light in the excitation light emission period that includes the second full line exposure period and at least a portion of the readout period that is chronologically subsequent to the second full line exposure period. (8) A medical observation system comprising: an imaging device including a rolling shutter type imaging element in which a plurality of pixels are arranged two-dimensionally in units of horizontal lines; a first light source emitting light in a visible wavelength band; a second light source emitting excitation light; and a light source control device controlling the first light source and the second light source, wherein the light source control device causes the first light source to emit light in the visible wavelength band in a first full line exposure period, which is a full line exposure period in which all of the horizontal lines of an effective pixel area of ​​the imaging element are simultaneously exposed, and a light source control unit causes the second light source to emit the excitation light in a second full line exposure period, which is the full line exposure period different from the first full line exposure period, and wherein the light source control unit, when controlling the operation of the second light source, emits the excitation light in an excitation light emission period that includes the second full line exposure period and at least a portion of a readout period that is adjacent to the second full line exposure period and in which charges accumulated in the plurality of pixels are read out. [Explanation of symbols]

[0054] 1 Medical observation system 2 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 21 Eyepiece 31 First Light Source 32 Second Light Source 51 Lens unit 52 Imaging unit 53 Communications Department 91 Communications Department 92 Memory 93 Observation image generation unit 94 Control Unit 95 Input section 96 Output section 97 Memory section 521 Excitation light cut filter 522 Image sensor 523 Signal Processing Unit 931 Memory Controller 932 Normal light image processing unit 933 Fluorescence Image Processing Unit 934 Superimposed Image Generation Unit 935 Display control section CN1,CN2 connector P1, P1´, P2, P2´ Timing TE,TE1,TE2 All line exposure period TE1´ First Period TIR excitation light emission period TIR´ 2nd Period TR,TRA,TRB read period TRA´,TRB´ period

Claims

1. a light source control unit that causes a first light source to emit light in a visible wavelength band during a first all-line exposure period, which is an all-line exposure period during which all horizontal lines of an effective pixel area of ​​an image sensor of a rolling shutter type in which a plurality of pixels are two-dimensionally arranged in horizontal line units are simultaneously exposed, and causes a second light source to emit excitation light during a second all-line exposure period, which is an all-line exposure period different from the first all-line exposure period; The light source control unit is When controlling the operation of the second light source, the excitation light is emitted in an excitation light emission period including the second full line exposure period and at least a part of a readout period adjacent to the second full line exposure period for reading out charges accumulated in the plurality of pixels; The excitation light emission period is A light source control device, the period including the second all-line exposure period and at least a part of the readout period that is chronologically preceding the second all-line exposure period.

2. The excitation light emission period is The light source control device according to claim 1 , wherein the period is from a timing after a timing at which exposure of a central horizontal line among all the horizontal lines starts to a timing at which the second all-line exposure period ends.

3. a light source control unit that causes a first light source to emit light in a visible wavelength band during a first all-line exposure period, which is an all-line exposure period during which all horizontal lines of an effective pixel area of ​​an image sensor of a rolling shutter type in which a plurality of pixels are two-dimensionally arranged in horizontal line units are simultaneously exposed, and causes a second light source to emit excitation light during a second all-line exposure period, which is an all-line exposure period different from the first all-line exposure period; The light source control unit is When controlling the operation of the second light source, the excitation light is emitted in an excitation light emission period including the second full line exposure period and at least a part of a readout period adjacent to the second full line exposure period for reading out charges accumulated in the plurality of pixels; The excitation light emission period is A light source control device, the light source control device being a period including the second all-line exposure period and at least a part of the readout period that is chronologically subsequent to the second all-line exposure period.

4. The excitation light emission period is 4. The light source control device according to claim 3, wherein the second all-line exposure period is a period from a start timing of the second all-line exposure period to a timing before a timing at which exposure of a central horizontal line among all the horizontal lines ends.

5. The excitation light emission period is 2. The light source control device according to claim 1, wherein the period includes the second full line exposure period, at least a portion of the readout period that is chronologically before the second full line exposure period, and at least a portion of the readout period that is chronologically after the second full line exposure period.

6. a light source control unit that causes a first light source to emit light in a visible wavelength band in a first all-line exposure period, which is an all-line exposure period in which all horizontal lines of an effective pixel area of ​​a rolling shutter type image sensor in which a plurality of pixels are two-dimensionally arranged in horizontal line units are simultaneously exposed, and causes a second light source to emit excitation light in a second all-line exposure period, which is an all-line exposure period different from the first all-line exposure period; an image acquisition unit that acquires a fluorescent image by irradiating an observation target with the excitation light and capturing, by an image capture unit, fluorescent light from the observation target excited by the excitation light; a region specifying unit that specifies a position of a fluorescent region, which is configured of pixels whose pixel level according to the fluorescence is higher than a specific threshold value, from within an entire image region of the fluorescent light image; The light source control unit is a light source control device that, when controlling an operation of the second light source, emits the excitation light in an excitation light emission period that includes the second full line exposure period and at least a portion of a readout period that is adjacent to the second full line exposure period and that reads out charge accumulated in the multiple pixels, and executes, based on a position of the fluorescent region, one of: a first excitation light emission control that emits the excitation light in the excitation light emission period that includes the second full line exposure period and at least a portion of the readout period that is chronologically prior to the second full line exposure period; a second excitation light emission control that emits the excitation light in the excitation light emission period that includes the second full line exposure period and at least a portion of the readout period that is chronologically prior to the second full line exposure period; and a third excitation light emission control that emits the excitation light in the excitation light emission period that includes the second full line exposure period and at least a portion of the readout period that is chronologically prior to the second full line exposure period, and at least a portion of the readout period that is chronologically prior to the second full line exposure period.

7. The excitation light emission period is The light source control device according to claim 1 , wherein the period is longer than the period for emitting light in the visible wavelength band.

8. The period during which light in the visible wavelength band is emitted is:

7. The light source control device according to claim 1, wherein the light source control is performed within the all-line exposure period.

9. An imaging device including a rolling shutter type imaging element in which a plurality of pixels are two-dimensionally arranged in horizontal line units; A first light source that emits light in the visible wavelength band; A second light source that emits excitation light; a light source control device that controls the first light source and the second light source, The light source control device includes: a light source control unit that causes the first light source to emit light in the visible wavelength band in a first all-line exposure period, which is an all-line exposure period in which all of the horizontal lines in an effective pixel area of ​​the image sensor are simultaneously exposed, and causes the second light source to emit the excitation light in a second all-line exposure period, which is an all-line exposure period different from the first all-line exposure period; The light source control unit is When controlling the operation of the second light source, the excitation light is emitted in an excitation light emission period including the second full line exposure period and at least a part of a readout period adjacent to the second full line exposure period for reading out charges accumulated in the plurality of pixels; The excitation light emission period is a period including the second full line exposure period and at least a part of the readout period chronologically preceding the second full line exposure period.

10. An imaging device including a rolling shutter type imaging element in which a plurality of pixels are two-dimensionally arranged in horizontal line units; A first light source that emits light in the visible wavelength band; A second light source that emits excitation light; a light source control device that controls the first light source and the second light source, The light source control device includes: a light source control unit that causes the first light source to emit light in the visible wavelength band in a first all-line exposure period, which is an all-line exposure period in which all of the horizontal lines in an effective pixel area of ​​the image sensor are simultaneously exposed, and causes the second light source to emit the excitation light in a second all-line exposure period, which is an all-line exposure period different from the first all-line exposure period; The light source control unit is When controlling the operation of the second light source, the excitation light is emitted in an excitation light emission period including the second full line exposure period and at least a part of a readout period adjacent to the second full line exposure period for reading out charges accumulated in the plurality of pixels; The excitation light emission period is a medical observation system, the period including the second full-line exposure period and at least a part of the readout period that is chronologically subsequent to the second full-line exposure period.

11. An imaging device including a rolling shutter type imaging element in which a plurality of pixels are two-dimensionally arranged in horizontal line units; A first light source that emits light in the visible wavelength band; A second light source that emits excitation light; a light source control device that controls the first light source and the second light source, The light source control device includes: a light source control unit that causes the first light source to emit light in the visible wavelength band in a first all-line exposure period, which is an all-line exposure period in which all of the horizontal lines in an effective pixel area of ​​the image sensor are simultaneously exposed, and causes the second light source to emit the excitation light in a second all-line exposure period, which is an all-line exposure period different from the first all-line exposure period; an image acquisition unit that acquires a fluorescent image by irradiating an observation target with the excitation light and capturing, by an image capture unit, fluorescent light from the observation target excited by the excitation light; a region specifying unit that specifies a position of a fluorescent region, which is configured of pixels whose pixel level according to the fluorescence is higher than a specific threshold value, from within an entire image region of the fluorescent light image; The light source control unit is a first excitation light emission control for emitting the excitation light in an excitation light emission period that includes the second full line exposure period and at least a portion of a readout period that is adjacent to the second full line exposure period and that reads out electric charges accumulated in the plurality of pixels, based on a position of the fluorescent region; a second excitation light emission control for emitting the excitation light in the excitation light emission period that includes the second full line exposure period and at least a portion of the readout period that is chronologically prior to the second full line exposure period; and a third excitation light emission control for emitting the excitation light in the excitation light emission period that includes the second full line exposure period and at least a portion of the readout period that is chronologically prior to the second full line exposure period.

Images