Medical observation system, medical light source control device, and method of operating the medical light source control device.

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 Art

[0002] Conventionally, there is known a medical observation system that uses a CMOS (Complementary Metal Oxide Semiconductor), which is an image sensor of a rolling shutter system, to image an observation target such as a living body and observe the observation target (for example, see Patent Document 1). The medical observation system described in Patent Document 1 generates a normal light image and a fluorescence image. Specifically, the normal light image is an image obtained by irradiating the observation target with normal light in a visible wavelength band 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 and imaging fluorescence from the observation target excited by the excitation light. Here, in the medical observation system described in Patent Document 1, in order to suppress luminance unevenness in the normal light image and the fluorescence image, the normal light and the excitation light are each caused to emit light only within an all-line exposure period in which all horizontal lines in the effective pixel region of the image sensor are exposed simultaneously.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problem to be Solved by the Invention

[0004] Incidentally, the fluorescence image has an extremely low signal level because the fluorescence from the observation target is very faint and the sensitivity of the image sensor in the wavelength band of the fluorescence is also low. For this reason, there is a problem that it is difficult to generate an image suitable for observation.

[0005] This disclosure is made in view of the above, and aims to provide a light source control device and a medical observation system that can generate images suitable for observation. [Means for solving the problem]

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

[0007] Furthermore, the medical observation system according to this disclosure includes an imaging device including a rolling shutter type image sensor in which a plurality of pixels are arranged two-dimensionally in units of horizontal lines, a first light source that emits light in the visible wavelength band, a second light source that emits excitation light, and a light source control device that controls 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 during a first full-line exposure period, which is a full-line exposure period in which all of the horizontal lines of the effective pixel area of ​​the image sensor are simultaneously exposed, and causes the second light source to emit the excitation light during a second full-line exposure period, which is a full-line exposure period different from the first full-line exposure period, wherein when the light source control device controls the operation of the second light source, it causes the excitation light to emit during an excitation light emission period that includes the second full-line exposure period and at least a portion of a readout period adjacent to the second full-line exposure period for reading out the charges accumulated in the plurality of pixels. [Effects of the Invention]

[0008] According to the light source control device and medical observation system described herein, it is possible to generate images suitable for observation. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows the configuration of the medical observation system according to Embodiment 1. [Figure 2] Figure 2 is a block diagram showing the configuration of the camera head and control device. [Figure 3] Figure 3 is a diagram illustrating the operation of the control device. [Figure 4] Figure 4 illustrates the first excitation light emission control performed by the control unit according to Embodiment 2. [Figure 5] Figure 5 illustrates the second excitation light emission control performed by the control unit according to Embodiment 2. [Figure 6] Figure 6 illustrates the third excitation light emission control performed by the control unit according to Embodiment 2. [Modes for carrying out the invention]

[0010] The embodiments for implementing this disclosure (hereinafter referred to as "embodiments") will be described below with reference to the drawings. However, the embodiments described below do not limit this disclosure. Furthermore, the same parts are denoted by the same reference numerals in the drawings.

[0011] (Embodiment 1) [Outline configuration of a medical observation system] Figure 1 shows the configuration of the medical observation system 1 according to Embodiment 1. Medical observation system 1 is a system used in the medical field to image (observe) the inside of a living body (object of observation). As shown in Figure 1, medical observation system 1 comprises an insertion unit 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 this embodiment 1, the insertion section 2 is made of a rigid endoscope. That is, the insertion section 2 has an elongated shape that is either entirely rigid or partially flexible with other parts rigid, and is inserted into the body. Inside this insertion section 2, there is an optical system made up of one or more lenses that focuses light from the subject.

[0013] One end of the light guide 4 is connected to the light source device 3, and under the control of the control device 9, it supplies light to the end of the light guide 4 to irradiate the living body. As shown in Figure 1, the light source device 3 comprises a first light source 31 and a second light source 32. The first light source 31 emits (lights up) normal light in the visible wavelength range. In this embodiment 1, the first light source 31 is composed of an LED (Light Emitting Diode) that emits white light.

[0014] The second light source 32 emits (luminesce) excitation light in a wavelength band different from the wavelength band of normal light. In this embodiment 1, the second light source 32 is composed of a semiconductor laser or LED that emits near-infrared excitation light in the near-infrared wavelength band (for example, a wavelength band of about 750 nm to 800 nm). This near-infrared excitation light is excitation light that excites fluorescent substances such as indocyanine green. When the fluorescent substance such as indocyanine green is excited by this near-infrared excitation light, it emits fluorescence in a wavelength band other than the visible range (for example, a wavelength band around 830 nm) whose center wavelength is longer than the center 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 to partially overlap, or they may be set to not overlap at all.

[0015] Then, in the light source device 3 according to the first embodiment, the first light source 31 is driven in the first period of the first and second periods that are alternately repeated under the control of the control device 9. That is, in the first period, the light source device 3 emits normal light (white light). Further, 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. Note that in the first embodiment, the light source device 3 is configured as a separate body from the control device 9, but the present invention is not limited to this, and a configuration 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 portion 2. The light guide 4 transmits the 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 portion 2. When normal light (white light) is applied into a living body, the normal light that has passed through the living body (the normal light reflected inside the living body) is collected by the optical system in the insertion portion 2. In addition, when near-infrared excitation light is applied into a living body, the near-infrared excitation light that has passed through the living body (the near-infrared excitation light reflected inside the living body) and the fluorescent light emitted from a fluorescent substance such as indocyanine green that accumulates in a lesion in the living body, which is excited by the near-infrared excitation light, are collected by the optical system in the insertion portion 2.

[0017] The camera head 5 corresponds to the imaging device according to the present disclosure. The camera head 5 is detachably connected to the proximal end of the insertion portion 2 (the eyepiece portion 21 (FIG. 1)). Then, under the control of the control device 9, the camera head 5 images the 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 "Configuration of Camera Head".

[0018] One end of the first transmission cable 6 is detachably connected to the control device 9 via the connector CN1 (Figure 1), and the other end is detachably connected to the camera head 5 via the connector CN2 (Figure 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 respectively. Note that the transmission of captured 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 captured images and the like as optical signals, or may be performed by transmitting them 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.

[0019] The display device 7 is constituted by a display using liquid crystal, 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 the light source control device according to the present disclosure. The control device 9 is configured with a CPU (Central Processing Unit), an FPGA (Field-Programmable Gate Array) or the like, and comprehensively controls the 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 "Configuration of 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 the control signal from the control device 9 to the light source device 3.

[0021] [Configuration of Camera Head] Next, the configuration of the camera head 5 will be described. Figure 2 is a block diagram showing the configuration of the camera head 5 and the control device 9. As shown in Figure 2, the camera head 5 comprises a lens unit 51, an imaging unit 52, and a communication unit 53. The lens unit 51 is composed of one or more lenses and focuses the light (normal light, near-infrared excitation light, and fluorescence) collected in the insertion section 2 onto the imaging surface of the imaging section 52 (image sensor 522).

[0022] The imaging unit 52 images the inside of a living body under the control of the control device 9. As shown in Figure 2, the imaging unit 52 comprises an excitation light cut filter 521, an image sensor 522, and a signal processing unit 523.

[0023] The excitation light cut filter 521 is provided between the lens unit 51 and the image sensor 522 and is composed of a band stop filter that removes a specific wavelength band. For the sake of explanation, in the following, the wavelength band that is cut (removed) by the excitation light cut filter 521 will be referred to as the cut band, the wavelength band that is shorter than the cut band and passes through the excitation light cut filter 521 will be referred to as the short-wave side transmission region, and the wavelength band that is longer than the cut band and passes through the excitation light cut filter 521 will be referred to as the long-wave side transmission region. Here, the cut-off band includes at least a portion of the wavelength band of the near-infrared excitation light. In this embodiment 1, the cut-off band includes the entire wavelength band of the near-infrared excitation light. Furthermore, the long-wave side transmission band includes the fluorescence wavelength band. In addition, the short-wave side transmission region includes the wavelength band of normal light (white light).

[0024] In other words, the excitation light cut filter 521 transmits normal light (white light) traveling from the lens unit 51 to the image sensor 522. For the sake of explanation, in the following, the normal light (white light) that passes through the excitation light cut filter 521 and travels to the image sensor 522 will be referred to as the subject image. On the other hand, the excitation light cut filter 521 removes near-infrared excitation light and transmits fluorescence traveling from the lens unit 51 to the image sensor 522. For the sake of explanation, in the following, the fluorescence that passes through the excitation light cut filter 521 and travels to the image sensor 522 will be referred to as the fluorescence image.

[0025] The image sensor 522 receives the subject image or fluorescence image transmitted through the excitation light cut filter 521 and converts it into an electrical signal (analog signal). In this embodiment 1, the image sensor 522 is composed of a CMOS, which is a rolling shutter type image sensor in which multiple pixels are arranged in a two-dimensional manner in units of horizontal lines. Here, although not shown in detail in the illustration, the image sensor 521 consists of an electrically unguaranteed invalid region, an optical black region (OB region), and an effective pixel region that converts the subject image formed by the lens unit 51 into an imaging signal for output. The image sensor 522, under the control of the control device 9, performs imaging in alternating first and second periods, synchronized with the light emission timing of the light source device 3. For the sake of explanation, in the following, the image generated by the image sensor 522 capturing the subject image (normal light) during the first period will be referred to as a normal light image, and the image generated by the image sensor 522 capturing a fluorescent image (fluorescence) during the second period will be referred to as a fluorescent image. Furthermore, the normal light image and the fluorescent image will be collectively referred to as the captured image. The signal processing unit 523 performs signal processing on the analog signal image generated by the image sensor 522 and outputs a digital signal image.

[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. This communication unit 53 is configured, for example, as a high-speed serial interface that communicates captured images with the control device 9 via the first transmission cable 6 at a transmission rate of 1 Gbps or more.

[0027] [Control device configuration] Next, the configuration of the control device 9 will be explained with reference to Figure 2. As shown in Figure 2, the control device 9 includes a communication unit 91, a memory 92, an observation image generation 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 the image acquisition unit according to this disclosure. The memory 92 is composed of, for example, DRAM (Dynamic Random Access Memory). This memory 92 can temporarily store multiple frames of captured images that are sequentially output from the camera head 5 (communication unit 53).

[0028] The observation image generation unit 93 processes the captured images received by the communication unit 91, which are sequentially output from the camera head 5 (communication unit 53) under the control of the control unit 94. As shown in Figure 2, the observation image generation unit 93 comprises a memory controller 931, a normal light image processing unit 932, a fluorescence 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 and from the memory 92. More specifically, the memory controller 931 sequentially writes the captured images (normal light images and fluorescence images) 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 the normal light images from the memory 92 at specific timings and inputs these read normal light images to the normal light image processing unit 932. Furthermore, the memory controller 931 reads the fluorescence images from the memory 92 at specific timings and inputs these read fluorescence images to the fluorescence image processing unit 933.

[0030] The normal light image processing unit 932 performs a first image processing operation on the input normal light image. Examples of this first image processing include optical black subtraction, white balance adjustment, demosaicing, color correction matrix processing, gamma correction processing, and YC processing, which converts RGB signals (normal light images) into luminance chrominance signals (Y, Cb / Cr signals).

[0031] The fluorescence image processing unit 933 performs a second image processing operation on the input fluorescence image, which is different from the first image processing operation. Examples of the second image processing include optical black subtraction, white balance adjustment, demosaicing, color correction matrix processing, gamma correction, and YC processing, which converts RGB signals (fluorescent images) into luminance chrominance signals (Y, Cb / Cr signals), similar to the first image processing described above.

[0032] The superimposed image generation unit 934 performs a superimposition process to generate a superimposed image by superimposing a fluorescence image, which has been processed by a second image processing unit 933, onto a normal light image, which has been processed by a first image processing unit 932. Here, the superposition process can be exemplified by the first and second superposition processes shown below. In the following, in a fluorescence image, the region consisting of pixels whose brightness value is above a certain threshold will be referred to as the fluorescence region. The first superposition process involves replacing areas in a normal light image that have the same pixel positions as the fluorescent regions with images of the fluorescent regions in the fluorescence image. The second superposition process is a process (so-called alpha blending) that changes the brightness of the fluorescent color applied to each pixel in the region that corresponds to the same pixel position in the fluorescent region of the normal light image, according to the brightness value of each pixel position in the fluorescent region of the fluorescent image.

[0033] The display control unit 935 generates a video signal for displaying the superimposed image generated by the superimposed image generation unit 934, under the control of the control unit 94. The display control unit 935 then 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 or FPGA, and controls the operation of the light source device 3, camera head 5, and 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 the function of a light source control unit according to this disclosure. The function of the light source control unit will be explained later in the section "Operation of the Control Device".

[0035] The input unit 95 is configured using operating devices such as a mouse, keyboard, and touch panel, and accepts user operations from users such as doctors. The input unit 95 then outputs an operation signal corresponding to the user operation to the control unit 94. The output unit 96 is configured using a speaker, printer, etc., and outputs various types of information. The memory unit 97 stores programs executed by the control unit 94, information necessary for processing by the control unit 94, and so on.

[0036] [Operation of the control device] Next, the operation of the control device 9 described above will be explained. For the sake of clarity, the following explanation will primarily focus on the control of the image sensor 522 by the control unit 94 (hereinafter referred to as "image control") and the control of the first and second light sources 31 and 32 by the control unit 94 (hereinafter referred to as "light source control"). Figure 3 is a diagram illustrating the operation of the control device 9. Specifically, Figure 3(a) shows the exposure timing of the image sensor 522, with the vertical axis representing the horizontal line of the image sensor 522 (the top row represents the uppermost horizontal line (the first horizontal line), and the bottom row represents the lowermost horizontal line (the final line)), and the horizontal axis representing time. In Figure 3(a), the parallelogram region that contributes to the generation of the normal light image is labeled as the WLI (White Light Imaging) field, and the parallelogram region that contributes to the generation of the fluorescence image is labeled as the IR (Infra-Red) field. Figure 3(b) shows the light source control, with the vertical axis representing the current values ​​supplied to the first and second light sources 31 and 32, and the horizontal axis representing time (the applied pulse width (current supply time) of the current supplied to the first and second light sources 31 and 32). In this light source control, the current value and the current supply time are actually changed based on the brightness (average value of luminance, etc.) of a specific region (detection region) in the normal light image or fluorescence image. However, for the sake of explanation, Figure 3(b) shows the case where the current value and the current supply time are set to the maximum. Also, in Figure 3(b), the emission of normal light is labeled as WLI, and the emission of excitation light is labeled as IR.

[0037] First, the imaging control is as follows: The control unit 94 performs exposure control using a so-called rolling shutter method, which sequentially starts exposure of the image sensor 522 for each horizontal line during one frame period, and sequentially reads out each horizontal line after a predetermined period (so-called shutter speed) has elapsed since the start of exposure. In this embodiment 1, as shown in Figure 3(a), the control unit 94 performs exposure control so that one frame period consists of a full-line exposure period TE in which all horizontal lines of the effective pixel area of ​​the image sensor 522 are exposed simultaneously, and a readout period TR in which the charge accumulated in multiple pixels of the image sensor 522 is read out.

[0038] Next, the light source control is as follows: As shown in Figure 3(b), the control unit 94 alternately repeats the emission of light from the first light source 31 and the emission of light from the second light source 32. Specifically, when the control unit 94 operates the first light source 31, in order to suppress brightness unevenness in the normal light image, it causes the first light source 31 to emit light for the entire first period TE1' within the total line exposure period TE1 in the WLI field, which is one of the WLI fields and IR fields that are alternately repeated. Note that in Figure 3(b), as described above, the current supply time is shown to be the maximum, so the first period TE1' is the same as the total line exposure period TE1. This total line exposure period TE1 corresponds to the first total line exposure period according to this disclosure.

[0039] On the other hand, when the control unit 94 operates the second light source 32, it causes the second light source 32 to emit light for the entire second period TIR' within the excitation light emission period TIR, which includes the entire line exposure period TE2 in the IR field among the alternately repeated WLI field and IR field, at least a portion of the readout period TRB' period TRB', and at least a portion of the readout period TRA' period TRA'. In Figure 3(b), as described above, the current supply time is shown to be the maximum, so the second period TIR' is the same as the excitation light emission period TIR. The entire line exposure period TE2 corresponds to the second entire line exposure period according to this disclosure.

[0040] Here, the readout period TRB is adjacent to the all-line exposure period TE2 and is the readout period TR that precedes the all-line exposure period TE2 in time series. In this embodiment 1, period TRB' is the period from a timing P1' that is later than the timing P1 in which the central horizontal line of the image sensor 522 begins exposure, to the start timing of the all-line exposure period TE2. Furthermore, the readout period TRA is adjacent to the all-line exposure period TE2 and is a readout period TR that is chronologically later than the all-line exposure period TE2. In this embodiment 1, period TRA' is the period from the end of the all-line exposure period TE2 to a timing P2' that is before the timing P2 in which the central horizontal line of all horizontal lines of the image sensor 522 finishes exposure.

[0041] For example, if the image sensor 522 is an NTSC image sensor, the total line exposure period TE is 8.0 ms. If the current supply time at the performance limit where the second light source 32 can continuously supply current at the maximum current value during overdrive is 12.0 ms, then the periods TRB' and TRA' will each be 2.0 ms. Overdrive refers to a method of making illumination brighter instantaneously by supplying a current that exceeds the current value that an LED or other light source supplies during steady-state illumination for a certain period of time. Furthermore, for example, if the image sensor 522 is a PAL type image sensor, the total line exposure period TE is 10.0 ms. And if the current supply time at the performance limit of the second light source 32 is 12.0 ms, then the periods TRB' and TRA' are 1.0 ms each. Note that if the image sensor 522 is a PAL type image sensor, in order to match the brightness balance between the normal light image and the fluorescent image with that of an NTSC type image sensor, the maximum value of the first period TE1' may be set to a shorter period (for example, 8.0 ms) than the total line exposure period TE of 10.0 ms.

[0042] According to the first embodiment described above, the following effects are achieved. The control device 9 according to this embodiment 1 causes the second light source 32 to emit light throughout the entire second period TIR' described above when controlling the operation of the second light source 32. In other words, compared to the conventional technique of emitting excitation light only during the entire line exposure period TE2, the amount of excitation light emitted can be increased. As a result, the brightness of the fluorescence associated with the excitation light can be increased, and sufficient brightness of the fluorescence image can be ensured. Here, the fluorescence associated with the excitation light from the second light source 32 leaks into the WLI field, but since this fluorescence is considerably dimmer than normal light, it has almost no effect on the image quality of the normal light image. Therefore, the control device 9 according to this embodiment 1 can generate images suitable for observation (normal light images and fluorescence images).

[0043] (Embodiment 2) Next, Embodiment 2 will be described. In the following description, components similar to those in Embodiment 1 described above are denoted by the same reference numerals, and their detailed descriptions are omitted or simplified. In this second embodiment, when the control unit 94 operates the second light source 32, it performs a different control from the light source control described in the first embodiment described above.

[0044] The control unit 94 in this second embodiment identifies the location of a fluorescence region in the fluorescence image that is composed of pixels whose pixel level is higher than a specific threshold. In other words, the control unit 94 functions as a region identification unit according to this disclosure. Here, the pixel level can be exemplified by a luminance value or RGB value (pixel value) corresponding to the Y signal (luminance signal). In this second embodiment, the luminance value is used 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, the control unit 94 executes the first excitation light emission control if the fluorescent region is located in the upper part of the fluorescence image. The control unit 94 also executes the second excitation light emission control if the fluorescent region is located in the lower part of the fluorescence image. Furthermore, the control unit 94 executes the third excitation light emission control if the fluorescent region is located in the vertical center of the fluorescence image.

[0045] Figure 4 illustrates the first excitation light emission control performed by the control unit 94. Figure 5 illustrates the second excitation light emission control performed by the control unit 94. Figure 6 illustrates the third excitation light emission control performed by the control unit 94. Specifically, Figures 4 to 6 correspond to Figure 3. Note that, for ease of explanation, only the IR field is shown in Figures 4 to 6. Specifically, the first excitation light emission control is a control that causes the second light source 32 to emit light for the entire second period TIR' within the excitation light emission period TIR, which includes the entire line exposure period TE2 in the IR field and at least a portion of the readout period TRB', as shown in Figure 4. Note that in Figure 4(b), as with Figure 3, the case where the current supply time is maximized is shown, so the second period TIR' is the same as the excitation light emission period TIR. Also, in Figure 4(b), since the current supply time at the performance limit of the second light source 32 is shown, the period TRB' is the sum of the period TRB' and period TRA' described in Embodiment 1 above. Note that the period TRB' shown in Figure 4(b) is the same as the period TRB' described in Embodiment 1 above, from the timing P1' after the timing P1 in which the central horizontal line of all horizontal lines of the image sensor 522 starts exposure, to the start timing of the entire line exposure period TE2.

[0046] Furthermore, the second excitation light emission control, as shown in Figure 5, is a control that causes the second light source 32 to emit light for the entire second period TIR' within the excitation light emission period TIR, which includes the entire line exposure period TE2 in the IR field and at least a portion of the readout period TRA'. Note that in Figure 5(b), as with Figure 3, the case where the current supply time is maximized is shown, so the second period TIR' is the same period as the excitation light emission period TIR. Also, in Figure 5(b), since the current supply time at the performance limit of the second light source 32 is shown, the period TRA' is the sum of the period TRB' and period TRA' described in Embodiment 1 above. Note that the period TRA' shown in Figure 5(b) is the same as the period TRA' described in Embodiment 1 above, from the end timing of the entire line exposure period TE2 to the timing P2' which is before the timing P2 in which the central horizontal line of all horizontal lines of the image sensor 522 finishes exposure.

[0047] Furthermore, the third excitation light emission control is similar to the light source control described in Embodiment 1 above, as shown in Figure 6.

[0048] According to this embodiment 2 described above, in addition to the same effects as in embodiment 1 described above, the following effects are achieved. The control device 9 according to this second embodiment executes one of the first to third excitation light emission controls based on the position of the fluorescence region. Specifically, executing the first excitation light emission control brightens the fluorescence region located in the upper part of the fluorescence image. Executing the second excitation light emission control brightens the fluorescence region located in the lower part of the fluorescence image. Furthermore, executing the third excitation light emission control brightens the fluorescence region located in the vertical center of the fluorescence image. Therefore, according to the control device 9 of this second embodiment, the fluorescent region can be made brighter, and a fluorescent image suitable for observation can be generated.

[0049] (Other embodiments) While we have described the forms for implementing this disclosure, this disclosure should not be limited solely to embodiments 1 and 2 described above. In the embodiment 1 described above, the excitation light emission period TIR (second period TIR') may be defined as the period encompassing the entire readout period TRB, the entire full-line exposure period TE2, and the entire readout period TRA. Similarly, in the second embodiment described above, the excitation light emission period TIR (second period TIR') in the first excitation light emission control may be a period that includes the entire readout period TRB and the entire full 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 that includes the entire full line exposure period TE2 and the entire readout period TRA. In the embodiments 1 and 2 described above, the periods TRB' and TRA' may be different periods. In the above-described Embodiment 1, the third excitation light emission control described in Embodiment 2 was performed, but the system is not limited to this, and it may also be configured to perform either the first or second excitation light emission control described in Embodiment 2. In the above-described embodiment 2, the configuration may also be such that any of the first to third excitation light emission control is performed based on the brightness (average value of luminance, etc.) of a specific region (detection region) in a normal light image or fluorescence image.

[0050] Incidentally, photodynamic diagnosis (PDD) is a known cancer diagnostic method that has been used to detect cancer cells. In this photodynamic diagnostic method, a photosensitive substance such as 5-aminolevulinic acid (hereinafter referred to as 5-ALA) is used. 5-ALA is a naturally occurring amino acid found in the bodies of plants and animals. After administration to the body, 5-ALA is taken up into cells and biosynthesized into protoporphyrin in the mitochondria. In cancer cells, this protoporphyrin accumulates excessively. Furthermore, the protoporphyrin that accumulates excessively in cancer cells is photoactive. Therefore, when this protoporphyrin is excited by excitation light (for example, blue visible light in the wavelength range of 375 nm to 445 nm), it emits fluorescence (for example, red fluorescence in the wavelength range of 600 nm to 740 nm). This cancer diagnostic method, which uses a photosensitive substance to cause cancer cells to fluoresce, is called photodynamic diagnostics. Furthermore, in the embodiments 1 and 2 described above, 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 (for example, blue visible light in the wavelength range of 375 nm to 445 nm) that excites protoporphyrin. Even in this configuration, the same effects as in embodiments 1 and 2 described above will be achieved.

[0051] In embodiments 1 and 2 described above, the first and second periods were set to repeat alternately, but the system is not limited to this. At least one of the first and second periods may be consecutive, and the frequency ratio of the first and second periods may be a ratio other than 1:1.

[0052] In the embodiments 1 and 2 described above, the light source control device according to this disclosure was mounted on a medical observation system 1 in which the insertion section 2 was composed of a rigid endoscope, but the invention is not limited to this. For example, the light source control device according to this disclosure may be mounted on a medical observation system in which the insertion section 2 is composed of a flexible endoscope. Furthermore, the light source control device according to this disclosure may be mounted on a medical observation system such as a surgical microscope (see, for example, Japanese Patent Application Publication No. 2016-42981) that magnifies and observes a predetermined field of view area inside a subject (inside a living body) or on the surface of a subject (on a living body surface). In the embodiments 1 and 2 described above, some of the components of the camera head 5 and some of the components of the control device 9 may be provided in, for example, connector CN1 and connector CN2.

[0053] Furthermore, the following configurations also fall within the technical scope of this disclosure. (1) A rolling shutter type image sensor in which a plurality of pixels are arranged in a two-dimensional manner in units of horizontal lines includes a light source control unit which causes a first light source to emit light in the visible wavelength band during a first full line exposure period, which is a full line exposure period in which all of the horizontal lines of the effective pixel area 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 the light source control unit controls the operation of the second light source, it causes the excitation light to emit during an excitation light emission period which includes the second full line exposure period and at least a portion of a readout period adjacent to the second full line exposure period for reading out the charges accumulated in the plurality of pixels. (2) The light source control device according to (1), wherein the excitation light emission period is a period that includes at least a portion of the readout period that is chronologically prior to the second full line exposure period and the second full line exposure period. (3) The light source control device according to (2), wherein the excitation light emission period is the period from a timing later than the timing at which the central horizontal line of all the horizontal lines begins exposure until the timing at which the second all-line exposure period ends. (4) The light source control device according to (1), wherein the excitation light emission period is a period that includes the second full line exposure period and at least a portion of the readout period which is chronologically later than the second full line exposure period. (5) The light source control device according to (4), wherein the excitation light emission period is the period from the start timing of the second all-line exposure period to a timing prior to the timing at which the central horizontal line among all the horizontal lines finishes exposure. (6) The light source control device according to (1), wherein the excitation light emission period is a period comprising the second full line exposure period, at least a portion of the readout period that is chronologically earlier than the second full line exposure period, and at least a portion of the readout period that is chronologically later than the second full line exposure period. (7) The light source control unit further comprises an image acquisition unit which acquires a fluorescence image captured by an imaging unit when the observation target is irradiated with the excitation light and fluorescence from the observation target excited by the excitation light is captured by the imaging unit, and a region identification unit which identifies the position of a fluorescence region in the entire image region of the fluorescence image which is composed of pixels whose pixel level corresponding to the fluorescence is higher than a specific threshold, and the light source control unit which causes the excitation light to emit during the excitation light emission period which includes the second full line exposure period and at least a portion of the readout period which is chronologically earlier to the second full line exposure period, based on the position of the fluorescence region, and the A light source control device according to any one of (1) to (6) above, which performs either a second excitation light emission control that causes the excitation light to be emitted during the excitation light emission period which includes the entire exposure period of the second line and at least a portion of the readout period which is chronologically later than the second entire exposure period, or a third excitation light emission control that causes the excitation light to be emitted during the excitation light emission period which includes the entire exposure period of the second line and at least a portion of the readout period which is chronologically earlier than the second entire exposure period and at least a portion of the readout period which is chronologically later than the second entire exposure period. (8) A medical observation system comprising an imaging device including a rolling shutter type image sensor in which a plurality of pixels are arranged in a two-dimensional manner in units of horizontal lines; a first light source that emits light in the visible wavelength band; a second light source that emits excitation light; and a light source control device that controls 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 during a first full line exposure period, which is a full line exposure period in which all of the horizontal lines of the effective pixel area of ​​the image sensor are simultaneously exposed, and a light source control device that causes the 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 the light source control device, when controlling the operation of the second light source, causes the second light source to emit 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 adjacent to the second full line exposure period for reading out the charges accumulated in the plurality of pixels. [Explanation of Symbols]

[0054] 1. Medical observation system 2 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 21 Eyepiece 31 First light source 32 Second light source 51 Lens Unit 52 Imaging Department 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 Optical Image Processing Unit 933 Fluorescence Image Processing Unit 934 Superimposed Image Generation Unit 935 Display Control Unit CN1, CN2 connectors P1, P1', P2, P2' timing TE, TE1, TE2 Exposure Period for the Entire Line TE1' First period TIR excitation light emission period TIR' Second Period TR, TRA, TRB readout period TRA´,TRB´ period

Claims

1. A first light source that emits light in a first wavelength band, which is the visible wavelength band, A second light source that emits light in a second wavelength band different from the first wavelength band, An imaging device including a rolling shutter type image sensor in which multiple pixels are arranged in a two-dimensional manner in units of horizontal lines, the image sensor captures a first image based on the reflected light of a first wavelength band, captures a second image based on the reflected light of a second wavelength band after the first image, and captures a third image based on the reflected light of the first wavelength band after the second image, A light source control unit that controls the first light source and the second light source, The system comprises an imaging control unit that controls the imaging device, The imaging control unit, The imaging device is controlled to read out a plurality of horizontal lines that contribute to the generation of the first image during a first readout period, a plurality of horizontal lines that contribute to the generation of the second image during a second readout period, and a plurality of horizontal lines that contribute to the generation of the third image during a third readout period. The light source control unit, A medical observation system that emits light in the first wavelength band during the exposure period between the second readout period and the third readout period, and emits light in the second wavelength band during the exposure period between the first readout period and the second readout period, and for at least a portion of the second readout period.

2. The light source control unit, Furthermore, the medical observation system according to claim 1, wherein light in the second wavelength band is emitted for at least a portion of the first readout period.

3. The light source control unit, The medical observation system according to claim 1, wherein light in the first wavelength band is emitted only during the exposure period between the second readout period and the third readout period.

4. The medical observation system according to claim 1, wherein the number of horizontal lines contributing to the generation of the first image, the number of horizontal lines contributing to the generation of the second image, and the number of horizontal lines contributing to the generation of the third image are the same as each other.

5. The imaging control unit, When the exposure timing is represented with the vertical axis as the horizontal line of the image sensor and the horizontal axis as time, the imaging device is controlled so that a first parallelogram region contributing to the generation of the first image, a second parallelogram region contributing to the generation of the second image, and a third parallelogram region contributing to the generation of the third image are formed. The first read period is, This is a readout period for reading out multiple horizontal lines in the region of the first parallelogram, The second read period is, This is a readout period for reading out multiple horizontal lines in the second parallelogram region, The third read period is, The medical observation system according to claim 1, wherein the reading period is for reading multiple horizontal lines in the third parallelogram region.

6. The light in the first wavelength band is, The medical observation system according to claim 1, wherein the light is white light.

7. The light in the second wavelength band is, A medical observation system according to claim 1, wherein the excitation light is used to excite fluorescence.

8. The aforementioned medical observation system is A medical observation system according to claim 1, which is an endoscopic system.

9. The aforementioned medical observation system is A medical observation system according to claim 1, which is a surgical microscope system.

10. A rolling shutter type image sensor in which multiple pixels are arranged two-dimensionally in units of horizontal lines, wherein in a first readout period, multiple horizontal lines contributing to the generation of a first image based on the reflected light of a first wavelength band which is the visible wavelength band are read out; in a second readout period which is the next readout period after the first readout period, multiple horizontal lines contributing to the generation of a second image based on the reflected light of a second wavelength band which is different from the first wavelength band are read out; and in a third readout period which is the next readout period after the second readout period, multiple horizontal lines contributing to the generation of a third image based on the reflected light of a first wavelength band are read out, the image sensor is controlled to expose the image sensor, and includes a first light source that emits light in the first wavelength band and a second light source that emits light in the second wavelength band, and a light source control unit that controls these, The light source control unit, A medical light source control device that emits light of the first wavelength band during the exposure period between the second readout period and the third readout period, and emits light of the second wavelength band during the exposure period between the first readout period and the second readout period, and for at least a portion of the second readout period.

11. The light source control unit, Furthermore, the medical light source control device according to claim 10, wherein light in the second wavelength band is emitted for at least a portion of the first readout period.

12. The light source control unit, The medical light source control device according to claim 10, wherein light in the first wavelength band is emitted only during the exposure period between the second readout period and the third readout period.

13. The medical light source control device according to claim 10, wherein the number of horizontal lines contributing to the generation of the first image, the number of horizontal lines contributing to the generation of the second image, and the number of horizontal lines contributing to the generation of the third image are the same as each other.

14. The aforementioned imaging sensor is When the exposure timing is represented with the vertical axis as the horizontal line of the image sensor and the horizontal axis as time, the system is controlled to form a first parallelogram region that contributes to the generation of the first image, a second parallelogram region that contributes to the generation of the second image, and a third parallelogram region that contributes to the generation of the third image. The first read period is, This is a readout period for reading out multiple horizontal lines in the region of the first parallelogram, The second read period is, This is a readout period for reading out multiple horizontal lines in the second parallelogram region, The third read period is, The medical light source control device according to claim 10, which is a readout period for reading out a plurality of horizontal lines in the third parallelogram region.

15. The light in the first wavelength band is, A medical light source control device according to claim 10, wherein the light is white.

16. The light in the second wavelength band is, A medical light source control device according to claim 10, wherein the excitation light is used to excite fluorescence.

17. The aforementioned medical light source control device is A medical light source control device according to claim 10, used in an endoscope system.

18. The aforementioned medical light source control device is A medical light source control device according to claim 10, used in a surgical microscope system.

19. A method for operating a medical light source control device, comprising a control unit for controlling a first light source that emits light in the first wavelength band and a second light source that emits light in the second wavelength band, in order to expose an image sensor of the rolling shutter type, in which a plurality of pixels are arranged in a two-dimensional manner in units of horizontal lines, wherein in a first readout period, a plurality of horizontal lines that contribute to the generation of a first image based on the reflected light of a first wavelength band which is the visible wavelength band are read out; in a second readout period which is the readout period following the first readout period, a plurality of horizontal lines that contribute to the generation of a second image based on the reflected light of a second wavelength band which is read out; and in a third readout period which is the readout period following the second readout period, a plurality of horizontal lines that contribute to the generation of a third image based on the reflected light of a first wavelength band which is the first wavelength band, are read out; The control unit, A method for operating a medical light source control device, which causes light of the first wavelength band to be emitted during the exposure period between the second readout period and the third readout period, and causes light of the second wavelength band to be emitted during the exposure period between the first readout period and the second readout period, and for at least a portion of the second readout period.

20. The control unit, Furthermore, the method for operating the medical light source control device according to claim 19, wherein light in the second wavelength band is emitted during at least a portion of the first readout period.

21. The control unit, A method for operating a medical light source control device according to claim 19, wherein light in the first wavelength band is emitted only during the exposure period between the second readout period and the third readout period.

22. The method for operating a medical light source control device according to claim 19, wherein the number of horizontal lines contributing to the generation of the first image, the number of horizontal lines contributing to the generation of the second image, and the number of horizontal lines contributing to the generation of the third image are the same as each other.

23. The aforementioned imaging sensor is When the exposure timing is represented with the vertical axis as the horizontal line of the image sensor and the horizontal axis as time, the control unit controls the formation of a first parallelogram region that contributes to the generation of the first image, a second parallelogram region that contributes to the generation of the second image, and a third parallelogram region that contributes to the generation of the third image. The first read period is, This is a readout period for reading out multiple horizontal lines in the region of the first parallelogram, The second read period is, This is a readout period for reading out multiple horizontal lines in the second parallelogram region, The third read period is, A method for operating a medical light source control device according to claim 19, wherein the reading period is for reading out a plurality of horizontal lines in the third parallelogram region.

24. The light in the first wavelength band is, A method for operating the medical light source control device according to claim 19, wherein the light source is white light.

25. The light in the second wavelength band is, A method for operating a medical light source control device according to claim 19, wherein the excitation light is used to excite fluorescence.

26. The method of operating the aforementioned medical light source control device is as follows: A method for operating the medical light source control device according to claim 19, used in an endoscope system.

27. The method of operating the aforementioned medical light source control device is as follows: A method for operating the medical light source control device according to claim 19, used in a surgical microscope system.

Images