Endoscope system and method of operation thereof

Abstract

To provide an endoscope system and an operation method thereof which can obtain an endoscopic image with more proper brightness when obtaining the plural types of endoscopic images by emitting plural types of illumination lights.SOLUTION: A processor generates an endoscopic image in a frame for light amount calculation, calculates an emission light amount being a light amount of illumination light that makes the endoscopic image have the target brightness, stores the emission light amount as a held emission light amount, selects the latest held emission light amount matching the type of illumination light in at least one or more held emission light amounts as a designated emission light amount, and causes a light source device to emit the illumination light in the designated emission light amount to an emission scheduled frame subsequent to the frame for light amount calculation.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present invention relates to an endoscope system and an operation method thereof that controls the amount of light when obtaining a plurality of types of endoscope images. [Background technology]

[0002] During endoscopic examinations, multiple types of illumination light are used for various observation purposes. For example, broadband illumination light is used for screening observations, while narrowband illumination light is used for observing the arrangement of blood vessels and pit patterns for diagnosing lesions. To enable doctors and other medical professionals to perform these observations accurately, it is known to perform exposure control, which controls the light intensity of each type of illumination light and ensures appropriate brightness for the endoscopic image.

[0003] For example, when multiple types of illumination light are emitted to an object to be observed, a technique is known in which the target light intensity of each illumination light is calculated based on brightness information of a key image obtained using a key illumination light and the light intensity ratio between the key illumination light and other types of illumination light, and the light intensity is controlled (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-188365 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional techniques, it is assumed that the light intensity ratio between the key illumination light and other types of illumination light is constant. However, because the spectral sensitivity of the object varies from frame to frame depending on the type of illumination light and the captured scene, adjusting the brightness of other types of image signals using an image signal obtained using the key illumination light can result in problems such as the other types of images being too dark or too bright, depending on the image signal obtained using the key illumination light. To solve this problem, there is a need for a technique that, when images are obtained using multiple types of illumination light, can obtain images with brightness appropriate for the purpose of acquiring each image.

[0006] An object of the present invention is to provide an endoscopic system and an operating method thereof that enable endoscopic images of more appropriate brightness to be obtained when emitting multiple types of illumination light to obtain multiple types of endoscopic images. [Means for solving the problem]

[0007] The endoscope system of the present invention includes an endoscope that captures an image of an observation object, a light source device that emits first illumination light and second illumination light having a spectrum different from that of the first illumination light, and a processor, wherein the processor generates, in a light intensity calculation frame, a first illumination light image obtained by capturing an image of the observation object using the first illumination light or a second illumination light image obtained by capturing an image of the observation object using the second illumination light, and at any timing chronologically after the light intensity calculation frame, generates a first emitted light intensity, which is the light intensity of the first illumination light that sets the first illumination light image to a first target brightness, and a second emitted light intensity, which is the light intensity of the second illumination light that sets the second illumination light image to a second target brightness that is different from the first target brightness. The emission light amount is calculated, the first emission light amount is stored as a first held emission light amount, and the second emission light amount is stored as a second held emission light amount; when emitting first illumination light in a scheduled emission frame that is chronologically later than the light amount calculation frame, the latest first held emission light amount is selected as a first specified emission light amount from among the at least one or more first held emission light amounts; when emitting second illumination light in the scheduled emission frame, the latest second held emission light amount is selected as a second specified emission light amount from among the at least one or more second held emission light amounts; and the light source device is caused to emit the first illumination light at the first specified emission light amount or the second illumination light at the second specified emission light amount in the scheduled emission frame.

[0008] It is preferable that the processor acquires first already-emission information, which is information indicating that a first illumination light has been emitted into a light intensity calculation frame and which associates a first target brightness and a first parameter for calculating the emitted light intensity, and second already-emission information, which is information indicating that a second illumination light has been emitted into a light intensity calculation frame and which associates a second target brightness and a parameter for calculating the second emitted light intensity, and calculates the first emitted light intensity using the first parameter for calculating the emitted light intensity associated with the first already-emission information, and calculates the second emitted light intensity using the second parameter for calculating the emitted light intensity associated with the second already-emission information.

[0009] The processor preferably associates the first amount of emitted light with the first already-emitted emission information to define a first held amount of emitted light, associates the second amount of emitted light with the second already-emitted emission information to define a second held amount of emitted light, acquires first planned emission information which is information indicating that the first illumination light will be emitted into the planned emission frame, or second planned emission information which is information indicating that the second illumination light will be emitted into the planned emission frame, and when the first planned emission information is acquired, selects a first specified amount of emitted light from the first held amounts of emitted light associated with the first already-emitted emission information, and when the second planned emission information is acquired, selects a second specified amount of emitted light from the second held amounts of emitted light associated with the second already-emitted emission information.

[0010] It is preferable that the processor acquires first already-emitted information or second already-emitted information regarding the light intensity calculation frames in at least two or more light intensity calculation frames, and acquires first planned emission information or second already-emitted information regarding the planned emission frames in at least one or more planned emission frames.

[0011] It is preferable that the processor acquires the first already-emission information by associating the first target brightness and the first parameters for calculating the emitted light intensity with the first planned emission information acquired chronologically before the light intensity calculation frame and updating the first already-emission information to indicate that the first illumination light has been emitted into the light intensity calculation frame, and acquires the second already-emission information by associating the second target brightness and the parameters for calculating the second emitted light intensity with the second planned emission information acquired chronologically before the light intensity calculation frame and updating the second already-emission information to indicate that the second illumination light has been emitted into the light intensity calculation frame.

[0012] It is preferable that the processor switches between a mono-emission mode in which only the first illumination light or the second illumination light is emitted from the light source device, a pattern-emission mode in which the first illumination light and the second illumination light are emitted from the light source device according to a specific emission pattern, and a flexible-emission mode in which the first illumination light and the second illumination light are emitted from the light source device irregularly, and acquires the first emission schedule information or the second emission schedule information at the timing of switching between the mono-emission mode, the pattern-emission mode, and the flexible-emission mode, respectively.

[0013] In the pattern light emission mode, the processor preferably acquires the first emission schedule information or the second emission schedule information at the timing when the specific light emission pattern is changed.

[0014] It is preferable that the light source device emits at least three or more types of illumination light for imaging the object to be observed onto a light intensity calculation frame, the processor acquires at least three or more types of endoscopic images of the object to be observed, calculates the emission light intensity, which is the light intensity of the illumination light for making the at least three or more types of endoscopic images a target brightness, stores the emission light intensity as a retained emission light intensity, selects a designated emission light intensity from at least one or more retained emission light intensities according to the type of illumination light to be emitted onto the intended emission frame, and causes the light source device to emit at least three or more types of illumination light onto the intended emission frame at the designated emission light intensity.

[0015] It is preferable that the processor calculates brightness based on the luminance value of the endoscopic image, and calculates the amount of emitted light using the brightness.

[0016] The endoscope system of the present invention includes an endoscope that captures an image of an observation object, a light source device that emits first illumination light and second illumination light having a spectrum different from that of the first illumination light according to a specific light emission pattern, and a processor, and the processor acquires, in a light intensity calculation frame, a first illumination light image obtained by capturing an image of the observation object using the first illumination light or a second illumination light image obtained by capturing an image of the observation object using the second illumination light, and the first illumination light image is a frame that is a specific number of frames after the light intensity calculation frame. A first emission light amount, which is the amount of first illumination light that sets the first illumination light image to a first target brightness, or a second emission light amount, which is the amount of second illumination light that sets the second illumination light image to a second target brightness that is different from the first target brightness, is calculated by the time of the scheduled emission frame, the first emission light amount is stored as a first held emission light amount, and the second emission light amount is stored as a second held emission light amount, and the light source device is caused to emit the first illumination light at the first held emission light amount or the second illumination light at the second held emission light amount in the scheduled emission frame.

[0017] The specific light emission pattern is a light emission cycle consisting of at least one illumination period during which the first illumination light or the second illumination light is emitted, and it is preferable that the specific number of frames is a number that matches the number of illumination periods included in the light emission cycle.

[0018] The specific number of frames is preferably the number of frames from when the first illumination light is emitted into the light intensity calculation frame until when the first illumination light is emitted, or the number of frames from when the second illumination light is emitted into the light intensity calculation frame until when the second illumination light is emitted.

[0019] The above-described endoscope system preferably further includes an image sensor that captures an image of the observation target using a pseudo-global shutter system.

[0020] A method for operating an endoscope system of the present invention includes the steps of imaging an object to be observed, emitting first illumination light and second illumination light having a spectrum different from that of the first illumination light, generating a first illumination light image obtained by imaging the object to be observed using the first illumination light or a second illumination light image obtained by imaging the object to be observed using the second illumination light in a light intensity calculation frame, and calculating, at any timing chronologically after the light intensity calculation frame, a first emitted light amount, which is the light amount of the first illumination light that sets the first illumination light image to a first target brightness, and a second emitted light amount, which is the light amount of the second illumination light that sets the second illumination light image to a second target brightness that is different from the first target brightness, and calculating the first emitted light amount as a second target brightness. the first held emission light amount as the first designated emission light amount; storing the second emission light amount as the second held emission light amount; when emitting the first illumination light into a scheduled emission frame that is chronologically later than the light amount calculation frame, selecting the latest first held emission light amount from among the at least one or more first held emission light amounts as the first designated emission light amount; when emitting the second illumination light into the scheduled emission frame, selecting the latest second held emission light amount from among the at least one or more second held emission light amounts as the second designated emission light amount; and emitting the first illumination light at the first designated emission light amount or the second illumination light at the second designated emission light amount from the light source device into the scheduled emission frame.

[0021] The method for operating the endoscope system of the present invention includes the steps of: capturing an image of an observation target; emitting a first illumination light and a second illumination light having a spectrum different from that of the first illumination light according to a specific emission pattern; and displaying, in a light intensity calculation frame, a first illumination light image of the observation target captured using the first illumination light; and and acquiring a second illumination light image by capturing an image of the observation object using the second illumination light. Steps toThe method includes the steps of calculating a first emission light amount, which is the light amount of the first illumination light that sets the first illumination light image to a first target brightness, or a second emission light amount, which is the light amount of the second illumination light that sets the second illumination light image to a second target brightness that is different from the first target brightness, by a frame that is a predetermined number of frames after the light amount calculation frame; storing the first emission light amount as a first held emission light amount; storing the second emission light amount as a second held emission light amount; and emitting the first illumination light at the first held emission light amount or the second illumination light at the second held emission light amount from the light source device in the predetermined emission frame. [Effects of the Invention]

[0022] According to the present invention, when a plurality of types of endoscopic images are obtained by emitting a plurality of types of illumination light, images with more appropriate brightness can be obtained. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is an external view of an endoscope system. [Figure 2] 1 is a block diagram showing functions of an endoscope system according to a first embodiment. FIG. [Figure 3] 10 is a graph showing the spectrum of the first illumination light. [Figure 4] 10 is a graph showing the spectrum of the second illumination light. [Figure 5] 10 is a graph showing the spectrum of a third illumination light. [Figure 6] 10A and 10B are explanatory diagrams showing an example of emission of illumination light in a mono light emission mode. [Figure 7] FIG. 4 is an explanatory diagram showing a first light emission pattern. [Figure 8] FIG. 10 is an explanatory diagram showing a second light emission pattern. [Figure 9] 10A and 10B are explanatory diagrams showing an example of emission of illumination light in a flexible light emission mode; [Figure 10] FIG. 2 is an explanatory diagram illustrating a configuration of an image sensor. [Figure 11] 1 is a graph showing the light transmittance of a color filter. [Figure 12] FIG. 1 is an explanatory diagram illustrating the relationship between an image sensor and illumination light in a pseudo global shutter system. [Figure 13] FIG. 1 is an explanatory diagram illustrating the relationship between an image sensor and illumination light in a general rolling shutter system. [Figure 14] FIG. 2 is a block diagram showing functions of an endoscopic image generating unit. [Figure 15] FIG. 3 is a block diagram showing the functions of an emitted light amount calculation unit. [Figure 16] 5A and 5B are explanatory diagrams showing a specific example of light intensity control when emitting first illumination light and second illumination light in the first embodiment. [Figure 17] 4A to 4C are explanatory diagrams showing specific examples of light intensity control when emitting first illumination light, second illumination light, and third illumination light in the first embodiment. [Figure 18] 10A and 10B are explanatory diagrams showing calculation of an emitted light amount using an emitted light amount calculation parameter. [Figure 19] 5A and 5B are explanatory diagrams showing a specific example of light intensity control in the first embodiment when emission schedule information and emission already information are acquired and first illumination light and second illumination light are emitted. [Figure 20] FIG. 3 is a block diagram showing the functions of an emission information acquisition unit in the first embodiment. [Figure 21] FIG. 10 is an explanatory diagram showing updating from extraction schedule information to extraction already performed information. [Figure 22] 10A and 10B are explanatory diagrams showing the emission of illumination light when the emission pattern is switched. [Figure 23] 4 is a flowchart showing a series of operational flows of the endoscope system in the first embodiment. [Figure 24] FIG. 10 is a block diagram showing the functions of the endoscope system of the second embodiment. [Figure 25] FIG. 10 is a block diagram showing the functions of an emission information acquisition unit in the second embodiment. [Figure 26] FIG. 10 is an explanatory diagram showing a first specific example of light amount control in the second embodiment. [Figure 27] FIG. 10 is an explanatory diagram showing a second specific example of light amount control in the second embodiment. [Figure 28] 10 is a flowchart showing a series of operational flows of the endoscope system according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] [First embodiment] 1, an endoscope system 10 includes an endoscope 12, a light source device 13, a processor device 14, a display 15, and a user interface 16. The endoscope 12 is optically connected to the light source device 13 and electrically connected to the processor device 14. The various connections are not limited to wired connections and may be wireless. Alternatively, they may be made via a network.

[0025] The light source device 13 supplies illumination light to the endoscope 12. The display 15 displays the Nth illumination light image as a display image, where N is a natural number equal to or greater than 1. The user interface 16 has a keyboard, mouse, microphone, foot switch, tablet, touch pen, etc., and accepts input operations such as function settings. The processor device 14 controls image processing, analysis, and display of image signals transmitted from the endoscope 12, and controls devices connected to the processor device 14, such as the light source device 13.

[0026] The endoscope 12 has an insertion section 12a, an operating section 12b, a bending section 12c, and a tip section 12d. The insertion section 12a is inserted into the body of the subject. The operating section 12b is provided at the base end of the insertion section 12a. The bending section 12c and the tip section 12d are provided on the tip side of the insertion section 12a. The bending section 12c is bent by operating the angle knob 12e of the operating section 12b. The tip section 12d is directed in a desired direction by bending the bending section 12c. The tip section 12d irradiates illumination light toward the observation object and receives reflected light from the observation object to capture an image of the observation object. A forceps channel (not shown) for inserting a treatment tool or the like may be provided from the insertion section 12a to the tip section 12d. The treatment tool is inserted into the forceps channel through the forceps port 12j.

[0027] The operation unit 12b is provided with an angle knob 12e, a mode changeover switch 12f, and a zoom operation unit 12i. The mode changeover switch 12f is used to change modes. The zoom operation unit 12i is used to operate the zoom lens .

[0028] 2, the light source device 13 includes a light source section 20, a light source control section 21, and an optical path coupling section 22. The light source control section 21 is controlled by a central control section 50 of the processor device 14.

[0029] The light source unit 20 is configured, for example, with a semiconductor light source such as a multi-colored LED (Light Emitting Diode), a combination of a laser diode and a phosphor, or a xenon lamp or a halogen light source. In the example of Fig. 2, the light source unit 20 has four colored LEDs: a V-LED (Violet Light Emitting Diode) 20a, a B-LED (Blue Light Emitting Diode) 20b, a G-LED (Green Light Emitting Diode) 20c, and an R-LED (Red Light Emitting Diode) 20d. The light source unit 20 also includes an optical filter or the like for adjusting the wavelength band of the light emitted by the LEDs or the like.

[0030] The light source control unit 21 emits multiple types of illumination light to illuminate the observation target by controlling the light source to turn on or off multiple color semiconductor light sources and independently control the light emission amount when turned on. The light source control unit 21 also controls the wavelength band of the illumination light by changing the optical filter, etc.

[0031] Variations in the type of illumination light include, for example, first and second illumination lights with different spectra, as shown in Figures 3 and 4. When emitting the first illumination light having the spectrum shown in Figure 3, the V-LED 20a emits purple light V with a central wavelength of 410±10 nm and a wavelength range of 380 to 420 nm. The B-LED 20b emits blue light B with a central wavelength of 450±10 nm and a wavelength range of 420 to 500 nm. The G-LED 20c emits green light G with a wavelength range of 480 to 600 nm. The R-LED 20d emits red light R with a central wavelength of 620 to 630 nm and a wavelength range of 600 to 650 nm.

[0032] When emitting the first illumination light, the light source control unit 21 controls the LEDs 20a to 20d so that the light intensity ratio combination among the purple light V, blue light B, green light G, and red light R is Vc:Bc:Gc:Rc. The first illumination light is broadband white light suitable for screening observation.

[0033] 4, the B-LED 20b, G-LED 20c, and R-LED 20d are simultaneously turned on to combine blue light B, green light G, and red light R. The light source controller 21 controls the LEDs 20a-20d so that the light intensity ratio of the purple light V, blue light B, green light G, and red light R is Vs:Bs:Gs:Rs. The second illumination light is a narrow-band special light suitable for calculating the oxygen saturation level in the observation target by utilizing the difference in the absorption coefficients of oxygenated hemoglobin and reduced hemoglobin and for detecting hypoxic regions that suggest the presence of a tumor.

[0034] The illumination light is not limited to this, and any type of illumination light (Nth illumination light) having a spectrum different from that of the first illumination light and the second illumination light may be configured by combining the light intensities emitted by the light sources. For example, when emitting third illumination light having the spectrum shown in FIG. 5, the G-LED 20c is turned on to emit green light G. The light source control unit 21 controls the LEDs 20a to 20d so that the light intensity ratio combination among the purple light V, blue light B, green light G, and red light R is Vt:Bt:Gt:Rt. The third illumination light is a special light for reflecting the concentration of vital pigments such as yellow pigment in the observation object in the calculation of oxygen saturation.

[0035] As with the second illumination light and the third illumination light, the combination of light intensity ratios includes a case where the ratio of at least one semiconductor light source is 0 (zero). For example, as with the third illumination light, a case where only one of the semiconductor light sources is turned on and the other three are not turned on also has a light intensity ratio and is one of the combinations of light intensity ratios.

[0036] In the first embodiment, the endoscope system 10 has a plurality of light emission modes with different illumination light emission methods. The light emission modes are broadly divided into two modes: a mono light emission mode and a multi light emission mode. The mono light emission mode is a light emission mode in which one type of illumination light among multiple types of illumination light is emitted. The multi light emission mode is a light emission mode in which multiple types of illumination light are switched and emitted.

[0037] In the mono light-emitting mode and the multi light-emitting mode, one type of illumination light is emitted for each illumination period LP, as shown in Figs. 6 to 9. In the mono light-emitting mode, as shown in Fig. 6, a first illumination light L1 is emitted for each illumination period LP. The illumination light emitted in the mono light-emitting mode may be any type of illumination light from the first illumination light to the Nth illumination light. In this case, the endoscope system 10 has mono light-emitting first illumination light mode to mono light-emitting Nth illumination light mode as the mono light-emitting modes.

[0038] The endoscopic system 10 has two multi-light emission modes: a pattern light emission mode in which multiple types of illumination light are emitted according to a specific light emission pattern, as shown in Figures 7 and 8, and a flexible light emission mode in which illumination light is emitted irregularly without a specific light emission pattern, as shown in Figure 9.

[0039] In the patterned light emission mode, as shown in Fig. 7, a first light emission pattern is repeated in which illumination light is sequentially emitted in the order of first illumination light L1, first illumination light L1, second illumination light L2, and third illumination light L3 for each illumination period LP in one light emission cycle LC. Alternatively, as shown in Fig. 8, a second light emission pattern may be repeated in which illumination light is sequentially emitted in the order of first illumination light L1, second illumination light L2, third illumination light L3, and second illumination light L2 for each illumination period LP in one light emission cycle LC. However, the light emission pattern is not limited to this, and the number of illumination periods included in one light emission cycle and the type of illumination light may be set arbitrarily.

[0040] 9, the flexible light-emitting mode does not have a specific light-emitting pattern, and the emitted illumination light is determined for each illumination period LP. The emitted illumination light is determined according to emission schedule information, which is information indicating the type of illumination light to be emitted for each frame (illumination period LP within one frame), as described below. In the flexible light-emitting mode, for example, an artificial intelligence provided inside or outside the processor device 14 generates emission schedule information to obtain an appropriate number of endoscopic images for each type of illumination light at an appropriate timing depending on the observation purpose, and transmits the emission schedule information to the emission information acquisition unit 140, which will be described later, and controls the light source unit 20 via the central control unit 50 and the light source control unit 21 to emit any type of illumination light.

[0041] The above modes can be switched via the central control unit 50 by a user such as a doctor operating the mode selector switch 12f. The mode may be switched via the user interface 16. Furthermore, at the time of switching the mode, it is preferable that the extraction schedule information is transmitted via the central control unit 50 to the extraction information acquisition unit 140, which will be described later.

[0042] The illumination light emitted from the light source unit 20 for each illumination period is incident on the light guide 23 via an optical path combining unit 22 composed of a mirror, a lens, etc. The light guide 23 is built into the endoscope 12 and a universal cord (a cord that connects the endoscope 12 with the light source device 13 and the processor device 14). The light guide 23 propagates the light from the optical path combining unit 22 to the tip 12d of the endoscope 12.

[0043] An illumination optical system 30 and an imaging optical system 40 are provided at the tip 12d of the endoscope 12. The illumination optical system 30 is an optical system for irradiating an observation object with illumination light, and has an illumination lens 31. The various types of illumination light propagated by the light guide 23 are irradiated onto the observation object via the illumination lens 31. It is also possible to omit the light guide 23 and have the light source unit 20 built into the tip 12d of the endoscope 12. In this case, the various types of illumination light emitted from the light source unit 20 are transmitted through the illumination lens 31 of the illumination optical system 30 and are emitted so as to illuminate the observation object.

[0044] The imaging optical system 40 is an optical system for forming an image of an object to be observed, and includes an objective lens 41, a zoom lens 42, and an imaging sensor 43. The imaging optical system 40 also includes an aperture and a shutter. The aperture and shutter do not have to be provided as components, and may be an electronic aperture or an electronic shutter. Various types of light, such as reflected light, scattered light, and fluorescent light from the object to be observed when irradiated with illumination light, enter the imaging sensor 43 via the objective lens 41 and the zoom lens 42, and an image of the object to be observed is formed on the imaging sensor 43. The zoom lens 42 is a lens for enlarging the object to be observed, and can be adjusted between a telephoto end and a wide-angle end by operating the zoom operation unit 12i. of The image of the object to be observed formed on the image sensor 43 is enlarged or reduced by moving between the two.

[0045] The imaging sensor 43 is a color imaging element that captures an optical image of an object to be observed and outputs an image signal. A CMOS (Complementary Metal-Oxide Semiconductor) image sensor is used as the imaging sensor 43. As shown in Fig. 10, a plurality of pixels 43b that generate pixel signals by photoelectric conversion are formed on an imaging surface 43a of the imaging sensor 43. The pixels 43b are arranged two-dimensionally in a matrix in the row direction (X direction) and column direction (Y direction).

[0046] A color filter array 44 is provided on the light incident side of the image sensor 43. The color filter array 44 has blue (B) filters 44a, green (G) filters 44b, and red (R) filters 44c. One of these filters is arranged on each pixel 43b. The color arrangement of the color filter array 44 is a Bayer arrangement, in which G filters 44b are arranged in a checkerboard pattern on every other pixel, and B filters 44a and R filters 44c are arranged in a square lattice pattern on the remaining pixels.

[0047] Hereinafter, the pixels 43b in which the B filter 44a is arranged will be referred to as B pixels, the pixels 43b in which the G filter 44b is arranged will be referred to as G pixels, and the pixels 43b in which the R filter 44c is arranged will be referred to as R pixels. In each even-numbered (0, 2, 4, . . . , M-1) pixel row, B pixels and G pixels are alternately arranged. In each odd-numbered (1, 3, 5, . . . , M) pixel row, G pixels and R pixels are alternately arranged. Here, M is an odd positive integer, and a pixel row refers to one row of pixels 43b arranged in the row direction. A pixel column refers to one column of pixels 43b arranged in the column direction.

[0048] The color filter array 44 has the spectral characteristics shown in Fig. 11. The B filter 44a has high light transmittance in the wavelength band of, for example, 380 nm to 560 nm. The G filter 44b has high light transmittance in the wavelength band of, for example, 450 nm to 630 nm. The R filter 44c has high light transmittance in the wavelength band of, for example, 580 nm to 760 nm.

[0049] The imaging sensor 43 is driven by the imaging control unit 45, and receives return light from the object of observation illuminated by the illumination light with a plurality of pixels 43b via the color filter array 44, and outputs an image signal. The imaging sensor 43 outputs a BGR image signal consisting of a B pixel signal, a G pixel signal, and an R pixel signal as the image signal.

[0050] CMOS image sensors generally perform imaging operations using a rolling shutter method. In the rolling shutter method, the image sensor 43 performs signal readout using a sequential readout method. In the sequential readout method, signals are read out from all pixels 43b one pixel row at a time, from the first pixel row "0" to the last pixel row "M."

[0051] The image sensor 43 can perform two reset methods: a "sequential reset method" and a "batch reset method." In the sequential reset method, pixel rows are reset one by one, from the first pixel row "0" to the last pixel row "M." In the batch reset method, all pixel rows are reset simultaneously.

[0052] It should be noted that, from a cost perspective, it is preferable to use a rolling shutter CMOS image sensor as the imaging sensor 43, but this is not limiting and a global shutter CMOS image sensor may also be used. Furthermore, instead of a CMOS image sensor, a CCD (Charge Coupled Device) image sensor may also be used as the imaging sensor 43.

[0053] When an image sensor 43 is provided that performs imaging operations using a rolling shutter method, in which signal readout is performed using a sequential readout method and resetting is performed using a sequential reset method, it is preferable to perform imaging operations using a pseudo-global shutter method, in which the exposure period is adjusted by emitting illumination light in pulses. Pulsed emission of illumination light means emitting illumination light so that an off period OP is provided between illumination periods LP in which illumination light is emitted, as shown in Figure 12.

[0054] The pseudo-global shutter method shown in Figure 12 is a sequential readout method in which pixel rows of the image sensor 43 are read out in order over time, as indicated by the diagonal lines in the direction of the "sequential readout" arrow. "One frame" for acquiring one endoscopic image includes an exposure period EP during which the pixels 43b of each pixel row of the image sensor 43 are exposed, and a readout period RP during which image signals are read out. Note that the period up to the exposure period EP within one frame is the "period until the illumination light is emitted," and is the illumination light off period OP. In the pseudo-global shutter method, an illumination period LP is set to coincide with the exposure period EP (hatched portion) during which all pixel rows are exposed.

[0055] By adopting the pseudo-global shutter method, it is possible to suppress distortion that occurs at the top and bottom of the read-out image. Also, by providing an off period OP between the illumination periods LP, it is possible to eliminate color mixing that occurs when switching between types of illumination light when the illumination light is always on. Furthermore, depending on the processing speed of the processor, it is possible to calculate the amount of emitted light used for light amount control, which will be described later, during the off period OP.

[0056] Note that imaging may also be performed using a general rolling shutter method, as shown in Figure 13. In a general rolling shutter method, illumination light is constantly emitted while switching types. The imaging sensor 43 reads out pixel rows in sequence over time, with one pixel row always being exposed to light. In Figure 13, the exposure period EP for each pixel row is indicated by the shaded area. In the general rolling shutter method, the period from the start of the exposure period EP of the first pixel row to the end of the readout period RP of the last pixel row is defined as "one frame."

[0057] Note that instead of the image sensor 43 provided with primary color filters, a complementary color image sensor provided with complementary color filters of C (cyan), M (magenta), Y (yellow), and G (green) may be used. When a complementary color image sensor is used, image signals of four colors, CMYG, are output. Therefore, by converting the four color image signals of CMYG into three color image signals of RGB through complementary color-primary color conversion, an RGB image signal similar to that of the image sensor 43 can be obtained. Also, instead of the image sensor 43, a monochrome sensor without color filters may be used.

[0058] The imaging sensor 43 is driven and controlled by a central control unit 50 (see FIG. 2) via an imaging control unit 45. The central control unit 50 controls the light emission of the light source unit 20 through a light source control unit 21 in synchronization with the driving of the imaging sensor 43.

[0059] By controlling the imaging sensor 43 so as to capture an image of the return light from the observation object illuminated with each type of illumination light, an image signal is output from each pixel 43b. When the observation object is captured using the first illumination light, a Bc image signal is output from the B pixel of the imaging sensor 43, a Gc image signal is output from the G pixel, and an Rc image signal is output from the R pixel. When the observation object is captured using the second illumination light, a Bs image signal is output from the B pixel of the imaging sensor 43, a Gs image signal is output from the G pixel, and an Rs image signal is output from the R pixel. When the observation object is captured using the third illumination light, a Bt image signal is output from the B pixel of the imaging sensor 43, a Gt image signal is output from the G pixel, and an Rt image signal is output from the R pixel.

[0060] A CDS / AGC (Correlated Double Sampling / Automatic Gain Control) circuit 46 performs correlated double sampling (CDS) and automatic gain control (AGC) on the analog image signal obtained from the image sensor 43. The image signal passed through the CDS / AGC circuit 46 is converted into a digital image signal by an A / D (Analog / Digital) converter 47. As a result, the digital image signal after A / D conversion is input to the processor device 14.

[0061] The processor device 14 includes a central control unit 50, an image signal acquisition unit 60, a DSP (Digital Signal Processor) 61, a noise reduction unit 62, an image signal storage unit 63, an endoscopic image generation unit 70, a display control unit 80, an emitted light amount calculation unit 90, and a specified emitted light amount selection unit 110 (see FIG. 2). In the processor device 14, programs relating to each process are stored in a program memory (not shown). The central control unit 50, which is made up of a processor, executes the programs in the program memory to realize the functions of the image signal acquisition unit 60, the DSP 61, the noise reduction unit 62, the image signal storage unit 63, the endoscopic image generation unit 70, the display control unit 80, the emitted light amount calculation unit 90, and the specified emitted light amount selection unit 110. As a result, the functions of the brightness calculation unit 91, brightness difference calculation unit 92, and emission light quantity output unit 93 included in the emission light quantity calculation unit 90, as well as the emission information acquisition unit 140, emission schedule information receiving unit 150, and emission light quantity memory unit 120 included in the specified emission light quantity selection unit 110 are realized.

[0062] The image signal acquisition unit 60 acquires a digital image signal input from the endoscope 12. The image signal acquisition unit 60 acquires image signals obtained by capturing an image of an observation target illuminated by each type of illumination light.

[0063] The acquired image signal is transmitted to the DSP 61. The DSP 61 performs digital signal processing such as color correction on the received image signal. The noise reduction unit 62 performs noise reduction processing, such as a moving average method or a median filter method, on the image signal that has been subjected to color correction and other processing by the DSP 61. The image signal with reduced noise is stored in the image signal storage unit 63.

[0064] The endoscopic image generating unit 70 acquires the noise-reduced image signal from the image signal storage unit 63. Next, the acquired image signal is subjected to signal processing such as color conversion processing, color enhancement processing, and structure enhancement processing as necessary to generate a color endoscopic image showing the object of observation. The endoscopic image refers to an Nth illumination light image generated from an image signal output by exposing the imaging sensor 43 to the Nth illumination light.

[0065] As shown in FIG. 14, the endoscopic image generating unit 70 includes a first illumination light image generating unit 71, a second illumination light image generating unit 72, and a third illumination light image generating unit 73. Furthermore, when four or more types of illumination light are emitted, up to an Nth illumination light image generating unit 74 may be included. The endoscopic image generating unit 70 acquires image signals from the image signal storage unit 63 according to the type of acquired image signal and generates each type of endoscopic image. That is, the first illumination light image generating unit 71 generates the first illumination light image, the second illumination light image generating unit 72 generates the second illumination light image, and the third illumination light image generating unit 73 generates the third illumination light image. Similarly, the Nth illumination light image generating unit 74 generates the Nth illumination light image. The Nth illumination light image generated by the endoscopic image generating unit 70 is transmitted to the display control unit 80 and the emitted light intensity calculation unit 90 (see FIG. 2).

[0066] The display control unit 80 receives the endoscopic image and performs control to display the endoscopic image as a display image on the display 15. The display control unit 80 generates a display image from the type of endoscopic image specified by the central control unit 50 and outputs it to the display 15 for display.

[0067] The light intensity control in the first embodiment will be described below. The first embodiment is an embodiment in which light intensity control is performed according to the type of illumination light emitted from a certain frame to a subsequent frame, without being limited to a specific light emission pattern. The endoscopic image generation unit 70 generates an endoscopic image using illumination light emitted to a light intensity calculation frame, which is a frame at an arbitrary point in time.

[0068] The emitted light amount calculation unit 90 calculates the emitted light amount, which is the amount of illumination light that sets the endoscopic image transmitted from the endoscopic image generation unit 70 to a target brightness. The emitted light amount calculation unit 90 includes a brightness calculation unit 91, a brightness difference calculation unit 92, and an emitted light amount output unit 93, as shown in FIG.

[0069] The brightness calculation unit 91 calculates the brightness Y of the endoscopic image based on the luminance value of the pixels in the endoscopic image. The brightness difference calculation unit 92 calculates the brightness difference ΔY between the calculated brightness Y and a target brightness preset for each type of endoscopic image. The emitted light amount output unit 93 outputs the emitted light amount Q based on the brightness difference ΔY. Furthermore, the emitted light amount Q is associated with the previously emitted illumination light information to set it as a retained emitted light amount, and is transmitted to the emitted light amount storage unit 120 of the specified emitted light amount selection unit 110 (see FIG. 2). The target brightness may be a fixed value or a value that varies depending on the imaging scene. Alternatively, a target luminance value may be set instead of the target brightness. The brightness of the endoscopic image may also be calculated based on a value other than a luminance value. For example, the brightness may be calculated from a relative luminance value calculated from the contrast ratio.

[0070] When emitting any type of illumination light to an expected emission frame, which is a frame chronologically subsequent to the light intensity calculation frame, the designated emission light intensity selection unit 110 selects, as the designated emission light intensity, the retained emission light intensity, which is the most recently calculated emission light intensity, from among the retained emission light intensities stored in the emission light intensity storage unit 120, which are emission light intensities based on the same type of illumination light as the illumination light to be emitted to the expected emission frame. The designated emission light intensity selection unit 110 transmits the designated emission light intensity to the emission instruction signal generation unit 130. The emission instruction signal generation unit 130 generates an emission instruction signal for emitting illumination light at the designated emission light intensity to the expected emission frame and transmits the signal to the central control unit 50. Based on the emission instruction signal, the central control unit 50 controls the light source unit 20 via the light source control unit 21 to emit illumination light to be emitted to the expected emission frame at the designated emission light intensity. The emission planned frame may be the frame immediately following the light intensity calculation frame, or may be a frame an arbitrary number of frames later.

[0071] A first specific example of emitting the first illumination light and the second illumination light will be described below with reference to FIG. 16. A frame 100a at time Tx1 is set as a light intensity calculation frame. When the first illumination light 21a is emitted in the light intensity calculation frame 100a, the endoscopic image generation unit 70 generates a first illumination light image 70a. Next, the emitted light intensity calculation unit 90 calculates a first emitted light intensity 90a, which is the light intensity of the first illumination light L1 that sets the first illumination light image 70a to a first target brightness, and transmits it to the emitted light intensity storage unit 120. The first emitted light intensity 90a is stored in the emitted light intensity storage unit 120 of the specified emitted light intensity selection unit 110 as a first held emitted light intensity 120a.

[0072] Here, (1) frame 100b at time Tx2 is set as the planned-emission frame. In this case, in order to emit the first illumination light 21b in the planned-emission frame 100b, the planned-emission-light-intensity selector 110 selects the first held emission light intensity 121, which is the most recently calculated first held emission light intensity SQ1, from the held emission light intensities stored in the emission light intensity storage unit 120 before the planned-emission frame 100b starts, as the first planned-emission-light intensity and transmits the selected first held emission light intensity 121 to the emission instruction signal generator 130. The emission instruction signal generator 130 generates an emission instruction signal to emit illumination light at the first planned-emission-light intensity (first held emission light intensity 121) in the planned-emission frame 100b, and controls the central controller 50 and the light source controller 21 to emit the first illumination light 21b at the first held emission light intensity 121 in the planned-emission frame 100b to which time Tx2 belongs.

[0073] (2) When the frame at time Tx3 is set as the expected emission frame, the specified emission light intensity selector 110 selects the first held emission light intensity 120a, which is the latest first held emission light intensity SQ1, as the first specified emission light intensity from among the held emission light intensities in order to emit the first illumination light 21c to the expected emission frame 100c. The emission instruction signal generator 130 generates an emission instruction signal to emit illumination light at the first specified emission light intensity (first held emission light intensity 120a) to the expected emission frame 100c, and controls the first illumination light 21c to be emitted at the first held emission light intensity 120a in the expected emission frame 100c to which time Tx3 belongs.

[0074] (3) When frame 100e at time Tx4 is set as the planned-emission frame, the designated emission light intensity selector 110 selects the first held emission light intensity 120c, which is the latest first held emission light intensity SQ1, as the first designated emission light intensity to emit the first illumination light 21e to the planned-emission frame 100e. The first held emission light intensity 120c is the first held emission light intensity SQ1 calculated and stored based on the first illumination light image 70c emitted to frame 100c. The emission instruction signal generator 130 generates an emission instruction signal to emit illumination light at the first designated emission light intensity (first held emission light intensity 120c) to the planned-emission frame 100e, and controls the first illumination light 21e to be emitted to the planned-emission frame 100e at the first held emission light intensity 120c.

[0075] Here, the first held emitted light amount 120b is stored in the emitted light amount storage unit 120, but since it is not the latest first held emitted light amount SQ1, the first held emitted light amount 120b is not selected as the first designated emitted light amount.

[0076] (4) If the frame at time Tx5 is the scheduled emission frame, the specified emission light intensity selector 110 selects the first held emission light intensity 120c, which is the latest first held emission light intensity SQ1, as the first specified emission light intensity to emit the first illumination light 21e to the scheduled emission frame 100f. The first held emission light intensity 120c is the first held emission light intensity SQ1 calculated and stored based on the first illumination light image 70c emitted to the frame 100c. The emission instruction signal generator 130 generates an emission instruction signal to emit illumination light at the first specified emission light intensity (first held emission light intensity 120c) to the scheduled emission frame 100c, and controls the first illumination light 21f to be emitted to the scheduled emission frame 100f at the first held emission light intensity 120c.

[0077] Here, at time points Tx4 and Tx5, the first held emitted light amount 100c is the latest first held emitted light amount SQ1, so the first held emitted light amount 100c is selected as the first specified emitted light amount for two consecutive frames, frame 100e and frame 100f.

[0078] (5) If the frame at time Tx6 is the scheduled emission frame, the specified emission light intensity selector 110 selects the first held emission light intensity 120e, which is the latest first held emission light intensity SQ1, as the first specified emission light intensity to emit the first illumination light 21g to the scheduled emission frame 100g. The first held emission light intensity 120e is the first held emission light intensity SQ1 calculated and stored based on the first illumination light image 70e emitted to the frame 100e. The emission instruction signal generator 130 generates an emission instruction signal to emit illumination light at the first specified emission light intensity (first held emission light intensity 120e) to the scheduled emission frame 100g, and controls the first illumination light 21g to be emitted to the scheduled emission frame 100g at the first held emission light intensity 120e.

[0079] (6) When frame 100h at time Tx7 is set as the planned emission frame, the designated emission light intensity selection unit 110 selects the second held emission light intensity 120d, which is the latest second held emission light intensity SQ2, as the second designated emission light intensity in order to emit the second illumination light 21h at the planned emission frame 100h. The second held emission light intensity 120d is calculated based on the second illumination light image 70d emitted to frame 100d and is stored as the second held emission light intensity SQ2. 2 The emission instruction signal generation unit 130 generates an emission instruction signal to emit illumination light at the second designated emission light amount (second held emission light amount 120d) in the emission scheduled frame 100h, and controls the second illumination light 21h to be emitted at the second held emission light amount 120d in the emission scheduled frame 100h to which time point Tx7 belongs.

[0080] 16, the dotted line box indicates the first emitted light amount that is the basis of the first held emitted light amount 121. Similarly, unless otherwise specified in the subsequent figures, the dotted line box indicates that any type of illumination light has been emitted, an endoscopic image has been generated, the emitted light amount has been calculated, the held emitted light amount has been stored, and previously emitted light information, which will be described later, has been acquired, or scheduled emission information, which will be described later, has been acquired.

[0081] As in the above configuration, the calculated light amount is temporarily stored and the stored amount is adjusted to match the illumination light to be emitted to a future frame. Light intensity By selecting the most recent light intensity from the list and performing light intensity control to emit illumination light at the selected light intensity, it is possible to obtain endoscopic images with appropriate brightness using illumination light emitted to future frames. With this configuration, even in cases where there is no specific light emission pattern and illumination light is emitted irregularly, such as in flexible light emission mode, appropriate light intensity control can be performed and endoscopic images with appropriate brightness can be obtained.

[0082] When three or more types of illumination light are emitted, the emission light intensity is calculated from the endoscopic image acquired in the light intensity calculation frame and temporarily stored, and illumination light is emitted at the designated emission light intensity in a scheduled emission frame at any time point after the light intensity calculation frame. FIG. 17 shows a second specific example when first, second, and third illumination lights are emitted. The frame at time point Tx8 is designated as the light intensity calculation frame 100i. When the first illumination light 21i is emitted in the light intensity calculation frame 100i, the endoscopic image generation unit 70 generates a first illumination light image 70i. Next, the emission light intensity calculation unit 90 calculates a first emission light intensity 90i, which is the emission light intensity of the first illumination light L1 that sets the first illumination light image 70i to a first target brightness, and transmits the first emission light intensity 90i to the emission light intensity storage unit 120. The first emitted light amount 90i is stored in the emitted light amount storage unit 120 of the designated emitted light amount selection unit 110 as a first held emitted light amount 120i.

[0083] Here, (7) frame 100k at time Tx9 is set as the planned emission frame. In this case, in order to emit the second illumination light 21k into the planned emission frame 100k, the planned emission light intensity selector 110 selects the second held emission light intensity 122, which is the most recently calculated second held emission light intensity SQ2, from among the held emission light intensities stored in the emission light intensity storage unit 120 before the planned emission frame 100k starts, as the second planned emission light intensity, and transmits the selected second held emission light intensity 122 to the emission instruction signal generator 130. The emission instruction signal generator 130 generates an emission instruction signal for emitting illumination light at the second planned emission light intensity (second held emission light intensity 122) into the planned emission frame 100k, and transmits the selected second held emission light intensity 122 to the light source controller 21 via the central controller 50 and the light source controller 21. k Then, the second illumination light 21k is controlled to be emitted at the second maintained emitted light amount 122.

[0084] (8) Even when the frame at time Tx10 is set as the scheduled emission frame, the latest second held emission light amount SQ2 is the second held emission light amount 122. In this case as well, the specified emission light amount selection unit 110 selects the second held emission light amount 122 as the second specified emission light amount, and the emission instruction signal generation unit 130 generates an emission instruction signal to emit illumination light at the second specified emission light amount (second held emission light amount 122) in the scheduled emission frame 100k, and controls the second illumination light 21l to be emitted at the second held emission light amount 122 in the scheduled emission frame 100l to which time Tx10 belongs.

[0085] (9) When the frame at time Tx11 is set as the scheduled emission frame, the specified emission light intensity selection unit 110 selects the first held emission light intensity 120i, which is the latest first held emission light intensity SQ1, as the first specified emission light intensity to emit the first illumination light 21m to the scheduled emission frame 100m. The first held emission light intensity 120i is the first held emission light intensity SQ1 calculated and stored based on the first illumination light image 70i emitted to the frame 100i. The emission instruction signal generation unit 130 generates an emission instruction signal to emit illumination light at the first specified emission light intensity (first held emission light intensity 120i) to the scheduled emission frame 100m, and controls the first illumination light 21m to be emitted at the first held emission light intensity 120i to the scheduled emission frame 100m to which time Tx11 belongs.

[0086] (10) When the frame at time Tx12 is set as the scheduled emission frame, the designated emission light intensity selector 110 selects the third held emission light intensity 120n, which is the latest third held emission light intensity SQ3, as the third designated emission light intensity to emit the third illumination light 21n to the scheduled emission frame 100n. The third held emission light intensity 120n is the third held emission light intensity SQ3 calculated and stored based on the third illumination light 21j emitted to the frame 100j. The emission instruction signal generator 130 generates an emission instruction signal to emit illumination light at the third designated emission light intensity (third held emission light intensity 120j) to the scheduled emission frame 100n, and controls the third illumination light 21n to be emitted at the third held emission light intensity 120j in the scheduled emission frame 100n to which time Tx12 belongs.

[0087] As described above, even if the number of types of illumination light is increased to three or more, the amount of illumination light to be emitted in the emission-destination frame after the light-intensity calculation frame at any point in time can be adjusted in the same manner. The number of types of illumination light can be increased from 2 to N.

[0088] When the illumination light is emitted, it is preferable to acquire previously emitted information indicating the type of the emitted illumination light. The previously emitted information is preferably associated with a target brightness and a parameter for calculating the amount of emitted light set for each type of illumination light. The amount of emitted light is preferably calculated using the parameter for calculating the amount of emitted light corresponding to the type of illumination light associated with the previously emitted information.

[0089] 18, when calculating the first emitted light amount 90о based on the first illumination light image 70о captured using the first illumination light 21о, the emission information acquisition unit 140 first acquires first previously emitted emission information Pr1, which is information indicating that the first illumination light 21о has been emitted. The first previously emitted emission information Pr1 is information in which the first target brightness and a parameter for calculating the first emitted light amount are associated. The first previously emitted emission information Pr1 is transmitted to the emitted light amount calculation unit 90 (see FIG. 2).

[0090] Next, the emitted light amount calculation unit 90 calculates a brightness difference ΔY1 from the brightness Y1 of the first illumination light image 70о and the first target brightness associated with the first previous emission information Pr1. Finally, the brightness Y1 and the brightness difference ΔY1 are substituted into the first illumination light emitted light amount calculation parameter f(Y1, ΔY1) associated with the first previous emission information Pr1 to calculate the first emitted light amount 90о.

[0091] Furthermore, when calculating the second emitted light amount 90p based on the second illumination light image 70p captured using the second illumination light 21p, the emission information acquisition unit 140 first acquires second previously emitted emission information Pr2, which is information indicating that the second illumination light 21p has been emitted. The second previously emitted emission information Pr2 is information that is associated with the second target brightness and parameters for calculating the second emitted light amount. The second previously emitted emission information Pr2 is transmitted to the emitted light amount calculation unit 90 (see FIG. 2).

[0092] The emitted light amount calculation unit 90 calculates a brightness difference ΔY2 from the brightness Y2 of the second illumination light image 70p and a second target brightness associated with the second previous emission information Pr2. Next, the brightness Y2 and the brightness difference ΔY2 are substituted into a parameter f(Y2, ΔY2) for calculating the emitted light amount for the second illumination light associated with the second previous emission information Pr2, to calculate a second emitted light amount 90p.

[0093] It is also possible to calculate the amount of emitted light by calculating a spectral sensitivity coefficient corresponding to the brightness of the calculated endoscopic image without using the parameter for calculating the amount of emitted light. However, in reality, the number of endoscopic images captured during an endoscopic examination is enormous, making it difficult to calculate the spectral sensitivity coefficient corresponding to the brightness of each endoscopic image. Therefore, by presetting a parameter for calculating the amount of emitted light corresponding to the type of illumination light used to capture the endoscopic image, the calculation speed of the amount of emitted light required for light source control can be significantly increased, making it possible to calculate the amount of emitted light for each illumination period.

[0094] Furthermore, it is preferable that the target brightness is set from the first target brightness to the Nth target brightness depending on the type of illumination light emitted, and the parameters for calculating the emitted light intensity are set from the first parameter for calculating the emitted light intensity to the Nth parameter for calculating the emitted light intensity.

[0095] It is preferable to acquire emission schedule information, which is information indicating the type of illumination light to be emitted in the emission schedule frame, and select the designated emission light intensity according to the emission schedule information. In this case, the emission information acquisition unit 140 acquires the emission schedule information for each frame via the central control unit 50 or the like, and transmits it to the emission schedule information reception unit 150 of the designated emission light intensity selection unit 110.

[0096] Furthermore, it is preferable to associate the emitted light amount acquired in the light amount calculation frame with the previous emission information and store it as a held emitted light amount. That is, it is preferable to store the held emitted light amount in a state in which it is possible to check for which type of illumination light the held emitted light amount corresponds to. The association of the emitted light amount with the previous emission information may be performed by the emitted light amount output unit 93, or a correlation unit (not shown) may be provided in the emitted light amount calculation unit 90. Furthermore, it is preferable to select the designated emitted light amount based on the previous emission information associated with the held emitted light amount and the emission schedule information.

[0097] In this case, the specified emission light amount selection unit 110 first compares the type of illumination light indicated in the emission schedule information transmitted to the emission schedule information receiving unit 150 with the type of illumination light indicated in the previous emission information associated with the retained emission light amount stored in the emission light amount storage unit 120, and extracts a combination in which the type of illumination light related to the emission schedule information matches the type of illumination light related to the previous emission information. The specified emission light amount selection unit 110 selects the retained emission light amount having the most recently calculated emission light amount from the combinations as the specified emission light amount.

[0098] A specific example of selecting a designated emitted light intensity by further referring to the emission schedule information in the example of FIG. 16 will be described with reference to FIG. 19. When frame 100a at time Tx1 is used as the light intensity calculation frame, first, a first illumination light image 70a is generated, and first previous emission information 140a in which the first illumination light 21a is emitted is acquired. Next, a first emitted light intensity 90a is calculated using a first target brightness and a first emitted light intensity calculation parameter associated with the first previous emission information 140a. The first emitted light intensity 90a is associated with the first previous emission information 140a and stored as a first held emitted light intensity 120a.

[0099] (11) When frame 100c at time Tx3 is set as the planned emission frame, the designated emission light intensity selection unit 110 refers to the first planned emission information 151 indicating that the first illumination light 21c is to be emitted to the planned emission frame 100c, and selects the first retained emission light intensity 120a, which is associated with the first existing emission information 140a, from the retained emission light intensities as the first designated emission light intensity.

[0100] (12) When frame 100e at time Tx4 is set as the planned-emission frame, the specified emission light intensity selection unit 110 refers to first emission plan information 153 indicating that the first illumination light 21e is to be emitted to the planned-emission frame 100e. Here, the stored held emission light intensities include, for example, a first held emission light intensity 120a associated with the first previous emission information 140a, a first held emission light intensity 120b associated with the first previous emission information 140b, and a first held emission light intensity 120c associated with the first previous emission information 140c. Of these, the specified emission light intensity selection unit 110 selects the first held emission light intensity 120c, which is the latest first held emission light intensity SQ1, as the first specified emission light intensity.

[0101] (13) When frame 100f at time Tx5 is set as the planned emission frame, the specified emission light intensity selection unit 110 refers to the first emission plan information 154 indicating that the first illumination light 21e is to be emitted to the planned emission frame 100f. Here, the held emission light intensities stored include, for example, a first held emission light intensity 120a associated with the first previous emission information 140a, a first held emission light intensity 120b associated with the first previous emission information 140b, a first held emission light intensity 120c associated with the first previous emission information 140c, and a second held emission light intensity 120d associated with the second previous emission information 140d.

[0102] The designated emitted light amount selection unit 110 first extracts the first held emitted light amounts 120a, 120b, and 120c associated with the first already emitted emission information Pr1 by referring to the first emission schedule information 154. Of these, the first held emitted light amount 120c, which is the latest first held emitted light amount SQ1, is selected as the first designated emitted light amount.

[0103] As in the above configuration, the type of illumination light to be emitted into the planned emission frame is referenced based on the planned emission information, and a specified emission light amount is selected from combinations that match the type of illumination light related to the existing emission information associated with the retained emission light amount, or the light amount calculated from the first illumination light image is used to control the light amount of the second illumination light, thereby preventing the light amount of one type of illumination light from being used to control the light amount of another type of illumination light.

[0104] It is preferable to acquire previously emitted light information indicating the type of illumination light emitted in at least two or more light intensity calculation frames, and acquire emission schedule information indicating the type of illumination light to be emitted in at least one or more emission schedule frames. With the above configuration, at least two or more held emitted light amounts are stored, and light intensity control can be performed using the held emitted light amounts in the emission schedule frame at least one or more frames after the light intensity calculation frame.

[0105] The previously emitted light information is preferably acquired by updating the emitted light schedule information to the previously emitted light information by associating the target brightness and the emitted light intensity calculation parameters with the emitted light schedule information acquired in a frame chronologically earlier than the light intensity calculation frame. In this case, as shown in FIG. 20, an emitted light information update unit 141 is provided in the emitted light information acquisition unit 140.

[0106] The emission information acquisition unit 140 transmits the emission schedule information to the emission schedule information receiving unit 150, but thereafter retains the emission schedule information and updates the emission schedule information to previous emission information at a certain timing. Specifically, as illustrated in Fig. 21 , the emission information update unit 141 updates first emission schedule information 157 for emitting the first illumination light 21q to first previous emission information 140q by associating the first target brightness and the first emission light intensity calculation parameters with the first emission schedule information 157.

[0107] The timing of the update may be when the first illumination light 21q is emitted, when the first illumination light image 70q is generated, or when the second emission schedule information 158 for emitting the second illumination light 21r is acquired. Similarly, the second emission schedule information 158 for emitting the second illumination light 21r is updated to the second previous emission information 140r by associating it with the second target brightness and the second emission light intensity calculation parameters. Also, the emission schedule information 159 for emitting the first illumination light 21s is updated to the previous emission information 140s by associating it with the first target brightness and the first emission light intensity calculation parameters.

[0108] With the above configuration, it is possible to acquire already-emitted information every time new emission schedule information is acquired for each frame, thereby increasing the processing speed of the processor, without having to acquire new already-emitted information from outside the processor device 14. Note that the already-emitted information may be acquired by the light source control unit 21 transmitting the type of emitted illumination light to the emission information acquisition unit 140 via the central control unit 50 at the time illumination light is emitted for each frame.

[0109] It is preferable that the emission information acquisition unit 140 acquires emission schedule information when the light emission mode is switched. Furthermore, in the pattern light emission mode, it is preferable that the emission schedule information be transmitted to the emission information acquisition unit 140 via the central control unit 50 when the light emission pattern is changed by operating the mode selector switch 12f (see FIG. 2). For example, when switching from the first light emission pattern to the second light emission pattern in the pattern light emission mode (i.e., when switching from the light emission cycle LC1 to the light emission cycle LC2), the regular light emission pattern may become irregular, as shown in FIG. 22. In this case, the type of illumination light to be emitted in each illumination period LP of the second light emission pattern is transmitted to the emission information acquisition unit 140 as emission schedule information. This configuration allows smooth light intensity control even when the light emission pattern becomes irregular when the light emission mode is switched.

[0110] A series of operational steps in the endoscope system of the first embodiment will be described with reference to the flowchart shown in FIG. 23. First, the light source unit 20 emits a certain type of illumination light into a light intensity calculation frame (step S101). Next, at an arbitrary timing chronologically after the light intensity calculation frame, the endoscopic image generation unit 70 generates an endoscopic image from an image signal obtained by illuminating the observation target with the previously emitted illumination light (step S102). Next, the emitted light intensity calculation unit 90 calculates the emitted light intensity for achieving a target brightness for the endoscopic image (step S103). Next, the emitted light intensity calculation unit 90 stores the emitted light intensity as a held emitted light intensity in the emitted light intensity storage unit 120 (step S104). Next, the designated emitted light intensity selection unit 110 selects the latest held emitted light intensity as a designated emitted light intensity (step S105). Finally, light intensity control is performed via the central control unit 50 and the light source control unit 21 so that the illumination light to be emitted in the emission scheduled frame is emitted at a designated emission light intensity (step S106).

[0111] [Second embodiment] The second embodiment is an embodiment in which illumination light is emitted according to a specific light emission pattern, unlike the first embodiment in which illumination light is not necessarily emitted according to a specific light emission pattern. In the second embodiment, the endoscope system 10 has a mono-light emission mode in which one type of illumination light from among multiple types of illumination light is emitted, and a multi-light emission mode in which multiple types of illumination light are switched and emitted according to a specific light emission pattern, and is set to either of the light emission modes.

[0112] 24 shows the functions of the endoscope system in the second embodiment. The endoscope 12, light source device 13, display 15, and user interface 16 are the same as those in the first embodiment. The functions of the image signal acquisition unit 60, DSP 61, noise reduction unit 62, image signal storage unit 63, and endoscopic image generation unit 70 of the processor device 14 are also the same as those in the first embodiment.

[0113] The light intensity control in the second embodiment will be described below. In the second embodiment, light intensity control is performed in which the calculated emitted light intensity is used in a frame after a specific number of frames have elapsed. In the second embodiment, the emission information acquisition unit 140 includes an emission pattern information acquisition unit 210, as shown in FIG. 25. The emission pattern information acquisition unit 210 acquires, via the central control unit 50, emission pattern information that indicates which type of illumination light is to be emitted for each frame according to the set emission mode.

[0114] The light emission pattern information is information that determines the type of illumination light to be emitted. In the mono light emission mode, the information indicates which type of illumination light, from the first illumination light to the Nth illumination light, will be emitted in each illumination period. In the multi light emission mode, a light emission cycle is made up of multiple illumination periods, and the information indicates which type of illumination light will be emitted in each illumination period of the light emission cycle. For example, the illumination light to be emitted is determined according to the first light emission pattern or the second light emission pattern.

[0115] The light emission pattern information acquisition unit 210 transmits the light emission pattern information to the emitted light amount calculation unit 90 (see FIG. 24). Furthermore, the endoscopic image generation unit 70 transmits the endoscopic image to the emitted light amount calculation unit 90. Based on the light emission pattern information, the emitted light amount is the amount of illumination light that will bring the endoscopic image transmitted from the endoscopic image generation unit 70 to a target brightness.

[0116] The emission pattern information preferably associates information on a target brightness according to the type of emitted illumination light with information on an emission light intensity calculation parameter. The emission light intensity is calculated based on an endoscopic image acquired according to the emission pattern information, the target brightness, and the emission light intensity calculation parameter. That is, when referring to the emission light intensity, the brightness calculation unit 91 of the emission light intensity calculation unit 90 calculates the brightness of the endoscopic image, the brightness difference calculation unit 92 calculates a brightness difference ΔY using the target brightness set for each type of endoscopic image in accordance with the emission pattern information, and the emission light intensity output unit 93 outputs the emission light intensity Q using the emission light intensity calculation parameter f(Y, ΔY) in accordance with the emission pattern information.

[0117] The calculated emitted light amount Q is sent to the emitted light amount storage unit 120 as the held emitted light amount (see FIG. 24). In the second embodiment, of the designated emitted light amount selection unit 110 in the first embodiment, only the emitted light amount storage unit 120 is used.

[0118] Moreover, in the second embodiment, a specific frame number setting unit (not shown) is further provided in the emitted light amount storage unit 120. The emitted light amount storage unit 120 temporarily stores, as a retained emitted light amount, the emitted light amount from the light amount calculation frame in which illumination light is emitted to the expected emission frame, which is the frame after the specific number of frames set by the specific frame number setting unit has elapsed.

[0119] The emitted light amount storage unit 120 transmits the retained emitted light amount to the emission instruction signal generation unit 130 in accordance with the light emission pattern information. The emission instruction signal generation unit 130 generates an emission instruction signal for controlling the illumination light to be emitted at the retained emitted light amount in the emission planned frame, which is a frame a specific number of frames after the light amount calculation frame, and transmits the signal to the light source control unit 21 via the central control unit 50 to control the light amount.

[0120] With the above configuration, when the timing at which the calculated light amount is used is regular, the number of steps can be reduced compared to when the light emission pattern is irregular, and light amount control can be smoothly performed to emit illumination light at a light amount that can obtain an endoscopic image of appropriate brightness, in accordance with the type of illumination light emitted during each illumination period.

[0121] The specific number of frames is preferably the "number of frames included in the light emission cycle" or the "number of frames from when a certain type of illumination light is emitted in a light intensity calculation frame until the same type of illumination light is emitted again." Alternatively, the specific number of frames may be any number of frames that is set in advance.

[0122] Regarding the light intensity control of the second embodiment, a first specific example showing a case where the light is emitted in an emission pattern of "first illumination light L1, first illumination light L1, first illumination light L1, second illumination light L2" and the specific number of frames is "the number of frames included in the emission cycle" will be described with reference to FIG. 26.

[0123] When the frame 200a at time Tx21 is used as the light intensity calculation frame, the endoscopic image generation unit 70 generates a first illumination light image 270a based on the emitted first illumination light 221a. Next, the emitted light intensity calculation unit 90 calculates a first emitted light intensity 290a that sets the first illumination light image 270a to a first target brightness included in the illumination pattern information for emitting the first illumination light 221a (emitted the first illumination light 221a). At this time, it is preferable to use a parameter for calculating the first emitted light intensity. The first emitted light intensity 290a is stored in the emitted light intensity storage unit 120 as the first held emitted light intensity 220a.

[0124] Here, the specific number of frames is the "number of frames included in the light emission cycle." In the case of FIG. 26, the light emission pattern indicated by the light emission pattern information is "first illumination light L1, first illumination light L1, first illumination light L1, second illumination light L2," which indicates that the light emission cycle is "first illumination light L1, first illumination light L1, second illumination light L2." In this case, the "number of frames included in the light emission cycle" is "4." Therefore, if frame 200a is used as the frame for light intensity calculation, the expected emission frame is frame 200e.

[0125] In this case, the emission instruction signal generation unit 130 generates an emission instruction signal that controls the first illumination light 221e to be emitted at the first maintained emission light amount 220a in the emission-destination frame 200e, which is a frame a specific number of frames after the light intensity calculation frame 200a, and transmits the signal to the light source control unit 21 via the central control unit 50 to control the light intensity.

[0126] Similarly, when frame 200b at time Tx22 is used as the frame for light intensity calculation, light intensity control is performed so that the first illumination light 221f is emitted at the first maintained emission light intensity 220b in the emission-scheduled frame 200f, which is the frame after a specific number of frames have elapsed.

[0127] Furthermore, when frame 200c at time Tx23 is used as the frame for light intensity calculation, light intensity control is performed so that the first illumination light 221g is emitted at the first maintained emission light intensity 220c to the emission-scheduled frame 200g, which is the frame after a specific number of frames have elapsed.

[0128] Furthermore, when frame 200d at time Tx24 is used as the frame for light intensity calculation, light intensity control is performed so that the second illumination light 221h is emitted at the second maintained emission light intensity 220d in the emission-scheduled frame 200h, which is the frame after a specific number of frames have elapsed.

[0129] With the above configuration, the calculated emitted light amount can be used for periodic light amount control. The method of determining the timing to use the calculated emitted light amount based on the number of frames included in a light emission cycle is effective from the viewpoint of the time required to reflect the calculated emitted light amount, particularly when the number of illumination periods included in one light emission cycle is small. Note that, as in the first embodiment, the types of illumination light may range from the first illumination light to the Nth illumination light.

[0130] Regarding the light intensity control of the second embodiment, a second specific example will be described with reference to FIG. 27, in which the light is emitted in an emission pattern of "first illumination light L1, second illumination light L2, third illumination light L3, second illumination light L2" and the specific number of frames is "the number of frames from when a certain type of illumination light is emitted in a light intensity calculation frame until the same type of illumination light is emitted again."

[0131] When the frame 200i at time Tx25 is used as the light intensity calculation frame, the endoscopic image generation unit 70 generates a first illumination light image 270i based on the emitted first illumination light 221i. Next, the emitted light intensity calculation unit 90 calculates a first emitted light intensity 290i that sets the first illumination light image 270i to a first target brightness included in the illumination pattern information for emitting the first illumination light 221i (emitted the first illumination light 221i). At this time, it is preferable to use a parameter for calculating the first emitted light intensity. The first emitted light intensity 290i is stored in the emitted light intensity storage unit 120 as the first held emitted light intensity 220i.

[0132] Here, the specific number of frames is "the number of frames from when a certain type of illumination light is emitted into a light intensity calculation frame until the same type of illumination light is emitted again." In the case of FIG. 27, the illumination pattern indicated by the illumination pattern information is "first illumination light L1, second illumination light L2, third illumination light L3, second illumination light L2." In this case, "the number of frames from when the first illumination light is emitted into a light intensity calculation frame until the first illumination light is emitted again" is "4," from frame 200i to frame 200m. Also, "the number of frames from when the second illumination light is emitted into a light intensity calculation frame until the second illumination light is emitted again" is "2," from frame 200j to frame 200l. Also, "the number of frames from when the third illumination light is emitted into a light intensity calculation frame until the third illumination light is emitted again" is "4," from frame 200k to frame 200o.

[0133] In this case, the emission instruction signal generation unit 130 generates an emission instruction signal that controls the first illumination light 221m to be emitted at the first maintained emission light intensity 220i in the emission-desired frame 200m, which is a frame a specific number of frames after the light intensity calculation frame 200i, and transmits the signal to the light source control unit 21 via the central control unit 50 to control the light intensity.

[0134] Similarly, when frame 200j at time Tx26 is used as the frame for light intensity calculation, light intensity control is performed so that the second illumination light 221l is emitted at the second maintained emission light intensity 220j to the emission-scheduled frame 200l, which is the frame after a specific number of frames have elapsed.

[0135] Furthermore, when frame 200k at time Tx27 is used as the frame for light intensity calculation, light intensity control is performed so that the third illumination light 221о is emitted at the second maintained emission light intensity 220k in the emission-scheduled frame 200о, which is the frame after a specific number of frames have elapsed.

[0136] With the above configuration, the calculated emitted light intensity can be used for periodic light intensity control. The method of determining the timing for using the calculated emitted light intensity based on the number of frames until the same type of illumination light as the previously emitted illumination light is emitted is effective in terms of the time it takes for the calculated emitted light intensity to be reflected when the number of illumination periods (the number of frames included in one light-emitting pattern) included in one light-emitting cycle is large, but the same type of illumination light is frequently emitted within one light-emitting cycle. Furthermore, depending on the processing speed of the processor, this method is also effective when the same type of illumination light is emitted continuously.

[0137] A series of operational flows in the endoscope system of the second embodiment will be described with reference to the flowchart shown in FIG. 28. First, the emission pattern information acquisition unit 210 of the emission information acquisition unit 140 acquires emission pattern information (step S201). Next, the light source unit 20 emits a certain type of illumination light to a light intensity calculation frame (step S202). Next, the endoscopic image generation unit 70 generates an endoscopic image (step S203). Next, the emission light intensity calculation unit 90 calculates the emission light intensity for achieving a target brightness for the endoscopic image (step S204). Next, the emission light intensity calculation unit 90 stores the emission light intensity as a maintained emission light intensity in the emission light intensity storage unit 120 (step S205). Finally, light intensity control is performed via the central control unit 50 and the light source control unit 21 to emit illumination light to be emitted to a planned emission frame, which is a frame a specific number of frames after the light intensity calculation frame, at the maintained emission light intensity (step S206).

[0138] The image sensor 43 in the second embodiment is preferably an image sensor 43 that captures images using the pseudo global shutter method, as in the first embodiment, but may also be an image sensor 43 that captures images using a general rolling shutter method.

[0139] In the above embodiment, the hardware structure of processing units that perform various processes, such as the central control unit 50, image signal acquisition unit 60, DSP 61, noise reduction unit 62, image signal storage unit 63, endoscopic image generation unit 70, display control unit 80, emitted light intensity calculation unit 90, and specified emitted light intensity selection unit 110, is made up of various processors as shown below. The various processors include a CPU (Central Processing Unit), which is a general-purpose processor that executes software (programs) to function as various processing units, a GPU (Graphical Processing Unit), a programmable logic device (PLD), such as an FPGA (Field Programmable Gate Array), whose circuit configuration can be changed after manufacture, and a dedicated electrical circuit, which is a processor having a circuit configuration designed specifically for performing various processes.

[0140] A single processing unit may be configured with one of these various processors, or may be configured with a combination of two or more processors of the same or different types (e.g., multiple FPGAs, a combination of a CPU and an FPGA, or a combination of a CPU and a GPU). Also, multiple processing units may be configured with a single processor. Examples of multiple processing units configured with a single processor include, first, a configuration in which one processor is configured with a combination of one or more CPUs and software, as typified by client or server computers, and this processor functions as multiple processing units. Second, a configuration in which a processor is used to realize the functions of an entire system including multiple processing units on a single IC (Integrated Circuit) chip, as typified by a system-on-chip (SoC). In this way, the various processing units are configured with one or more of the above-mentioned various processors as a hardware structure.

[0141] Furthermore, the hardware structure of these various processors is, more specifically, an electric circuit formed by combining circuit elements such as semiconductor elements. The hardware structure of the storage unit is a hard disk drive (HDD). k These are storage devices such as SSDs (solid state drives) and hard disk drives (HDDs). [Explanation of symbols]

[0142] 10 Endoscopy System 12 Endoscopy 12a Insertion part 12b Operation section 12c curved section 12d Tip 12e Angle Knob 12f Mode switch 12i Zoom control 12j forceps mouth 13 Light source device 14 Processor unit 15 Display 16 User Interface 20 Light source section 20a V-LED 20b B― LED 20c G-LED 20d R-LED 21 Light source control unit 21a, 21b, 21c, 21d, 21e, 21f, 21g, 21h, 21i, 21j, 21k, 21l, 21m, 21n, 21о, 21p, 21q, 21r, 21s, 2 21a, 221b, 221c, 221d, 221e, 221f, 221g, 221h, 221i, 221j, 221k, 221l, 221m, 221n, 221о, 221p illumination light 22 Optical path coupling section 23 Light Guide 30 Illumination optical system 31 Lighting lens 40 Imaging optical system 41 Objective Lens 42 Zoom Lens 43 Image sensor 43a Imaging surface 43b pixels 44 Color Filter Array 44a Blue filter 44b Green filter 44c Red filter 45 Imaging control unit 46 CDS / AGC circuit 47 A / D converter 50 Central Control Unit 60 Image signal acquisition unit 61 DSP 62 Noise reduction section 63 Image signal storage unit 70 Endoscopic image generation unit 70a, 70b, 70c, 70d, 70e, 70f, 70g, 70h, 70i, 70j, 70k, 70l, 70m, 70n, 70о, 70p, 70q, 70r, 70s, 270a, 270b, 270c, 270d, 270e, 270f, 270g, 270h, 270i, 270j, 270k, 270l, 270m, 270n, 270о, 221p Endoscopic images 71 first illumination light image generation unit 72 Second illumination light image generation unit 73 Third illumination light image generation unit 74 Nth illumination light image generation unit 80 Display control unit 90 Output light amount calculation section 90a, 90b, 90c, 90d, 90e, 90f, 90g, 90i, 90j, 90k, 90l, 90m, 90о, 90p, 290a, 2 90b, 290c, 290d, 290e, 290f, 290g, 290i, 290j, 290k, 290l, 290m, 290n, 290о Output light amount 91 Brightness calculation unit 92 Brightness difference calculation section 93 Light output unit 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h, 100i, 100j, 100k, 100l, 100m, 100n, 200a, 200b, 200c, 200d, 200e, 200f, 200g, 200h, 200i, 200j, 200k, 200l, 200m, 200n, 200о, 200p Frame 110 Specified output light amount selection unit 120 Output light amount storage unit 120a, 120b, 120c, 120d, 120e, 120f, 120g, 120i, 120j, 120k, 120l, 120m, 121, 122, 220a, 220b, 220c, 220d, 220e, 220f, 220g, 220i, 220j, 220k, 220l, 220m, 220n, 220о Retained output light amount 130 Ejection instruction signal generation section 140 Emission information acquisition section 140a, 140b, 140c, 140d, 140e, 140f, 140g, 140h, 140о, 140p, 140q, 140r, 140s Previously released information 141 Output information update section 150 Extraction schedule information receiver 150q, 150r, 150s, 151, 152, 153, 154, 155, 156 Launch schedule information 210 Light emission pattern information acquisition unit

Claims

1. an endoscope for capturing an image of an object to be observed; a light source device that emits a first illumination light and a second illumination light having a spectrum different from that of the first illumination light; A processor, an instruction means, and a memory unit, The processor: generating a first illumination light image obtained by capturing an image of the observation object using the first illumination light and a second illumination light image obtained by capturing an image of the observation object using the second illumination light in a light intensity calculation frame; calculating, at any timing after the light intensity calculation frame in a time series, a first emitted light intensity, which is the light intensity of the first illumination light that sets the first illumination light image to a first target brightness, and a second emitted light intensity, which is the light intensity of the second illumination light that sets the second illumination light image to a second target brightness that is different from the first target brightness; storing the first emitted light amount in the storage unit as a first held emitted light amount; storing the second emitted light amount in the storage unit as a second held emitted light amount; when emitting the first illumination light to an emission planned frame that is chronologically later than the light intensity calculation frame, selecting the latest first held emission light intensity from at least one of the first held emission light intensity as a first designated emission light intensity; When emitting the second illumination light in the intended emission frame, selecting the latest second held emission light amount from among at least one of the second held emission light amounts as a second designated emission light amount; causing the light source device to emit the first illumination light at the first designated emission light amount or the second illumination light at the second designated emission light amount in the emission intended frame; the instruction means causes the processor to execute control content regarding generation of the first illumination light image and the second illumination light image, calculation of the first emitted light amount and the second emitted light amount, selection of the first designated emitted light amount and the second designated emitted light amount, and emission of the first illumination light and the second illumination light, The storage unit stores the first held emitted light amount and the second held emitted light amount.

2. The processor: acquiring first previously emitted information, which is information indicating that the first illumination light has been emitted into the light intensity calculation frame and which associates the first target brightness with a first emitted light intensity calculation parameter, and second previously emitted information, which is information indicating that the second illumination light has been emitted into the light intensity calculation frame and which associates the second target brightness with a second emitted light intensity calculation parameter; calculating the first emitted light amount using the first emitted light amount calculation parameter associated with the first previously emitted light information; The endoscope system according to claim 1 , wherein the second emitted light amount is calculated using the second emitted light amount calculation parameter associated with the second emitted light information.

3. The processor: The first emitted light amount is associated with the first previously emitted light information to define the first held emitted light amount; The second emitted light amount is associated with the second previously emitted light information to define the second held emitted light amount; acquiring first emission schedule information which is information indicating that the first illumination light is to be emitted in the emission scheduled frame, or second emission schedule information which is information indicating that the second illumination light is to be emitted in the emission scheduled frame; When the first emission schedule information is acquired, the first designated emission light amount is selected from the first held emission light amounts associated with the first emission information; The endoscope system according to claim 2 , wherein when the second emission schedule information is acquired, the second specified emission light amount is selected from the second held emission light amounts associated with the second already-emission information.

4. The processor:

4. The endoscope system according to claim 3, wherein the first already-emitted information or the second already-emitted information regarding the light intensity calculation frames is acquired in at least two or more of the light intensity calculation frames, and the first scheduled emission information or the second already-emitted information regarding the scheduled emission frame is acquired in at least one or more of the scheduled emission frames.

5. The processor: acquiring the first already-emission information by associating the first target brightness and the first emission light intensity calculation parameter with the first emission planned information acquired chronologically before the light intensity calculation frame, and updating the first already-emission information to the first already-emission information indicating that the first illumination light has been emitted in the light intensity calculation frame; The endoscopic system according to claim 3 or 4, wherein the second target brightness and the second emitted light intensity calculation parameter are associated with the second emission planned information acquired chronologically before the light intensity calculation frame, and the second already-emitted information is acquired by updating the second already-emitted information to indicate that the second illumination light has been emitted into the light intensity calculation frame.

6. The processor: switching between a mono-emission mode in which only the first illumination light or the second illumination light is emitted from the light source device, a patterned emission mode in which the first illumination light and the second illumination light are emitted from the light source device according to a specific emission pattern, and a flexible emission mode in which the first illumination light and the second illumination light are emitted from the light source device irregularly; The endoscope system according to any one of claims 3 to 5, wherein the first emission schedule information or the second emission schedule information is acquired at the timing of switching between the mono emission mode, the pattern emission mode, and the flexible emission mode, respectively.

7. The processor: The endoscope system according to claim 6 , wherein, in the pattern emission mode, the first emission schedule information or the second emission schedule information is acquired at a timing when the specific emission pattern is changed.

8. The light source device is emitting at least three types of illumination light for imaging the observation target to the light amount calculation frame; The processor: acquiring at least three or more types of endoscopic images of the object to be observed; calculating an output light amount, which is the amount of light of the illumination light required to achieve target brightness for at least three or more types of the endoscopic images; storing the emitted light amount as a retained emitted light amount; selecting a designated emission light amount from at least one of the held emission light amounts in accordance with the type of the illumination light to be emitted to the emission-destination frame; The endoscope system according to claim 1 , wherein the light source device emits at least three types of illumination light at the designated emission light intensity to the emission intended frame.

9. The processor: Calculating brightness based on the luminance value of the endoscopic image; The endoscope system according to claim 8 , wherein the brightness is used to calculate the amount of emitted light.

10. an endoscope for capturing an image of an object to be observed; a light source device that emits a first illumination light and a second illumination light having a spectrum different from that of the first illumination light according to a specific light emission pattern; A processor, an instruction means, and a memory unit, The processor: a first illumination light image obtained by capturing an image of the observation object using the first illumination light and a second illumination light image obtained by capturing an image of the observation object using the second illumination light are acquired in a light intensity calculation frame; calculating a first emission light amount, which is the light amount of the first illumination light that makes the first illumination light image have a first target brightness, or a second emission light amount, which is the light amount of the second illumination light that makes the second illumination light image have a second target brightness that is different from the first target brightness, by an emission-intended frame that is a frame a specific number of frames after the light-intensity calculation frame; storing the first emitted light amount in the storage unit as a first held emitted light amount; storing the second emitted light amount in the storage unit as a second held emitted light amount; causing the light source device to emit the first illumination light at the first maintained emission light amount or the second illumination light at the second maintained emission light amount in the emission intended frame; the instruction means causes the processor to acquire the first illumination light image and the second illumination light image, calculate the first emitted light amount and the second emitted light amount, store the first held emitted light amount and the second held emitted light amount, and control content regarding emission of the first illumination light and the second illumination light, The storage unit stores the first held emitted light amount and the second held emitted light amount.

11. the specific light emission pattern is a light emission cycle consisting of at least one illumination period during which the first illumination light or the second illumination light is emitted, The endoscope system according to claim 10 , wherein the specific number of frames is equal to the number of illumination periods included in the light emission cycle.

12. 11. The endoscope system according to claim 10, wherein the specific number of frames is the number of frames from when the first illumination light is emitted into the light intensity calculation frame until when the first illumination light is emitted again, or the number of frames from when the second illumination light is emitted into the light intensity calculation frame until when the second illumination light is emitted again.

13. 13. An endoscope system according to claim 1, further comprising an image sensor that captures an image of the observation target using a pseudo global shutter system.

14. capturing an image of an object to be observed; emitting a first illumination light and a second illumination light having a spectrum different from that of the first illumination light; generating, in a light intensity calculation frame, a first illumination light image obtained by capturing an image of the observation object using the first illumination light and a second illumination light image obtained by capturing an image of the observation object using the second illumination light; calculating, at any timing after the light intensity calculation frame in a time series, a first emitted light intensity, which is the light intensity of the first illumination light that sets the first illumination light image to a first target brightness, and a second emitted light intensity, which is the light intensity of the second illumination light that sets the second illumination light image to a second target brightness that is different from the first target brightness; storing the first emitted light amount as a first held emitted light amount; storing the second emitted light amount as a second held emitted light amount; selecting, as a first designated emission light amount, the latest first held emission light amount from at least one of the first held emission light amounts when emitting the first illumination light in an emission planned frame that is chronologically later than the light amount calculation frame; selecting, as a second designated emission light amount, the latest second held emission light amount from among at least one of the second held emission light amounts when emitting the second illumination light in the emission planned frame; A method for operating an endoscopic system, comprising a step of causing a light source device to emit the first illumination light at the first specified emission light amount or the second illumination light at the second specified emission light amount in the intended emission frame.

15. capturing an image of an object to be observed; emitting a first illumination light and a second illumination light having a spectrum different from that of the first illumination light according to a specific light emission pattern; acquiring, in a light intensity calculation frame, a first illumination light image obtained by capturing an image of the observation object using the first illumination light and a second illumination light image obtained by capturing an image of the observation object using the second illumination light; calculating a first emission light amount, which is the light amount of the first illumination light that makes the first illumination light image have a first target brightness, or a second emission light amount, which is the light amount of the second illumination light that makes the second illumination light image have a second target brightness that is different from the first target brightness, by an emission-intended frame that is a frame a specific number of frames after the light-intensity calculation frame; storing the first emitted light amount as a first held emitted light amount; storing the second emitted light amount as a second held emitted light amount; A method for operating an endoscopic system, comprising a step of causing a light source device to emit the first illumination light at the first maintained emission light amount or the second illumination light at the second maintained emission light amount in the intended emission frame.

Images