JP2016158837A - Endoscope light source device, endoscope system, and operation method of endoscope light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endoscope light source device, an endoscope system, and an operation method of the endoscope light source device capable of adjusting a contrast of a blood vessel flexibly, according to depth and thickness under a mucosa.SOLUTION: An endoscope light source device comprises: a first light source 20a for emitting V-light having a depth resolution with respect to blood vessels under a mucosa which are observation targets; a second light source 20b for emitting a white light having a continuous spectrum with a wider band wider than that of the V-light; a Bs-light generation band restriction filter 25 for generating, from the white light, Bs-light having a thickness resolution with respect to the blood vessels under the mucosa which exist at a same depth; a light amount ratio setting part 23 for setting a light amount ratio of the V-light and Bs-light, and setting a blood vessel contrast to the mucosa to a target contrast according to depth and thickness of the blood vessels; and a light source control part 22 for controlling the first and second light sources, using the light amount ratio set by the light amount ratio setting part 23.SELECTED DRAWING: Figure 16

Description

  The present invention relates to an endoscope light source device, an endoscope system, and an operation method of an endoscope light source device that form illumination light to be irradiated on an observation object using a plurality of light sources.

  In the medical field, diagnosis using an endoscope system including an endoscope light source device, an endoscope, and a processor device is widely performed. An endoscope light source device is a device that generates light (hereinafter referred to as illumination light) that irradiates an observation target such as a mucous membrane of a body cavity. Conventionally, xenon lamps have been used for endoscope light source devices, but in recent years, semiconductors such as LEDs (Light Emitting Diodes) and laser diodes (hereinafter referred to as LDs (Laser Diodes)) instead of xenon lamps. Light sources are being used.

  For example, in the endoscope systems of Patent Document 1 and Patent Document 2, two LDs LD1 and LD2 are mounted on an endoscope light source device, and laser light emitted by these LDs is used as a phosphor (wavelength conversion member). By passing the light, the observation target is irradiated with white light formed by the laser light transmitted through the phosphor and the fluorescence emitted by the phosphor. In particular, in Patent Document 1, an image having a contrast suitable for diagnosis is obtained by changing the white light component by adjusting the light quantity ratio between LD1 and LD2. In the endoscope system of Patent Document 2, it is described that the contrast (brightness ratio) between the blood vessel and the mucous membrane is changed by adjusting the light quantity ratio between the LD1 and the LD2. By setting the light quantity ratio between LD1 and LD2 to be 6 or more, the ability to extract blood vessels (hereinafter referred to as surface blood vessels) at a relatively shallow position under the mucous membrane is obtained.

  The endoscope system of Patent Document 3 uses an LED that emits purple light, and a white light source that emits white light by combining an LED that emits blue light and a phosphor. An observation mode for observing using white light, such as by inserting and removing a dichroic mirror arranged in these optical paths, and an observation mode for observing using violet light and partial light of white light Has been switched.

  Also, in recent years, endoscope systems that enable so-called narrow-band light observation that make it easier to observe the presence or absence of blood vessels and traveling patterns than when irradiating with white light have become widespread. Narrowband light observation is performed by, for example, using a band-limiting filter for broadband light that limits the wavelength band of broadband light. Narrowband light in the wavelength band (hereinafter referred to as green narrowband light) is generated. Then, by combining and using a signal obtained by photographing the observation target with blue narrow band light and a signal obtained by photographing the observation target with green narrow band light, an image that facilitates observation of the blood vessel is provided.

JP 2013-034753 A JP 2012-105784 A International Publication No. 2012/101904

  The light source used in the endoscope system is being replaced from a xenon lamp to a semiconductor light source. However, white light emitted by a xenon lamp or the like and white light generated by a semiconductor light source, each of which has a spectral spectrum, even if it is white light. Is different. For this reason, blood vessels are observed according to the depth and thickness of the submucosa when irradiating the observation object with conventional white light from a xenon lamp or the like and when irradiating the observation object with white light from a semiconductor light source. Differences in ease.

  For example, when focusing on blood vessels of a certain depth and thickness under the mucous membrane, using a semiconductor light source has higher contrast to the mucosa and easier to observe than using a xenon lamp. If attention is paid to the blood vessel having a large thickness, there is a case where the contrast to the mucous membrane is lower and the observation is difficult when the semiconductor light source is used than when the xenon lamp is used. The difference in the appearance of the blood vessel caused by the difference in the spectral spectrum between the xenon lamp and the semiconductor light source becomes particularly noticeable when performing narrow-band light observation that emphasizes the blood vessel. Therefore, doctors who have used an endoscope system using a xenon lamp may be confused by the difference in the appearance of blood vessels as described above when using an endoscope system using a semiconductor light source. We want to reproduce the appearance of blood vessels similar to the case of using a xenon lamp in an endoscope system using a semiconductor light source. Especially, blood vessels for narrow-band light observation that generate blue narrow-band light and green narrow-band light from the white light of the xenon lamp. There is a desire to recreate the way it looks.

  On the other hand, in order to make a more accurate and detailed diagnosis, there is also a demand for better observation of blood vessels having a depth and thickness that are difficult to observe with a xenon lamp. When a semiconductor light source is used, blood vessels that are difficult to observe with a xenon lamp may be often observed due to a difference in spectral spectrum from the xenon lamp. The same applies to narrow band light observation. That is, it is desired to take advantage of the advantages of using a semiconductor light source.

  Therefore, in order to meet the above two demands, in an endoscope system using a semiconductor light source, the blood vessel contrast can be freely adjusted according to the depth and thickness of the blood vessel under the mucous membrane so that observation can be performed. It is desirable. The present invention provides an endoscope light source device, an endoscope system, and an operation method of the endoscope light source device that can freely adjust the contrast of blood vessels according to the depth and thickness of the submucosa. With the goal.

  An endoscope light source device according to the present invention includes a first light source that emits light in a first wavelength band having depth resolution to a blood vessel under a mucous membrane to be observed, and a wider band than the first wavelength band. A second light source that emits light in the second wavelength band having a specific spectrum, and light in the third wavelength band having thickness resolution with respect to a blood vessel at the same depth below the mucous membrane. A first band-limiting filter generated from the light source, a light amount ratio between the light in the first wavelength band and the light in the third wavelength band, and the contrast of the blood vessel with respect to the mucous membrane is set to a target contrast corresponding to the depth and thickness of the blood vessel. And a light source control unit that controls the first light source and the second light source using the light amount ratio set by the light amount ratio setting unit.

  The peak wavelength of light in the first wavelength band is on the shorter wavelength side than the peak of the absorption spectrum of hemoglobin, and the peak wavelength of light in the third wavelength band is on the longer wavelength side of the peak of the absorption spectrum of hemoglobin. It is preferable.

  The first wavelength band is preferably a violet wavelength band, and the third wavelength band is preferably a blue wavelength band.

  The light amount ratio setting unit irradiates the observation target with the blue narrow band light generated from the broadband light having a wider wavelength band than the light in the first wavelength band or the light in the third wavelength band using the band limiting filter for broadband light. In this case, it is preferable to set the light amount ratio by setting the blood vessel contrast as the target contrast.

  The light amount ratio setting unit sets the light amount ratio that makes the contrast balance of a plurality of blood vessels having different submucosal depths and different thicknesses equal to the balance when irradiating an observation target with blue narrowband light. It is preferable to do.

  The light amount ratio setting unit sets a light amount ratio that makes the contrast balance of a plurality of blood vessels having different submucosal depths and the same thickness equal to the balance when irradiating an observation target with blue narrowband light. It is preferable.

  It is preferable that the light amount ratio setting unit sets a light amount ratio that makes the blood vessel contrast equal to the blood vessel contrast when the observation target is irradiated with blue narrowband light.

  The broadband light is preferably white light emitted from a xenon lamp.

  Based on the contrast of the blood vessel when irradiating the observation target with the blue narrow band light generated using the band limiting filter from the broadband light having a wider wavelength band than the light of the first wavelength band or the light of the third wavelength band, The light intensity ratio setting unit is a light intensity that makes the contrast ratio or difference of multiple blood vessels with the same submucosal depth and different thickness larger than the contrast ratio or difference when irradiating blue narrowband light. It is preferable to set the ratio.

  Based on the contrast of the blood vessel when irradiating the observation target with the blue narrowband light generated from the light of the first wavelength band or the broadband light having a wider wavelength band than the light of the third wavelength band, Setting a light intensity ratio that makes the contrast ratio or difference of blood vessels of different submucosal depth and equal thickness larger than the contrast ratio or difference when irradiating blue narrowband light Is preferred.

  A second band limiting filter that generates light of a fourth wavelength band that is different from the third wavelength band and has a thickness resolution with respect to a blood vessel from the light of the second wavelength band; and Observation mode for switching between a first observation mode for observation using light and a second observation mode for observation using light in the first wavelength band, light in the third wavelength band, and light in the fourth wavelength band And a switching unit.

  The fourth wavelength band is preferably a green wavelength band.

  The light source control unit preferably controls the light emission amounts of the first light source and the second light source using the light amount ratio set by the light amount ratio setting unit.

  It is preferable that the light quantity ratio setting unit controls the light emission times of the first light source and the second light source using the light quantity ratio set by the light quantity ratio setting unit.

  It is preferable to irradiate light in the third wavelength band and light in the fourth wavelength band in a time-sharing manner.

  The endoscope system according to the present invention includes a first light source that emits light of a first wavelength band having depth resolution to a blood vessel under a mucous membrane to be observed, and a continuous band that is wider than the first wavelength band. A second light source that emits light in a second wavelength band having a spectrum and a blood in a third wavelength band having a thickness resolution from a light in the second wavelength band to a blood vessel at the same depth below the mucous membrane. The first band limiting filter to be generated and the light amount ratio between the light in the first wavelength band and the light in the third wavelength band are set, and the contrast of the blood vessel with respect to the mucous membrane is set to the target contrast according to the depth and thickness of the blood vessel. A light amount ratio setting unit, a light source control unit that controls the first light source and the second light source using the light amount ratio set by the light amount ratio setting unit, and a light amount ratio controlled by the light amount ratio setting unit. Illumination light including light in the first wavelength band or light in the third wavelength band is illuminated. And an imaging sensor for imaging the observation target that is.

  The operation method of the endoscope light source device according to the present invention includes a first light source that emits light of a first wavelength band having depth resolution to a blood vessel under a mucous membrane to be observed, and a wider band than the first wavelength band. And a second light source that emits light in the second wavelength band having a continuous spectrum, and light in the third wavelength band having thickness resolution with respect to a blood vessel at the same depth below the mucous membrane. A first band limiting filter generated from the light of the endoscope, and a light amount ratio setting unit sets a light amount ratio of the light in the first wavelength band and the light in the third wavelength band And a step of the light source control unit controlling the first light source and the second light source using the light amount ratio set by the light amount ratio setting unit.

  An endoscope light source device, an endoscope system, and an operation method of the endoscope light source device according to the present invention include: a first wavelength band light having a depth resolution for a blood vessel under a mucous membrane to be observed; By setting the light intensity ratio of light in the third wavelength band with thickness resolution for blood vessels at the same depth under the mucous membrane, the contrast of the blood vessel with respect to the mucosa is adjusted according to the depth and thickness of the blood vessel. Since the target contrast is set, the blood vessel contrast can be freely adjusted according to the depth and thickness of the submucosa.

It is an external view of an endoscope system. It is a block diagram which shows the function of an endoscope system. It is a graph which shows the spectrum of the light which a light source emits. It is a graph which shows the spectrum of illumination light. It is explanatory drawing which shows the depth of the blood vessel with respect to a mucous membrane, and the thickness of the blood vessel. It is a graph which shows the reflectance of several blood vessels from which a mucous membrane differs in depth and thickness. It is a graph which shows how to obtain | require the brightness with respect to a mucous membrane. It is a graph which shows the brightness of the blood vessel obtained when violet light is irradiated. It is a graph which shows the contrast of the blood vessel obtained when violet light is irradiated. It is the graph which rearranged the graph which shows the contrast of the blood vessel obtained when irradiating purple light in order of the depth for every same depth. It is a graph which shows the brightness of the blood vessel obtained when it irradiates with blue light. It is a graph which shows the contrast of the blood vessel obtained when irradiating blue light. It is the graph which rearranged the graph which shows the contrast of the blood vessel obtained when irradiating blue light in order of the depth for every same depth. It is a schematic diagram which shows the relationship between the absorption spectrum of hemoglobin, and the violet light and blue light used for illumination light. It is a graph which shows the spectral characteristic of a color filter. It is a graph which shows the balance of the contrast of the blood vessel obtained when various light quantity ratios are set. It is a block diagram of the endoscope system of 2nd Embodiment which performs narrow-band light observation. It is a graph which shows the spectrum of the illumination light which the endoscope system of 2nd Embodiment uses. It is a graph which shows the spectrum of the illumination light used by the conventional endoscope system which performs narrow-band light observation. It is a graph of the spectrum of blue narrow-band light. It is a graph which shows the contrast of the blood vessel obtained by the conventional blue narrow-band light. It is a graph which shows the contrast ratio of the blood vessel with respect to the conventional endoscope system. It is a graph which shows the contrast ratio between the blood vessels from which the submucosa depth is equal and thickness differs. It is a graph which shows the contrast ratio between the blood vessels in which thickness is equal and submucosal depth differs. It is a schematic diagram of a band limiting filter used when two types of narrowband light are sequentially generated. It is the schematic of a capsule endoscope.

[First Embodiment]
As shown in FIG. 1, the endoscope system 10 includes an endoscope 12, an endoscope light source device 14, a processor device 16, a monitor 18, and a console 19. The endoscope 12 is optically connected to the endoscope light source device 14 and electrically connected to the processor device 16. The endoscope 12 includes an insertion portion 12a to be inserted into a subject, an operation portion 12b provided at a proximal end portion of the insertion portion 12a, a bending portion 12c and a distal end portion provided at the distal end side of the insertion portion 12a. 12d. By operating the angle knob 12e of the operation unit 12b, the bending unit 12c performs a bending operation. By this bending operation, the distal end portion 12d is directed in a desired direction. In addition to the angle knob 12e, the operation unit 12b is provided with a zoom operation unit 13 and the like.

  The processor device 16 is electrically connected to the monitor 18 and the console 19. The monitor 18 outputs and displays images in each observation mode and image information attached to the images. The console 19 functions as a user interface that receives input operations such as function settings. The processor device 16 may be connected to an external recording unit (not shown) for recording images, image information, and the like.

  As shown in FIG. 2, the endoscope light source device 14 is a device that generates illumination light that irradiates an observation target, and includes a light source unit 20 having a plurality of light sources and a light source control that controls each light source of the light source unit 20. A light amount ratio setting unit 23 for setting light amount ratios of a plurality of light sources, and an optical path coupling unit 24 for coupling optical paths of light emitted from the light source unit 20.

  The light source unit 20 includes two types of light sources: a first light source 20a that emits light in the first wavelength band, and a second light source 20b that emits light in the second wavelength band having a continuous spectral spectrum in a wider band than the first wavelength band. A light source is provided. The first light source 20a is a purple LED (hereinafter referred to as a V-LED (Violet Light Emitting Diode)). The second light source 20b generates fluorescence from the green wavelength band to the red wavelength band by blue LED (hereinafter referred to as B-LED (Blue Light Emitting Diode)) and blue light emitted from the B-LED (hereinafter referred to as B light). White light is generated by the B light transmitted through the phosphor and the fluorescence emitted by the phosphor.

  As shown in FIG. 3, the V-LED that constitutes the first light source 20a is a violet light source that emits violet light (hereinafter referred to as V light) having a center wavelength of 415 nm and a wavelength band of about 400 to 430 nm. In this embodiment, the center wavelength of the V-LED is 415 nm, but a V-LED having a center wavelength of about 400 to 430 nm can be used. The B-LED that constitutes the second light source 20b is a blue light source that emits blue light (hereinafter referred to as B light) having a center wavelength of 450 nm and a wavelength band of 430 to 470 nm, and the phosphor that constitutes the second light source 20b is B Fluorescence with a wavelength band ranging from 480 to 650 nm is emitted by light irradiation. For this reason, the fluorescence emitted from the phosphor includes green light (hereinafter referred to as G light) having a wavelength band of about 480 to 600 nm and red light (hereinafter referred to as R light) having a wavelength band of about 600 nm to 680 nm. . Therefore, the light emitted from the second light source 20b emits white light composed of B light transmitted through the phosphor and G light and R light included in the fluorescence generated by the phosphor when the B light is irradiated as excitation light. . Although details will be described later, the light in the first wavelength band emitted from the first light source 20a is V light, and the first wavelength band is a violet wavelength band corresponding to the V light. The light in the second wavelength band emitted from the second light source 20b is white light, and the second wavelength band is the wavelength band from B light to R light.

  The center wavelength of the V-LED and B-LED has a width of about ± 5 nm to ± 10 nm. The center wavelength is the wavelength at the center of the wavelength band, and the wavelength corresponding to the peak of the spectrum (hereinafter referred to as the peak wavelength) does not always match the center wavelength depending on the shape of the spectrum. The V light used in the endoscope system 10 may have a different center wavelength and a peak wavelength, or the center wavelength and the peak wavelength may substantially match. The center wavelength and peak wavelength of the V light in the present embodiment are substantially the same. Similarly, the B light used in the endoscope system 10 may have a different center wavelength and peak wavelength, or the center wavelength and peak wavelength may be substantially the same. The center wavelength and the peak wavelength of the B light in this embodiment are almost the same.

  Of the B light and G light emitted by the B-LED that constitutes the second light source 20b, light having a wavelength of about 450 nm to about 500 nm reduces the contrast of fine structures such as surface blood vessels and pit patterns. In the optical path of the second light source 20b, there is a band limiting filter (first band limiting filter; hereinafter referred to as a Bs light generation band limiting filter) 25 for reducing light in the wavelength band of about 450 nm to about 500 nm. Has been placed. For this reason, the band limiting filter 25 for generating Bs light mainly includes blue light (hereinafter referred to as Bs light) and green light (hereinafter referred to as Bs light) in which components in a wavelength band from about 450 nm to about 500 nm are reduced from white light emitted by the second light source 20b. Hereinafter, it is referred to as Gs light). The peak wavelength of Bs light is about 440 nm to 450 nm, and Bs light is light in the third wavelength band generated from light in the second wavelength band (white light). The Bs light, the V light, the Gs light, and the R light are mixed by the optical path coupling unit 24 to become the illumination light 26 shown in FIG.

  That is, the light source unit 20 emits illumination light 26 having a spectrum in which V light, Bs light, Gs light, and R light are superimposed by a plurality of light sources that independently emit light of different colors. Since the light emission amount (hereinafter simply referred to as light amount), the length of the light emission time, and the like of the first light source 20a and the second light source 20b can be controlled independently, the spectral spectrum of the illumination light includes the first light source 20a and second light source It can be changed by changing the light amount of the light source 20b, the length of the light emission time, and the like.

  The light source controller 22 uses the light amount ratio set by the light amount ratio setting unit 23 to drive current, drive voltage, and drive current of the V-LED that constitutes the first light source 20a and the B-LED that constitutes the second light source 20b. Alternatively, the drive voltage is controlled. Specifically, by individually controlling the pulse width, pulse length, etc. of the control pulse input to each LED, the emission timing and light quantity of the V light emitted from the first light source 20a and the white light emitted from the second light source 20b Control the length of light emission time and the like. Thereby, the light source control part 22 changes the substantial spectral spectrum of illumination light. In the present embodiment, the light source control unit 22 controls the light amounts of the V-LEDs constituting the first light source 20a and the B-LEDs constituting the second light source 20b.

  The light amount ratio setting unit 23 sets the light amount ratio of V light and Bs light to the light source control unit 22. Specifically, the light amount ratio setting unit 23 sets the light amount of the V light emitted from the V-LED of the first light source 20a and the light amount of the B light emitted from the B-LED of the second light source 20b. The amounts of V light and Bs light included in the light 26 are set. That is, the light amount ratio set by the light amount ratio setting unit 23 is a control parameter of the V-LED configuring the first light source 20a and the B-LED configuring the second light source 20b, and considers the length of the light emission time. This is a substantial light amount ratio (broad light amount ratio). In the present embodiment, the light source control unit 22 controls the ratio of the light emission amounts per unit time (the light amount ratio in a narrow sense) by making the lengths of the light emission times of the first light source 20a and the second light source 20b the same. For this reason, the light quantity ratio setting unit 23 adjusts the light emission amount per unit time of the V-LED configuring the first light source 20a and the B-LED configuring the second light source 20b in accordance with the control method of the light source control unit 22. The ratio is set as the light quantity ratio.

  The light amount ratio setting unit 23 has at least a first wavelength band light having a depth resolution with respect to a blood vessel under the mucosa to be observed and a thickness resolution with respect to a blood vessel at the same depth under the mucosa. The light amount ratio of the light in the third wavelength band is set for the light source control unit 22. That is, the light amount ratio setting unit 23 sets the light amount ratio between the V light and the Bs light. Thereby, the light quantity ratio setting unit 23 sets the contrast of the blood vessel with respect to the mucous membrane to a target contrast corresponding to the depth and thickness of the blood vessel.

  The target contrast is a target of contrast balance with respect to the mucous membranes of a plurality of blood vessels having different depths and thicknesses, and corresponds one-to-one with the light amount ratio set by the light amount ratio setting unit 23. A plurality of light quantity ratios and target contrasts are preset in the light quantity ratio setting unit 23, but the settings can be arbitrarily selected or changed using an input device such as the operation unit 12b or the console 19.

  Depth resolution means that the contrast to the mucosa changes depending on the depth of blood vessels from the mucosal surface, and the depth can be identified by the change in contrast to the mucosa. Thickness resolution means that the contrast to the mucosa changes depending on the thickness of the blood vessel, and the thickness of the blood vessel can be identified by the change in contrast to the mucosa.

  As shown in FIG. 5, when the distance from the observed mucosa to the upper end of the blood vessel (the location closest to the mucosa) is the blood vessel depth “d” μm, and the blood vessel diameter is the blood vessel thickness “φ” μm FIG. 6 is a graph in which the reflectance of a plurality of blood vessels with different depths and thicknesses is calculated by simulation. In FIG. 6 and below, the depth from the mucosal surface is represented by a numerical value “d”, and the thickness of the blood vessel is represented by a numerical value “φ”. For example, a blood vessel having a depth of 5 μm and a diameter of 20 μm is represented by “d5φ20”. The same applies to blood vessels of other depths and thicknesses. In FIG. 6, in addition to blood vessels of d5φ20, blood vessels of d5φ40 (depth of 5 μm and diameter of 40 μm), blood vessels of d15φ20 (depth of 15 μm and diameter of 20 μm), d50φ10 (depth) A graph of each reflectance of a blood vessel having a thickness of 50 μm and a diameter of 10 μm and a blood vessel having a d50φ20 (a depth of 50 μm and a diameter of 20 μm) is shown.

  As can be seen from FIG. 6, in the graph of the reflectance of a plurality of blood vessels having different depths and thicknesses, the depth “d” is the same in the wavelength band of approximately 450 nm or less even though the thickness “φ” is different. Are converged to substantially the same reflectivity, and the convergent reflectivity values differ depending on the difference in depth “d”. The blood vessel located at a shallow position under the mucous membrane has a lower reflectance, and the blood vessel located at a deeper position under the mucosa has a higher reflectance, which approaches the reflectance of the mucosa. The contrast of the blood vessel is, for example, the ratio (or difference) between the reflectance of the mucosa and the reflectance of the blood vessel, and the greater the difference in brightness with respect to the mucosa, the higher the visibility. For this reason, when imaging an observation target by irradiating light of approximately 450 nm or less, a blood vessel having a depth of 5 μm (d5) has the lowest reflectance among blood vessels whose reflectance graph is shown in FIG. Therefore, the contrast to the mucous membrane is high and the visibility is good. On the contrary, a blood vessel having a depth of 50 μm (d50) has the closest reflectance to the mucous membrane and is a bright blood vessel. Therefore, the contrast to the mucous membrane is low and the visibility is the worst. Therefore, when an observation target is imaged by irradiating light with a wavelength band of approximately 450 nm or less, a contrast is obtained depending on the depth of the blood vessel regardless of the thickness of the blood vessel. When blood vessels having different depths are compared, the contrast of the blood vessels varies depending on the depth of the blood vessels. Accordingly, light having a wavelength band of approximately 450 nm or less has depth resolution for a plurality of blood vessels having different depths and thicknesses.

  On the other hand, in the wavelength band of approximately 450 nm to 600 nm, even if the depth “d” is different, if the thickness “φ” is the same, it converges to substantially the same reflectance, and the difference in the thickness “φ”. The value of the reflectivity to be converged differs depending on the type. The thicker the blood vessel, the lower the reflectance, and the thinner the blood vessel, the higher the reflectance, approaching the reflectance of the mucous membrane. For this reason, when an observation target is imaged by irradiating light of approximately 450 nm or less, a blood vessel having a thickness of 40 μm (φ40) has the lowest reflectance among blood vessels whose reflectance graph is shown in FIG. Therefore, the contrast to the mucous membrane is high and the visibility is good. Conversely, a blood vessel having a thickness of 10 μm (φ10) has the closest reflectance to the mucous membrane and can be a bright blood vessel, so the contrast to the mucous membrane is low and the visibility is the worst. Therefore, when the observation target is imaged by irradiating light in a wavelength band of approximately 450 nm to 600 nm, a contrast is obtained depending on the thickness of the blood vessel regardless of the depth of the blood vessel. When blood vessels with different thicknesses are compared, the contrast of the blood vessels varies depending on the thickness of the blood vessels. Therefore, light in a wavelength band of approximately 450 nm to 600 nm has a thickness resolution for blood vessels having different depths and thicknesses.

  According to FIG. 6, the light in the wavelength band of approximately 600 nm or more has a wavelength band of 600 nm or more because the reflectance of all blood vessels is close to the reflectance of the mucosa regardless of the depth and thickness of the blood vessel. It can be seen that the blood vessels are difficult to observe even if the observation object is imaged by irradiating the light.

  As shown in FIG. 7, the brightness of the blood vessel of d5φ20 when irradiated with light having a wavelength of 415 nm is expressed as “reflectance R1 of blood vessel of d5φ20 R1 / reflectance R0 of mucosa” using the graph of FIG. Alternatively, the brightness of d5φ20 blood vessel mucosa when irradiated with a wavelength of 450 nm is calculated as “d5φ20 blood vessel reflectance R3 / mucosal reflectance R2”. (Or d5φ20 blood vessel reflectance R3-mucosal reflectance R2). Therefore, the ratio (or difference) of the value integrated in the wavelength band of the light irradiating the reflectance of the blood vessel to the value integrated in the wavelength band of the light irradiating the mucosal reflectance is the brightness of the blood vessel with respect to the mucous membrane. And the reciprocal of the brightness of the blood vessel with respect to the mucous membrane represents the contrast of the blood vessel.

  When irradiating V light, the brightness with respect to the mucous membrane of the several blood vessel from which depth and thickness differ is as showing in FIG. Moreover, when irradiating V light, the contrast of the some blood vessel from which depth and thickness differ is as showing in FIG. According to the bar graph of FIG. 9, the contrast of blood vessels having different depths and thicknesses at the time of V light irradiation is substantially equal when the depths are equal. Further, as can be seen from FIG. 10 in which the bar graphs of FIG. 9 are rearranged in the depth order in the φ20 group and the φ40 group, when comparing blood vessels of the same thickness, the shallower the submucosa, the higher the contrast. It is higher and the deeper the position, the lower the contrast to the mucous membrane. Therefore, the V light has a depth resolution. In the present embodiment, the first wavelength band having depth resolution is a violet wavelength band corresponding to V light.

  Bs light is light having a wavelength band near 450 nm and is at the boundary between the wavelength band on the short wavelength side having depth resolution and the wavelength band on the long wavelength side having thickness resolution. (See FIG. 6). In order to examine the characteristics of the Bs light, the brightness of a plurality of blood vessels with different depths and thicknesses is calculated in the same manner as the V light, and the graph of FIG. FIG. 12 is a graph showing the contrast of a plurality of blood vessels having different depths and thicknesses with respect to the mucous membranes, grouped for each depth of the blood vessels and represented by a bar graph in order of thickness, and grouped for each thickness of the blood vessels. FIG. 13 is a graph represented by a bar graph in order of depth.

  As can be seen from FIG. 12, when comparing the contrast of blood vessels with different thicknesses at the same depth below the mucous membrane, when the Bs light is irradiated, the thicker the blood vessel, the higher the contrast with respect to the mucous membrane. That is, Bs light has a thickness resolution for blood vessels at the same depth below the mucous membrane. Therefore, in the present embodiment, the light in the third wavelength band having a thickness resolution with respect to a blood vessel at the same depth below the mucous membrane is Bs light, and the third wavelength band is a blue wavelength corresponding to the Bs light. It is a band.

  As can be seen from FIG. 13, when irradiating Bs light, comparing the contrast of blood vessels with the same thickness and different depths to the mucous membrane, the blood vessels in the shallower submucosal region have higher contrast and deeper positions. Some blood vessels have lower contrast to the mucosa. Therefore, Bs light has depth resolution for blood vessels of the same thickness.

  Further, as shown in FIG. 14, the peak of the absorption spectrum of hemoglobin is from about 420 nm to about 430 nm. The peak wavelength of the V light (light in the first wavelength band) is on the shorter wavelength side than the peak of the absorption spectrum of hemoglobin, and the peak wavelength of the Bs light (light in the third wavelength band) is that of hemoglobin. It is on the longer wavelength side than the peak of the absorption spectrum. And if the light quantity in each peak wavelength of V light and Bs light is equal, the absorption intensity of hemoglobin will become the same grade. For this reason, the depth resolution of V light and the thickness resolution of a blood vessel at the same depth of Bs light are not due to the difference in the absorption intensity of hemoglobin, but are the properties of V light and Bs light, respectively.

  Illumination light generated by the light source unit 20 and the Bs light generation band limiting filter 25 is incident on the light guide 41 passed through the insertion unit 12a via the optical path coupling unit 24 (see FIG. 2). The light guide 41 is built in the endoscope 12 and a universal cord (a cord connecting the endoscope 12, the endoscope light source device 14, and the processor device 16), and is guided from the optical path coupling unit 24. The illumination light propagates to the distal end portion 12d of the endoscope 12. A multimode fiber can be used as the light guide 41. As an example, a thin fiber cable having a core diameter of 105 μm, a clad diameter of 125 μm, and a diameter of φ0.3 to 0.5 mm including a protective layer serving as an outer skin can be used.

  The distal end portion 12d of the endoscope 12 is provided with an illumination optical system 30a and an imaging optical system 30b. The illumination optical system 30 a has an illumination lens 45, and the illumination light propagated by the light guide 41 is irradiated to the observation object via the illumination lens 45. The imaging optical system 30 b includes an objective lens 46, a zoom lens 47, and an imaging sensor 48. Return light from the observation target (light that includes fluorescent light generated from the observation target in addition to reflected light) enters the image sensor 48 via the objective lens 46 and the zoom lens 47. Thereby, the observation object is imaged on the image sensor 48. The zoom lens 47 is freely moved between the tele end and the wide end by operating the zoom operation unit 13, and enlarges or reduces the observation target imaged on the image sensor 48.

  The image sensor 48 is a color image sensor, images the return light from the observation target, and outputs an image signal. As the image sensor 48, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) image sensor can be used. As shown in FIG. 15, the image sensor 48 is provided with three color filters, R (red) color filter, G (green) color filter, and B (blue) color filter, for each pixel. The return light from the observation target is imaged and an image signal for each color is output. That is, the imaging sensor 48 includes an R pixel (red pixel) provided with an R color filter, a G pixel (green pixel) provided with a G color filter, and a B pixel (blue pixel) provided with a B color filter. The RGB image signal is output by outputting the image signal from each pixel. Specifically, the imaging sensor 48 receives each return light of V light and Bs light in the illumination light by the B pixel, and outputs a blue image signal (hereinafter referred to as B image signal). Similarly, the G light return light of the illumination light is received by the G pixel, a green image signal (hereinafter referred to as G image signal) is output, the R light return light is received by the R pixel, and the red image signal ( (Hereinafter referred to as R image signal).

  The light quantity ratio setting unit 23 sets the light quantity ratio between the V light having depth resolution with respect to the blood vessel under the mucosa to be observed and the Bs light having thickness resolution with respect to the blood vessel at the same depth under the mucosa. In the B image signal among the image signals of the respective colors described above, the contrast of the blood vessel with respect to the mucous membrane is a target contrast corresponding to the depth and thickness of the blood vessel.

  In place of the image sensor 48 which is a primary color image sensor, a complementary color image sensor having complementary color filters of C (cyan), M (magenta), Y (yellow) and G (green) may be used. When the complementary color imaging sensor is used, CMYG four-color image signals are output. By converting the CMYG four-color image signals into RGB three-color image signals by complementary color-primary color conversion, An RGB image signal similar to that of the image sensor 48 can be obtained. Further, instead of the imaging sensor 48, a monochrome sensor without a color filter may be used. In this case, for example, by providing a rotary band limiting filter (color filter) in the light source unit 20, the light source control unit 22 time-divides the V light, B light, G light, and R light as necessary. Light up. However, since both the V light and the B light are received by the B pixel, the V light and the B light may be turned on simultaneously.

  An image signal output from the image sensor 48 is transmitted to the CDS / AGC circuit 50. The CDS / AGC circuit 50 performs correlated double sampling (CDS) and automatic gain control (AGC) on an image signal that is an analog signal. The image signal that has passed through the CDS / AGC circuit 50 is converted into a digital image signal by the A / D converter 51. The digital image signal after A / D conversion is input to the processor device 16.

  The processor device 16 includes a receiving unit 53, a DSP (Digital Signal Processor) 56, a noise removing unit 58, an image generating unit 62, and a video signal generating unit 66.

  The receiving unit 53 receives a digital RGB image signal from the endoscope 12. The DSP 56 performs various signal processing such as defect correction processing, offset processing, gain correction processing, linear matrix processing, gamma conversion processing, and demosaicing processing on the received image signal. In the defect correction process, the signal of the defective pixel of the image sensor 48 is corrected. In the offset process, the dark current component is removed from the RGB image signal subjected to the defect correction process, and an accurate zero level is set. In the gain correction process, the signal level is adjusted by multiplying the RGB image signal after the offset process by a specific gain. The RGB image signal after the gain correction process is subjected to a linear matrix process for improving color reproducibility. After that, brightness and saturation are adjusted by gamma conversion processing. The RGB image signal after the linear matrix processing is subjected to demosaic processing (also referred to as isotropic processing or synchronization processing), and a signal of a color lacking in each pixel is generated by interpolation. By this demosaic processing, all the pixels have RGB signals.

  The noise removal unit 58 removes noise from the RGB image signal by performing noise removal processing (for example, using a moving average method or a median filter method) on the RGB image signal that has been demosaiced by the DSP 56. The RGB image signal from which noise has been removed is transmitted to the image generation unit 62.

  The image generation unit 62 performs color conversion processing, color enhancement processing, and structure enhancement processing on the RGB image signal to generate an image (hereinafter referred to as an endoscopic image). In color conversion processing, color conversion processing is performed on RGB image signals by 3 × 3 matrix processing, gradation conversion processing, three-dimensional LUT (look-up table) processing, and the like. The color enhancement process is performed on the RGB image signal that has been subjected to the color conversion process. The structure enhancement process is a process for enhancing the structure of the observation target such as a surface blood vessel or a pit pattern, and is performed on the RGB image signal after the color enhancement process. As described above, a color image using an RGB image signal subjected to various types of image processing up to the structure enhancement processing is an endoscopic image. The video signal generating unit 66 converts the endoscopic image generated by the image generating unit 62 into a video signal that can be displayed on the monitor 18. Using this video signal, the monitor 18 displays an endoscopic image.

  Next, the operation of the endoscope system 10 will be described. In the endoscope system 10, the light amount ratio setting unit 23 sets the light amount ratio of the V light and the Bs light so that the contrast of the blood vessel with respect to the mucous membrane becomes a target contrast according to the depth and thickness of the blood vessel. For example, as shown in Table 1, the light amount ratio setting unit 23 is preset with the light amount ratios A0 to A10 of the V light and the Bs light, and the doctor determines the depth and thickness of the B image signal from these. The light quantity ratio is selected and set so that the contrast balance between different blood vessels is the target contrast balance. The values of the light amount ratios A1 to A9 in Table 1 are the light amount of the peak wavelength of V light / the light amount of the peak wavelength of Bs light. The light amount ratio A0 is a setting that turns off the V-LED of the first light source 20a and turns on the B-LED of the second light source 20b so that the component of the wavelength band received by the B pixel is only Bs light. The light amount ratio A10 is a setting in which the V-LED of the first light source 20a is turned on and the B-LED of the second light source 20b is turned off so that the component of the wavelength band received by the B pixel is only V light.

  FIG. 16 shows the contrast of the blood vessel with respect to the mucous membrane when the light amount ratio between the V light and the Bs light is set to each light amount ratio of A0 to A10. In FIG. 16, bar graphs representing the contrast of blood vessels having different depths and thicknesses obtained by setting the respective light amount ratios are arranged in the order of d5φ20, d5φ40, d15φ20, d15φ40, d50φ20, and d50φ40 from the left. As can be seen from FIG. 16, the greater the V light component, the smaller the difference in contrast between blood vessels of different thicknesses, and the blood vessel contrast with the mucosa is increased according to the submucosal depth. Conversely, the greater the Bs light component, the greater the difference in contrast depending on the thickness of the blood vessel as well as the submucosal depth.

  The doctor determines the target contrast according to the characteristics of the lesion to be differentiated or according to the purpose such as eliminating the difference in feeling of use with the conventional endoscope system, and the light quantity ratios A0 to A10 at which the determined target contrast is obtained. To select a desired light quantity ratio. The light source control unit 22 controls the first light source 20a and the second light source 20b so that the light amount ratio between the V light and the Bs light becomes the light amount ratio set by the light amount ratio setting unit 23. For this reason, in the B image signal obtained by the B pixel that receives the return light of the V light and the Bs light, the balance of the contrast of a plurality of blood vessels having different depths and thicknesses is a balance corresponding to the set light amount ratio. Become. Since the image generation unit 62 generates an endoscopic image using the B image signal, the endoscopic image generated and displayed by the endoscope system 10 has a blood vessel contrast with respect to the mucous membrane, a blood vessel depth, and the like. Target contrast according to thickness.

  In the first embodiment, 11 types of light quantity ratios A0 to A10 are exemplified. However, in the endoscope system 10, the light quantity ratio of the V light and the Bs light can be arbitrarily set. 10 can freely adjust the contrast of blood vessels according to the depth and thickness of the submucosa.

[Second Embodiment]
An endoscope system 200 according to the second embodiment shown in FIG. 17 is an endoscope system that can perform so-called narrow-band light observation that is performed in a conventional endoscope system. In the endoscope system 200, blue narrow-band light (same as Bs light of the first embodiment) having a blue wavelength band of about 450 nm or less from white light emitted from the second light source 20b in the optical path of the second light source 20b. Therefore, the green wavelength band (fourth wavelength band) of about 530 nm to 550 nm, which is different from the wavelength band (third wavelength band) of Bs light, and has a thickness resolution with respect to the blood vessel. A band limiting filter 225 for generating Bs light and Gn light generation for generating green narrow band light (hereinafter referred to as Gn light) having s is provided so as to be insertable / removable. The green wavelength band of Gn light is the fourth wavelength band, which is different from the wavelength band of Bs light (third wavelength band) and has a thickness resolution with respect to blood vessels (see FIG. 6). The band limiting filter 225 for generating Bs light and Gn light is a first band limiting filter and a second band limiting filter.

  Insertion / extraction of the band limiting filter 225 for generating Bs light and Gn light is controlled by the mode switching unit 230. The observation mode switching unit 230 operates by operating an observation mode switching button (not shown) on the operation unit 12b or a foot switch (not shown), and inserts / extracts the band limiting filter 225 for generating Bs light and Gn light to thereby obtain white light. The first observation mode in which observation is performed using and the second observation mode in which observation is performed using V light, Bs light, and Gn light are switched. The first observation mode is a so-called normal observation mode, and the second observation mode is a so-called narrow-band observation mode. Therefore, when the second observation mode for narrow-band light observation is selected, the observation mode switching unit 230 sets the band limiting filter 225 for generating Bs light and Gn light to the second light source 20b. When the first observation mode that is inserted into the optical path and irradiates white light for normal observation is selected, the band limiting filter 225 for generating Bs light and Gn light is retracted from the optical path of the second light source 20b. .

  As shown in FIG. 18, the illumination light 226 in the case of performing narrow-band light observation with the endoscope system 200 is composed of V light, Bs light, and Gn light. In the image generation unit 62 of the endoscope system 200, the B image signal obtained by imaging the return light of the V light and the Bs light by the B pixel is used as the B channel (the B pixel of the endoscope image to be generated). Assigned to the G channel (G pixel of the endoscope image to be generated), and the G image signal obtained by imaging the return light of the Gn light with the G pixel was assigned to the R channel (R pixel of the endoscope to be generated) An endoscopic image (hereinafter referred to as a narrowband light observation image) is generated. The rest is the same as the endoscope system 10 of the first embodiment.

  As shown in FIG. 19, in a conventional endoscope system, a band limiting filter that limits the wavelength band of broadband light from broadband light having a wider wavelength band than V light or Bs light (hereinafter, band limiting filter for broadband light). Narrowband light is observed using the narrowband light generated by For example, when a xenon lamp is used as the light source, the broadband light is white light 227 emitted from the xenon lamp, and blue light having a wavelength band of about 350 nm to 450 nm is obtained from the white light 227 using a band limiting filter for broadband light. Narrow-band light (hereinafter referred to as Bn light) and Gn light are generated, and an observation object is imaged using these as illumination light. When performing narrow-band light observation, the Gn light of the endoscope system 200 can have substantially the same spectral spectrum as the Gn light of the conventional endoscope system, and therefore the depth and thickness of the G image signal are different. The contrast balance of the plurality of blood vessels is almost equal to that of the conventional endoscope system. On the other hand, as shown in FIG. 20, the spectrums of the Bn light used in the conventional endoscope system and the V light and Bs light used in the endoscope system 200 do not match. For this reason, the B image signal obtained when narrowband light observation is performed with the conventional endoscope system and the B image signal obtained when narrowband light observation is performed with the endoscope system 200, the depth and The contrast balance for the mucous membranes of blood vessels with different thicknesses is not the same.

  However, the endoscope system 200 can freely balance the contrast between a plurality of blood vessels having different depths and thicknesses in the B image signal by setting the light amount ratio of the V light and the Bs light by the light amount ratio setting unit 23. Can be adjusted to. That is, the endoscope system 200 sets the contrast of the blood vessel when irradiating the observation target with Bn light generated from the broadband light using the band limiting filter for broadband light as the target contrast, and the light amounts of the V light and the Bs light. By setting the ratio, the contrast balance of a plurality of blood vessels having different depths and thicknesses in the B image signal is matched with the contrast balance in the B image signal of the conventional endoscope system for performing narrowband light observation. be able to. As a result, the appearance of blood vessels in the narrow-band light observation image generated and displayed by the endoscope system 200 can be made to substantially match the appearance of blood vessels in the conventional narrow-band light observation image.

  First, as shown in FIG. 21, the balance of the blood vessel contrast of the B image signal obtained when the conventional Bn light generated from the broadband light is irradiated is determined by the endoscope system 200 using only the Bs light (light quantity ratio A0). ) Or the contrast balance of the B image signal when only V light (light quantity ratio A10) is irradiated.

  On the other hand, FIG. 22 shows the contrast of blood vessels with respect to the mucous membrane when the light amount ratio setting unit 23 sets the light amount ratio of V light and Bs light to the light amount ratios A0 to A10 (see Table 1) of the first embodiment. The contrast ratio obtained by normalizing with the contrast of the blood vessel with respect to the mucous membrane in the case of irradiation with Bn light. FIG. 22 shows contrast ratios of a plurality of blood vessels having different depths and thicknesses. For this reason, the graph of FIG. 22 indicates that the closer the value is to 100%, the closer the contrast of the blood vessel to the mucous membrane is as in the case of irradiating conventional Bn light.

  As can be seen from FIG. 22, when the light amount ratio is set to A0 to A6, the variation in blood vessel depth and depth increases, but the contrast (100%) when many blood vessels irradiate conventional Bn light. Visibility is improved more than before. On the other hand, when the light quantity ratio is set to A7 to A10, it is slightly lower than the contrast when irradiating the conventional Bn light, but the variation in contrast due to the depth and thickness of the blood vessel is reduced, and the conventional Bn light is irradiated. A close contrast balance is obtained.

  FIG. 23 shows blood vessels having the same submucosal depth and different thicknesses when the light amount ratio setting unit 23 sets the light amount ratios A0 to A10 (see Table 1) of V light and Bs light. The graph of the contrast ratio between is shown. Specifically, in FIG. 23, the contrast ratio (φ40 / φ20) of the φ40 blood vessel to the φ20 blood vessel is shown for three types of depths d5, d15, and d50. In addition, the graph of FIG. 23 is normalized by the contrast ratio in the case of irradiating conventional Bn light. Therefore, the closer the value is to 100%, the smaller the submucosal depth and the different thickness between blood vessels. This indicates that the contrast ratio is close to that of conventional Bn light irradiation.

  As can be seen from FIG. 23, when the light amount ratios A0 to A6 are set, the contrast ratio between blood vessels having the same submucosal depth and different thicknesses varies greatly depending on the depth, but the value is large. It exceeds 100% and is generally larger than the case of irradiating with conventional Bn light. For this reason, when the light amount ratio is set to A0 to A6, blood vessels having the same submucosal depth and different thicknesses can be observed more clearly and specially than when the conventional Bn light is irradiated. On the other hand, when the light amount ratio is set to A7 to A10, the contrast ratio between blood vessels having the same submucosal depth and different thickness may be slightly lower than the conventional case of irradiating Bn light. The variation due to the difference is small, and a value close to the contrast ratio when the conventional Bn light is irradiated can be maintained. In particular, when the light quantity ratio is set from A7 to A9, the contrast ratio between the blood vessels having the same submucosal depth and different thickness is hardly varied due to the difference in depth, and the conventional Bn light is used. It almost matches the contrast ratio in the case of irradiation.

  FIG. 24 shows a case where the light amount ratio setting unit 23 sets the light amount ratios A0 to A10 of V light and Bs light (see Table 1) between blood vessels having the same thickness and different submucosal depths. A graph of contrast ratio is shown. Specifically, in FIG. 24, for two types of blood vessels of φ20 and φ40, the contrast ratio (d5 / d15) of the blood vessel with depth d5 to the blood vessel with depth d15 and the depth with respect to the blood vessel with depth d50 are shown. The blood vessel contrast ratio (d15 / d50) is shown. The graph of FIG. 24 is standardized by the contrast ratio in the case of irradiating conventional Bn light. Therefore, the closer the value is to 100%, the larger the thickness and the submucosal depth are different. This indicates that the contrast ratio is close to that of conventional Bn light irradiation.

  As can be seen from FIG. 24, the contrast ratio between the blood vessels having the same thickness and different submucosal depths is almost the same as when the conventional Bn light is irradiated, regardless of the setting of the light amount ratio. It is done. However, with the condition of the light quantity ratio A7 as a boundary, the contrast ratio of a relatively thin blood vessel (φ20) tends to be lowered at the light quantity ratios A0 to A6 with a large amount of Bs light component, and the variation due to the difference in the thickness of the blood vessels increases. Further, when the light amount ratio A7 is set to a boundary with the light amount ratio A7 as a boundary, the contrast ratio due to the difference in the blood vessel depths of all the thicknesses varies depending on the difference in the thickness. The contrast ratio in the case of irradiating with conventional Bn light is exceeded while remaining small. Therefore, when the light amount ratio is set to A8 to A10, blood vessels having the same thickness and different submucosal depths can be easily identified as compared with the case of irradiating conventional Bn light.

  Table 2 also shows (1) the contrast balance between blood vessels of different depth and thickness, (2) the contrast ratio between blood vessels of equal submucosal depth and different thickness, and (3) B image signal obtained when the light quantity ratio is set to A0 to A10 in the endoscope system 200 from the three viewpoints of the contrast ratio between blood vessels having the same thickness and different submucosal depths. And the result of five-stage evaluation of 1-5 functionally with the B image signal obtained by irradiating conventional Bn light is shown. In the evaluation, the evaluation that is far from the case where the conventional Bn light is irradiated is “1”, and the evaluation that is the closest to the case where the conventional Bn light is irradiated is “5”. The evaluation result is an average value of the results evaluated by a plurality of people.

From the above, the blue narrow band light used in the endoscope system 200 is formed of V light and Bs light, which is different from the conventional Bn light formed from broadband light, and the spectrums do not match. If the light amount ratio setting unit 23 sets the light amount ratio of the V light and the Bs light to the value “A7” (the light amount of the peak wavelength of the V light / the light amount of the peak wavelength of the Bs light = 5.0), the contrast of the blood vessel Is approximately equal to the size of the blood vessel contrast when the observation object is irradiated with Bn light,
It is possible to obtain a B image signal in which the contrast balance for the mucous membranes of a plurality of blood vessels having different depths and thicknesses substantially coincides with the case of irradiation with conventional Bn light. For this reason, the endoscope system 200 can generate and display a narrowband light observation image in which the appearance of blood vessels is substantially equal to the conventional narrowband light observation image.

  As described above, in order to obtain a narrow-band light observation image in which the appearance of blood vessels is substantially equal to the conventional narrow-band light observation image, the light amount ratio setting unit 23 sets the light amount ratio of V light and Bs light to a value “A7”. However, if the value of “light quantity of peak wavelength of V light / light quantity of peak wavelength of Bs light” is 2.0 (light quantity ratio A6) or more and 8.0 (light quantity ratio A8) or less, Thus, it is possible to obtain a narrow-band light observation image in which the appearance of blood vessels is substantially equal to the conventional narrow-band light observation image. Further, if the value of “light quantity of peak wavelength of V light / light quantity of peak wavelength of Bs light” is about 1.0 (light quantity ratio A4) or more, a narrow band imitating a conventional narrow band light observation image without a sense of incongruity. Light observation images can be generated and displayed.

  In addition, in the endoscope system 200, the light amount ratio setting unit 23 sets the light amount ratio of the V light and the Bs light to “A0” to “A6” so that the submucosal depth is equal and the thickness is set. Blood vessels in the case of irradiating an observation target with Bn light generated by using a band limiting filter for broadband light from broadband light having a wider wavelength band than V light or Bs light. The contrast ratio or difference can be made larger than this. That is, by setting the light amount ratio to “A0” to “A6”, the contrast ratio or difference of a plurality of blood vessels having different submucosal depths and different thicknesses is used when conventional Bn light is used. It is possible to provide a new narrow-band light observation image that is more emphasized.

  In the endoscope system 200, the light amount ratio setting unit 23 sets the light amount ratio of the V light and the Bs light to “A8” to “A10”, so that the submucosal depth is different and the thickness is different. The contrast ratio or difference between a plurality of equal blood vessels can be made larger than this on the basis of the blood vessel contrast ratio or difference when the observation target is irradiated with Bn light. That is, by setting the light amount ratio to “A8” to “A10”, the contrast ratio or difference of a plurality of blood vessels having different submucosal depths and equal thicknesses is used when conventional Bn light is used. It is possible to provide a new narrow-band light observation image that is more emphasized.

  In the second embodiment, Bn light and Gn light are generated and used from the white light 227 emitted from the xenon lamp as the endoscope system 200 and the conventional endoscope system that performs narrow-band light observation. Although there is a comparison with an endoscope system, there is also an endoscope system that performs narrow-band light observation using a light source (for example, a white LED) that emits broadband light other than a xenon lamp. In the same manner as in the second embodiment, the endoscope system 200 is configured so that a narrow-band light observation image and blood vessel appearance obtained by such a conventional endoscope system can be obtained by setting an appropriate light amount ratio by the light amount ratio setting unit 23. Narrow-band light observation images that are almost equal can be obtained.

  In the second embodiment, the Bs light and the Gn light generation band limiting filter 225 are used to simultaneously generate the Bs light and the Gn light from the white light emitted from the second light source 20b. Instead, for example, FIG. The light source control unit 22 sequentially generates Bs light and Gn light, and irradiates the observation target with Bs light and Gn light in a time-sharing manner using a rotary band-limiting filter (hereinafter referred to as a rotary filter) 235 shown in FIG. May be. The rotary filter 235 generates Bs light from white light emitted from the second light source 20b. The Bs light generation band limiting filter 235a (first band limiting filter; corresponding to the Bs light generation band limiting filter 25 of the first embodiment). And a Gn light generation band limiting filter 235b (second band limiting filter) for generating Gn light at the outer periphery, and white light emitted from the second light source 20b is transmitted through the inner periphery. It has a blank portion 235c. When the second observation mode for performing the narrow-band light observation is selected, the observation mode switching unit 230 alternately switches the Bs light generation band-limiting filter 235a and the Gn light generation band-limiting filter 235b to the second light source 20b. The rotation filter 235 is disposed so as to cross the optical path and is rotated. On the other hand, when the first observation mode for normal observation is selected, the observation mode switching unit 230 arranges the element missing portion 235c in the optical path of the second light source 20b. When a monochrome sensor is used as the image sensor 48, it is preferable to use the rotary filter 235 or the like to sequentially generate Bs light and Gn light as described above and perform time-division irradiation.

  In addition, instead of the V-LED and B-LED used in the first and second embodiments, other semiconductor light sources having different center wavelengths, peak wavelengths, and the like can be used. For example, in the first embodiment and the second embodiment, a V-LED that emits V light having a center wavelength of 415 nm is used. Alternatively, for example, an LED that emits V light having a center wavelength of 405 nm can be used. . Even when an LED having a center wavelength of 405 nm is used, the light amount ratio set by the light amount ratio setting unit 23 is substantially the same as the light amount ratio in the first and second embodiments. Moreover, other semiconductor light sources such as laser diodes may be used instead of LEDs.

  In the first embodiment and the second embodiment, the light source control unit 22 uses the light amount ratio set by the light amount ratio setting unit 23 to change the V-LED of the first light source 20a and the B-LED of the second light source 20b. Light amount (light emission amount) is controlled, but instead of controlling the light amount, the light emission time of the V-LED and B-LED is controlled, and the light amount ratio setting unit 23 sets the light amount ratio of V light and Bs light. It may be a ratio. Alternatively, the light quantity ratio between the V light and the Bs light may be set to the light quantity ratio set by the light quantity ratio setting unit 23 by controlling both the light quantity and the light emission time. The amount of light of the V-LED or B-LED has a limit, but if the light emission time is controlled, or if both the light amount and the light emission time are controlled, the V light and Bs can be realized at a light amount ratio that cannot be realized only by the light amount control. Illumination light including light can be generated.

  In the first embodiment and the second embodiment, Bs light is generated from B light and used as illumination light. However, B light may be used as illumination light as it is. However, as described above, using Bs light makes it easier to obtain blood vessel contrast with respect to the mucous membrane.

  In the first embodiment and the second embodiment, the present invention is implemented by the endoscope system in which the endoscope 12 provided with the imaging sensor 48 is inserted into the subject for observation. The present invention is also suitable for an endoscope system. For example, as shown in FIG. 26, the capsule endoscope system includes at least a capsule endoscope 400 and a processor device (not shown).

  The capsule endoscope 400 includes a light source 402, a control unit 403, an image sensor 404, an image generation unit 406, and a transmission / reception antenna 408. The light source 402 includes a V-LED that emits V light, a B-LED that emits B light, a phosphor that emits fluorescence when irradiated with B light, and a band limiting filter for generating Bs light. This corresponds to the light source unit 20 of the first embodiment and the second embodiment.

  The control unit 403 functions in the same manner as the light source control unit 22 and the light amount ratio setting unit 23 of the first and second embodiments, and controls the light source 402 to emit light by setting the light amount ratio of V light and Bs light. . Further, the control unit 403 can communicate wirelessly with the processor device of the capsule endoscope system by the transmission / reception antenna 408. The processor device of the capsule endoscope system is substantially the same as the processor device 16 of each of the above-described embodiments and modifications, but the image generation unit 406 is provided in the capsule endoscope 400, and the generated endoscope image is The signal is transmitted to the processor device via the transmission / reception antenna 408. The image sensor 404 is configured similarly to the image sensor 48 of the first embodiment and the second embodiment.

10, 200, 250 Endoscope system 12 Endoscope 14 Endoscope light source device 16 Processor device 20a First light source 20b Second light source 22 Light source control unit 23 Light quantity ratio setting unit 25, 235a Band limiting filter for Bs light generation 225 Band limiting filter for generating Bs light and Gn light 235b Band limiting filter for generating Gn light 226 Observation mode switching unit

Claims (17)

A first light source that emits light in a first wavelength band having depth resolution to a blood vessel under a mucous membrane to be observed;
A second light source that emits light in a second wavelength band having a continuous spectrum in a wider band than the first wavelength band;
A first band-limiting filter that generates light of a third wavelength band having a thickness resolution from the light of the second wavelength band for a blood vessel at the same depth under the mucous membrane;
A light amount ratio setting unit that sets a light amount ratio between the light in the first wavelength band and the light in the third wavelength band, and sets the contrast of the blood vessel to the mucous membrane to a target contrast according to the depth and thickness of the blood vessel;
A light source control unit that controls the first light source and the second light source using the light amount ratio set by the light amount ratio setting unit;
An endoscope light source device comprising:   The peak wavelength of the light in the first wavelength band is shorter than the peak of the absorption spectrum of hemoglobin, and the peak wavelength of the light in the third wavelength band is longer than the peak of the absorption spectrum of hemoglobin. The endoscope light source device according to claim 1 on the side.   The endoscope light source device according to claim 1, wherein the first wavelength band is a violet wavelength band, and the third wavelength band is a blue wavelength band.   The light amount ratio setting unit is configured to contrast a blood vessel when the observation target is irradiated with blue narrow-band light generated from broadband light having a wider wavelength band than the first wavelength band light or the third wavelength band light. The endoscope light source device according to claim 1, wherein the light quantity ratio is set with the target contrast as the target contrast.   The light quantity ratio setting unit is configured to make the contrast balance of a plurality of blood vessels having different submucosal depths and different thicknesses equal to a balance when irradiating the observation target with the blue narrow band light. The endoscope light source device according to claim 4, wherein the ratio is set.   The light amount ratio setting unit is configured to make the balance of contrast between a plurality of blood vessels having different submucosal depths and equal thicknesses equal to a balance when irradiating the observation target with the blue narrow band light. The endoscope light source device according to claim 4 or 5, wherein a ratio is set.   The light quantity ratio setting unit sets the light quantity ratio that makes the magnitude of the blood vessel contrast equal to the magnitude of the blood vessel contrast when the observation target is irradiated with the blue narrow-band light. The endoscope light source device according to claim 1.   The endoscope light source device according to any one of claims 4 to 7, wherein the broadband light is white light emitted by a xenon lamp. Based on the contrast of the blood vessel when irradiating the observation target with blue narrowband light generated from broadband light having a wider wavelength band than the first wavelength band light or the third wavelength band light,
The light quantity ratio setting unit is configured to set a contrast ratio or difference between a plurality of blood vessels having different submucosal depths and different thicknesses from the contrast ratio or difference when the blue narrow-band light is irradiated. The endoscope light source device according to claim 1, wherein the light amount ratio to be increased is set. Based on the contrast of the blood vessel when irradiating the observation target with blue narrowband light generated from broadband light having a wider wavelength band than the first wavelength band light or the third wavelength band light,
The light amount ratio setting unit has a contrast ratio or difference between a plurality of blood vessels having different submucosal depths and equal thicknesses than the contrast ratio or difference when the blue narrow-band light is irradiated. The endoscope light source device according to claim 1, wherein the light amount ratio to be increased is set. A second band limiting filter that generates light of a fourth wavelength band, which is different from the third wavelength band and has a thickness resolution with respect to a blood vessel, from the light of the second wavelength band;
A first observation mode in which observation is performed using light in the second wavelength band; and first observation in which light is transmitted in the first wavelength band, light in the third wavelength band, and light in the fourth wavelength band. An observation mode switching unit for switching between two observation modes;
An endoscope light source device according to any one of claims 1 to 10.   The endoscope light source device according to claim 10, wherein the fourth wavelength band is a green wavelength band.   The said light source control part controls the light emission amount of a said 1st light source and a said 2nd light source using the said light quantity ratio which the said light quantity ratio setting part sets. The inside of any one of Claims 1-12 Endoscopic light source device.   The said light quantity ratio setting part controls the light emission time of a said 1st light source and a said 2nd light source using the said light quantity ratio which the said light quantity ratio setting part sets. Endoscope light source device.   The endoscope light source device according to any one of claims 11 to 14, wherein light in the third wavelength band and light in the fourth wavelength band are irradiated in a time-sharing manner. A first light source that emits light in a first wavelength band having depth resolution to a blood vessel under a mucous membrane to be observed;
A second light source that emits light in a second wavelength band having a continuous spectrum in a wider band than the first wavelength band;
A first band-limiting filter that generates light of a third wavelength band having a thickness resolution from the light of the second wavelength band for a blood vessel at the same depth under the mucous membrane;
A light amount ratio setting unit that sets a light amount ratio between the light in the first wavelength band and the light in the third wavelength band, and sets the contrast of the blood vessel to the mucous membrane to a target contrast according to the depth and thickness of the blood vessel;
A light source control unit that controls the first light source and the second light source using the light amount ratio set by the light amount ratio setting unit;
An imaging sensor that images the observation object irradiated with the light of the first wavelength band or the light of the third wavelength band controlled using the light quantity ratio set by the light quantity ratio setting unit;
An endoscope system comprising: A first light source that emits light in a first wavelength band having depth resolution to a blood vessel under a mucous membrane to be observed; and a second wavelength band having a continuous spectrum that is wider than the first wavelength band. A first band-limiting filter that generates light of a third wavelength band having a thickness resolution with respect to a second light source that emits light and a blood vessel at the same depth below the mucous membrane from the light of the second wavelength band In an operating method of an endoscope light source device comprising:
A light amount ratio setting unit setting a light amount ratio between the light in the first wavelength band and the light in the third wavelength band;
A light source control unit controlling the first light source and the second light source using the light amount ratio set by the light amount ratio setting unit;
A method of operating an endoscope light source device comprising:

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