JP6970777B2 - Endoscope system - Google Patents

Description

The present invention relates to an endoscope system that processes an image taken by an endoscope.

In the medical field, endoscopic diagnosis using an endoscopic system is widespread. The endoscope system has an endoscope that is inserted into a living body and has an insertion part having an image pickup element and an illumination window at the tip, a light source device that supplies light to the endoscope, and an image signal output by the image pickup element. It is equipped with a processor device (image processing device) for processing. The endoscope has a built-in light guide composed of a plurality of optical fibers, and the light supplied from the light source device is guided to the illumination window by the light guide and radiates to the observation site.

In recent endoscopic diagnosis, in addition to the normal observation of observing the overall properties of the surface of living tissue under normal light, which is white light, special light using special light limited to a specific wavelength is used. Light observation is also being carried out. There are various types of special light observation, but for example, by utilizing the optical characteristics of living tissue that the depth of penetration from the mucosal surface layer differs depending on the wavelength, the surface blood vessels existing near the mucosal surface layer and the surface blood vessels are more than the surface blood vessels. There is known a blood vessel-enhanced observation in which the middle-deep blood vessels in the deep layer are emphasized and displayed (see, for example, Patent Document 1 and Patent Document 2). Since the state of blood vessels in abnormal tissues such as cancer that develops in living tissues is different from that in normal tissues, blood vessel emphasis observation has been recognized to be useful for the detection of early stage cancer.

The absorption coefficient of hemoglobin in blood has a wavelength dependence, rapidly increases in the wavelength region of about 450 nm or less, and has a peak in the vicinity of 405 nm in the blue region. Further, although the wavelength is lower than 450 nm or less, it has a peak even when the wavelength in the green region is about 530 nm to 560 nm. When the observation site is irradiated with light having a wavelength having a large absorption coefficient, the blood vessel absorbs a large amount of light, so that an image having a high contrast between the blood vessel and the other portion can be obtained. Therefore, in the endoscope system of Patent Document 1, blue light in the wavelength region of about 390 to 445 nm is used for enhancing surface blood vessels, and green light in the wavelength region of about 530 to 550 nm is used for enhancing middle and deep blood vessels. By utilizing it, a blood vessel-enhanced image that emphasizes each of the superficial blood vessel and the middle-deep blood vessel is acquired.

In the endoscope system described in Patent Document 1, a white light source such as a xenon lamp and a rotating filter having light transmission in the wavelength ranges of blue and green are combined to generate blue light and green light. .. Further, Patent Document 1 discloses a technique for calibrating a color tone by photographing a color reference object with an endoscope and adjusting the gain of an image signal for each obtained color (paragraph 0035). , 0036). According to this, even when the transmission characteristics of the optical system differ depending on the model of the endoscope, an image having an appropriate color tone can be obtained regardless of the model.

In the endoscope system described in Patent Document 2, a semiconductor light source such as a laser diode (LD) or an LED is used as a light source that emits blue light or green light. The larger the amount of blue light or green light, the higher the contrast of blood vessels. If a semiconductor light source is used, a high output can be obtained as compared with the xenon lamp of Patent Document 1, so that it is easy to obtain a high-contrast image.

Japanese Unexamined Patent Publication No. 2005-131130 Japanese Unexamined Patent Publication No. 2011-041758

However, when the light transmittance of the light guide of the existing endoscope was investigated, as shown in FIG. 17, the light transmittance in the short wavelength region was lower than that in the long wavelength region, and in particular, the wavelength was about 430 nm or less. It was found that the light transmittance dropped sharply in the blue region of. If the light transmittance of the light guide is low, the amount of emitted light that is guided by the light guide and emitted to the observation site also decreases, so it is difficult to utilize the performance of the semiconductor light source. Therefore, the development of an improved endoscope having a light guide with improved light transmittance in the blue region is being studied.

Even when developing an improved endoscope, considering the convenience of the user who owns the existing endoscope (the surgeon who performs endoscopy), the improved endoscope and the existing endoscope It is desirable to ensure compatibility between the two in the light source device so that both can be used.

However, if the light transmission characteristics of the light guide are different, the amount of emitted light will differ depending on the model of the endoscope. In normal observation, the brightness of a part of the wide wavelength range from blue to red is reduced, so the effect is small. The decrease in the light transmittance of blue light has a large effect because it causes a decrease in the contrast of the superficial blood vessels, which are the main observation targets.

Patent Documents 1 and 2 do not specify or suggest such problems and their solutions. Patent Document 1 discloses a technique for calibrating a color tone by adjusting the gain of an image signal for each color in an image processing apparatus that acquires an image signal from an endoscope. For example, the above problem cannot be solved because it is a process of increasing the brightness of the entire screen including the bright part and the dark part in one screen with respect to the blue image signal.

The present invention has been made in view of the above problems, and an object thereof is to capture observation images taken by each of a plurality of types of endoscopes having different optical characteristics of a light guide, even when performing blood vessel-enhanced observation. , To obtain a similar observation image.

The endoscope system of the present invention is the first and second light guides for guiding the illumination light that illuminates the observation site in the living body, and there is a difference in the light transmission rate with respect to the light for observing blood vessel information. The types of the connection part that interchangeably connects the first and second endoscopes with built-in 1st and 2nd light guides and the type of endoscope connected to the connection part are the first and second endoscopy. An endoscope identification unit that identifies which of the mirrors it is, and an image processing unit that performs image processing on the image signals output by each of the first and second endoscopes, and is for observing blood vessel information. In the vessel-enhanced observation mode using light, the content is changed based on the difference in light transmission rate depending on whether the type of endoscope connected to the connection part is the first endoscope or the second endoscope. It is provided with an image processing unit that performs image processing.

The image processing is preferably a contrast adjustment processing.

The image processing is preferably gradation correction processing.

The image processing is preferably edge enhancement processing.

The image processing is preferably a process for widening the density difference between the blood vessel region and the region where no blood vessel exists.

The image processing preferably includes pseudo color processing.

A first light source module that emits white light including a first light in a blue region and a fluorescence emitted by irradiating a phosphor with the first light, and a second light source module that emits a second light in a wavelength region close to the ultraviolet region. It is preferable that the light for observing blood vessel information includes at least one of a green component light contained in the light emitted by the first light source module and a blue component light contained in the light emitted by the second light source module. ..

It is equipped with a white light source composed of semiconductor light sources of three colors of blue, green, and red, and a second light source composed of a semiconductor light source that emits a second light in a wavelength region close to the ultraviolet region, and is used for observing blood vessel information. The light preferably contains at least one of a green component light contained in the white light emitted by the white light source and a blue component light contained in the light emitted by the second light source.

The semiconductor light source is preferably an LED.

The second light is preferably blue light having a wavelength of 430 nm or less.

The wavelength of blue light is preferably 410 ± 10 nm.

The white light preferably contains green light having a wavelength in the wavelength range of 530 nm to 560 nm.

The first and second write guides are preferably fiber bundles in which optical fibers are bundled.

According to the present invention, even when blood vessel-enhanced observation is performed using a plurality of types of endoscopes having different optical characteristics of the light guide, the same observation image can be obtained in the observation images taken by each of them.

It is an external view of the endoscope system of this invention. It is a front view of the tip of an endoscope. It is a block diagram which shows the electrical structure of an endoscope system. It is a graph which shows the spectral spectrum of an illumination light. It is a graph which shows the absorption spectrum of hemoglobin. It is a graph which shows the scattering coefficient of a living tissue. It is a graph which shows the spectral characteristic of the color microfilter of an image sensor. It is explanatory drawing which shows the irradiation timing and the image pickup timing of an illumination light. It is explanatory drawing of the structure which identifies the model of an endoscope. It is a graph which shows the light transmission characteristic of a light guide. It is a graph which shows the relationship between the drive current value and the amount of emitted light. It is explanatory drawing which shows the image processing procedure in a normal observation mode. It is explanatory drawing which shows the image processing procedure in the blood vessel emphasis observation mode. It is explanatory drawing of the contrast adjustment processing. It is a flowchart which shows the image processing procedure in the blood vessel emphasis observation mode. It is explanatory drawing which shows another mode of light for blood vessel enhancement. It is a graph which shows the light transmission characteristic of the conventional light guide.

As shown in FIG. 1, the endoscope system 10 of the first embodiment of the present invention includes an endoscope 11 that captures an observation site in a living body and an observation image of the observation site based on a signal obtained by the imaging. A processor device 12 for generating an observation image, a light source device 13 for supplying light illuminating an observation site to the endoscope 11, and a monitor 14 for displaying an observation image are provided. The processor device 12 is provided with a console 15 which is an operation input unit such as a keyboard and a mouse.

The endoscope system 10 includes a normal observation mode for observing an observation site under white light and a blood vessel highlighting observation mode for highlighting blood vessels existing in the observation site using special light. The blood vessel-enhanced observation mode is a special light observation mode for grasping the properties such as the pattern of blood vessels and making a diagnosis such as good / bad discrimination of a tumor. Narrow band light is used.

The endoscope 11 includes an insertion unit 16 inserted into the digestive tract of the subject, an operation unit 17 provided at the base end portion of the insertion unit 16, an operation unit 17, a processor device 12, and a light source device 13. It is equipped with a universal cord 18 for connecting the spaces.

The insertion portion 16 is composed of a tip portion 19, a curved portion 20, and a flexible tube portion 21, which are connected in order from the tip. As shown in FIG. 2, on the tip surface of the tip portion 19, the illumination window 22 that irradiates the observation portion with the illumination light, the observation window 23 in which the image light reflected at the observation portion is incident, and the observation window 23 are cleaned. An air supply / water supply nozzle 24 for supplying air / water, a forceps outlet 25 for projecting a treatment tool such as a forceps or an electric knife, and the like are provided. An image sensor 44 (see FIG. 3) and an optical system for imaging are built in the back of the observation window 23.

The curved portion 20 is composed of a plurality of connected curved pieces, and by operating the angle knob 26 of the operating portion 17, the curved portion 20 is curved in the vertical and horizontal directions. By bending the curved portion 20, the direction of the tip portion 19 is directed to a desired direction. The flexible tube portion 21 is flexible so that it can be inserted into a winding tube such as the esophagus or the intestine. The insertion unit 16 has a communication cable for communicating a drive signal for driving the image pickup element 44 and an image signal output by the image pickup element 44, and a light guide 43 for guiding the illumination light supplied from the light source device 13 to the illumination window 22. (See FIG. 3) is inserted.

In addition to the angle knob 26, the operation unit 17 is provided with a forceps port 27 for inserting a treatment tool, an air supply / water supply button for performing air supply / water supply operation, a release button for capturing a still image, and the like. There is.

A communication cable and a light guide 43 extending from the insertion portion 16 are inserted into the universal cord 18, and a connector 28 is attached to one end of the universal cord 18 on the side of the processor device 12 and the light source device 13. The connector 28 is a composite type connector including a communication connector 28a and a light source connector 28b. One end of the communication cable is arranged in the communication connector 28a, and the communication connector 28a is detachably connected to the receptacle connector 42a (see FIG. 3) of the processor device 12. The incident end of the light guide 43 is arranged on the light source connector 28b, and the light source connector 28b is detachably connected to the receptacle connector 42b (see FIG. 3) of the light source device 13.

As shown in FIG. 3, the light source device 13 includes two types of first and second light source modules 31 and 32 having different emission wavelengths, and a light source control unit 34 for driving and controlling them. The light source control unit 34 controls the drive timing, synchronization timing, and the like of each unit of the light source device 13.

The first and second light source modules 31 and 32 have laser diodes LD1 and LD2 that emit narrow band light in a specific wavelength range, respectively. As shown in FIG. 4, the laser diode LD1 emits narrow band light N1 having a wavelength range of 440 ± 10 nm and a center wavelength of 445 nm in the blue region, for example. In the blue region, the laser diode LD2 emits narrow-band light N2, which is narrow-band light having a wavelength range of, for example, 410 ± 10 nm and a center wavelength of 405 nm. As the laser diodes LD1 and LD2, InGaN-based, InGaNAs-based, and GaNAs-based laser diodes can be used. Further, as the laser diodes LD1 and LD2, a broad area type laser diode having a wide stripe width (width of the waveguide) capable of increasing the output is preferable.

The first light source module 31 is a light source that emits white light for normal observation. The first light source module 31 has a phosphor 36 in addition to the laser diode LD1. As shown in FIG. 4, the phosphor 36 is excited by the narrow band light N1 in the blue region of 445 nm emitted by the laser diode LD1 to emit fluorescent FL in the wavelength region extending from the green region to the red region. The phosphor 36 absorbs a part of the narrow band light N1 to emit fluorescent FL, and at the same time, transmits the remaining narrow band light N1. The narrow band light N1 transmitted through the phosphor 36 is diffused by the phosphor 36. White light is generated by the transmitted narrow band light N1 and the excited fluorescent FL. As the phosphor 36, for example, a fluorescent material such as YAG type or BAM (BgMgAl ₁₀ O ₁₇ ) type is used. Two first light source modules 31 are provided so that the amount of white light is large.

The second light source module 32 is a light source for enhancing surface blood vessels. In FIG. 5, which shows the absorption spectrum of hemoglobin in blood, the absorption coefficient μa of hemoglobin in blood has a wavelength dependence, rapidly increases in the region where the wavelength is 450 nm or less, and has a peak in the vicinity of 405 nm. There is. Further, although it is a low value as compared with the wavelength of 450 nm or less, it also has a peak at a wavelength of 530 nm to 560 nm. When the observation site is irradiated with light having a wavelength having a large absorption coefficient μa, the blood vessel absorbs a large amount of light, so that an image having a large contrast between the blood vessel and the other portion can be obtained. In FIG. 5, the absorption spectrum Hb shows the absorption spectrum of reduced hemoglobin not bound to oxygen, and the absorption spectrum HbO2 shows the absorption spectrum of oxidized hemoglobin bound to oxygen.

Further, as shown in FIG. 6, the light scattering characteristics of living tissues also have a wavelength dependence, and the shorter the wavelength, the larger the scattering coefficient μS. Scattering affects the depth of light penetration into living tissue. That is, the larger the scattering, the more light is reflected near the mucosal surface layer of the living tissue, and the less light reaches the mesopelagic zone. Therefore, the shorter the wavelength, the lower the depth of penetration, and the longer the wavelength, the higher the depth of penetration. The wavelength of light for enhancing blood vessels is selected in consideration of the absorption characteristics of hemoglobin and the light scattering characteristics of living tissues.

The 405 nm narrow band light N2 emitted by the second light source module 32 is used as light for enhancing the surface blood vessels because the depth of penetration is low and the absorption by the surface blood vessels is large. By using the narrow band light N2, the surface blood vessels can be visualized with high contrast in the observation image. Further, as the light for enhancing the blood vessels in the mesopelagic zone, the green component of the white light emitted by the first light source module 31 is used. In the absorption spectrum shown in FIG. 5, the absorption coefficient changes slowly in the green region of 530 nm to 560 nm as compared with the blue region of 450 nm or less. Is not required to be. Therefore, as will be described later, a green component color-separated from the white light by the G-color microcolor filter of the image sensor 44 is used.

The light source control unit 34 controls the lighting, extinguishing, and the amount of light of the laser diodes LD1 and LD2 via the driver 37. Specifically, the light source control unit 34 is turned on by applying a drive pulse to the laser diodes LD1 and LD2. Then, by performing PWM control for controlling the duty ratio of the drive pulse, the drive current value is changed to control the output (light emission amount). The control of the drive current value may be PAM control or the like in which the amplitude of the drive pulse is changed.

A branch type light guide 41 is provided on the downstream side of the optical path of the first and second light source modules 31 and 32. The branched light guide 41 is an optical path integration unit that integrates the optical paths of the first and second light source modules 31 and 32 into one optical path. Since the light guide 43 of the endoscope 11 has only one incident end, each module is used in the previous stage of supplying the light of the first and second light source modules 31 and 32 to the endoscope 11 by the branched light guide 41. The optical paths of 31 and 32 are integrated. The branched light guide 41 has branched portions 41a to 41c whose incident ends are branched into a plurality of branches, and emits light incident from each of the branched portions 41a to 41c from one emission end 41e.

The two first light source modules 31 are arranged so as to face the incident surfaces of the branched portions 41a and 41b of the branched light guide 41, respectively, and the second light source module 32 faces the incident surface of the branched portion 41c. Be placed.

The emission end 41e of the branched light guide 41 is arranged near the receptacle connector 42b to which the connector 28b of the endoscope 11 is connected. The emission end 41e is provided with a homogenizer 50 that equalizes the light amount distribution in the cross section of the luminous flux, and the light of the first and second light source modules 31 and 32 incident on the branched light guide 41 is the homogenizer 50. Is supplied to the light guide 43 of the endoscope 11 arranged in the connector 28b via the above.

The endoscope 11 includes a light guide 43, an image pickup element 44, an analog processing circuit 45 (AFE: Analog Front End), and an image pickup control unit 46. The light guide 43 is a fiber bundle in which a plurality of optical fibers are bundled, and when the connector 28 is connected to the light source device 13, the incident end of the light guide 43 faces the exit end of the homogenizer 50 of the light source device 13. .. The emission end of the light guide 43 is branched into two at the front stage of the lighting window 22 so that the light is guided to the two lighting windows 22.

An irradiation lens 48 is arranged behind the illumination window 22. The light supplied from the light source device 13 is guided to the irradiation lens 48 by the light guide 43 and is irradiated from the illumination window 22 toward the observation portion. The irradiation lens 48 is composed of a concave lens, and widens the divergence angle of the light emitted from the light guide 43. As a result, the illumination light is applied to a wide range of the observation site.

An objective optical system 51 and an image pickup device 44 are arranged behind the observation window 23. The image light reflected at the observation site is incident on the objective optical system 51 through the observation window 23, and is imaged on the image pickup surface 44a of the image pickup element 44 by the objective optical system 51.

The image pickup element 44 is composed of a CCD image sensor, a CMOS image sensor, or the like, and has an image pickup surface 44a in which a plurality of photoelectric conversion elements constituting pixels such as a photodiode are arranged in a matrix. The image sensor 44 photoelectrically converts the light received by the image pickup surface 44a, and accumulates signal charges corresponding to the amount of light received in each pixel. The signal charge is converted into a voltage signal by the amplifier and read out. The voltage signal is output from the image pickup device 44 as an image signal, and the image signal is sent to the AFE 45.

The image pickup device 44 is a color image pickup device, and microcolor filters of three colors B, G, and R having spectral characteristics as shown in FIG. 7 are assigned to each pixel on the image pickup surface 44a. The microcolor filter disperses the white light emitted by the first light source module 31 into three colors B, G, and R. The arrangement of the microcolor filters is, for example, the Bayer arrangement.

As shown in FIG. 8, in the normal observation mode, the image pickup device 44 performs a storage operation for accumulating signal charges and a read operation for reading out the accumulated signal charges within the acquisition period of one frame. As shown in FIG. 8A, in the normal observation mode, the laser diode LD1 is turned on in accordance with the accumulation timing, and the observation portion is irradiated with white light composed of narrow band light N1 and fluorescent FL as illumination light. The reflected light is incident on the image pickup element 44. In the image pickup element 44, the white light is color-separated by a micro color filter, the reflected light corresponding to the narrow band light N1 is received by the B pixel, and the G component in the fluorescent FL is received by the G pixel in the fluorescent FL. The R pixel receives the reflected light corresponding to the R component. The image sensor 44 sequentially outputs one frame of image signals B, G, and R in which the pixel values of the B, G, and R pixels are mixed according to the read timing. Such an imaging operation is repeated while the normal observation mode is set.

In the blood vessel emphasis observation mode, as shown in FIG. 8B, the second light source module 32 is turned on in addition to the first light source module 31 in accordance with the accumulation timing. When the first light source module 31 is turned on, the observation portion is irradiated with white light (N1 + FL) composed of narrow band light N1 and fluorescent FL as illumination light, as in the normal observation mode. When the second light source module 32 is turned on, narrow band light N2 is added to the white light (N1 + FL), and these are irradiated to the observation site as illumination light.

Similar to the normal observation mode, the illumination light to which the narrow band light N2 is added to the white light is separated by the micro color filters of B, G, and R of the image pickup device 44. In the image sensor 44, the B pixel receives the narrow band light N2 in addition to the narrow band light N1. The G pixel receives the G component of the fluorescent FL. The R pixel receives the R component of the fluorescent FL. Even in the blood vessel-enhanced observation mode, the image pickup device 44 sequentially outputs the image signals B, G, and R according to the frame rate in accordance with the readout timing. Such an imaging operation is repeated while the blood vessel-enhanced observation mode is set.

In FIG. 3, the AFE 45 is composed of a correlated double sampling circuit (CDS), an automatic gain control circuit (AGC), and an analog-to-digital converter (A / D) (all not shown). The CDS performs a correlated double sampling process on the analog image signal from the image sensor 44 to remove noise caused by resetting the signal charge. AGC amplifies the image signal from which noise has been removed by CDS. The A / D converts the image signal amplified by the AGC into a digital image signal having a gradation value corresponding to a predetermined number of bits and inputs the image signal to the processor device 12.

The image pickup control unit 46 is connected to the controller 56 in the processor device 12, and inputs a drive signal to the image pickup element 44 in synchronization with the base clock signal input from the controller 56. The image sensor 44 outputs an image signal to the AFE 45 at a predetermined frame rate based on the drive signal from the image pickup control unit 46.

The ID memory 47 is a storage unit in which the endoscope ID, which is identification information for identifying the model and individual of the endoscope 11, is stored, and is composed of, for example, a non-volatile memory such as an EEPROM or a flash memory. The endoscope ID is output to the processor device 12 through the connector 28a. Of course, as the ID memory 47, an RFID tag or the like capable of wirelessly transmitting information may be used.

As shown in FIG. 9, the endoscope system 10 can use a plurality of types of endoscopes 11A and 11B. The endoscope 11B is an existing endoscope having a light guide 43B, and the endoscope 11A is an improved endoscope having a light guide 43A having improved light transmission characteristics with respect to the light guide 43B. be.

As shown in FIG. 10, in the light transmittance characteristic B of the light guide 43B, the light transmittance drops in the blue region having a wavelength of 430 nm or less, particularly in the vicinity of about 410 nm. On the other hand, the light transmittance A of the light guide 43A has an improved light transmittance mainly in the blue region as compared with the light guide 43B.

Comparing the light transmittance characteristics A and B, the difference d2 between the light transmittances TA2 and TB2 in the blue region is large, and the difference d1 between the light transmittances TA1 and TB1 in the green region having a longer wavelength than the blue region is small. Therefore, the output of the light supplied from the light source device 13 to the endoscopes 11A and 11B and the light guides 43A and 43B of the endoscopes 11A and 11B are guided and emitted from the respective illumination windows 22 to the observation portion. The relationship with the amount of emitted light is as shown in FIG.

In FIG. 11, the drive current value is a current value for driving the laser diodes LD1 and LD2, and corresponds to the output of the light of the first light source modules 31 and 32, respectively. The graphs GA and GB are the relationship between the output of the G component of the white light emitted by the first light source module 31 and the amount of emitted light when the endoscopes 11A and 11B are used, and the graphs N2A and N2B are the second. This is the relationship between the output of the light source module 32 and the amount of emitted light.

As shown in the graphs GA and GB, regarding the G component of the white light emitted by the first light source module 31, the difference Δ1 between the light transmittances TA1 and TB1 of the light guides 43A and 43B corresponding to the G component is small, so that the first light source When the outputs of the modules 31 are the same, the difference in the amount of emitted light is also small. On the other hand, as shown in the graphs N2A and N2B, for the narrow band light N2 emitted by the second light source module 32, the difference Δ1 between the light transmittances TA2 and TB2 of the light guides 43A and 43B is large, so that the second light source When the outputs of the modules 32 are the same, the difference in the amount of emitted light is also large. Since the light transmittance TB2 of the light guide 43B is about half of the light transmittance TA2 of the light guide 43A, the amount of emitted light also drops to about half.

In FIGS. 3 and 9, the processor device 12 includes a DSP (Digital Signal Processor) 57, an image processing unit 58, a frame memory 59, and a display control circuit 60, in addition to the controller 56. The controller 56 includes a CPU, a ROM that stores a control program and setting data necessary for control, a RAM that loads the program and functions as a work memory, and the like. When the CPU executes the control program, each part of the processor device 12 To control.

The ROM in the controller 56 stores a model table (TBL) 56a that stores the correspondence between the endoscope ID and the model information representing any of the endoscopes 11A and 11B. The controller 56 transmits the model information identified by referring to the model table 56a to the image processing unit 58. Since the endoscopes 11A and 11B have different light transmission characteristics of the light guides 43A and 43B, the image processing unit 58 changes the content of image processing according to the model information, as will be described later.

The DSP 57 acquires an image signal output by the image sensor 44. The DSP 57 separates an image signal in which signals corresponding to each pixel of B, G, and R are mixed into an image signal of B, G, and R, and performs pixel interpolation processing on the image signal of each color. In addition, the DSP 57 performs signal processing such as gamma correction and white balance correction for each of the B, G, and R image signals.

Further, the DSP 57 calculates the exposure value based on the image signals B, G, and R, and when the light amount of the entire image is insufficient (underexposure), the light amount is high so as to increase the light amount of the illumination light. If it is too much (overexposure), an exposure control signal is transmitted to the light source device 13 via the controller 56 so as to reduce the amount of illumination light.

The frame memory 59 stores the image data output by the DSP 57 and the processed data processed by the image processing unit 58. The display control circuit 60 reads image data that has undergone image processing from the frame memory 59, converts it into a video signal such as a composite signal or a component signal, and outputs it to the monitor 14.

As shown in FIG. 12, in the normal observation mode, the image processing unit 58 displays a display image for normal observation based on the image signals B, G, and R color-separated into B, G, and R colors by the DSP 57. (Observation image P) is generated. The generated observation image P is output to the monitor 14. The image processing unit 58 updates the displayed image every time the image signals B, G, and R in the frame memory 59 are updated. In the observation image P, the overall properties of the observation site such as the mucous membrane, the surface blood vessel 61, and the mesopelagic blood vessel 62 are displayed in full color.

In the normal observation mode, the observation portion is irradiated with white light (N1 + FL) output from the first light source module 31 to perform imaging. Since there is no big difference in the light transmission characteristics of the light guides 43A and 43B for white light, the image processing unit 58 performs image processing with the same contents for both the image signals output from the endoscopes 11A and 11B. conduct.

As shown in FIG. 13, in the blood vessel enhancement observation mode, the image processing unit 58 generates a display image for blood vessel enhancement observation based on the image signals B, G, and R. Since the image signal B in the blood vessel-enhanced observation mode contains information on the narrow-band light N2 in addition to the B component of the white light (including a part of the narrow-band light N1 and the fluorescent FL), the surface blood vessel is formed. It is drawn with high contrast. In lesions such as cancer, blood vessel patterns tend to be higher than in normal tissues, and the blood vessel pattern is characteristic. Therefore, in vascular emphasis observation for the purpose of distinguishing between good and bad tumors, It is preferable that the superficial blood vessels are clearly visualized. Further, since the image signal G contains a lot of information on the mesopelagic blood vessels, the image signal G is subjected to contour enhancement processing or the like to emphasize the mesopelagic blood vessels.

Since the display image for blood vessel-enhanced observation is generated based on the three-color image signals B, G, and R as in the case of normal observation, the observation site can be displayed in full color, but the blood vessel-enhanced observation can be performed. The image signal B in the mode has a higher density of blue than the image signal B in the normal observation mode. Therefore, when a display image for blood vessel-enhanced observation is generated, color correction is performed so that the color tone is the same as that of the display image for normal observation. The image processing unit 58 generates a display image (observation image PE) for blood vessel enhancement observation every time the image signals B, G, and R in the frame memory 59 are updated. In the observation image PE, the observation site is displayed in full color as in the observation image P, but the surface blood vessel 61 and the mesopelagic blood vessel 62 are visualized and highlighted with high contrast as compared with the observation image P.

In the blood vessel-enhanced observation mode, in addition to the white light, the narrow-band light N2 output by the second light source module 32 is irradiated to the observation site to perform imaging. Since there is a large difference in the light transmission characteristics of the light guides 43A and 43B for the narrow band light N2 (see FIG. 12), the image processing unit 58 determines whether the output source of the image signal is the endoscope 11A or the endoscope. The content of the image processing is changed according to whether it is 11B.

As shown in FIG. 13A, the above-mentioned image processing is performed on the image signal output from the endoscope 11A having a high light transmittance for the narrow band light N2. On the other hand, as shown in FIG. 13B, for the image signal output from the endoscope 11B having a low light transmission rate for the narrow band light N2, the image processing unit 58 receives the endoscope 11A. In addition to the image processing for the image, contrast enhancement processing is performed. Since the image signal corresponding to the narrow band light N2 is the blue image signal B, the contrast enhancement process is executed for the image signal B.

As shown in FIG. 14, the image processing unit 58 obtains a density histogram for the image signal B when performing the contrast adjustment processing. As is well known, the density histogram is a graph in which the pixel value (luminance value) is plotted on the horizontal axis and the frequency is plotted on the vertical axis. The surface blood vessel 61 and the mesopelagic blood vessel 62 are depicted in the image PB corresponding to the image signal B.

Since the narrow band light N2 has a wavelength range of 405 nm, which has a high extinction coefficient of hemoglobin, the amount of reflected light is small and the pixel value is low in the regions of the surface blood vessel 61 and the mesopelagic blood vessel 62. On the other hand, since the region where no blood vessel does not exist is not absorbed by hemoglobin, the amount of reflected light is large and the pixel value is high. Therefore, in the image PB, the concentration of the surface blood vessel 61 and the mesopelagic blood vessel 62 is higher than that of the region in which the surrounding blood vessels do not exist.

Further, since the narrow band light N2 has a wavelength region in the blue region, the scattering is strong and the depth of penetration is low, so that the amount of light reaching the mesopelagic blood vessel 62 is small and the absorption in the surface blood vessel 61 is large. In the image PB, the concentration of the surface blood vessel 61 is higher than that of the mesopelagic blood vessel 62. The density histogram of the image PB has three peaks, that is, the peak a of the surface blood vessel 61, the peak b of the mesopelagic blood vessel 62, and the peak c of the mucous membrane in which no blood vessel exists, in descending order of density (decreased pixel value).

The image signal B output by the endoscope 11B has a smaller amount of light of the narrow band light N2 as compared with the endoscope 11A. This appears in the density histogram as the difference in the dynamic range DR, which is the width of the maximum value (max) and the minimum value (min) of the pixel value. The dynamic range DR of the image PB obtained by the endoscope 11B is narrower than the dynamic range DR of the image PB obtained by the endoscope 11A.

The image processing unit 58 has an internal memory such as a ROM, and the gradation correction table 58a is stored in the internal memory. The gradation correction table 58a has a gradation correction curve in which the horizontal axis represents an input value and the vertical axis represents an output value, and the correspondence between the input value and the output value is shown. In order to increase the contrast, the low density portion of the original image before processing may have a lower density, and the high density portion may have a higher density. Therefore, the image processing unit 58 performs the contrast enhancement processing. Gradation correction is performed based on the substantially S-shaped gradation correction curve shown in FIG. 14, and the dynamic range DR of the image PB is widened. As a result, the concentration difference between the blood vessel region and the region where the blood vessel does not exist is widened, and the contrast of the blood vessel is improved. Since the image PB contains a large amount of information on the surface blood vessel 61, the contrast of the surface blood vessel 61 is particularly improved.

By performing such a contrast enhancement process, the contrast of the surface blood vessels is improved in the image signal B output by the endoscope 11B. As a result, the shortage of the narrow band light N2 in the endoscope 11B is compensated.

In this example, as a method for generating a display image for observing enhanced blood vessels, a full-color image is generated using three-color image signals B, G, and R, but a method other than this method may be used, for example. The image signal B is generated in only two colors of the image signals B and G without using the image signal R, and the image signal B is used for the B channel and the G channel of the monitor 14, and the signal corresponding to the image signal G is used for the R channel of the monitor 14. A method of displaying the observed part in pseudo color, such as a method of allocating, may be adopted.

Hereinafter, the operation of the above configuration will be described with reference to the flowchart of FIG. When performing endoscopic diagnosis, the endoscope 11 is connected to the processor device 12 and the light source device 13 with a connector 28, the processor device 12 and the light source device 13 are turned on, and the electronic endoscope system 10 is started. do.

The insertion portion 16 of the endoscope 11 is inserted into the gastrointestinal tract of the subject, and observation in the gastrointestinal tract is started. In the normal observation mode, as shown in FIG. 8A, the first light source module 31 is turned on. White light, which is a mixture of the narrow band light N1 emitted by the laser diode LD1 and the fluorescent FL emitted by the phosphor 36, is supplied to the endoscope 11. The supplied light is guided to the illumination window 22 through the light guide 43 and irradiates the observation site.

As shown in FIGS. 8A and 12, the observation site is imaged by the image pickup device 44 while irradiating with white light (N1 + FL), and the image signals of B, G, and R are generated by the DSP 57. In the normal observation mode, the image processing unit 58 generates a display image for normal observation based on the image signals of B, G, and R. The display control circuit 60 converts the generated display image into a video signal and displays the observation image P on the monitor 14. In the normal observation mode, such a process is repeated.

In the normal observation mode, only the white light emitted by the first light source module 31 is used as the illumination light. Since the difference in the light transmission rate of white light is small between the light guide 43A of the endoscope 11A and the light guide 43B of the endoscope 11B, the image processing unit 58 does not distinguish the output source of the image signal. The same image processing is applied to both. Since the same observation image can be obtained regardless of whether the endoscope 11A or the endoscope 11B is used, the operator can use either the endoscope 11A or the endoscope 11B without any problem. can.

When performing blood vessel-enhanced observation, a mode switching operation is performed by the console 15, and the processor device 12 is set to the blood vessel-enhanced observation mode. As shown in FIG. 15, in the blood vessel emphasis observation mode, the light source control unit 34 first acquires the endoscope ID from the ID memory 47 of the endoscope 11 via the processor device 12 (S101). The controller 56 identifies whether the connected endoscope 11 is either the endoscope 11A or the endoscope 11B based on the acquired endoscope ID (S102), and performs image processing on the model information. It is transmitted to the unit 58.

The image processing unit 58 changes the content of image processing according to the model information (S103). When the model information is the endoscope 11A, as shown in FIG. 13A, image processing is performed based on the image signals B, G, and R to generate a display image. When the model information is the endoscope 11B, contrast adjustment processing is performed on the image signal B as shown in FIG. 13 (B) (S104). Then, a display image is generated based on the processed image signal B and the image signals G and R. As a result, the same observation image PE can be obtained regardless of whether the endoscopes 11A or 11B are used. Such processing is repeated until the blood vessel enhancement observation mode ends (S105).

In the above embodiment, a light source (second light source module 32) that emits narrow band light N2 having a wavelength of 405 nm and a white light source (first light source module 31) are used as the light source of the blood vessel enhancement observation mode for superficial blood vessel enhancement. The narrow band light N2 has been described with an example of using the G component of white light for enhancing mid-deep blood vessels, but as shown in FIG. 16, instead of or in addition to the white light source, for enhancing mid-deep blood vessels. A light source that emits narrow-band light N3 (green narrow-band light having a wavelength of about 530 to 560 nm) may be used.

Further, as a white light source, a light source composed of a light emitting element that emits blue excitation light and a phosphor that emits yellow fluorescence has been described as an example. However, as a white light source, a light emitting element that emits blue excitation light and red light emission are described. It may be composed of two light source elements of the element and a phosphor that emits green fluorescence, or may be composed of three color light source elements of blue, green, and red without using a phosphor.

In the above embodiment, blood vessel-enhanced observation has been described as an example of blood vessel-enhanced observation. However, in addition to blood vessel-enhanced observation, oxygen saturation of blood is calculated and imaged for observation. There is saturation observation. The present invention can also be applied to oxygen saturation observation.

Illumination light for observing oxygen saturation includes, for example, light having a difference in absorption coefficient between oxidized hemoglobin and reduced hemoglobin such as light having a wavelength of 445 nm or 473 nm, and light having a wavelength of 405 nm and reduced to oxidized hemoglobin. Light at an isosbestic point with the same absorption coefficient of hemoglobin is used. Then, an operation is performed between a plurality of images acquired at each wavelength to calculate the oxygen saturation. In the inter-image calculation, a coefficient or the like used for the calculation is set on the premise that the ratio of the amount of emitted light of the light of each wavelength is maintained at a predetermined ratio. Therefore, it is not preferable that the ratio of the amount of emitted light changes depending on the model of the endoscope. Therefore, the accuracy of the inter-image calculation can be improved by performing the contrast enhancement processing for compensating for the decrease in the amount of light of the narrow band light N2 (405 nm) in the endoscope 11B.

Further, in oxygen saturation observation, as an example, three or more types of light having different wavelengths are used, but in blood vessel emphasis observation, in addition to blue light and green light, the wavelength is increased to emphasize deeper blood vessels. In some cases, three or more types of light are used, such as using long red light. The present invention may be applied when three or more types of light are used.

In the above embodiment, as a plurality of types of endoscopes, an existing endoscope and an improved endoscope having improved light transmission characteristics of the light guide in the blue region have been described as an example, but the existing endoscope and the existing endoscope have been described. The improved endoscope is an example. Not limited to this, in the present invention, the plurality of types of endoscopes are a plurality of endoscopes having a built-in light guide having different light transmittances for at least one of the two types of light for observing blood vessel information. good.

In the above embodiment, the laser diode has been described as an example of the semiconductor light source, but other semiconductor light sources such as LEDs may be used. Further, the present invention combines a white light source that emits white light having a wide wavelength range from blue to red, such as a xenon lamp and a halogen lamp, and a rotary filter having transparency in a specific wavelength range such as narrow band light N2. It can also be applied to an endoscopic system that produces light for observing vascular information.

However, in the spectral spectrum of white light emitted by a xenon lamp, a halogen lamp, or the like, the light intensity in a wavelength region close to the ultraviolet region, such as narrow band light N2 (wavelength is about 405 nm), is often relatively low. Therefore, when observing blood vessel information using the narrow band light N2, it is preferable to use a semiconductor light source, and the present invention is particularly effective when such a semiconductor light source is used.

Further, in the above embodiment, the contrast enhancement processing is performed on the image signal B corresponding to the narrow band light N2 in the blue region, but the light transmittance of the light guide is a wavelength other than the blue region such as the green region. If it decreases in a region, contrast enhancement processing may be performed on the image signal for that wavelength region. Further, regarding the light transmittance of the light guide, when there is a large difference in the light transmittance in a plurality of wavelength regions such as a blue region and a green region, contrast enhancement processing is performed on the image signal corresponding to each wavelength region. You may do it.

However, as shown in the above embodiment, the present invention is particularly necessary when narrow band light in the blue region is used as the light for observing blood vessel information. The reason is as follows. As shown in FIG. 5, in the absorption spectrum of hemoglobin, the change in the absorption coefficient is steeper in the blue region as compared with the green region. Therefore, the light in the blue region for enhancing the surface blood vessels is preferably narrow-band light having a narrower wavelength range than the light in the green region for enhancing the mesopelagic blood vessels. The narrower the wavelength range, the lower the amount of light. In addition, if the light transmittance is low in the blue region of the light guide, the amount of light will be further reduced. The greater the shortage of the amount of light, the higher the need to compensate for the decrease in contrast by the contrast enhancement process as in the present invention. Therefore, the present invention is particularly effective when observing blood vessel information using narrow band light in the blue region with an endoscope having a light guide having a low light transmittance in the blue region.

Further, the contrast enhancement process may be an edge enhancement process that detects and enhances the edges of blood vessels in the image in place of or in addition to the gradation correction process.

Further, in the above embodiment, the content of the image processing is changed only based on the model information of the endoscope, but the content of the image processing is changed when the following conditions are satisfied in addition to the model information. You may. Even when the endoscope 11B is connected, if the output of the second light source module 32 that emits the narrow band light N2 can be increased as compared with the case where the endoscope 11A is connected, the narrow band light N2 by the light guide 43B can be increased. It is possible to compensate for the decrease in the amount of emitted light. Therefore, when the endoscope 11B is connected, first, in the light source device 13, the output of the second light source module 32 is increased so as to be the same as the amount of emitted light when the endoscope 11A is connected. Then, when the output of the second light source module 32 reaches the upper limit value and the output cannot be further increased, the content of the image processing is changed.

In the above embodiment, a simultaneous method of simultaneously acquiring images of a plurality of colors by color-separating white light with a micro color filter using a color image pickup element provided with B, G, and R micro color filters will be described as an example. However, it may be applied to the surface sequential method in which images of each color are sequentially acquired by using a monochrome image pickup element provided with no color filter.

In the above embodiment, the example in which the light source device and the processor device that performs image processing are configured separately has been described, but the two devices may be integrally configured. The present invention may also be applied to other forms of endoscope systems, such as a system consisting of an ultrasonic endoscope having an image pickup element and an ultrasonic transducer built in at the tip thereof and a processor device that performs image processing. can.

10 Endoscope system 11, 11A, 11B Endoscope 12 Processor device (image processing device)
13 Light source device 28 Connector 31 First light source module 32 Second light source module 34 Light source control units 42a, 42b Receptacle connector (connection part)
43, 43A, 43B Light guide 47, 47A, 47B ID memory 56 controller (endoscope identification unit)
58 Image processing unit 58a Gradation correction table LD1, LD2 Laser diode

Claims (13)

The first and second light guides for guiding the illumination light that illuminates the observation site in the living body, and the first and second light guides with different light transmittances for the light for observing blood vessel information are built-in, respectively. A connection that interchangeably connects the first and second endoscopes
An endoscope identification unit that identifies whether the type of endoscope connected to the connection unit is the first or second endoscope, and an endoscope identification unit.
It is an image processing unit that performs image processing on the image signals output by each of the first and second endoscopes, and is connected to the connection unit in the blood vessel enhancement observation mode using light for observing blood vessel information. An image processing unit that changes the content and performs the image processing based on the difference in the light transmission rate depending on whether the type of the endoscope is the first endoscope or the second endoscope. An endoscopic system characterized by being equipped with. The endoscope system according to claim 1, wherein the image processing is a contrast adjustment processing. The endoscope system according to claim 1, wherein the image processing is a gradation correction processing. The endoscope system according to claim 1, wherein the image processing is an edge enhancement processing. The endoscope system according to claim 1, wherein the image processing is a processing for widening a density difference between a blood vessel region and a region where no blood vessel exists. The endoscope system according to any one of claims 1 to 5, wherein the image processing includes pseudo color processing. A first light source module that emits white light including first light in a blue region and fluorescence emitted by irradiating a phosphor with the first light.
It is equipped with a second light source module that emits second light in a wavelength region close to the ultraviolet region.
The light for observing blood vessel information includes at least one of a green component light contained in the light emitted by the first light source module and a blue component light contained in the light emitted by the second light source module. 6. The endoscope system according to any one of 6. A white light source composed of three color semiconductor light sources, blue, green, and red,
It is equipped with a second light source composed of a semiconductor light source that emits second light in a wavelength region close to the ultraviolet region.
The light for observing blood vessel information includes at least one of a green component light contained in white light emitted by the white light source and a blue component light contained in light emitted by the second light source, according to claims 1 to 6. The endoscopic system according to any one of the following items. The endoscope system according to claim 8, wherein the semiconductor light source is an LED. The endoscope system according to any one of claims 7 to 9, wherein the second light is blue light having a wavelength of 430 nm or less. The endoscope system according to any one of claims 7 to 10, wherein the blue light has a wavelength of 410 ± 10 nm. The endoscope system according to any one of claims 7 to 11, wherein the white light includes green light having a wavelength in the wavelength range of 530 nm to 560 nm. The endoscope system according to any one of claims 1 to 12, wherein the first and second light guides are fiber bundles in which optical fibers are bundled.

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