JP6694046B2 - Endoscope system - Google Patents

Description

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

  In the medical field, endoscopic diagnosis using an endoscopic system has become widespread. An endoscope system is an endoscope that has an insertion portion that is inserted into a living body and that has an image sensor and an illumination window at its tip, a light source device that supplies light to the endoscope, and an image signal that the image sensor outputs. And 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 applied to the observation site.

  In recent years endoscopic diagnosis, in addition to normal observation of observing the overall properties of the surface of living tissue under normal light that is white light, special light using special light limited to a specific wavelength is used. Light observation is also being conducted. There are various types of special light observation, but for example, by utilizing the optical characteristics of biological tissue that the depth of penetration from the mucosal surface varies depending on the wavelength, surface blood vessels that exist near the mucosal surface layer and BACKGROUND ART Blood vessel emphasis observation is known in which medium to 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 is different from that of normal tissues in abnormal tissues such as cancers that occur in living tissues, the blood vessel emphasis observation has been found to be useful for the detection of early cancer.

  The absorption coefficient of hemoglobin in blood has wavelength dependence, and it rapidly increases in a wavelength region of about 450 nm or less, and has a peak near 405 nm in the blue region. Further, although it has a low value as compared with a wavelength of 450 nm or less, it also has a peak in the wavelength range of about 530 nm to 560 nm in the green region. When an observation site is irradiated with light having a wavelength with a large extinction coefficient, the blood vessel absorbs a large amount of light, so that an image with a high contrast between the blood vessel and other portions can be obtained. Therefore, in the endoscope system of Patent Document 1, blue light in the wavelength range of approximately 390 to 445 nm is used for surface layer blood vessel enhancement, and green light in the wavelength range of approximately 530 to 550 nm is used for mid-deep layer blood vessel enhancement. By utilizing this, a blood vessel-enhanced image that emphasizes each of the superficial blood vessels and the medium-deep blood vessels is acquired.

  In the endoscope system described in Patent Document 1, a white light source such as a xenon lamp is combined with a rotating filter having a light transmitting property for blue and green wavelength ranges to generate blue light and green light. .. Further, Patent Document 1 discloses a technique of performing color tone calibration by photographing a color reference object with an endoscope and adjusting a gain of an image signal for each obtained color (paragraph 0035). , 0036). According to this, even when there is a difference in the transmission characteristics of the optical system depending on the model of the endoscope, it is possible to obtain an image with an appropriate color tone 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 greater the amount of blue light or green light, the higher the contrast of blood vessels. If a semiconductor light source is used, a higher output can be obtained as compared with the xenon lamp of Patent Document 1, so that a high-contrast image can be easily obtained.

JP, 2005-131130, A JP, 2011-041758, A

  However, as a result of examining the light transmission characteristics of the light guide of the existing endoscope, as shown in FIG. 17, the light transmission in the short wavelength region is lower than that in the long wavelength region, and in particular, the wavelength is about 430 nm or less. It was found that the light transmittance dropped sharply in the blue region. When 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, development of an improved endoscope having a light guide with improved light transmittance in the blue region is under study.

  Even when developing an improved endoscope, considering the convenience of the user who has the existing endoscope (operator who performs endoscopy), the improved endoscope and the existing endoscope are 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 differ, the amount of emitted light varies depending on the model of the endoscope. In normal observation, the brightness is reduced only in part of the wide wavelength range from blue to red, so there is little effect, but in the case of blood vessel emphasis observation, since monochromatic light such as blue light or green light is used, A 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 is a main observation target.

  Patent Documents 1 and 2 do not specify or suggest such problems and their solutions. Patent Document 1 discloses a technique of performing color tone calibration by adjusting a 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 for increasing the brightness of the entire screen including a bright part and a dark part in one screen for a blue image signal.

  The present invention has been made in view of the above problems, and an object thereof is to perform blood vessel emphasis observation using multiple types of endoscopes having different optical characteristics of a light guide, even in observation images taken by each. , To obtain similar blood vessel contrast.

The endoscope system of the present invention includes a first light source module that emits white light including first light in the blue region and fluorescence emitted by irradiating the phosphor with the first light, and a wavelength region near the ultraviolet region. A second light source module that emits the second light, and first and second light guides for guiding the illumination light that illuminates the observation site in the living body, and the green component light included in the light that the first light source module emits. , And the first and second light guides each having a different light transmittance with respect to the light for vascular information observation including at least one of the blue component light included in the light emitted from the second light source module. And an endoscope identification for identifying which one of the first and second endoscopes is the type of the endoscope connected to the connection portion, the connection portion connecting the second endoscope in a replaceable manner. And images output by the first and second endoscopes, respectively An image processing unit that performs image processing on signals, in contrast vessel observation mode using the light for a blood vessel information observed, compensating the difference of the light transmittance with respect to one of the first and second endoscopes And an image processing unit that performs image processing for performing the above.

  The image processing is preferably contrast adjustment processing.

  The image processing is preferably gradation correction processing.

  The image processing is preferably edge enhancement processing.

  The image processing is preferably processing 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.

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

  The blue light preferably has a wavelength of 410 ± 10 nm.

The white light preferably includes green light having a wavelength range of 530 nm to 560 nm.

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

  According to the present invention, even when performing blood vessel emphasis observation using a plurality of types of endoscopes having different optical characteristics of the light guide, it is possible to obtain the same blood vessel contrast in the observation images captured by the endoscopes.

It is an external view of the endoscope system of this invention. It is a front view of the front-end | tip part of an endoscope. It is a block diagram which shows the electric constitution of an endoscope system. It is a graph which shows the spectrum of illumination light. It is a graph which shows the absorption spectrum of hemoglobin. It is a graph which shows the scattering coefficient of biological tissue. It is a graph which shows the spectral characteristic of the color micro filter of an image sensor. It is explanatory drawing which shows the irradiation timing of illumination light, and an imaging timing. 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 a drive current value and the amount of emitted light. It is explanatory drawing which shows the image processing procedure in 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 contrast adjustment processing. It is a flow chart which shows the image processing procedure in blood vessel emphasis observation mode. It is explanatory drawing which shows another aspect of the light for a 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 according to the first embodiment of the present invention includes an endoscope 11 that images an observation site in a living body, and an observation image of the observation site based on a signal obtained by the imaging. And a light source device 13 that supplies the endoscope 11 with light that illuminates an observation site, and a monitor 14 that displays an observation image. 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 has a normal observation mode for observing an observation site under white light, and a blood vessel emphasis observation mode for highlighting blood vessels existing in the observation site by using special light. The blood vessel emphasis observation mode is a special light observation mode for recognizing properties such as blood vessel patterns and making a diagnosis such as good or bad discrimination of a tumor, and as a special light, it is used in a wavelength range where the absorbance of blood hemoglobin is high. Narrow band light is used.

  The endoscope 11 includes an insertion portion 16 to be inserted into the digestive tract of a subject, an operation portion 17 provided at a proximal end portion of the insertion portion 16, an operation portion 17, a processor device 12, and a light source device 13. And a universal cord 18 connecting the two.

  The insertion portion 16 is composed of a distal end portion 19, a bending portion 20, and a flexible tube portion 21, which are sequentially provided from the distal end. As shown in FIG. 2, on the tip surface of the tip portion 19, in order to wash the illumination window 22 for illuminating the observation site with illumination light, the observation window 23 through which the image light reflected by the observation site enters, and the observation window 23. An air / water supply nozzle 24 for performing air / water supply, a forceps outlet 25 for projecting a treatment tool such as forceps or an electric scalpel, and the like are provided. An image sensor 44 (see FIG. 3) and an optical system for image formation are built in the back of the observation window 23.

  The bending portion 20 is composed of a plurality of bending pieces connected to each other, and by operating the angle knob 26 of the operation portion 17, the bending portion 20 is bent in the vertical and horizontal directions. By bending the bending portion 20, the direction of the tip portion 19 is oriented in a desired direction. The flexible tube portion 21 has flexibility so that it can be inserted into a tortuous duct such as an esophagus or an intestine. In the insertion section 16, a communication cable for communicating a drive signal for driving the image sensor 44 and an image signal output by the image sensor 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 / water supply button for air / water supply operation, a release button for capturing a still image, and the like. There is.

  A communication cable extending from the insertion portion 16 and a light guide 43 are inserted into the universal cord 18, and a connector 28 is attached to the processor device 12 and the light source device 13 side at one end. The connector 28 is a composite type connector including a communication connector 28a and a light source connector 28b. The communication connector 28a is provided with one end of a communication cable, and the communication connector 28a is detachably connected to the receptacle connector 42a (see FIG. 3) of the processor device 12. The light source connector 28b is provided with the incident end of the light guide 43, 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 controller 34 for driving and controlling these. The light source control unit 34 controls the drive timing and synchronization timing 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 respectively emit narrowband light in a specific wavelength range. As shown in FIG. 4, the laser diode LD1 emits the narrow band light N1 having a central wavelength of 445 nm, for example, the wavelength range of which is limited to 440 ± 10 nm in the blue region. In the blue region, the laser diode LD2 emits the narrow band light N2 which is a narrow band light having a wavelength of 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 (waveguide width) capable of achieving high 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 from the laser diode LD1, and emits the fluorescence 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 and emits the fluorescence FL, and transmits the remaining narrow band light N1. The narrow band light N1 that passes through the phosphor 36 is diffused by the phosphor 36. White light is generated by the transmitted narrow band light N1 and the excited fluorescence FL. As the phosphor 36, for example, a YAG-based, BAM (BgMgAl ₁₀ O ₁₇ ) -based phosphor or the like is used. Two first light source modules 31 are provided so that the amount of white light increases.

  The second light source module 32 is a light source for emphasizing surface blood vessels. In FIG. 5, which shows the absorption spectrum of hemoglobin in blood, the absorption coefficient μa of hemoglobin in blood has wavelength dependence, sharply increases in the wavelength region of 450 nm or less, and has a peak in the vicinity of 405 nm. There is. Further, although it has a low value as compared with a 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 with a large extinction coefficient μa, absorption is large in the blood vessel, so that an image with a large contrast between the blood vessel and other portions can be obtained. In FIG. 5, an absorption spectrum Hb shows an absorption spectrum of reduced hemoglobin that is not bound to oxygen, and an absorption spectrum HbO2 shows an absorption spectrum of oxygenated hemoglobin that is bound to oxygen.

  Further, as shown in FIG. 6, the light scattering characteristics of the living tissue also have wavelength dependency, and the shorter the wavelength, the larger the scattering coefficient μS. Scattering affects the depth of light penetration into living tissue. That is, the greater the scattering, the more light is reflected in the vicinity of the surface layer of the mucous membrane of living tissue, and the less the light reaches the middle and deep layers. 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 blood vessel enhancement is selected in consideration of the light absorption characteristics of hemoglobin and the light scattering characteristics of living tissues.

  The narrow-band light N2 of 405 nm emitted from the second light source module 32 has a low depth of penetration and is largely absorbed by the surface blood vessels, and thus is used as light for emphasizing surface blood vessels. By using the narrow band light N2, the superficial blood vessel can be drawn with high contrast in the observation image. The green component of the white light emitted from the first light source module 31 is used as the light for emphasizing the middle and deep blood vessels. In the absorption spectrum shown in FIG. 5, as compared with the blue region of 450 nm or less, in the green region of 530 nm to 560 nm, the absorption coefficient changes gently. Is not required. Therefore, as will be described later, a green component color-separated from white light is used by the G color micro color filter of the image sensor 44.

  The light source controller 34 turns on and off the laser diodes LD1 and LD2 and controls the amount of light through the driver 37. Specifically, the light source controller 34 turns on the laser diodes LD1 and LD2 by applying a drive pulse to the laser diodes LD1 and LD2. Then, by performing the 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 that changes the amplitude of the drive pulse.

  A branch type light guide 41 is provided on the downstream side of the optical paths of the first and second light source modules 31 and 32. The branch type 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 entrance end, each module is provided in a stage before the light of the first and second light source modules 31 and 32 is supplied to the endoscope 11 by the branched light guide 41. The light paths of the light of 31, 32 are integrated. The branch type light guide 41 has branch parts 41a to 41c whose entrance ends are branched into a plurality of parts, and emits the light entered from each of the branch parts 41a to 41c from one exit end 41e.

  The two first light source modules 31 are arranged so as to face the incident surfaces of the branch portions 41a and 41b of the branched light guide 41, respectively, and the second light source module 32 faces the incident surface of the branch portion 41c. Will 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 exit end 41e is provided with a homogenizer 50 that homogenizes the light amount distribution in the cross section of the light flux, and the light of the first and second light source modules 31 and 32 incident on the branch type light guide 41 is homogenized by the homogenizer 50. Is supplied to the light guide 43 of the endoscope 11 arranged in the connector 28b.

  The endoscope 11 includes a light guide 43, an image pickup device 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 emission end of the homogenizer 50 of the light source device 13. .. The emission end of the light guide 43 is branched into two in front of the illumination window 22 so that light is guided to the two illumination 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 site. The irradiation lens 48 is 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 area of the observation site.

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

  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 forming pixels such as photodiodes are arranged in a matrix. The image pickup device 44 photoelectrically converts the light received by the image pickup surface 44a, and accumulates signal charges corresponding to the respective received light amounts in each pixel. The signal charges are converted into voltage signals by the amplifier and read out. The voltage signal is output from the image sensor 44 as an image signal, and the image signal is sent to the AFE 45.

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

  As shown in FIG. 8, in the normal observation mode, the image pickup device 44 performs the accumulation operation of accumulating the signal charges and the reading operation of reading 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 synchronization with the accumulation timing, and white light including the narrow band light N1 and the fluorescent light FL is irradiated to the observation site as illumination light. The reflected light enters the image sensor 44. In the image sensor 44, the white light is color-separated by the 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 light FL is detected by the G pixel. The R pixel receives the reflected light corresponding to the R component. The image sensor 44 sequentially outputs the image signals B, G, and R for one frame in which the pixel values of B, G, and R pixels are mixed in accordance with the read timing in accordance with the frame rate. 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, white light (N1 + FL) composed of the narrow band light N1 and the fluorescence FL is emitted to the observation site as illumination light, as in the normal observation mode. When the second light source module 32 is turned on, the narrow band light N2 is added to the white light (N1 + FL), and these are radiated to the observation site as illumination light.

  Similar to the normal observation mode, the illumination light in which the narrow band light N2 is added to the white light is dispersed by the B, G, and R micro color filters of the image pickup element 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 light FL. The R pixel receives the R component of the fluorescence FL. Also in the blood vessel emphasis observation mode, the image pickup element 44 sequentially outputs the image signals B, G, and R in accordance with the frame rate at the read timing. Such an imaging operation is repeated while the blood vessel emphasis 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 / digital converter (A / D) (all not shown). The CDS performs correlated double sampling processing on the analog image signal from the image sensor 44, and removes noise caused by resetting the signal charge. The AGC amplifies the image signal from which noise has been removed by the CDS. The A / D converts the image signal amplified by the AGC into a digital image signal having a gradation value according to a predetermined number of bits and inputs the digital image signal to the processor device 12.

  The imaging control unit 46 is connected to the controller 56 in the processor device 12, and inputs a drive signal to the imaging element 44 in synchronization with the base clock signal input from the controller 56. The image pickup element 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 that stores an endoscope ID that is identification information for identifying the model and individual body of the endoscope 11, and is composed of a nonvolatile 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. is there.

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

  Comparing the light transmission characteristics A and B, the difference d2 between the respective 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 site. 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 light output of each of the first light source modules 31 and 32. Graphs GA and GB show the relationship between the output of the G component of the white light emitted from the first light source module 31 and the amount of emitted light when the endoscopes 11A and 11B are used, and graphs N2A and N2B show the second It 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, for the G component of the white light emitted from the first light source module 31, the difference Δ1 between the light transmittances TA1 and TB1 of the light guides 43A and 43B corresponding thereto is small, so that the first light source When the output of the module 31 is 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 from 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, and thus 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.

  3 and 9, the processor device 12 includes a controller 56, a DSP (Digital Signal Processor) 57, an image processing unit 58, a frame memory 59, and a display control circuit 60. The controller 56 includes a CPU, a ROM that stores a control program and setting data necessary for control, a RAM that functions as a working memory by loading the program, and the like. To control.

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

  The DSP 57 acquires the image signal output by the image sensor 44. The DSP 57 separates the image signal in which the signals corresponding to the B, G, and R pixels are mixed into the B, G, and R image signals, and performs pixel interpolation processing on the image signals of the respective colors. In addition, the DSP 57 performs signal processing such as gamma correction and white balance correction on 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 of the illumination light is increased so as to increase. If 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 the image-processed image data from the frame memory 59, converts the image data into a video signal such as a composite signal or a component signal, and outputs the video signal 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 by the DSP 57 into B, G, and R colors. (Observation image P) is generated. The generated observation image P is output to the monitor 14. The image processing unit 58 updates the display image every time the image signals B, G, and R in the frame memory 59 are updated. In the observation image P, the entire properties of the observation site such as the mucous membrane, the superficial blood vessel 61, and the mid-deep blood vessel 62 are displayed in full color.

  In the normal observation mode, white light (N1 + FL) output from the first light source module 31 is applied to the observation site and imaging is performed. Since there is no great difference in the light transmission characteristics of the light guides 43A and 43B for white light, the image processing unit 58 performs the same image processing on the image signals output from the endoscopes 11A and 11B. To do.

  As shown in FIG. 13, in the blood vessel emphasis observation mode, the image processing unit 58 generates a display image for blood vessel emphasis observation based on the image signals B, G, and R. Since the image signal B in the blood vessel emphasis observation mode contains the information of the narrow band light N2 in addition to the B component of the white light (including the narrow band light N1 and part of the fluorescence FL), the surface layer blood vessel It is depicted with high contrast. In lesions such as cancers, compared to normal tissues, there is a characteristic of the blood vessel pattern such that the density of superficial blood vessels tends to be higher, so in blood vessel emphasis observation for the purpose of distinguishing between good and bad tumors, It is preferable that the superficial blood vessels are clearly drawn. Further, since the image signal G contains a large amount of information on the medium-deep blood vessels, the image signal G is subjected to contour enhancement processing or the like to emphasize the medium-deep blood vessels.

  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, so that the observation site can be displayed in full color. The image signal B in the mode has higher blue density than the image signal B in the normal observation mode. Therefore, when a display image for blood vessel emphasis observation is generated, color correction is performed so that it has the same tint as the display image for normal observation. The image processing unit 58 generates a display image (observation image PE) for blood vessel emphasis 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 as compared with the observation image P, the superficial blood vessel 61 and the mid-deep blood vessel 62 are drawn in high contrast and highlighted.

  In the blood vessel emphasizing observation mode, in addition to white light, the narrow band light N2 output from the second light source module 32 is applied 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 narrowband 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 depending on whether it is 11B.

  As shown in FIG. 13A, the above-described image processing is performed on the image signal output from the endoscope 11A having a high light transmittance with respect to the narrowband light N2. On the other hand, as shown in FIG. 13B, for the image signal output from the endoscope 11B having a low light transmittance for the narrowband light N2, the image processing unit 58 causes the endoscope 11A to operate. In addition to the image processing for, the 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 on 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 horizontal axis represents the pixel value (luminance value) and the vertical axis represents the frequency. In the image PB corresponding to the image signal B, the superficial blood vessel 61 and the medium-deep blood vessel 62 are drawn.

  Since the narrow-band light N2 has a wavelength region of 405 nm in which the absorption coefficient of hemoglobin is high, the amount of reflected light is small and the pixel value is low in the regions of the superficial blood vessel 61 and the medium-deep blood vessel 62. On the other hand, a region where blood vessels do not exist has a large amount of reflected light and a high pixel value because it is not absorbed by hemoglobin. Therefore, in the image PB, the surface layer blood vessel 61 and the medium-deep layer blood vessel 62 have higher densities as compared with the surrounding regions where blood vessels do not exist.

  Further, since the narrow band light N2 has a wavelength range in the blue region, the scattering is strong and the depth of penetration is low. In the image PB, the density of the superficial blood vessel 61 is depicted higher than that of the medium-deep blood vessel 62. The density histogram of the image PB has three peaks in the descending order of density (in order of decreasing pixel value): the peak a of the superficial blood vessel 61, the peak b of the middle-deep blood vessel 62, and the peak c of the mucous membrane without blood vessels.

  The image signal B output from the endoscope 11B has a smaller amount of narrow band light N2 than that of the endoscope 11A. This appears as a difference in the dynamic range DR, which is the width between the maximum value (max) and the minimum value (min) of the pixel values in the density histogram. 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 showing the correspondence between the input value and the output value, with the horizontal axis representing the input value and the vertical axis representing the output value. In order to increase the contrast, the low density portion of the unprocessed original image has a lower density and the high density portion has a higher density. Therefore, the image processing unit 58 performs the contrast enhancement processing as follows. Gradation correction is performed based on the substantially S-shaped gradation correction curve shown in FIG. 14 to widen the dynamic range DR of the image PB. As a result, the density difference between the blood vessel region and the region where no blood vessel exists is widened, and the blood vessel contrast is improved. Since the image PB contains much information on the surface blood vessel 61, the contrast of the surface blood vessel 61 is particularly improved.

  By performing such contrast enhancement processing, in the image signal B output by the endoscope 11B, the contrast of the superficial blood vessels is improved. This compensates for the shortage of the narrowband light N2 in the endoscope 11B.

  In this example, a full-color image is generated using the three-color image signals B, G, and R as a method for generating a display image for blood vessel emphasis observation, but a method other than this method may be used. Without using the image signal R, only the two colors of the image signals B and G are generated, and the image signal B is output to the B channel and G channel of the monitor 14, and the signal corresponding to the image signal G is output to the R channel of the monitor 14. A method of displaying an observed region in pseudo color, such as a method of assigning it, may be adopted.

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

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

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

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

  When performing the blood vessel emphasized observation, a mode switching operation is performed by the console 15, and the processor device 12 is set to the blood vessel emphasized 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 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. 13B (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 which of the endoscopes 11A and 11B is used. Such processing is repeated until the blood vessel emphasis observation mode ends (S105).

  In the above-described embodiment, as a light source in the blood vessel emphasis observation mode, a light source (second light source module 32) that emits a narrow band light N2 having a wavelength of 405 nm and a white light source (first light source module 31) are used for surface layer blood vessel emphasis. Although the narrowband light N2 has been described as an example in which the G component of white light is used for emphasizing the medium-deep layer blood vessel, instead of or in addition to the white light source, as shown in FIG. A light source that emits the narrow band light N3 (green narrow band light having a wavelength of approximately 530 to 560 nm) may be used.

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

  In the above-mentioned embodiment, the blood vessel information observation is described as an example of the blood vessel emphasized observation. However, in the blood vessel information observation, in addition to the blood vessel emphasized observation, the oxygen saturation of the blood is calculated and the oxygen to be observed by imaging it Saturation observation etc. The present invention can also be applied to oxygen saturation observation.

  Illumination light in the observation of oxygen saturation includes, for example, light having a wavelength of 445 nm or 473 nm, which has a difference in absorption coefficient between oxyhemoglobin and reduced hemoglobin, and light having a wavelength of 405 nm, which is reduced with oxyhemoglobin. Light having the same absorption point with the same absorption coefficient of hemoglobin is used. Then, the oxygen saturation is calculated by performing a calculation between the plurality of images acquired at each wavelength. In the inter-image calculation, the coefficient and the like used in the calculation are set on the assumption that the ratio of the emitted light amount of 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 that compensates for the decrease in the light amount of the narrow band light N2 (405 nm) in the endoscope 11B.

  In addition, in oxygen saturation observation, as an example, three or more kinds of light having different wavelengths are used, but in blood vessel emphasis observation, in addition to blue light and green light, a wavelength of more wavelength is used 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 to the case of utilizing three or more kinds of light.

  In the above-described embodiment, as the endoscopes of a plurality of models, the description has been given by taking an existing endoscope and an improved endoscope in which the light transmission characteristics of the light guide in the blue region are improved, as an example. The improved endoscope is one example. Not limited to this, in the present invention, a plurality of types of endoscopes are provided as long as they are a plurality of endoscopes each including a light guide having a different light transmittance with respect to at least one of the two types of light for observing blood vessel information. Good.

  In the above embodiment, the laser diode is described as an example of the semiconductor light source, but other semiconductor light sources such as LEDs may be used. The present invention also combines a white light source, such as a xenon lamp or a halogen lamp, which emits white light having a wide wavelength range from blue to red, and a rotary filter having transparency in a specific wavelength range such as a narrow band light N2. In addition, it can be applied to an endoscope system that generates light for observing blood vessel information.

  However, in the spectral spectrum of white light emitted from a xenon lamp, a halogen lamp, or the like, the light intensity in a wavelength range close to the ultraviolet range, such as narrow-band light N2 (having a wavelength of about 405 nm), is often relatively low. Therefore, when performing blood vessel information observation 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-described embodiment, the example in which the contrast enhancement processing is performed on the image signal B corresponding to the narrow band light N2 in the blue region has been described, but the light transmittance of the light guide such as the green region is at wavelengths other than the blue region. In the case of a decrease in the wavelength range, the contrast enhancement process may be executed on the image signal for that wavelength range. Also, regarding the light transmittance of the light guide, if there is a large difference in light transmittance in a plurality of wavelength regions such as a blue region and a green region, contrast enhancement processing is performed on image signals corresponding to the respective wavelength regions. You may execute.

  However, the present invention is highly necessary especially when narrow band light in the blue region is used as the light for observing blood vessel information, as shown in the above embodiment. 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 than in the green region. Therefore, it is preferable that the light in the blue region for emphasizing the superficial blood vessels is a narrow band light having a narrower wavelength range than the light in the green region for emphasizing the deep blood vessels. When the wavelength range is narrow, the amount of light decreases accordingly. 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 more the light quantity is insufficient, the higher the need for compensating for the decrease in contrast by the contrast enhancement processing according to the present invention. Therefore, the present invention is particularly effective in the case where an endoscope having a light guide having a low light transmittance in the blue region is used to perform blood vessel information observation using narrow band light in the blue region.

  Further, as the contrast emphasis processing, instead of or in addition to the gradation correction processing, edge emphasis processing for detecting and emphasizing the edge of the blood vessel in the image may be performed.

  Further, in the above embodiment, the contents of the image processing are changed only based on the model information of the endoscope, but the contents of the image processing are changed when the following conditions are satisfied in addition to the model information. May be. 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 more than when the endoscope 11A is connected, the narrow band light N2 by the light guide 43B can be emitted. 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 emitted light amount 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-described embodiment, a simultaneous method in which white light is color-separated by the micro color filter and images of a plurality of colors are simultaneously acquired by using the color image pickup device provided with the B, G, and R micro color filters is described. However, it may be applied to a frame sequential method in which images of respective colors are sequentially acquired by using a monochrome image sensor having no color filter.

  In the above embodiment, the light source device and the processor device that performs image processing are separately configured, but the two devices may be integrated. The present invention can also be applied to endoscope systems of other forms, such as a system including an ultrasonic endoscope having an imaging element and an ultrasonic transducer built in the distal end portion thereof and a processor device that performs image processing. it can.

10 Endoscope Systems 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 controller 42a, 42b receptacle connector (connector)
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 (10)

A first light source module that emits white light including first light in the blue region and fluorescent light that is emitted by irradiating the phosphor with the first light;
A second light source module that emits second light in a wavelength range close to the ultraviolet range;
It is the 1st and 2nd light guide for guiding the illumination light which illuminates the observation part in a living body, The light of the green component contained in the light which the said 1st light source module emits, and the said 2nd light source module emits. Replacing the first and second endoscopes respectively having first and second light guides having different light transmittances with respect to the blood vessel information observing light including at least one of the blue component light included in the light Connection part to connect possible,
An endoscope identification unit that identifies which of the first and second endoscopes the type of endoscope connected to the connection unit is,
An image processing unit that performs image processing on image signals output from each of the first and second endoscopes, and in the blood vessel emphasis observation mode using the light for observing the blood vessel information, the first and second An endoscope system comprising: an image processing unit that performs image processing for compensating for the difference in light transmittance with respect to one of the two endoscopes.   The endoscope system according to claim 1, wherein the image processing is contrast adjustment processing.   The endoscope system according to claim 1, wherein the image processing is gradation correction processing.   The endoscope system according to claim 1, wherein the image processing is edge enhancement processing.   The endoscope system according to claim 1, wherein the image processing is processing for widening a density difference between a blood vessel region and a region where blood vessels do not exist.   The endoscope system according to claim 1, wherein the image processing includes pseudo color processing.   The endoscope system according to any one of claims 1 to 6, wherein the second light is blue light having a wavelength of 430 nm or less. 8. The endoscope system according to claim 7 , wherein the blue light has a wavelength of 410 ± 10 nm. The endoscope system according to any one of claims 1 to 8, wherein the white light includes green light having a wavelength range of 530 nm to 560 nm.   The endoscope system according to any one of claims 1 to 9, wherein the first and second light guides are fiber bundles obtained by bundling optical fibers.

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