JP5208223B2 - Endoscope system - Google Patents

Description

  The present invention relates to an endoscope system that performs special light observation using light of two types of specific wavelengths.

  In recent years, endoscope systems that can perform so-called special light observation, such as irradiating a living tissue with light of a specific narrow wavelength band (narrowband light) to obtain an observation image in which blood vessels in the living tissue are emphasized, are known. (For example, refer to Patent Document 1). Since the light absorption spectrum of a blood vessel (hemoglobin) has an absorption peak in a band near 415 nm or 540 nm, this endoscope system has a wavelength in a band with a high light absorption rate near 415 nm as narrowband light. Blue (B) narrow band light and green (G) narrow band light having a wavelength in a band having a high light absorption rate near 540 nm are used as illumination light.

  When narrowband light corresponding to a band where the light absorption rate of blood vessels (hemoglobin) is high is used, in the observation image, the blood vessels are dark because light is absorbed, and they are not absorbed by the surrounding tissues, but are scattered and reflected. To be bright. By narrowing the illumination light, the wavelength outside the band with high light absorptance is removed from the illumination light, so that the components scattered and reflected in the blood vessel portion are reduced, and the contrast between the blood vessel and the surrounding tissue is enhanced. An observed image can be obtained.

  Moreover, since the light scattering characteristics in the living tissue become lower as the wavelength becomes longer, the light having a longer wavelength reaches the deeper layer of the living tissue (the degree of penetration is higher). Therefore, by using two types of narrowband light, blue narrowband light and longer wavelength green narrowband light, an image that emphasizes the surface blood vessels in the surface layer near the surface of the living tissue is obtained by blue narrowband light. By using the green narrow band light, it is possible to obtain an image in which deeper middle-deep blood vessels are emphasized.

  An endoscope system described in Patent Literature 1 includes a white light source and a rotary filter provided with two types of bandpass filters that respectively transmit blue narrow-band light and green narrow-band light. By rotating the, the time-sequential imaging that images two types of narrow-band light observation images in a time-division manner with an image sensor in accordance with the timing when two types of band-pass filters are alternately inserted into the optical path of the white light source The method is adopted. In the frame sequential method, an observation image in which both the surface layer and the middle-deep blood vessel are emphasized is displayed on the monitor by combining the two observed images.

Japanese Patent Laid-Open No. 2001-170009

  However, the frame sequential method described in Patent Document 1 has a problem that it is difficult to increase the frame rate because the observation images using two types of narrowband light are sequentially captured. As a solution to this problem, for example, a circular filter in which two types of filter regions for generating two types of narrow-band light are formed in two semicircular regions each having a half circular region is used as a white light source. A mixed simultaneous irradiation method in which two types of narrowband light are simultaneously irradiated on the optical path and an observation image by each narrowband light is simultaneously acquired has been studied. According to the mixed simultaneous irradiation method, the frame rate can be increased as compared with the frame sequential method.

  However, in the simultaneous irradiation method, since the light emitted from the white light source passes through the two filter regions in half, the amount of light transmitted through each filter region is halved. In the case of foreground observation in which the endoscope is in close proximity to the site to be observed, the distance from the site to be observed is close, so insufficient light intensity is not a problem, but observation is performed at a distance from the site to be observed. In the case of distant view observation, a new problem arises that the amount of light is insufficient and the entire screen becomes dark and difficult to observe.

  There is a method to deal with such a problem by signal processing such as increasing the gain of the signal output of the image pickup device. However, if the gain is increased, the noise increases, so when the signal output is small, the S / N is remarkably high. descend. In special light observation, since image capturing is performed with a small amount of light as compared with normal observation using white light, signal output is often small, and thus it is difficult to adopt a method that deals with signal processing.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a mixed simultaneous irradiation type endoscope system capable of obtaining a good observation image in both foreground observation and distant view observation.

  In order to achieve the above object, an endoscope system according to the present invention includes a broadband light source that emits white broadband light, and first and first wavelength bands that are partially transmitted through the broadband light and used for special light observation. 2 is a filter unit having first and second filter regions for generating two types of narrowband light, each having first and second types of filter regions, and a relatively large amount of transmitted light. A filter unit having a distant view observation filter, a near view observation filter having a relatively small amount of transmitted light, and the first and second filter regions are inserted into the optical path of the broadband light source at the same time. , A filter insertion means for selectively inserting one of the distant view observation filter and the near view observation filter, and an image of the observation site irradiated with the first and second types of narrowband light Characterized by comprising an imaging unit, an that.

  It is preferable that the first and second filter regions of the distant view observation filter have a light transmission characteristic having a half-value width expanded as compared with the first and second filter regions of the near view observation filter. .

  Mode switching means for switching between a normal mode in which the observation site is illuminated by the broadband light and a special mode in which the first and second types of narrow band light are used to illuminate the observation site; Based on the imaging signal acquired by the imaging of the means, imaging is performed in the near-field observation state where the distance between the endoscope distal end and the observed site is close or the distant view observation state where the distance is far An observation state determination unit that determines whether or not the image has been broken, and the filter insertion unit includes the near-field observation filter when the observation state determination unit determines that the observation mode determination unit is in the foreground observation state during the special mode. It is preferable to insert the far view observation filter into the optical path when it is inserted into the optical path and it is determined that the distant view observation state exists.

  The filter insertion means retracts the near view observation filter and the far view observation filter from the optical path in the normal mode, and the imaging means is configured to illuminate with the broadband light in the normal mode. Is preferably imaged.

  The filter unit is a single rotating body including the near view observation filter and the far view observation filter, and the filter insertion means inserts the rotating body into the optical path in the special mode, and Rotating body moving means for retracting the rotator from the optical path in the mode, and the near-view observation filter is inserted in the optical path when the close-up observation state is in the special mode. In some cases, it is preferable to include rotation driving means for rotating the rotating body so that the distant view observation filter is inserted into the optical path.

  The filter unit is a single rotating body including the near-field observation filter, the far-field observation filter, and an opening that transmits the entire area of the broadband light, and the filter insertion unit is configured so that the opening is in the normal mode. The near view observation filter is inserted into the optical path when the special mode is in the near view observation state, and the far view observation filter is inserted into the optical path when the special mode is in the far view observation state. Thus, it is preferable to rotate the rotating body.

  The observation state determination unit detects an exposure amount from an imaging signal acquired by the imaging unit, determines that the foreground observation state is present when the detected exposure amount is equal to or greater than a certain value, and is less than the certain value It is preferable to determine that the camera is in the distant view observation state.

  The first filter region has a light transmission characteristic of transmitting blue narrowband light corresponding to a wavelength band having a large amount of absorption on the short wavelength side of the light absorption spectrum of hemoglobin, and the second filter region has a light transmission characteristic of the absorption spectrum. It is preferable to have a light transmission characteristic of transmitting green narrowband light corresponding to a wavelength band having a large amount of absorption on the long wavelength side.

  The first filter region of the distant view observation filter preferably has a light transmission characteristic that is expanded only on the short wavelength side with respect to the light transmission property of the first filter region of the near view observation filter.

  In the first filter region of the foreground viewing filter, the transmittance peak is around 460 nm, the transmittance sharply decreases on the longer wavelength side than the transmittance peak near 460 nm, and the transmittance is transmitted from 400 nm to 460 nm. The transmittance gradually decreases, and has a light transmission characteristic in which the transmittance sharply decreases below 400 nm. In the second filter region of the foreground viewing filter, the transmittance peak is 550 nm, and the half-value width is It is preferable that it is 20 nm-40 nm.

  In the endoscope system of the present invention, the near view observation filter and the far view observation filter can be selectively inserted into the optical path of the broadband light emitted from the broadband light source. Observation can be performed under illumination light with an optimal amount of light. As a result, a good special light image can be obtained in both the foreground observation and the distant view observation.

It is a perspective view of an endoscope system. It is the block diagram which showed the electric constitution of the endoscope system. It is sectional drawing of a filter turret. It is the graph which showed the light transmission characteristic of the filter for near view observation. It is the graph which showed the light transmission characteristic of the filter for distant view observation. It is the graph which showed the light absorption characteristic of blood (hemoglobin). It is the graph which showed the light-scattering characteristic of the biological tissue. It is a front view of a micro filter. It is explanatory drawing for demonstrating the function of a micro filter. It is the flowchart which showed the flow of the process in special light observation mode. It is explanatory drawing for demonstrating the kind of light photoelectrically converted by CCD at a near view observation mode. It is explanatory drawing which showed an example of the foreground special light image. It is explanatory drawing for demonstrating the kind of light photoelectrically converted by CCD at a distant view observation mode. It is explanatory drawing which showed an example of the special light image for distant views. It is the block diagram which showed the electric constitution of the endoscope system of 2nd Embodiment. It is sectional drawing of the filter turret of 3rd Embodiment. It is the flowchart which showed the flow of rotation control of the filter turret of 3rd Embodiment.

[First Embodiment]
As shown in FIG. 1, an endoscope system 10 includes an electronic endoscope 11 that captures an inside of a patient's digestive tract and trachea (observed site), and an imaging signal obtained by the electronic endoscope 11. Is provided with a processor device 12 for generating an observation image in the tube, a light source device 13 for emitting illumination light for illuminating the inside of the tube to the electronic endoscope 11, and a monitor 14 for displaying the observation image.

  In the endoscope system 10, the inside of the tube is illuminated with broadband light such as white light to observe the entire inside of the tube (normal mode), and the inside of the tube is illuminated with narrow band light to emphasize surface blood vessels. There are two observation modes: a special light observation mode (special mode) for observation in the displayed state. The special light observation mode includes a near-field observation mode in which observation is performed in a close-up state where the distance between the distal end portion of the electronic endoscope 11 and the living tissue in the tube is short, and observation is performed in a distant state where the distance from the living tissue is long. There are two observation modes, a distant view observation mode to be performed.

  The electronic endoscope 11 is connected to a flexible insertion portion 16 to be inserted into a tube and a proximal end portion of the insertion portion 16, and is used for gripping the electronic endoscope 11 and operating the insertion portion 16. And a universal cord 18 for connecting the operation unit 17 to the processor device 12 and the light source device 13, respectively.

  The insertion portion distal end portion 16a that is the distal end portion of the insertion portion 16 incorporates an optical system, an image sensor, and the like that are used for illumination inside the tube and photographing. Further, in addition to the observation window 19 (see FIG. 2) and the illumination window 20 (see FIG. 2), an air / water supply nozzle, which is not shown, is inserted into the distal end surface of the insertion portion distal end portion 16a. A forceps outlet or the like serving as an outlet of the forceps channel is provided. A bendable bending portion 16b is connected to the rear end of the insertion portion distal end portion 16a.

  The operation unit 17 is provided with an angle knob 21, an operation button 22, a forceps inlet 23, and the like. The angle knob 21 is rotated when adjusting the bending direction and the bending amount of the insertion portion 16. The operation button 22 is used for various operations such as air / water supply and suction. The forceps inlet 23 communicates with the forceps channel.

  The universal cord 18 incorporates an air / water channel, a signal cable, a light guide, and the like. A connector portion 25 a is provided at the distal end portion of the universal cord 18. This connector portion 25 a is connected to the light source device 13. Further, the connector part 25b branches from the connector part 25a. This connector portion 25 b is connected to the processor device 12.

  As shown in FIG. 2, the light source device 13 includes a broadband light source 30, a condenser lens 31, a disc-shaped filter turret (filter unit, rotating body) 32, a turret shift mechanism (rotating body moving means) 33, And a turret rotation mechanism (rotation drive means) 34. Here, the turret shift mechanism 33 and the turret rotation mechanism 34 constitute the filter insertion means of the present invention.

  The broadband light source 30 is, for example, a xenon lamp, a white LED, a micro white light source, or the like, and generates white broadband light BB having a wavelength ranging from a red region to a blue region (about 470 to 700 nm). The broadband light source 30 always emits broadband light BB during endoscopic examination.

  The condenser lens 31 is disposed on the optical path of the broadband light BB emitted from the broadband light source 30. The condenser lens 31 makes the light guide 35 receive illumination light (hereinafter simply referred to as illumination light) such as broadband light BB that is directly incident from the broadband light source 30 or narrowband light that is incident through the filter turret 32.

  The filter turret 32 is disposed between the broadband light source 30 and the condenser lens 31 in the special light observation mode. The filter turret 32 transmits specific narrowband light determined for each of the near view observation mode and the distant view observation mode out of the broadband light BB incident from the broadband light source 30.

  As shown in FIG. 3, the filter turret 32 is provided with a half-distance foreground observation filter 37 used in the near-field observation mode and a half-distance foreground observation filter 38 used in the distant-view observation mode. . The near view observation filter 37 and the far view observation filter 38 are provided so as to be symmetrical with respect to a straight line passing through the center of the rotation shaft 32 a of the filter turret 32.

  The foreground viewing filter 37 transmits narrowband light of two different wavelength bands used in the foreground viewing mode of the broadband light BB. The foreground viewing filter 37 includes a first blue filter area (first filter area) Bn1f and a first green filter area (second filter area) Gn1f.

  The distant view observation filter 38 transmits narrow band light of two different wavelength bands used in the distant view observation mode out of the broadband light BB. The distant view observation filter 38 includes a second blue filter area (first filter region) Bn2f and a second green filter area (second filter region) Gn2f.

  As shown in FIG. 4, the first blue filter area Bn1f transmits blue narrowband light (hereinafter referred to as first blue narrowband light) Bn1 limited to a specific wavelength band of blue among the broadband light BB. . The first green filter area Gn1f transmits the narrowband light (hereinafter referred to as the first green narrowband light) Gn1 limited to the specific wavelength band of green among the broadband light BB. The first blue narrowband light Bn1 corresponds to the first narrowband light of the present invention, and the first green narrowband light Gn1 corresponds to the second narrowband light of the present invention.

  The first blue narrow-band light Bn1 matches the absorption peak of the light absorption spectrum of hemoglobin, for example, the light amount reaches a peak value as shown by the light transmittance in the figure at a wavelength of around 460 nm, and around 460 nm. On the longer wavelength side, the amount of light sharply decreases, and the amount of light becomes substantially “0” between about 460 nm and about 500 nm. On the other hand, on the shorter wavelength side than near 460 nm, the amount of light decreases from near 460 nm to near 400 nm, but the light amount becomes “0” when it falls below near 400 nm, although it is not as sharp as the decrease in the light amount on the long wavelength side. . Further, the half width hB1 of the first blue narrow band light Bn1 is, for example, about 35 nm to 45 nm. In addition, the half value width here is a wavelength band of a value indicating the half of the peak value of the light transmittance (hereinafter referred to as peak half value).

  The first green narrow-band light Gn1 matches the absorption peak of the absorption spectrum of the hemoglobin light, for example, the light amount reaches a peak value near the wavelength of 550 nm, and is shorter than the vicinity of 540 nm and longer than the vicinity of 560 nm. On the wavelength side, the amount of light sharply decreases to “0”. In addition, the half-value width hG1 of the first green narrowband light Gn1 is, for example, about 20 nm to 40 nm.

  As shown in FIG. 5, the second blue filter area Bn2f transmits the second blue narrowband light Bn2 whose half-value width is wider than that of the first blue narrowband light Bn1 in the broadband light BB. In addition, the second green filter area Gn2f transmits the second green narrowband light Gn2 whose half-value width is wider than that of the first green narrowband light Gn1 in the broadband light BB. The second blue narrowband light Bn2 corresponds to the first narrowband light of the present invention, and the second green narrowband light Gn2 corresponds to the second narrowband light of the present invention.

  Similar to the first blue narrow band light Bn1, the light intensity of the second blue narrow band light Bn2 rapidly decreases on the longer wavelength side than the vicinity of 460 nm where the light quantity reaches the peak value. On the other hand, on the shorter wavelength side than near 460 nm, unlike the first blue narrow band light Bn1, the light amount gradually decreases while maintaining a relatively high light amount between about 460 nm and about 400 nm. Then, the light amount starts to decrease rapidly in the vicinity of 400 nm, and the light amount becomes “0” when it falls below the vicinity of 400 nm.

  Further, the half width hB2 of the second blue narrow band light Bn2 is, for example, about 75 nm to 95 nm. The longest wavelength of the peak half value of the second blue narrow band light Bn2 is substantially the same as the shortest wavelength of the first blue narrow band light Bn1, whereas the shortest wavelength of the peak half value is the shortest wavelength of the first blue narrow band light Bn1. Is shorter. Accordingly, the second blue narrow band light Bn2 is light in which the light quantity on the short wavelength side is not substantially changed from the vicinity of 460 nm and the light quantity on the short wavelength side is increased compared to the first blue narrow band light Bn1.

  The second green narrowband light Gn2 reaches a peak value in the vicinity of 550 nm in the same manner as the first green narrowband light Gn1, whereas the half-value width hG2 is wider than the first green narrowband light Gn1. For example, it is about 50 to 70 nm. For this reason, the amount of light of the second green narrowband light Gn2 is increased by the amount by which the half-value width is expanded compared to the first green narrowband light Gn1.

  The reason why the first blue narrow-band light Bn1 and the second blue narrow-band light Bn2 have the light quantity distributions shown in FIGS. 4 and 5, respectively, is as follows. In FIG. 6 showing the absorption characteristics of hemoglobin, light having a wavelength lower than about 460 nm of the irradiated light is very strongly absorbed by blood (hemoglobin) in the surface blood vessel in the living tissue, but conversely, near 460 nm. Light exceeding this value is transmitted as it is without being almost absorbed by hemoglobin.

  On the other hand, in FIG. 7 showing the scattering characteristics of the living tissue, the irradiated light is more scattered in the living tissue as the wavelength becomes shorter. From the knowledge about the light scattering characteristics of the living tissue, most of the irradiated light is absorbed by the surface blood vessel and does not return to the insertion portion tip 16a unless the wavelength of the irradiated light exceeds about 470 nm. On the contrary, in the living tissue around the superficial blood vessel, most of the irradiated light is reflected by the relatively strong scattering characteristics and returns to the insertion portion distal end portion 16a. As a result, the contrast between the superficial blood vessel and the surrounding biological tissue becomes extremely high, so that the superficial blood vessel and the like can be sufficiently highlighted.

  In order to sufficiently highlight the superficial blood vessels and the like in this way, light with a light amount of “0” is irradiated in a wavelength region exceeding about 470 nm in both the near view observation and the distant view observation. Is essential. On the other hand, if it does not exceed about 470 nm, the superficial blood vessels and the like can be sufficiently highlighted. Therefore, the first blue narrow-band light Bn1 and the second blue narrow-band light Bn2 are lights that can be highlighted such as surface blood vessels, and the second blue narrow-band light Bn2 is further expanded by expanding the half-value width to the short wavelength side. The amount of light increases.

  The reason why the first green narrowband light Gn1 and the second green narrowband light Gn2 have the light quantity distributions shown in FIGS. 4 and 5 is as follows. As shown in FIG. 6, the light absorption characteristic with respect to hemoglobin is low for light exceeding 460 nm, but the light absorption characteristic with respect to hemoglobin is high in the vicinity of 500 nm to 600 nm, particularly in the vicinity of 530 nm to 570 nm. And the absorption characteristic becomes low again about the light exceeding 600 nm vicinity.

  Further, as shown in FIG. 7, although the scattering coefficient gradually decreases as the wavelength increases, the scattering characteristics do not change abruptly in the vicinity of 500 nm to 600 nm. From the knowledge about the light scattering characteristics of biological tissues, the light reaches the middle-deep blood vessels that are deeper than the superficial blood vessels when the wavelength of the irradiated light is between 500 nm and 600 nm, especially between 530 nm and 570 nm. While this light is absorbed by the middle-deep blood vessel, it is reflected and scattered by the living tissue around the middle-deep blood vessel. As a result, the contrast between the mid-deep blood vessel and the surrounding biological tissue is increased, so that the mid-deep blood vessel and the like can be sufficiently highlighted.

  In this way, in order to sufficiently highlight the middle-deep blood vessels and the like, the wavelength band of the irradiated light is between 500 nm to 600 nm, preferably from 530 nm to both observations during the near view observation and the distant view observation. It is indispensable to be around 570 nm. If it is within this range, the middle-deep blood vessels and the like can be sufficiently highlighted. Therefore, the first green narrow-band light Gn1 and the second green narrow-band light Gn2 are lights that can be highlighted, such as a middle-deep blood vessel, and the second green narrow-band light Bn2 increases in light amount by expanding the half-value width. To do.

  Returning to FIG. 2, the turret shift mechanism 33 is between the insertion position where the filter turret 32 is inserted into the optical path of the broadband light BB emitted from the broadband light source 30 and the retracted position where the filter turret 32 is retracted from the optical path. Move. The insertion position is a position where the circular trajectory passing through the center of each of the near view observation filter 37 and the far view observation filter 38 around the rotation axis 32a and the optical path of the broadband light BB are orthogonal to each other. The turret shift mechanism 33 moves the filter turret 32 to the retracted position in the normal observation mode, and moves the filter turret 32 to the insertion position in the near view observation mode and the distant view observation mode.

  The turret rotation mechanism 34 is connected to the rotation shaft 32a, and rotates the filter turret 32 when the observation mode is switched to the near view observation mode or the distant view observation mode. In the turret rotation mechanism 34, both filter areas Bn1f and Gn1f of the foreground observation filter 37 are simultaneously inserted into the optical path of the broadband light BB in the near view observation mode, and both filter areas Bn2f and Gn2f of the distant view observation filter 38 in the distant view observation mode. The filter turret 32 is rotated so that is simultaneously inserted into the optical path of the broadband light BB.

  With each configuration described above, the light source device 13 emits the broadband light BB to the light guide 35 in the normal observation mode, and emits the first blue narrowband light Bn1 and the first green narrowband light Gn1 to the light guide 35 in the foreground observation mode. In the distant view observation mode, the second blue narrow band light Bn2 and the second green narrow band light Gn2 are emitted to the light guide 35.

  The electronic endoscope 11 includes a light guide 35, a CCD image sensor (hereinafter referred to as “CCD” imaging means) 44, an analog processing circuit (AFE: Analog Front End) 45, and an imaging control unit 46. The light guide 35 is a large-diameter optical fiber, a bundle fiber, or the like. The light guide 35 has an incident end inserted into the light source device 13 and an emission end opposed to an irradiation lens 48 provided in the insertion portion distal end portion 16a. The illumination light incident on the irradiation lens 48 from the light guide 35 is irradiated into the tube through the illumination window 20. Then, the light reflected in the tube enters the condenser lens 51 through the observation window 19.

  The CCD 44 has an imaging surface 44 a in which a plurality of photodiodes 52 (hereinafter referred to as PD 52, refer to FIG. 9) are two-dimensionally arranged, and subject light incident from the condenser lens 51 is electrically captured by each PD 52. It converts into a signal and outputs it to AFE45. A MOS type image sensor may be used instead of the CCD. An imaging control unit 46 controlled by the processor device 12 is connected to the CCD 44. The CCD 44 outputs an imaging signal to the AFE 45 at a predetermined frame rate based on the drive signal from the imaging control unit 46.

  As shown in FIGS. 8 and 9, the CCD 44 is a color CCD including red, green, and blue microfilters 53 </ b> R, 53 </ b> G, and 53 </ b> B arranged two-dimensionally on each PD 52. As a result, the CCD 44 has an R pixel composed of the microfilter 53R and the PD 52 disposed below (in the figure, laterally, the same hereinafter), a G pixel composed of the microfilter 53G and the PD 52 disposed below the microfilter 53R, A B pixel including a micro filter 53B and a PD 52 disposed below the micro filter 53B is provided.

  The microfilter 53R transmits the red light R in the red band out of the broadband light BB. The microfilter 53G transmits the green light G in the green band among the broadband light BB. The microfilter 53B transmits blue light B in the blue band out of the broadband light BB. Each of the microfilters 53R, 53G, and 53B can separate light incident on the imaging surface 44a into three colors of red, green, and blue. The blue light B includes the first and second blue narrow band lights Bn1 and Bn2, and the green light G includes the first and second green narrow band lights Gn1 and Gn2.

  Returning to FIG. 2, although not shown, the AFE 45 includes a correlated double sampling circuit (CDS), an automatic gain control circuit (AGC), and an analog / digital converter (A / D). The CDS performs correlated double sampling processing on the imaging signal from the CCD 44 to remove noise. The AGC amplifies the imaging signal from which noise has been removed by CDS. The A / D converts the image pickup signal amplified by the AGC into a digital image pickup signal having a predetermined number of bits and sends it to the processor device 12.

  The processor device 12 includes a CPU 54, a digital signal processor (DSP) 55, a frame memory 56, an observation state determination unit 57, a display control circuit 58, and an observation mode changeover switch 59. . The CPU 54 is connected to each part of the processor device 12 and the turret shift mechanism 33 and the turret rotation mechanism 34 of the light source device 13 through signal lines, and comprehensively controls them.

  The DSP 55 performs signal processing such as white balance adjustment, color tone processing, gradation processing, and sharpness processing on the imaging signal input from the AFE 45. When the observation mode is set to the normal observation mode, the DSP 55 performs the above-described signal processing on the blue image pickup signal, the green image pickup signal, and the red image pickup signal input from the AFE 45, so that the three colors B, G, and R are displayed. Normal image data having a pixel value of is generated. The normal image data is stored in the frame memory 56.

  On the other hand, the DSP 55 appropriately performs signal processing on each of the first blue narrowband imaging signal and the first green narrowband imaging signal input from the AFE 45 when the observation mode is set to the foreground observation mode. Thus, the foreground special light image data is generated. In addition, the DSP 55 appropriately performs signal processing on each of the second blue narrow-band imaging signal and the second green narrow-band imaging signal input from the AFE 45 when the observation mode is set to the distant view observation mode. Thus, the special light image data for distant view is generated. These foreground special light image data and distant view special light image data are also stored in the frame memory 56.

  The observation state determination unit 57 detects the exposure amount on the basis of the luminance signal of one of the near-field special light image data and the far-field special light image data newly stored in the frame memory 56. The observation state determination unit 57 determines that the current state is in the near view observation state when the exposure amount is equal to or greater than a certain value, and indicates that the subject is in the distant view observation state when the exposure amount is less than the certain value. judge. This determination result is sequentially input to the CPU 54.

  When the observation mode is the normal observation mode, the display control circuit 58 reads the normal image data from the frame memory 56 and displays the normal image on the monitor 14 based on the normal image data. When a normal image is displayed on the monitor 14, as shown in FIG. 9, the pixel values of the three colors B, G, and R of the normal image data are assigned to the B channel, G channel, and R channel of the monitor 14, respectively. Output.

  On the other hand, when the observation mode is the foreground observation mode, the display control circuit 58 reads out the foreground special light image data from the frame memory 56, and sends the foreground special light to the monitor 14 based on the foreground special light image data. Display an image. When displaying this special light image, the first blue narrow-band imaging signal acquired by the B pixel of the CCD 44 is assigned to the B and G channels of the monitor 14, and the first green narrow-band imaging signal acquired by the G pixel is monitored. 14 R channels are assigned (see FIG. 11). The surface layer blood vessel portion of the special light image displayed on the monitor 14 has the pixel values of the first blue narrowband imaging signal close to “0” due to the absorption of the first blue narrowband light Bn. Since it becomes dark and only the R channel becomes relatively bright, it is displayed in brown. Further, since the R channel becomes dark due to the absorption of the first green narrow-band light Gn1, the middle-deep blood vessel portion is displayed in cyan mixed with the B and G channels.

  Further, when the observation mode is the distant view observation mode, the display control circuit 58 reads the distant special light image data from the frame memory 56 and monitors the distant special light image based on the distant special light image data. To display. Note that the assignment of the second blue narrow-band imaging signal and the second green narrow-band imaging signal to the B channel, G channel, and R channel of the monitor 14 is the same as in the foreground viewing mode (see FIG. 13).

  The observation mode switch 59 is operated when switching the observation mode of the endoscope system 10 to the normal observation mode or the special light observation mode.

  When the normal observation mode is selected by the observation mode switch 59, the CPU 54 sets the observation mode to the normal observation mode. Further, when the special light observation mode is selected by the observation mode changeover switch 59, the CPU 54 sets the observation mode to the near view observation mode or the distant view observation mode based on the determination result of the observation state determination unit 57. Then, the CPU 54 controls the turret shift mechanism 33 and the turret rotation mechanism 34 according to the set observation mode type, and switches the type of illumination light emitted from the light source device 13.

  Next, the operation of the endoscope system 10 having the above configuration, particularly the operation in the special light observation mode will be described in detail with reference to FIG. Note that. The preparation process for endoscopy, the insertion of the insertion portion 16 into the patient's digestive tract and trachea, and the normal observation using the broadband light BB are basically the same as those in the prior art. Omitted.

  When switching from normal observation to special light observation, the observation mode switch 59 is switched from the normal observation mode to the special light observation mode. In the special light observation mode, the foreground observation mode is set as an initial setting. The CPU 54 of the processor device 12 issues a filter insertion command to the turret shift mechanism 33 of the light source device 13 when the observation mode changeover switch 59 is switched to the special light observation mode, and then further to the turret rotation mechanism 34. Issue a foreground viewing filter set command.

  The turret shift mechanism 33 receives the filter insertion command from the CPU 54 and moves the filter turret 32 from the retracted position to the insertion position. Next, the turret rotation mechanism 34 receives the near view observation filter set command from the CPU 54 and rotates the filter turret 32 so that the near view observation filter 37 is positioned in the optical path of the broadband light BB. As a result, the first blue filter area Bn1f and the first green filter area Gn1f are simultaneously inserted into the optical path. Note that when the foreground viewing filter 37 is inserted in the optical path of the broadband light BB in the initial setting, it is not necessary to rotate the filter turret 32.

  As shown in FIG. 11, by inserting the foreground viewing filter 37 into the optical path of the broadband light BB, the first blue narrowband light Bn1 and the first green narrowband light Gn1 of the broadband light BB are respectively first. The light passes through the blue filter area Bn1f and the first green filter area Gn1f. The first blue narrowband light Bn1 and the first green narrowband light Gn1 are irradiated into the patient's tube through the condenser lens 31, the light guide 35, the irradiation lens 48, and the illumination window 20. As a result, the first blue narrowband light Bn1 and the first green narrowband light Gn1 reflected / scattered in the tube enter the observation window 19 and enter the CCD 44 through the condenser lens 51.

  Of the first blue narrowband light Bn1 and the first green narrowband light Gn1 incident on the CCD 44, the first blue narrowband light Bn1 incident on the microfilter 53B is transmitted through the microfilter 53B and disposed below the first filter. Light is received by the PD 52. Further, the first green narrowband light Gn1 incident on the microfilter 53G passes through the microfilter 53G and is received by the PD 52 disposed below the first filter. Each PD 52 converts the received light into an electrical imaging signal and outputs it to the AFE 45. The AFE 45 performs various signal processing on the image pickup signal from the CCD 44 and outputs the digital first blue narrowband image pickup signal and the first green narrowband image pickup signal to the DSP 55 of the processor device 12.

  The first blue narrow-band image signal and the first green narrow-band image signal are subjected to various signal processing by the DSP 55 and then stored in the frame memory 56 as foreground special light image data. The display control circuit 58 reads the foreground special light image data newly stored in the frame memory 56 under the control of the CPU 54. Then, as shown in FIG. 12, the display control circuit 58 causes the monitor 14 to display the foreground special light image 60 based on the foreground special light image data.

  Returning to FIG. 10, under the control of the CPU 54, the observation state determination unit 57 detects the exposure amount at the time of shooting based on the luminance signal of the foreground special light image data newly stored in the frame memory 56. Next, the observation state determination unit 57 determines that the camera is in the foreground observation state when the exposure amount detection result is equal to or greater than a predetermined value, and sends the determination result to the CPU 54. In response to the determination result from the observation state determination unit 57, the CPU 54 continues the foreground observation mode. Hereinafter, until the observation state determined by the observation state determination unit 57 changes to the distant view observation state, the display of the above-described near view special light image 60, the detection of the exposure amount based on the foreground special light image data, and the observation state The determination is repeated.

  The observation state determination unit 57 determines that the observation state is switched to the distant view observation state when the exposure amount detection result is less than a certain value, and sends the determination result to the CPU 54. In response to the determination result from the observation state determination unit 57, the CPU 54 switches the special light observation mode from the near view observation mode to the distant view observation mode.

  The CPU 54 issues a distant view observation filter set command to the turret rotation mechanism 34. In response to this distant view observation filter set command, the turret rotation mechanism 34 rotates the filter turret 32 by 180 °. As a result, the second blue filter area Bn2f and the second green filter area Gn2f of the distant view observation filter 38 are simultaneously inserted into the optical path of the broadband light BB.

  As shown in FIG. 13, among the broadband light BB, the second blue narrowband light Bn2 and the second green narrowband light Gn2 respectively transmitted through the second blue filter area Bn2f and the second green filter area Gn2f are light guides 35. The tube is irradiated from the illumination window 20 through the like. Then, the second blue narrow band light Bn 2 and the second green narrow band light Gn 2 reflected / scattered in the tube enter the CCD 44 through the observation window 19 and the condenser lens 51.

  The second blue narrowband light Bn2 incident on the microfilter 53B of the CCD 44 and the second green narrowband light Gn2 incident on the microfilter 53G are transmitted through the microfilters 53B and 53G and received by the PD 52, respectively. Thereafter, as in the foreground viewing mode, the second blue narrowband imaging signal and the second green narrowband imaging signal are sent from the AFE 45 to the DSP 55, and the far-field special light image data is generated by the DSP 55 and the frame memory 56. Is remembered.

  As shown in FIG. 14, under the control of the CPU 54, the display control circuit 58 reads the distant special light image data newly stored in the frame memory 56, and based on the distant special light image data, the distant special light The image 61 is displayed on the monitor 14. In this case, the second blue narrow band light Bn2 and the second green narrow band light Gn2 used as illumination light are respectively used for the surface blood vessels and the middle deep blood vessels in view of the absorption characteristics shown in FIG. 6 and the scattering characteristics shown in FIG. Within the range that can be highlighted, the amount of light is increased by widening the half-value width for each of the narrow-band lights Bn1 and Gn1 in the foreground viewing mode. For this reason, a shortage of light amount is prevented even when performing a distant view observation, and a good distant view special light image 61 is obtained.

  Returning to FIG. 10, under the control of the CPU 54, the observation state determination unit 57 detects the exposure amount at the time of shooting based on the brightness signal of the special light image data for distant view newly stored in the frame memory 56. Then, the observation state determination unit 57 determines that the distant view observation state is maintained when the exposure amount detection result is less than a predetermined value, and sends the determination result to the CPU 54. In response to the determination result from the observation state determination unit 57, the CPU 54 continues the distant view observation mode. Hereinafter, until the observation state determined by the observation state determination unit 57 changes to the foreground observation state, the display of the above-mentioned special light image 61 for the far view, the detection of the exposure amount based on the special light image data for the far view, and the observation state The determination is repeated.

  The observation state determination unit 57 determines that the observation state is switched to the foreground observation state when the exposure amount detection result exceeds a certain value, and sends the determination result to the CPU 54. In response to the determination result from the observation state determination unit 57, the CPU 54 switches the special light observation mode to the foreground observation mode. Thereby, as shown in FIGS. 10 to 12, the display of the foreground special light image 60, the detection of the exposure amount, and the determination of the observation state are executed. At this time, the first blue narrow-band light Bn1 and the first green narrow-band light Gn1 used as illumination light are suppressed in light quantity with respect to the respective narrow-band lights Bn2 and Gn2 in the distant view observation mode. This prevents the foreground special light image 60 from becoming too bright and difficult to see.

  Hereinafter, when the observation state determination unit 57 determines that the foreground observation state is reached until the special light observation is finished, the special light observation under the illumination light composed of the first blue narrowband light Bn1 and the first green narrowband light Gn1 is performed. When it is determined that the distant view observation state is set, special light observation is performed under illumination light composed of the second blue narrow band light Bn2 and the second green narrow band light Gn2. Since the near view observation and the distant view observation are performed under the illumination light with the optimum light amount, a good special light image can be obtained.

[Second Embodiment]
Next, an endoscope system 70 according to a second embodiment of the present invention will be described. In the endoscope system 10 of the first embodiment, the near-view observation filter 37 and the far-view observation filter 38 are provided in the turret type filter turret 32. However, in the endoscope system 70, both filters 37 and 38 are provided. Each is provided independently. Since the endoscope system 70 has basically the same configuration as that of the first embodiment, the same functions and configurations as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted. .

  The light source device 13 of the endoscope system 70 is provided with a filter shift mechanism (filter insertion means) 71 instead of the filter turret 32, the turret shift mechanism 33, and the turret rotation mechanism 34 of the first embodiment. . The filter shift mechanism 71 moves the near view observation filter 37 and the far view observation filter 38 between an insertion position where each of the near view observation filter 37 and the far view observation filter 38 is inserted into the optical path of the broadband light BB and a retracted position where the filter is retracted from the optical path.

  When the normal observation mode is selected by the observation mode switch 59, the CPU 54 controls the filter shift mechanism 71 to move the foreground observation filter 37 and the far view observation filter 38 to the retracted position. Further, when the special light observation mode is selected by the observation mode switch 59, the CPU 54 controls the filter shift mechanism 71 according to the determination result of the observation state determination unit 57.

  Specifically, when the observation state determination unit 57 determines that the observation state determination unit 57 is in the foreground observation state, the CPU 54 controls the filter shift mechanism 71 to move the foreground observation filter 37 to the insertion position and at the same time, the distant view observation filter 38. Is moved to the retracted position. Conversely, the CPU 54 controls the filter shift mechanism 71 to move the distant view observation filter 38 to the insertion position and the near view observation filter 37 when the observation state determination unit 57 determines that the distant view observation state is present. Is moved to the retracted position.

  As described above, also in the endoscope system 70, the illumination light composed of the first blue narrowband light Bn1 and the first green narrowband light Gn1 is emitted from the light source device 13 in the near view observation state, and in the distant view observation state. Illumination light composed of the second blue narrow band light Bn2 and the second green narrow band light Gn2 is emitted from the light source device 13. Therefore, the same effects as those described in the first embodiment can be obtained.

[Third Embodiment]
Next, an endoscope system according to a third embodiment of the present invention will be described. In the endoscope system 10 of the first embodiment, in the normal mode, the filter turret 32 is retracted from the optical path of the broadband light BB to irradiate the patient's tube with the broadband light BB. On the other hand, the endoscope system according to the third embodiment has a configuration capable of irradiating the broadband light BB without retracting the filter turret.

  As shown in FIG. 16, the filter turret 75 of the endoscope system of the third embodiment has an opening 76 that allows the broadband light BB to pass as it is, in addition to the near-field observation filter 37 and the far-field observation filter 38. Yes. The endoscope system of the third embodiment is basically the same as that of the first embodiment except that a filter turret 75 is provided instead of the filter turret 32 and the turret shift mechanism 33 of the first embodiment. Since they have the same configuration, the same components as those in the first embodiment in terms of function and configuration are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 17, when the normal observation mode is selected as the observation mode, the CPU 54 controls the turret rotation mechanism 34 so that the aperture 76 is inserted into the optical path of the broadband light BB. The turret 75 is rotated. As a result, the broadband light BB can be irradiated without retracting the filter turret 75 from the optical path. Further, unlike the first embodiment, the turret shift mechanism 33 is not necessary, and the manufacturing cost can be reduced.

  Further, as described in the first embodiment, when the near view observation mode is selected as the observation mode, the CPU 54 inserts the foreground observation filter 37 into the optical path of the broadband light BB and selects the distant view observation mode. If so, the turret rotation mechanism 34 is controlled to rotate the filter turret 75 so that the distant view observation filter 38 is inserted into the optical path of the broadband light BB. Thereby, the effect similar to 1st Embodiment is acquired.

  In each of the above embodiments, illumination light composed of blue narrowband light and green narrowband light is emitted from the light source device 13 in the special light observation mode, but the wavelength band of the narrowband light used as illumination light is particularly limited. Instead, for example, red narrow-band light may be emitted from the light source device 13.

  In each of the embodiments described above, the second blue narrow band light Bn2 having a half-value width wider than that of the first blue narrow band light Bn1 is emitted from the light source device 13 in order to compensate for the shortage of light amount in the distant view observation mode. The second blue narrow-band light whose band is wider than the first blue narrow-band light Bn1 may be emitted from the light source device 13. Further, instead of expanding the half width or the wavelength band, the area of the second blue filter area Bn2f and the light transmittance may be increased. The same applies to the increase in the amount of light of the second green narrowband light Gn2.

  In each of the embodiments described above, each unit of the light source device 13 is controlled by the CPU of the processor device 12. However, a control unit such as a CPU that controls these units may be provided in the light source device 13. In the above-described embodiment, the 1 CCD type CCD 44 has been described as the color image sensor. Instead, a so-called 3 CCD type consisting of three CCDs and a prism may be adopted.

  In each of the above embodiments, in order to eliminate the shortage of light amount in the distant view observation mode, the second blue narrow band light Bn2 having a half-value width wider than that of the first blue narrow band light Bn1, and the first green narrow band light Gn1. The second green narrow-band light Gn2 having an expanded half-value width is used as illumination light. When the amount of light is insufficient, either the second blue narrow-band light Bn2 or the second green narrow-band light Gn2 is used. The half-value width or wavelength band may be expanded.

  In the above embodiment, broadband light and each color narrow band light are emitted from the light source device 13 to the electronic endoscope 11. However, the light source (for example, LED) of each broadband light or each color narrow band light is inserted into the insertion portion distal end portion 16a. It may be provided inside.

  In the above-described embodiment, the endoscope system that performs the special light observation of the surface blood vessel and the middle-deep blood vessel using light of two types of specific wavelengths has been described as an example, but the two types of specific wavelengths are described. The present invention is applied to an endoscope system used for various observations and diagnoses such as fluorescence observation (Auto Fluorescence Imaging), infrared light observation (Infra Red Imaging), and photodynamic diagnosis (Photodynamic diagnosis). Can be applied.

DESCRIPTION OF SYMBOLS 10,70 Endoscope system 11 Electronic endoscope 12 Processor apparatus 13 Light source apparatus 30 Broadband light source 32,75 Filter turret 33 Turret shift mechanism 34 Turret rotation mechanism 37 Foreground observation filter 38 Distant view observation filter 44 CCD
54 CPU
59 Observation mode switching switch 71 Filter shift mechanism BB Broadband light Bn1 First blue narrowband light Bn2 Second blue narrowband light Gn1 First green narrowband light Gn2 Second green narrowband light Bn1f First blue filter area Bn2f Second blue Filter area Gn1f First green filter area Gn2f First green filter area

Claims (8)

A broadband light source that emits white broadband light;
A filter unit having first and second filter regions for transmitting a part of the broadband light and generating first and second types of narrowband light having different wavelength bands used for special light observation. A filter unit having a first and second types of filter regions, each having a far view observation filter having a relatively large amount of transmitted light and a near view observation filter having a relatively small amount of transmitted light;
Filter insertion means for selectively inserting either the distant view observation filter or the near view observation filter so that the first and second types of filter regions are simultaneously inserted into the optical path of the broadband light source. When,
Imaging means for imaging an observed site irradiated with the first and second types of narrowband light;
Equipped with a,
The first filter region has a light transmission characteristic of transmitting blue narrowband light corresponding to a wavelength band having a large amount of absorption on the short wavelength side of the light absorption spectrum of hemoglobin, and the second filter region has a light transmission characteristic of the absorption spectrum. Has a light transmission characteristic that transmits green narrowband light corresponding to a wavelength band with a large amount of absorption on the long wavelength side,
Furthermore, the first filter region of the distant view observation filter has a light transmission characteristic that is expanded only on the short wavelength side with respect to the light transmission property of the first filter region of the near view observation filter. system.   The first and second filter regions of the distant view observation filter have light transmission characteristics having a half-value width wider than that of the first and second filter regions of the near view observation filter. The endoscope system according to claim 1. Mode switching means for switching between a normal mode in which the observation site is illuminated with the broadband light and a special mode in which the first and second types of narrow band light are used to illuminate the observation site;
Based on the imaging signal acquired by imaging by the imaging means, imaging is performed in a near-field observation state where the distance between the distal end portion of the endoscope and the site to be observed is close or a distant view observation state where the distance is far. An observation state determination means for determining whether or not it has been performed,
The filter insertion means inserts the foreground observation filter into the optical path and determines that the camera is in the distant view observation state when the observation state determination means determines that the close view observation state is in the special mode during the special mode. The endoscope system according to claim 1 or 2, wherein the far-view observation filter is inserted into the optical path in a case where the distant view observation filter is inserted. The filter insertion means, in the normal mode, retracts the near view observation filter and the far view observation filter from the optical path,
The endoscope system according to claim 3, wherein the imaging unit images the observation site illuminated by the broadband light in the normal mode. The filter unit is a single rotating body including the near view observation filter and the far view observation filter,
The filter insertion means includes
Rotating body moving means for inserting the rotator into the optical path during the special mode and retracting the rotator from the optical path during the normal mode;
In the special mode, the near view observation filter is inserted into the optical path when the close view observation state is set, and the far view observation filter is inserted into the optical path when the special mode is set. The endoscope system according to claim 3, further comprising: a rotation driving unit that rotates the rotating body. The filter unit is a single rotating body including the near-field observation filter, the far-field observation filter, and an aperture that transmits the entire area of the broadband light,
In the normal mode, the filter insertion means inserts the opening into the optical path, and in the close-up observation state in the special mode, the near-view observation filter is inserted into the optical path, and the distant view observation state in the special mode. 4. The endoscope system according to claim 3, wherein the rotating body is rotated so that sometimes the distant view observation filter is inserted into the optical path.   The observation state determination unit detects an exposure amount from an imaging signal acquired by the imaging unit, determines that the foreground observation state is present when the detected exposure amount is equal to or greater than a certain value, and is less than the certain value The endoscope system according to any one of claims 3 to 6, wherein the endoscope is determined to be in the distant view observation state. In the first filter region of the foreground viewing filter, the transmittance peak is around 460 nm, the transmittance sharply decreases on the longer wavelength side than the transmittance peak near 460 nm, and the transmittance is transmitted from 400 nm to 460 nm. The light transmission characteristic is such that the transmittance gradually decreases and the transmittance rapidly decreases when the ratio is less than 400 nm.
The endoscope according to any one of claims 1 to 7, wherein the second filter region of the near-field observation filter has a transmittance peak of 550 nm and a half-value width of 20 nm to 40 nm. system.

Images