JP2012045264A - Electronic endoscope system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic endoscope system capable of obtaining sufficiently bright video images without affecting observation with special light even when the system is in a distant view observation condition in which light quantity is short.SOLUTION: In a distant view observation mode, image pickup is executed by irradiating a body cavity with a second blue narrow band light Bn2 obtained by expanding a half value width of a first blue narrow band light Bn1 used in a short range view observation mode and a second green narrow band light Gn2 obtained by expanding a half value width of a first green narrow band light Gn1 used similarly in the short range view observation mode. The narrow band light such as the first blue narrow band light Bn1 is generated by transmitting a wide band light to either of a plurality of specific wavelength transmissive filters provided in a rotating filter. In the rotating filter, the specific wavelength transmissive filters are arranged so that a blank period when images of the body cavity are not obtained can be short even when in either the short range or distant view observation state.

Description

  The present invention relates to an electronic endoscope system having a special light observation function that highlights a superficial blood vessel using narrow band light.

  In the medical field in recent years, many diagnoses and treatments using an electronic endoscope have been performed. The electronic endoscope includes an elongated insertion portion that is inserted into the body cavity of a subject, and an imaging device such as a CCD is built in the distal end of the insertion portion. In addition, the electronic endoscope is connected to the light source device, and light emitted from the light source device is irradiated to the inside of the body cavity from an irradiation window provided at the distal end portion of the electronic endoscope. The light reflected in the body cavity is imaged by the imaging device in the distal end portion through an observation window provided in the distal end portion of the electronic endoscope. An image obtained by imaging is displayed on a monitor after various processing is performed by a processor device connected to the electronic endoscope. Therefore, by using an electronic endoscope, an image in the body cavity of the subject can be confirmed in real time, so that diagnosis and the like can be performed reliably.

  A white light source such as a xenon lamp capable of emitting white broadband light having a wavelength ranging from a blue region to a red region is used for the light source device. By using white broadband light for irradiation in the body cavity, the entire subject tissue can be grasped from the captured image. However, although the entire subject tissue can be roughly grasped from the captured image obtained when broadband light is irradiated, subjects such as fine blood vessels, pit patterns (gland opening structure), uneven structures such as depressions and bumps, etc. Tissues can be difficult to observe clearly.

  It is known that such a subject tissue can be clearly observed by irradiating a narrow band light whose wavelength is limited to a specific region so that a fine blood vessel is emphasized. On the other hand, since the half-value width of the light applied to the subject tissue is narrowed, the amount of light that illuminates the body cavity is reduced, so that the inside of the body cavity becomes dark overall.

  In order to solve such a problem, in Patent Document 1, image processing is performed to compensate for an insufficient light amount for an imaging signal obtained when narrow band light is irradiated. Thereby, even when the inside of the body cavity becomes dark due to the irradiation of the narrow band light, the image quality of the video image displayed on the monitor is not deteriorated.

Japanese Patent No. 4009626

  However, even in the case of irradiating narrow band light, when observing the distal end of the endoscope close to the subject tissue in a close-up view, the light amount of the narrow band light is not insufficient and the surface blood vessels can be sufficiently emphasized. Are known. On the other hand, when observing the distal end portion of the endoscope away from the subject tissue in a distant view, it is known that the surface blood vessels may not be sufficiently emphasized because the amount of narrowband light is insufficient. ing.

  This knowledge is not described at all in Patent Document 1 and is not suggested. Therefore, during distant view observation, the superficial blood vessels cannot be highlighted due to insufficient light quantity, so that image processing that compensates for insufficient light quantity for the imaging signal is required as in Patent Document 1. However, during close-up viewing, it is bright enough to highlight the surface blood vessels. When image processing such as that described in Patent Document 1 is performed in a sufficiently bright state in this manner, the image becomes too bright, which may make it difficult to see the video.

  The present invention affects special light observation even in a distant view state where the amount of light is insufficient when performing special light observation that highlights and observes superficial blood vessels using narrowband light. An object of the present invention is to provide an electronic endoscope system that can acquire a sufficiently bright video without any problems.

  An electronic endoscope system according to the present invention includes a broadband light source that emits broadband light having a wavelength ranging from a blue region to a red region, and a plurality of first narrow bands that transmit first narrow band light having a specific wavelength among the broadband light. A first narrow-band light transmission filter having a plurality of second narrow-band light transmission filters that transmit the second narrow-band light in which the half-width of the first narrow-band light is expanded in a certain range among the light transmission filter and the broadband light And the second narrowband light transmission filter are arranged alternately along the circumferential direction so that the first narrowband light and the second narrowband light are alternately irradiated into the body cavity by rotation. Based on the imaging signal, an imaging signal acquisition means for acquiring an imaging signal by imaging the inside of a body cavity illuminated by the first or second narrowband light with an imaging element in the distal end portion of the endoscope. The subject in the endoscope tip and body cavity Whether the image was taken in a near-field observation state where the distance to the tissue is close, or was taken in a distant view observation state where the distance between the distal end of the endoscope and the subject tissue in the body cavity is far When it is determined that the observation state determination means and the foreground observation state, the image is taken when the first narrow-band light is irradiated, and when it is determined that the distant view observation state, An image pickup control unit that controls the image pickup device so as to pick up an image when the second narrowband light is irradiated is provided.

  The first narrowband light includes first blue narrowband light limited to a specific band in a blue wavelength region, and first green narrowband light limited to a specific band in a green wavelength region, The two narrow-band lights are a second blue narrow-band light in which the half-value width of the first blue narrow-band light is expanded in a certain range, and a second green narrow band in which the half-value width of the first green narrow-band light is expanded in a certain range. The first rotation filter includes a first blue narrowband light transmission filter that transmits the first blue narrowband light in the broadband light and a first green narrowband light that transmits the first green narrowband light in the broadband light. The plurality of first narrowband light transmission filters including the green narrowband light transmission filter, the second blue narrowband light transmission filter that transmits the second narrowband light of the broadband light, and the second green narrowband of the broadband light. Second green narrow band that transmits light and second green narrow band light that transmits light It is preferred to have a plurality of second narrow band light transmitting filter comprising the pass transmission filter.

  The first rotation filter includes a blue light transmission filter that transmits blue light in a blue band of broadband light, a green light transmission filter that transmits green light in a green band of broadband light, and a red band of R in broadband light. A first filter area in which red light transmission filters that transmit light are provided in this order, and an area provided on the inner side or the outer side with respect to the first filter area, the first blue narrow band light transmission filter A second blue narrowband light transmission filter, a first green narrowband light transmission filter, and a second green narrowband light transmission filter that transmits the second green narrowband light are provided in this order along the circumferential direction. When the normal light observation is performed using B light, G light, and R light, the first filter area is set on the optical path of the broadband light and the first rotary filter is rotated. Thus, B light, G light, and R light are irradiated into the body cavity in this order, and the first blue narrow band light, the second blue narrow band light, the first green narrow band light, and the second green narrow band light are emitted. When special light observation is performed using the first blue narrowband light, the second blue narrowband light, the first blue filter, and the second blue narrowband light by setting the second filter area on the optical path of the broadband light and rotating the first rotary filter. It is preferable to irradiate the body cavity with 1 green narrowband light and 2nd green narrowband light in this order.

  A blue light transmitting filter that transmits blue light in the broadband light among the broadband light, a green light transmitting filter that transmits green light in the green band among the broadband light, and a red light that transmits red light in the red band among the broadband light. When a normal light observation is performed using B light, G light, and R light, which includes a light transmission filter and a second rotation filter provided with an opening that transmits the broadband light as it is in this order. Irradiates B light, G light, and R light in this order in the body cavity by rotating the second rotating filter in a state where the first rotating filter is retracted from the optical path of the broadband light. When special light observation is performed using narrowband light, second blue narrowband light, first green narrowband light, and second green narrowband light, an aperture of the second rotation filter is provided on the optical path of the broadband light. With the first part set. By rotating the motor, the first blue narrow-band light, the second blue narrow-band light, first green narrowband light, it is preferable to irradiate the body cavity a second green narrowband light in this order.

  The observation state determination unit detects an exposure amount from the imaging signal acquired by the imaging signal acquisition 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. In this case, it is preferable to determine that the camera is in a distant view observation state.

  According to the present invention, when it is determined that the camera is in the distant view observation state, the second blue narrow band light and the first blue narrow band light obtained by expanding the half-value width of the first blue narrow band light used in the close view observation state within a certain range. Since the imaging is performed when the second green narrowband light in which the half width of the 1 green narrowband light is widened within a certain range is taken, even in a distant view state where the amount of light is insufficient, A sufficiently bright image can be acquired without affecting special light observation.

  In addition, in the present invention, the rotary filter used for generating the special light such as the first blue narrow band light can capture an image of the inside of the body cavity regardless of the observation state of the near view observation state or the distant view observation state. Since the transmission filter such as the first blue narrow-band light transmission filter is arranged so that the blank period that cannot be performed is shortened, image diagnosis or the like when using the endoscope can be performed reliably.

1 is a schematic diagram of an electronic endoscope system according to a first embodiment of the present invention. It is a block diagram of an electronic endoscope system. It is the schematic of a rotation filter. It is a graph which shows the spectral transmittance of the blue light transmissive filter of a rotation filter, a green transmissive filter, and a red transmissive filter. (A) is the spectral transmittance of the first blue narrow-band light transmission filter and the first green narrow-band light transmission filter of the rotation filter, and (B) is the second blue narrow-band light transmission filter and the second green narrow filter of the rotation filter. It is a graph which shows the spectral transmittance of a zone light transmissive filter. (A) is a graph which shows the light absorption coefficient in the blood vessel, (B) is a graph which shows the light scattering coefficient in a biological tissue. 2A and 2B show CCD imaging control in the first embodiment, in which (A) shows imaging control during normal light observation, (B) shows imaging control during special light observation (near view), and (C) shows special light observation. It is explanatory drawing which shows the imaging control of time (distant view). It is an image figure of the special light image displayed on a monitor at the time of near view observation. It is an image figure of the special light image displayed on a monitor at the time of distant view observation. It is a flowchart which shows the effect | action of this invention. It is a block diagram of the electronic endoscope system of 2nd Embodiment of this invention. It is the schematic of the rotation filter for normal light. It is the schematic of the rotation filter for special lights. The CCD imaging control in 2nd Embodiment is shown, (A) is imaging control at the time of normal light observation, (B) is imaging control at the time of special light observation (near view), (C) is special light observation. It is explanatory drawing which shows the imaging control of time (distant view). It is explanatory drawing for demonstrating the imaging period when the inside of a body cavity is imaged with CCD, and the blank period which is not imaged when the rotation filter of an Example is used. It is explanatory drawing for demonstrating the imaging period which images the inside of a body cavity with CCD, and the blank period which is not imaged when the rotation filter of a comparative example is used.

  As shown in FIG. 1, an electronic endoscope system 10 according to a first embodiment of the present invention includes an electronic endoscope 11 that images a body cavity of a subject, and a body cavity based on a signal obtained by the imaging. A processor device 12 for generating an image of the body, a light source device 13 for supplying light for irradiating the inside of the body cavity, and a monitor 14 for displaying the image in the body cavity.

  In the electronic endoscope system 10, a normal light image mode in which the subject tissue is entirely observed by illuminating the body cavity with broadband light such as white light, and a surface layer blood vessel by illuminating the body cavity with narrowband light. Etc. are highlighted, and there are two observation modes of special light image mode. In the special light image mode, the near-field observation mode when observing in the near-field state where the distance between the distal end portion 16a of the electronic endoscope 11 and the subject tissue is close, and the far-field state where the distance between the subject tissue is far away It has a distant view observation mode.

  The electronic endoscope 11 includes a flexible insertion portion 16 to be inserted into a body cavity, 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 for connecting the two. A bending portion 19 in which a plurality of bending pieces are connected is formed at the distal end of the insertion portion 16. The bending portion 19 is bent in the vertical and horizontal directions by operating the angle knob 21 of the operation portion. The distal end of the bending portion 19 is provided with a distal end portion 16a incorporating an optical system for in-vivo imaging, and the distal end portion 16a is directed in a desired direction in the body cavity by the bending operation of the bending portion 19. .

  A connector 24 is attached to the universal cord 18 on the processor device 12 and the light source device 13 side. The connector 24 is a composite type connector including a communication connector and a light source connector, and the electronic endoscope 11 is detachably connected to the processor device 12 and the light source device 13 via the connector 24.

  As shown in FIG. 2, the light source device 13 includes a broadband light source 30, a rotary filter 31, and a filter switching unit 32. The broadband light source 30 is a xenon lamp, a white LED, a micro white light source, or the like, and generates 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 is always lit while the electronic endoscope 11 is in use. The broadband light BB emitted from the broadband light source 30 enters the condenser lens 34 via the rotary filter 31. The light condensed by the condenser lens 34 enters the light guide 35.

  The rotary filter 31 is rotated at a constant speed around the rotary shaft 31a by the motor 36. The rotary filter 130 transmits the light used in the normal light image mode in the broadband light BB from the broadband light source 30 and the first filter area 38 that transmits the light used in the special light image mode in the broadband light BB. The first filter area 38 is provided on the inner side of the second filter area 39. The filter switching unit 32 is attached to the rotation shaft 31 a of the rotary filter 31, and the first filter area 38 in the normal light image mode and the second filter area 39 in the special light image mode are on the optical path of the broadband light source 30. The rotary filter 31 is moved in the radial direction so as to be positioned.

  As shown in FIG. 3, in the first filter area 38, a blue light transmission filter 40 that transmits blue band light (B light) of the broadband light BB, and green band light (G light) of the broadband light BB. ) And a red light transmission filter 42 that transmits red band light (R light) of the broadband light BB is provided in this order along the circumferential direction. Therefore, as the rotary filter 31 rotates, B light, G light, and R light are emitted in order from the rotary filter 31. The B light, the G light, and the R light that are sequentially emitted from the rotary filter 31 in this way are referred to as surface sequential light.

  Here, the blue light transmission filter 40 has a spectral transmittance shown in the graph B, the green light transmission filter 41 has a spectral transmittance shown in the graph G, and the red light transmission filter 42 has a graph R as shown in FIG. It has the spectral transmittance shown. Further, the long wavelength side of graph B and the short wavelength side of graph G partially overlap, and the long wavelength side of graph G and the short wavelength side of graph R partially overlap. Therefore, the surface-sequential light irradiated into the body cavity has one wavelength at which the light intensity reaches a peak in each of the blue band, the green band, and the red band, and graphs B, G, and R at other wavelengths. Since they partially overlap each other, the light intensity of a certain level or more is maintained without interruption from the blue band to the red band.

  As shown in FIG. 3, the second filter area 39 includes a first blue narrowband light transmission filter 65 that transmits the first blue narrowband light Bn1 used in the foreground viewing mode of the broadband light BB, and the broadband light BB. Among them, the second blue narrow-band light transmission filter 66 that transmits the second blue narrow-band light Bn2 used in the distant view observation mode, and the first green narrow-band light Gn1 that is used in the near view observation mode among the broadband light BB are transmitted. A first green narrowband light transmission filter 67 and a second green narrowband light transmission filter 68 that transmits the second green narrowband light Gn2 used in the distant view mode of the broadband light BB are arranged in this order in the circumferential direction. It is provided along.

  Since the spectral transmittance of the first blue narrowband light transmission filter 65 has a distribution as shown in the graph Bn1 of FIG. 5A, the first blue narrowband light Bn1 irradiated into the body cavity is The amount of light reaches a peak value near the central wavelength of about 450 nm, the amount of light sharply decreases on the longer wavelength side than 450 nm, and the amount of light becomes substantially “0” between 450 nm and 500 nm. On the other hand, on the shorter wavelength side than 450 nm, the amount of light decreases from 450 nm to 400 nm, but the amount of light becomes “0” when it falls below 400 nm, although it is not as sharp as the decrease in the amount of light on the longer wavelength side.

  On the other hand, since the spectral transmittance of the second blue narrow-band light transmission filter 66 has a distribution as shown in the graph Bn2 of FIG. 5B, the second blue color irradiated into the body cavity. Similar to the first blue narrow-band light Bn1, the narrow-band light Bn2 has a sudden drop in light quantity on the longer wavelength side than the central wavelength of about 450 nm where the light quantity reaches the peak value. On the other hand, on the shorter wavelength side than about 450 nm, unlike the first blue narrow-band light Bn1, the light amount gradually decreases slowly while maintaining a relatively high light amount between 450 nm and 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 400 nm. Therefore, the second blue narrow-band light Bn2 is a light obtained by increasing the light quantity on the short wavelength side without changing the light quantity on the long wavelength side of about 450 nm of the central wavelength of the first blue narrow-band light Bn1. ing.

  The reason why the first blue narrow-band light Bn1 and the second blue narrow-band light Bn2 have the light quantity distribution as described above is as follows. As shown in the distribution of the extinction coefficient in FIG. 6A, light having a wavelength below 450 nm in the irradiated light is very strongly absorbed by surface blood vessels in the living tissue, whereas light exceeding 450 nm is superficial. It penetrates as it is without being absorbed in blood vessels. As shown in the distribution of the scattering coefficient in FIG. 6B, the shorter the wavelength of the irradiated light, the stronger the scattering in the living tissue. From the knowledge about the light absorption characteristics of these blood vessels and the light scattering characteristics of biological tissues and other knowledge, most of the light emitted by the strong light absorption characteristics in the superficial blood vessels unless the wavelength of the irradiated light exceeds 470 nm. Does not return to the distal end portion 16a of the electronic endoscope. On the other hand, in the living tissue surrounding the superficial blood vessel, most of the irradiated light is reflected by the relatively strong scattering characteristics and is reflected on the distal end portion 16a of the electronic endoscope. Will come back. 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.

  Therefore, in order to sufficiently highlight the superficial blood vessels and the like, it is indispensable to irradiate light having no light quantity in a wavelength region exceeding 470 nm in both the near-field observation and the distant-view observation. . On the other hand, if it does not exceed 470 nm, the superficial blood vessels and the like can be sufficiently highlighted. Therefore, when viewing a distant view where the amount of light is insufficient, the first blue narrow-band light Bn1 is shorter than the vicinity of 470 nm. The second blue narrow-band light Bn2 having an increased amount of light is used.

  On the other hand, since the spectral transmittance of the first green narrowband light transmission filter 67 has a distribution as shown in the graph Gn1 of FIG. 5A, the first green narrowband light irradiated into the body cavity. Gn1 has a center wavelength of around 550 nm and a half width of 10 nm to 20 nm. On the other hand, since the spectral transmittance of the second green narrowband light transmission filter 68 has a distribution as shown in the graph Gn2 of FIG. 5B, the second green color irradiated into the body cavity. The narrow-band light Gn2 has a center wavelength of 550 nm as in the case of the first green narrow-band light Gn1, whereas the half-width is 20 to 40 nm, unlike the first green narrow-band light Gn1. That is, the second green narrowband light Gn2 has a half width wider than that of the first green narrowband light Gn1. Therefore, the second green narrowband light Gn2 has a larger amount of light than the first green narrowband light Gn1 because the half-value width is widened.

  The reason why the first green narrow-band light Gn1 and the second green narrow-band light Gn2 have the light quantity distribution as described above is as follows. As shown in the distribution of the extinction coefficient in FIG. 6 (A), the light absorption characteristics with respect to the blood vessels are low for light exceeding 450 nm, but the light absorption for the middle blood vessels is between 500 nm and 600 nm, particularly in the vicinity of 530 nm to 570 nm. Absorption characteristics are improved. And the absorption characteristic becomes low again for light exceeding 600 nm. Further, as shown in the distribution of the scattering coefficient in FIG. 6B, although the scattering coefficient gradually decreases as the wavelength increases, the scattering characteristics in the living tissue vary so much between 500 nm and 600 nm. is not.

  Therefore, from the knowledge about the light absorption characteristics of these blood vessels and the light scattering characteristics of biological tissues and other knowledge, when the wavelength of the irradiated light is between 500 nm and 600 nm, especially in the vicinity of 530 nm to 570 nm, the biological tissues including the middle layer blood vessels. Therefore, the amount of light reflected by the living tissue and returning to the distal end portion 16a of the electronic endoscope is substantially constant. On the other hand, since the middle layer blood vessel contained in the living tissue exhibits a relatively high light absorption characteristic with respect to light between 500 nm and 600 nm, particularly around 530 nm to 570 nm, electrons out of the light irradiated on the middle layer blood vessel The proportion of light that returns to the distal end portion 16a of the endoscope decreases. Accordingly, when the irradiated light is between 500 nm and 600 nm, particularly under the vicinity of 530 nm to 570 nm, the contrast between the middle blood vessel and the surrounding biological tissue is increased, so that the middle blood vessel can be sufficiently highlighted. .

  Therefore, in order to sufficiently highlight the middle-layer blood vessel and the like, the wavelength band of the irradiated light is between 500 nm to 600 nm, preferably 530 nm to 570 nm, both in the near-field observation and the far-field observation. It is essential. If it is in the range of 500 nm to 600 nm, preferably in the range of 530 nm to 570 nm, it is possible to sufficiently highlight the middle-layer blood vessels, etc., so that the center wavelength is about 550 nm during distant view observation where the amount of light is insufficient. The second green narrow-band light Gn2 is used in which the half-value width of the first green narrow-band light Gn1 is further widened to increase the amount of light.

  As shown in FIG. 2, the electronic endoscope 11 includes a light guide 35, a CCD 44, an analog processing circuit 45 (AFE: Analog Front End), and an imaging control unit 46. The light guide 35 is a large-diameter optical fiber, a bundle fiber, or the like. The incident end is inserted into the light source device 13 and the emission end is directed to the irradiation lens 48 provided at the tip portion 16a. The light emitted from the light source device 13 is guided by the light guide 43 and then emitted toward the irradiation lens 48. The light incident on the irradiation lens 48 is irradiated into the body cavity through the illumination window 49 attached to the end surface of the distal end portion 16a. The light reflected in the body cavity enters the condenser lens 51 through the observation window 50 attached to the end face of the distal end portion 16a.

  The CCD 44 receives light from the condensing lens 51 on the imaging surface 44a, photoelectrically converts the received light to accumulate signal charges, and reads the accumulated signal charges as imaging signals. The read imaging signal is sent to the AFE 45. The CCD 44 is a monochrome CCD having a predetermined spectral sensitivity. The AFE 45 includes 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 image pickup signal from the CCD 44 to remove noise generated by driving the CCD 44. The AGC amplifies the imaging signal from which noise has been removed by CDS. The A / D converts the imaging signal amplified by the AGC into a digital imaging signal having a predetermined number of bits and inputs the digital imaging signal to the processor device 12.

  The imaging control unit 46 is connected to a controller 59 in the processor device 12, and sends a drive signal to the CCD 44 when an instruction is given from the controller 59. 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. When the normal light image mode is set, as shown in FIG. 7A, while the B light is irradiated from the rotary filter 31, that is, while the rotary filter 31 rotates by 1/3, A total of two operations, a step of photoelectrically converting the B light and accumulating signal charges and a step of reading the accumulated signal charges as a blue image pickup signal, are repeated a predetermined number of times.

  Next, when the light emitted from the rotary filter 31 is switched from the B light to the G light, in the same way, while the rotary filter 31 rotates by 1/3, the G light is photoelectrically converted to obtain a signal charge. A total of two operations, ie, a step of accumulating and a step of reading the accumulated signal charge as a green imaging signal, are repeated a predetermined number of times. Next, when the light emitted from the rotary filter 31 is switched from the G light to the R light, in the same manner, while the rotary filter 31 rotates by 1/3, the R light is photoelectrically converted to obtain a signal charge. A total of two operations, ie, a step of accumulating and a step of reading the accumulated signal charge as a red imaging signal, are repeated a predetermined number of times.

  On the other hand, when the special light image mode is in the foreground observation state, as shown in FIG. 7B, while the first blue narrow band light Bn1 is being emitted from the rotary filter 31, That is, the total of the step of photoelectrically converting the first blue narrowband light Bn1 and accumulating signal charges and the step of reading the accumulated signal charges as the first blue narrowband imaging signal while the rotary filter 31 rotates by 1/4. Two operations are repeated a predetermined number of times. Next, the light irradiated from the rotary filter 31 is switched from the first blue narrowband light Bn1 to the second blue narrowband light Bn2, and the second blue narrowband light Bn2 is being irradiated, that is, the rotary filter 31 is 1 During the / 4 rotation, signal charge accumulation and image pickup signal reading are not performed.

  Next, the light emitted from the rotary filter 31 is switched from the second blue narrowband light Bn2 to the first green narrowband light Gn1, and during the irradiation of the first green narrowband light Gn1, that is, the rotary filter 31 is set to 1. During / 4 rotation, a total of two operations including a step of photoelectrically converting the first green narrowband light Gn1 and accumulating signal charges and a step of reading the accumulated signal charges as the first green narrowband imaging signal are predetermined. This is repeated for the number of times. Next, the light emitted from the rotary filter 31 is switched from the first green narrow-band light Gn1 to the second green narrow-band light Gn2, and the second green narrow-band light Gn2 is being irradiated, that is, the rotary filter 31 is 1 During the / 4 rotation, signal charge accumulation and image pickup signal reading are not performed.

  In the special light image mode, when the subject is in a distant view observation state, as shown in FIG. 7C, while the first blue narrow-band light Bn1 is irradiated from the rotary filter 31, that is, the rotary filter. During the quarter rotation of the signal 31, signal charge accumulation and image pickup signal reading are not performed. Next, the light irradiated from the rotary filter 31 is switched from the first blue narrowband light Bn1 to the second blue narrowband light Bn2, and the second blue narrowband light Bn2 is being irradiated, that is, the rotary filter 31 is 1 During / 4 rotation, a total of two operations including a step of photoelectrically converting the second blue narrowband light Bn2 and storing the signal charge and a step of reading the stored signal charge as the second blue narrowband imaging signal are predetermined. Repeated a number of times.

  Next, the light emitted from the rotary filter 31 is switched from the first blue narrowband light Bn1 to the first green narrowband light Gn1, and the first green narrowband light Gn1 is being irradiated, that is, the rotary filter 31 is set to 1. During the / 4 rotation, signal charge accumulation and image pickup signal reading are not performed. Next, the light emitted from the rotary filter 31 is switched from the first green narrow-band light Gn1 to the second green narrow-band light Gn2, and the second green narrow-band light Gn2 is being irradiated, that is, the rotary filter 31 is 1 During the / 4 rotation, a total of two operations including a step of photoelectrically converting the second green narrowband light Gn2 and storing the signal charge and a step of reading the stored signal charge as the second green narrowband imaging signal are predetermined. This is repeated for the number of times.

  As shown in FIG. 2, the processor device 12 includes a digital signal processor 55 (DSP (Digital Signal Processor)), a frame memory 56, an observation state determination unit 57, and a display control circuit 58. Controls each part. The DSP 55 performs signal processing such as white balance adjustment, color tone processing, gradation processing, and sharpness processing on the imaging signal output from the AFE 45 of the electronic endoscope. In the DSP 55, when the normal light image mode is set, normal light image data is generated by performing the signal processing on the blue image pickup signal, the green image pickup signal, and the red image pickup signal output from the AFE. The generated normal light image data is stored in the frame memory 56.

  On the other hand, when the foreground observation mode is set in the special light image mode, the signal processing is performed on each of the first blue narrow-band imaging signal and the first green narrow-band imaging signal output from the AFE. Each image signal subjected to the signal processing is stored in the frame memory as foreground special light image data. Further, when the special light image mode is set to the distant view observation mode, each of the second blue narrow band image pickup signal and the second green narrow band image pickup signal is subjected to the above signal processing in the same manner as the near view observation mode. Is applied to the frame memory 56 as the special light image data for distant view.

  The observation state determination unit 57 detects the exposure amount from either one of the near-field special light image data and the far-field special light image data stored in the frame memory 56. If the detected exposure amount is greater than or equal to a certain value, it is determined that the foreground viewing state is currently set. If it is determined that the camera is in the foreground viewing state, the foreground viewing mode is automatically set. When the foreground viewing mode is set, the imaging control unit 46 is instructed to acquire the first blue narrowband imaging signal and the first green narrowband imaging signal when the next imaging is performed (FIG. 7B). )reference). On the other hand, when the detected exposure amount is less than a certain value, it is determined that the subject is in a distant view observation state at the present time. If it is determined that the subject is in the far-field observation state, the remote-view observation mode is automatically set. When the distant view observation mode is set, the imaging control unit 46 is instructed to acquire the second blue narrowband imaging signal and the second green narrowband imaging signal when the next imaging is performed (FIG. 7C )reference).

  When in the normal light image mode, the display control circuit 58 reads the normal light image data from the frame memory 56 and displays the normal light image on the monitor 14 based on the read normal light image data. On the other hand, when in the foreground observation mode in the special light image mode, the foreground special light image data is read from the frame memory 56. Then, based on the read foreground special light image data, a special light image at the time of near view observation as shown in FIG. 8 is displayed on the monitor 14.

  Further, when the special light image mode is in the distant view observation mode, the special light image data for distant view is read from the frame memory 56. Then, based on the read distant view special light image data, a special light image at the time of distant view observation as shown in FIG. In the present invention, the shortage of light quantity at the time of distant view observation is compensated by widening the half-value width of the light irradiated into the body cavity. At that time, since the half-value width is widened in view of the light absorption characteristics of the blood vessels and the scattering characteristics of the living tissue around the blood vessels, special light observation for highlighting the surface blood vessels and the like is not affected.

  Next, the operation of the present invention will be described with reference to the flowchart of FIG. First, the normal light image mode is switched to the special light image mode by operating the image mode switching SW50. In the special light image mode, the foreground observation mode is set as the initial setting. The filter switching unit 131 sets the second filter area 39 of the rotary filter 31 on the optical path of the broadband light source 30 according to switching to the special light image mode. By rotating the rotary filter 31 in this state, the first blue narrowband light Bn1, the second blue narrowband light Bn2, the first green narrowband light Gn1, and the second green narrowband light Gn2 (these are also referred to as special lights). Are irradiated into the body cavity in this order. In the special light image mode, the initial setting may be the far view observation mode instead of the near view observation mode.

  Then, the imaging control unit 46 instructs to read the imaging signal from the CCD 44 only when the first blue narrowband light Bn1 and the first green narrowband light Gn1 are irradiated. Thereby, a 1st blue narrow-band imaging signal and a 1st green narrow-band imaging signal are obtained. The obtained first blue narrowband imaging signal and first green narrowband imaging signal are subjected to signal processing such as white balance adjustment, color tone processing, gradation processing, sharpness processing, and the like by the DSP 55, and then the special light for foreground It is stored in the frame memory 56 as image data. Then, based on the foreground special light image data read from the frame memory 56, a special light image at the time of foreground observation as shown in FIG. 8 is displayed.

  The observation state determination unit 57 detects the exposure amount from the foreground special light image data stored in the frame memory 56. If the exposure amount is equal to or greater than a certain value, the current observation state is determined to be the foreground observation state, and the foreground observation mode is maintained as it is. On the other hand, when the exposure amount is less than a certain value, the current observation state is determined to be a distant view observation state. If it is determined that the distant view observation state is set, the foreground observation mode is switched to the distant view observation mode.

  In response to switching to the distant view observation mode, the imaging control unit 46 instructs to read the imaging signal from the CCD 44 only when the second blue narrow band light Bn2 and the second green narrow band light Gn2 are irradiated. Thereby, a 2nd blue narrow-band imaging signal and a 2nd green narrow-band imaging signal are obtained. The obtained second blue narrow-band image signal and second green narrow-band image signal are subjected to the same signal processing in the DSP 55 as in the foreground viewing mode, and then stored in the frame memory 56 as the special light image data for the far view. Is done. Then, based on the distant view special light image data read from the frame memory 56, a special light image at the time of distant view observation as shown in FIG. 9 is displayed.

  Even in the distant view observation mode, the observation state is determined by the observation state determination unit as in the distant view observation mode. Therefore, when the exposure amount exceeds a certain value, the distant view observation mode is switched to the near view observation mode. On the other hand, when the exposure amount is less than a certain value (when the exposure amount is less than a certain value but the surface blood vessels are sufficiently highlighted), as long as the special light image mode is set, the distant view is observed. Keep the mode.

  As shown in FIG. 11, the electronic endoscope system 100 according to the second embodiment of the present invention is different from the first embodiment in which RGB frame sequential light or special light is irradiated into the body cavity with only one rotary filter. The two rotary filters are used to irradiate RGB frame sequential light or special light. In the following description, only the parts that are different between the first embodiment and the second embodiment will be described, and the description of other parts will be omitted.

  In the light source device 13 of the electronic endoscope system 100, a normal light rotation filter 101 and a special light rotation filter 102 are provided. The normal light rotation filter 101 and the special light rotation filter 102 are rotated at a constant speed around the rotation shafts 101a and 102a by motors 103 and 103, respectively.

  As shown in FIG. 12, the normal light rotation filter 101 includes a blue light transmission filter 110 that transmits blue band light (B light) of the broadband light BB, and a green band light (G of the broadband light BB). Green light transmission filter 111 that transmits light), red light transmission filter 112 that transmits red band light (R light) out of broadband light BB, and opening 113 that transmits broadband light BB as they are in this order. It is provided along the circumferential direction. The normal light rotation filter 101 is provided so that one of the blue light transmission filter 110, the green light transmission filter 111, the red light transmission filter 112, and the opening 113 is located on the optical path of the broadband light source 30. (See FIG. 11).

  On the other hand, as shown in FIG. 13, the special light rotary filter 102 includes a first blue narrowband light transmission filter 115 that transmits the first blue narrowband light Bn1 used in the foreground observation of the broadband light BB, and a wideband. The second blue narrow-band light transmission filter 116 that transmits the second blue narrow-band light Bn2 that is used for viewing the distant view of the light BB, and the first green narrow-band light Gn1 that is used for the foreground viewing of the broadband light BB are transmitted. The first green narrowband light transmission filter 117 and the second green narrowband light transmission filter 118 that transmits the second green narrowband light Gn2 used for distant view observation of the broadband light BB are arranged in this order along the circumferential direction. Is provided. The special light rotary filter 102 is provided with a filter switching unit 120 that moves the rotary shaft 102a in a direction orthogonal to the optical path of the broadband light BB (see FIG. 11). By this filter switching unit 120, the special light rotary filter 102 is changed into a first blue narrowband light transmission filter 115, a second blue narrowband light transmission filter 116, a first green narrowband light transmission filter 117, and a second green narrowband light transmission filter 116. It is movable between an insertion position where any one of the band light transmission filters 118 is positioned on the optical path of the broadband light source 30 and a retreat position where the entire rotary filter is retracted from the optical path of the broadband light BB. .

  In the second embodiment, when the normal light image mode is set, the special light rotation filter 102 is set at the retracted position. Therefore, the broadband light BB from the broadband light source 30 is irradiated to the normal light rotation filter 101 as it is. In this state, when the normal light rotation filter 101 rotates, the body light is irradiated with B light, G light, R light, and broadband light BB in this order. In the second embodiment, by providing the special light transmitting opening 113 in the normal light rotating filter 101, in addition to B light, G light, and R light, broadband light BB is irradiated into the body cavity. become. Therefore, when the CCD 44 that receives the reflected light in the body cavity is controlled by the imaging control unit 46, as shown in FIG. 14, when the B light, G light, and R light are irradiated, the same as in the first embodiment. Although signal accumulation and readout are performed, signal accumulation and readout are not performed when the broadband light BB is irradiated.

  On the other hand, when the special light image mode is set, the special light rotation filter 102 is set at the insertion position. Then, when the opening 113 of the normal light rotation filter 101 is positioned on the optical path of the broadband light BB, the rotation of the normal light rotation filter 101 is stopped. In this state, when the special light rotary filter 102 rotates, the first blue narrow band light Bn1, the second blue narrow band light Bn2, the first green narrow band light Gn1, and the second green narrow band are formed in the body cavity. Light Gn2 is irradiated in this order. In the special light image mode, the type and order of the light emitted into the body cavity are exactly the same (see FIGS. 7B and 7C), and thus the description of the control of the CCD 44 by the imaging control unit 46 is omitted. .

  In the above embodiment, the full width at half maximum of the blue narrow-band light or the green narrow-band light is expanded to compensate for the shortage of light during distant view observation. When observing, the full width at half maximum of the red narrow band light may be increased.

  In the above embodiment, the half-value width is changed between the near-field observation and the far-field observation. However, this is further generalized, and the half-value width of the narrowband light according to the distance between the endoscope tip and the subject tissue. It is preferable that the full width at half maximum increases as the distance from the subject distance increases, and the full width at half maximum decreases as the distance decreases.

  Hereinafter, the present invention will be described more specifically in Examples and Comparative Examples.

[Example]
In the embodiment, in the foreground observation mode in the special light image mode, imaging in the body cavity is performed using the rotation filter 31 as shown in FIG. The rotary filter 31 is the same as that shown in the first embodiment. The rotary filter 31 is provided with a first filter area 38 used in the normal light image mode and a second filter area 39 used in the special light image mode. In the second filter area 39, a first blue narrowband light transmission filter 65, a second blue narrowband light transmission filter 66, a first green narrowband light transmission filter 67, and a second green narrowband light transmission filter 68 are provided. They are provided along the circumferential direction in this order. Therefore, by rotating the rotary filter 31 with the second filter area 39 set on the optical path of the broadband light BB, the first blue narrowband light Bn1, the second blue narrowband light Bn2, and the first green narrowband are rotated. Light Gn1 and second green narrowband light Gn2 are irradiated into the body cavity in this order.

  Then, in the CCD in the distal end portion of the endoscope, first, when the first blue narrow-band light Bn1 is incident, signal accumulation and reading are performed within the imaging period (period in which the rotary filter 31 rotates ¼). When the second blue narrow band light Bn2 irradiated into the body cavity after the first blue narrow band light Bn1 enters the CCD, no signal is stored and read out. Therefore, a period during which the first blue narrow band light Bn2 is being irradiated (a period in which the rotary filter 31 rotates by ¼) is a blank period during which the inside of the body cavity cannot be imaged.

  When the first green narrowband light Gn1 irradiated into the body cavity after the second blue narrowband light Bn2 enters the CCD, the signal is again transmitted within the imaging period (period in which the rotary filter 31 rotates 1/4). Is stored and read out. When the second green narrow-band light Gn2 irradiated into the body cavity after the first green narrow-band light Bn2 enters the CCD, no signal is stored or read out. Therefore, while the second blue narrow-band light Gn2 is being irradiated (a period in which the rotary filter 31 rotates ¼), a blank period during which the inside of the body cavity cannot be imaged is a blank period.

[Comparative example]
In the comparative example, imaging in the body cavity is performed using the rotation filter 200 as shown in FIG. 16 in the foreground observation mode in the special light image mode. Similarly to the rotary filter 31, the rotary filter 200 is also provided with a first filter area 201 used in the normal light image mode and a second filter area 202 used in the special light image mode. In the second filter area 202, unlike the rotary filter 31, the first blue narrow band light transmission filter 65, the first green narrow band light transmission filter 67, the second blue narrow band light transmission filter 66, and the second green narrow band are included. The light transmission filter 68 is provided along the circumferential direction in this order. Therefore, by rotating the rotary filter 200 with the second filter area 202 set on the optical path of the broadband light BB, the first blue narrowband light Bn1, the first green narrowband light Gn1, and the second blue narrowband are rotated. Light Bn2 and second green narrowband light Gn2 are irradiated into the body cavity in this order.

  Then, in the CCD in the distal end portion of the endoscope, first, when the first blue narrow band light Bn1 is incident, the period during which the first blue narrow band light Bn1 is incident (the rotary filter 200 rotates by 1/4). Period), signal accumulation and readout. When the first green narrowband light Gn1 irradiated into the body cavity after the first blue narrowband light Bn1 enters the CCD, the period during which the first green narrowband light Gn1 is incident (rotary filter) The signal is stored and read out during a period in which 200 is rotated by 1/4. Therefore, during the period in which the first blue narrow-band light Bn1 is imaged and the period in which the first green narrow-band light Gn1 is imaged, that is, while the rotary filter 200 rotates 1/2, the blank cannot be imaged in the body cavity. It becomes a period.

[Comparison between Examples and Comparative Examples]
As described above, in the embodiment, in the foreground observation mode, the blank period is only during the quarter rotation of the rotary filter, whereas in the comparative example, the blank period is during the half rotation of the rotary filter. Therefore, the blank period of the comparative example is longer than that of the example. Therefore, in the embodiment, since the period during which the inside of the body cavity cannot be imaged is shorter than that in the comparative example, it is possible to reliably perform image diagnosis or the like when using the endoscope. Note that the difference between the blank period in this example and the comparative example is the same in the distant view observation mode.

10,100 Electronic endoscope system 30 Broadband light source 31 Rotating filter 44 Image sensor 45, 115 First blue narrowband light transmission filter 46, 116 Second blue narrowband light transmission filter 47, 117 First green narrowband light transmission filter 48, 118 Second green narrow-band light transmission filter 46 Imaging control unit 55 DSP
57 Observation state determination unit 59 Controller 102 Rotating filter for special light

Claims (5)

A broadband light source that emits broadband light with a wavelength ranging from the blue region to the red region;
A plurality of first narrowband light transmission filters that transmit first narrowband light having a specific wavelength among the broadband light, and second narrowband light in which the half-value width of the first narrowband light is widened within a certain range among the broadband light. A plurality of second narrow-band light transmission filters to be transmitted, and the first narrow-band light transmission filter and the second narrow-band light transmission filter alternately rotate the first narrow-band light and the second narrow-band light. First rotating filters arranged alternately along the circumferential direction so as to be irradiated into the body cavity;
Imaging signal acquisition means for acquiring an imaging signal by imaging the inside of a body cavity illuminated with the first or second narrowband light with an imaging element in an endoscope distal end;
Based on the imaging signal, the image is captured in a near-field observation state where the distance between the endoscope tip and the subject tissue in the body cavity is close, or the distance between the endoscope tip and the subject tissue in the body cavity is An observation state determination means for determining whether or not the image is captured in a distant view observation state in a distant state;
When it is determined that the subject is in the foreground viewing state, an image is taken when the first narrow band light is irradiated, and when it is determined that the subject is in the far view observation state, the second narrow band light is irradiated. An electronic endoscope system comprising: an imaging control unit that controls the imaging device so that an image is captured when the image is captured. The first narrowband light includes first blue narrowband light limited to a specific band in the blue wavelength region and first green narrowband light limited to a specific band in the green wavelength region,
The second narrowband light includes a second blue narrowband light in which the half-value width of the first blue narrowband light is widened within a certain range and a second blue width in which the half-value width of the first green narrowband light is widened within a certain range. Including green narrowband light,
The first rotary filter includes:
The plurality of first filters including a first blue narrowband light transmission filter that transmits first blue narrowband light among the broadband light and a first green narrowband light transmission filter that transmits first green narrowband light among the broadband light. A narrow band light transmission filter, a second blue narrow band light transmission filter that transmits the second narrow band light of the broadband light, and a second green narrow band light that transmits the second green narrow band light of the broadband light are transmitted. The electronic endoscope system according to claim 1, further comprising a plurality of second narrowband light transmission filters including a second green narrowband light transmission filter. The first rotary filter includes:
Blue light transmission filter that transmits blue light B in broadband light, green light transmission filter that transmits green light G in broadband light, and red light transmission that transmits red light R in broadband light A first filter area in which filters are provided in this order;
An area provided inside or outside the first filter area, the first blue narrowband light transmission filter, the second blue narrowband light transmission filter, the first green narrowband light transmission filter, and the second green color A second green narrowband light transmission filter that transmits the narrowband light includes a second filter area provided along the circumferential direction in this order,
When normal light observation is performed using B light, G light, and R light, by setting the first filter area on the optical path of the broadband light and rotating the first rotating filter, the B light, G light, Irradiate R light into the body cavity in this order,
When special light observation is performed using the first blue narrowband light, the second blue narrowband light, the first green narrowband light, and the second green narrowband light, the second filter area is provided on the optical path of the broadband light. Is set and the first rotation filter is rotated to irradiate the body cavity with the first blue narrow band light, the second blue narrow band light, the first green narrow band light, and the second green narrow band light in this order. The electronic endoscope system according to claim 2. A blue light transmitting filter that transmits blue light in the broadband light among the broadband light, a green light transmitting filter that transmits green light in the green band among the broadband light, and a red light that transmits red light in the red band among the broadband light. A light transmission filter, and a second rotation filter provided with an opening that transmits the broadband light as it is along this order,
When normal light observation is performed using B light, G light, and R light, by rotating the second rotary filter with the first rotary filter retracted from the optical path of the broadband light, Irradiate the body cavity with G light and R light in this order,
When special light observation is performed using the first blue narrowband light, the second blue narrowband light, the first green narrowband light, and the second green narrowband light, the second rotation is performed on the optical path of the broadband light. By rotating the first rotating filter with the filter opening set, the first blue narrowband light, the second blue narrowband light, the first green narrowband light, and the second green narrowband light are sequentially arranged in this order. The electronic endoscope system according to claim 2, which irradiates a body cavity.   The observation state determination unit detects an exposure amount from the imaging signal acquired by the imaging signal acquisition 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. 5. The electronic endoscope system according to claim 1, wherein the electronic endoscope system is determined to be in a distant view observation state.

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