JPWO2016072172A1 - Endoscope system - Google Patents

Abstract

The endoscope system has a first transmittance in which a transmittance in a first wavelength band including an excitation wavelength for generating fluorescence is a predetermined transmittance and a transmittance in a second wavelength band is a first transmittance. An optical path of light emitted from the light source, a second filter in which the transmittance in the first wavelength band is a predetermined transmittance and the transmittance in the second wavelength band is the second transmittance By interposing the first or second filter, the light source device that emits light in the first and second wavelength bands, the camera unit, and the brightness of the reflected light image are maintained at the reference value. A control unit that performs control for switching the filter inserted on the optical path from the first filter to the second filter when the brightness of the reflected light image becomes less than the reference value after the control is performed; Have.

Description

  The present invention relates to an endoscope system, and more particularly to an endoscope system used for fluorescence observation.

  In endoscopic observation in the medical field, for example, the generation state of fluorescence when a desired subject is irradiated with excitation light for exciting a fluorescent substance present in the living body or a fluorescent agent administered into the living body. Based on the above, fluorescence observation, which is an observation method for diagnosing whether or not a lesion site is included in the desired subject, has been conventionally performed. For example, Japanese Unexamined Patent Application Publication No. 2006-288760 discloses an endoscope system that can be used for fluorescence observation.

  Further, in fluorescence observation, in order to identify the fluorescence generation site generated in response to irradiation of excitation light on a desired subject in a living body, for example, reference light having a wavelength band different from the wavelength band of the fluorescence is used. Conventionally, a method of irradiating a desired subject is used.

  By the way, in the fluorescence observation using the reference light, for example, the brightness of the image obtained by imaging the reflected light of the reference light decreases as the observation distance increases, and the fluorescence based on the image is reduced. There is a problem that it may be difficult to visually recognize the background of the generation site.

  However, Japanese Patent Application Laid-Open No. 2006-288760 does not particularly mention a method or the like that can solve the above-described problems, that is, there are still problems corresponding to the above-described problems.

  The present invention has been made in view of the above-described circumstances, and provides an endoscope system capable of performing observation while maintaining as much as possible a state in which fluorescence generation sites can be identified in fluorescence observation. It is aimed.

  In the endoscope system of one embodiment of the present invention, the transmittance in the first wavelength band including the excitation wavelength for exciting the fluorescent agent administered into the subject to generate fluorescence is a predetermined transmittance. And a transmission characteristic such that the transmittance of the second wavelength band, which is a wavelength band different from the first wavelength band, is a first transmittance lower than the predetermined transmittance. The transmittance of the first optical filter and the first wavelength band is the predetermined transmittance, the transmittance of the second wavelength band is higher than the first transmittance, and the predetermined transmittance. A second optical filter formed with a transmission characteristic such that the second transmittance is lower than the first transmittance, the first optical filter and the second optical filter, and a single light source On the optical path of the light emitted from the first optical filter or A light source device configured to emit the light of the first wavelength band and the light of the second wavelength band by interposing any one of the second optical filters; Imaging the fluorescence generated when the subject in the specimen is irradiated with the light of the first wavelength band and the reflected light generated when the subject is irradiated with the light of the second wavelength band And a brightness reference corresponding to the brightness immediately after the first optical filter is inserted on the optical path, and the brightness of the reflected light image obtained by imaging the reflected light. An optical filter inserted on the optical path when the brightness of the reflected light image is detected to be less than the brightness reference value after performing a predetermined control for maintaining the value; Cut from the first optical filter to the second optical filter A control for obtaining and a control unit configured to perform relative to the light source device.

The figure which shows the structure of the principal part of the endoscope system which concerns on an Example. The figure for demonstrating an example of the internal structure of the endoscope system which concerns on an Example. The figure which shows an example of the transmission characteristic of the excitation light cut filter used in the endoscope system which concerns on an Example, and a primary color filter. The figure which shows an example of a structure of the rotation filter used in the endoscope system which concerns on an Example. The figure which shows an example of the transmission characteristic of the filter for white light observation provided in the rotation filter of FIG. The figure which shows an example of the transmission characteristic of the filter for the 1st fluorescence observation provided in the rotary filter of FIG. The figure which shows an example of the transmission characteristic of the 2nd filter for fluorescence observation provided in the rotary filter of FIG. The figure which shows an example of the gradation conversion function TF1 used in the gradation conversion process of the endoscope system which concerns on an Example. The figure which shows an example of the gradation conversion function TF2 used in the gradation conversion process of the endoscope system which concerns on an Example. The figure which shows an example of the gradation conversion function TF3 used in the gradation conversion process of the endoscope system which concerns on an Example. The figure which shows an example of the gradation conversion function TF4 used in the gradation conversion process of the endoscope system which concerns on an Example.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 11 relate to an embodiment of the present invention.

  As shown in FIG. 1, an endoscope system 1 is configured to be inserted into a subject and to image a subject such as a living tissue in the subject and output it as an imaging signal. 2, a light source device 3 configured to supply illumination light for illuminating the subject to the endoscope 2, and image processing by performing signal processing on an imaging signal output from the endoscope 2 A video processor 4 configured to generate and output a signal, and a monitor 5 configured to display an image or the like corresponding to a video signal output from the video processor 4 on a screen. Yes. FIG. 1 is a diagram illustrating a configuration of a main part of the endoscope system according to the embodiment.

  The endoscope 2 includes an optical viewing tube 2A having an elongated insertion portion 6 and a camera unit 2B that can be attached to and detached from the eyepiece 7 of the optical viewing tube 2A.

  The optical viewing tube 2A includes an elongated insertion portion 6 to be inserted into a subject, a gripping portion 8 provided at the proximal end portion of the insertion portion 6, and an eyepiece portion provided at the proximal end portion of the gripping portion 8. 7.

  As shown in FIG. 2, a light guide 11 for transmitting illumination light supplied via a cable 13a is inserted into the insertion portion 6. FIG. 2 is a diagram for explaining an example of the internal configuration of the endoscope system according to the embodiment.

  As shown in FIG. 2, the emission end of the light guide 11 is disposed in the vicinity of the illumination lens 15 at the distal end of the insertion portion 6. Further, the incident end portion of the light guide 11 is disposed in a light guide base 12 provided in the grip portion 8.

  As shown in FIG. 2, a light guide 13 for transmitting illumination light supplied from the light source device 3 is inserted into the cable 13a. A connection member (not shown) that can be attached to and detached from the light guide base 12 is provided at one end of the cable 13a. A light guide connector 14 that can be attached to and detached from the light source device 3 is provided at the other end of the cable 13a.

  An illumination window (not shown) in which an illumination lens 15 for emitting illumination light transmitted by the light guide 11 to the outside is disposed on the distal end surface of the insertion portion 6 and an optical according to light incident from the outside. An objective window (not shown) in which an objective lens 17 for obtaining an image is arranged is provided adjacent to each other.

  As shown in FIG. 2, a relay lens 18 for transmitting an optical image obtained by the objective lens 17 to the eyepiece unit 7 is provided inside the insertion unit 6.

  As shown in FIG. 2, an eyepiece lens 19 is provided inside the eyepiece unit 7 so that the optical image transmitted by the relay lens 18 can be observed with the naked eye.

  As shown in FIG. 2, the camera unit 2 </ b> B includes an excitation light cut filter 21, an imaging lens 22, a lens driving mechanism 23, and a CCD 24. The camera unit 2B includes a signal cable 27 provided with an end portion of a signal connector 28 that can be attached to and detached from the video processor 4.

  The excitation light cut filter 21 is formed to have a transmission characteristic that blocks the wavelength band of the excitation light emitted from the light source device 3 and transmits a wavelength band other than the wavelength band of the excitation light. Specifically, the excitation light cut filter 21 cuts off a wavelength band of 710 nm to 790 nm corresponding to a wavelength band of excitation light (described later) emitted from the light source device 3, as shown in FIG. It is formed with a transmission characteristic that transmits a wavelength band other than the wavelength band of the excitation light. FIG. 3 is a diagram illustrating an example of transmission characteristics of the excitation light cut filter and the primary color filter used in the endoscope system according to the embodiment.

  The imaging lens 22 is configured to form an optical image formed through the eyepiece lens 19 and the excitation light cut filter 21. Further, the imaging lens 22 is configured to be movable along the optical axis direction in accordance with the operation of the lens driving mechanism 23.

  The lens driving mechanism 23 is configured to be able to move the imaging lens 22 within a movable range between the tele end and the wide end based on a lens drive control signal output from the video processor 4.

  That is, the imaging lens 22 and the lens driving mechanism 23 of the camera unit 2B have a function as an optical zoom mechanism, and perform an optical scaling operation in accordance with control of a control circuit 53 (described later) of the video processor 4. It is configured as follows.

  The CCD 24 is configured to be connected to the video processor 4 via a signal line in the signal cable 27. The CCD 24 has a plurality of pixels (not shown) for photoelectrically converting an optical image formed by the imaging lens 22, and a primary color provided on an imaging surface in which the plurality of pixels are two-dimensionally arranged. And a color filter 25. Further, the CCD 24 is configured to set an exposure period and a reading period when an optical image formed by the imaging lens 22 is picked up in accordance with a CCD drive signal output from the video processor 4. The CCD 24 generates an imaging signal by capturing an optical image imaged by the imaging lens 22 (received on the imaging surface), and the generated imaging signal is connected to the video processor to which the signal cable 27 is connected. 4 is configured to output to 4.

  The primary color filter 25 includes an R filter that transmits part of the red region and the near infrared region, a G filter that transmits the green region, and a B filter that transmits the blue region at positions corresponding to the pixels of the CCD 24. It is formed by arranging in a Bayer array (in a checkered pattern). Specifically, the R filter, the G filter, and the B filter of the primary color filter 25 are formed to have transmission characteristics as shown in FIG. 3, for example.

  The light source device 3 includes a xenon lamp 31, a filter switching device 32, a condenser lens 33, and a light source control circuit 34.

  The xenon lamp 31 is configured to emit or extinguish according to the control of the light source control circuit 34. The xenon lamp 31 is configured to generate light having a light amount according to the control of the light source control circuit 34.

  The filter switching device 32 is emitted from the xenon lamp 31 by being rotationally driven in accordance with the control of the light source control circuit 34 and a rotary filter 32A provided so as to traverse the optical path of the light emitted from the xenon lamp 31 vertically. And a motor 32B that switches a filter interposed on the optical path of light to one of the filters of the rotary filter 32A.

  For example, the rotary filter 32A has a disk shape. Further, for example, as shown in FIG. 4, the rotary filter 32 </ b> A is provided with a white light observation filter 321, a first fluorescence observation filter 322, and a second fluorescence observation filter 323. . FIG. 4 is a diagram illustrating an example of a configuration of a rotary filter used in the endoscope system according to the embodiment.

  For example, as shown in FIG. 5, the white light observation filter 321 is formed as an optical filter having a transmission characteristic that transmits a wavelength band of 400 nm to 700 nm. FIG. 5 is a diagram illustrating an example of transmission characteristics of the white light observation filter provided in the rotary filter of FIG.

  For example, as shown in FIG. 6, the first fluorescence observation filter 322 has a transmittance in the wavelength band of 400 nm to 570 nm of TA% and a transmittance in the wavelength band of 710 nm to 790 nm of TB% (however, It is formed as an optical filter having transmission characteristics such that TB> TA). That is, the first fluorescence observation filter 322 has a transmittance in the first wavelength band of 710 nm to 790 nm including the excitation wavelength (774 nm) of ICG (indocyanine green) of TB%, and the first wavelength. The second wavelength band of 400 nm to 570 nm, which is different from the band, is formed to have a transmission characteristic such that the transmittance is TA% lower than TB%. FIG. 6 is a diagram illustrating an example of transmission characteristics of the first fluorescence observation filter provided in the rotary filter of FIG.

  For example, as shown in FIG. 7, the second fluorescence observation filter 323 has a transmittance in the wavelength band of 400 nm to 570 nm of k × TA% (assuming that k> 1), and 710 nm to 710 nm. It is formed as an optical filter having transmission characteristics such that the transmittance at 790 nm is TB% (assuming that TB> k × TA). That is, the second fluorescence observation filter 323 has a transmittance of TB% in the first wavelength band of 710 nm to 790 nm including the excitation wavelength (774 nm) of ICG (Indocyanine Green), and the first wavelength. The second wavelength band of 400 nm to 570 nm, which is different from the band, is formed to have a transmission characteristic such that the transmittance is higher than TA% and lower than TB% k × TA%. FIG. 7 is a diagram illustrating an example of transmission characteristics of a second fluorescence observation filter provided in the rotary filter of FIG.

  According to the configuration of the filter switching device 32 as described above, the white light observation filter 321, the first fluorescence observation filter 322, and the like are driven by rotating the motor 32 </ b> B according to the control of the light source control circuit 34. Inserting one of the second fluorescence observation filters 323 on the optical path of the light emitted from the xenon lamp 31 and retracting the other two filters other than the one filter from the optical path Can do.

  Here, for example, the distance between the distal end surface of the insertion portion 6 and the surface of the subject is defined as an observation distance, and light having a wavelength band of 400 nm to 570 nm transmitted through the first fluorescence observation filter 322 is set to a predetermined range. The image obtained by imaging the reflected light generated when the reference subject is irradiated has a brightness suitable for observation within the range from the observation distance DL to the observation distance DH (assuming that DL <DH). Assuming that the information is obtained as known information, the value of k can be set by the following formula (1).

k = (DH / DL) ² (1)

Alternatively, for example, the optical magnification in the optical scaling operation (hereinafter also referred to as optical zoom) according to the movement of the imaging lens 22 can be changed within the range from the minimum optical magnification ML to the maximum optical magnification MH. Is obtained as known information, the value of k can be set by the following mathematical formula (2).

k = (MH / ML) ² (2)

The condensing lens 33 is configured to condense the light that has passed through the filter switching device 32 and emit it to the light guide 13.

  The light source control circuit 34 is configured to control the xenon lamp 31 and the filter switching device 32 in accordance with the illumination control signal output from the video processor 4.

  According to the configuration of the light source device 3 as described above, the first fluorescence observation filter 322 or the second fluorescence observation filter 322 is disposed on the optical path of light emitted from the xenon lamp 31 that is a single light source. By interposing either, excitation light in a wavelength band of 710 nm to 790 nm including the excitation wavelength of ICG and reference light in a wavelength band of 400 nm to 570 nm can be emitted simultaneously.

  The video processor 4 includes a CCD driver 41, an amplifier 42, a preprocess circuit 43, an A / D conversion circuit 44, a color separation circuit 45, a color balance adjustment circuit 46, a gradation conversion circuit 47, and image processing. The circuit 48, the video signal generation circuit 49, the operation panel 52, and the control circuit 53 are configured.

  The CCD driver 41 is configured to generate and output a CCD driving signal for setting an exposure period and a reading period in the CCD 24.

  The amplifier 42 is configured to amplify an imaging signal output via the signal cable 27 and output the amplified image signal to the preprocess circuit 43.

  The preprocess circuit 43 extracts a signal component included in the image pickup signal by performing signal processing such as correlated double sampling processing on the image pickup signal output from the amplifier 42, and further extracts the signal component included in the extracted signal component. A corresponding image signal is generated and output to the A / D conversion circuit 44.

  The A / D conversion circuit 44 generates a digital image signal by performing A / D conversion processing on the analog image signal output from the preprocess circuit 43, and color-separates the generated digital image signal. It is configured to output to the circuit 45.

  The color separation circuit 45 uses the luminance value Rs of the red color component obtained by imaging the image signal output from the A / D conversion circuit 44 and the light transmitted through the R filter of the primary color filter 25, and the primary color filter 25. The luminance value Gs of the green color component obtained by imaging the light transmitted through the G filter and the luminance value Bs of the blue color component obtained by imaging the light transmitted through the B filter of the primary color filter 25 It is configured to perform color separation processing for separation. The color separation circuit 45 is configured to generate an image signal corresponding to the luminance value of each color component obtained by the color separation processing described above, and output the generated image signal to the color balance adjustment circuit 46. Yes.

  The color balance adjustment circuit 46 is configured to perform color balance adjustment of the image signal output from the color separation circuit 45 under the control of the control circuit 53.

  The gradation conversion circuit 47 is configured to perform gradation conversion processing on the image signal output from the color balance adjustment circuit 46 under the control of the control circuit 53 and output the image signal to the image processing circuit 48 and the control circuit 53. Has been.

  The image processing circuit 48 has a function as an electronic zoom processing unit, and performs electronic scaling processing (hereinafter referred to as “image scaling signal”) for each color component image signal output from the gradation conversion circuit 47 under the control of the control circuit 53. , Which is also referred to as electronic zoom processing) and the like, and output to the video signal generation circuit 49.

  Under the control of the control circuit 53, the video signal generation circuit 49 converts the luminance values of the respective color components included in the image signal output from the image processing circuit 48 into the R (red) channel, G (green) channel, and B of the monitor 5. A video signal is generated by selectively assigning to a (blue) channel, and the generated video signal is output to the monitor 5.

  The operation panel 52 includes one or more input devices capable of giving instructions according to user operations. Specifically, the operation panel 52 gives an instruction to set (switch) the observation mode of the endoscope system 1 to either the white light observation mode or the fluorescence observation mode, for example, according to a user operation. Observation mode changeover switch (not shown). The operation panel 52 includes, for example, an optical zoom switch (not shown) that can give an instruction to set the optical magnification of the optical zoom in the white light observation mode in accordance with a user operation. ing.

  The control circuit 53 generates an illumination control signal for emitting illumination light according to the observation mode of the endoscope system 1 based on an instruction given by the observation mode changeover switch of the operation panel 52 and supplies the illumination control signal to the light source control circuit 34. It is configured to output. The control circuit 53 controls the color balance adjustment circuit 46, the gradation conversion, and the control for performing the operation according to the observation mode of the endoscope system 1 based on the instruction given by the observation mode changeover switch of the operation panel 52. The circuit 47, the image processing circuit 48, and the video signal generation circuit 49 are configured to be performed on each part.

  When the control circuit 53 detects that the observation mode of the endoscope system 1 is set to the white light observation mode, the control circuit 53 uses the optical zoom switch of the operation panel 52 to perform an optical operation corresponding to the instruction. A lens drive control signal for moving the imaging lens 22 to a position where optical zoom is performed at a magnification is generated and output to the generated lens drive mechanism 23. In addition, when the control circuit 53 detects that the observation mode of the endoscope system 1 is set to the fluorescence observation mode, the control circuit 53 invalidates the instruction made on the optical zoom switch of the operation panel 52, while A lens drive control signal for moving the imaging lens 22 to a position where the optical zoom is performed at an optical magnification according to the brightness of the image signal output from the tone conversion circuit 47 is generated, and the generated lens drive is generated. It is configured to output to the mechanism 23. In addition, when the control circuit 53 detects that the observation mode of the endoscope system 1 is set to the fluorescence observation mode, the control circuit 53 performs electronic zoom processing at a magnification corresponding to the reciprocal of the current optical magnification. Control is performed on the image processing circuit 48.

  Subsequently, the operation of the endoscope system 1 according to the present embodiment will be described.

  After connecting each part of the endoscope system 1 and turning on the power, the user performs an operation on the operation panel 52 to set the observation mode of the endoscope system 1 to the white light observation mode.

  When detecting that the white light observation mode is set, the control circuit 53 generates an illumination control signal for emitting white light from the light source device 3 and outputs the illumination control signal to the light source control circuit 34.

  The light source control circuit 34 performs control for lighting the xenon lamp 31 with a predetermined light amount AL in accordance with the illumination control signal output from the control circuit 53, and white light on the optical path of the light emitted from the xenon lamp 31. Control for inserting the observation filter 321 is performed on the filter switching device 32.

  Then, by performing the control as described above in the light source control circuit 34, white light having a wavelength band of 400 nm to 700 nm is emitted as illumination light through the illumination lens 15, and according to the reflected light of the white light. The formed optical image is picked up by the CCD 24 of the camera unit 2B.

  On the other hand, when the control circuit 53 detects that the white light observation mode is set, the control circuit 53 uses a gain value calculated in advance to adjust the white balance of each color component included in the image signal output from the color separation circuit 45. Control for performing color balance adjustment is performed on the color balance adjustment circuit 46.

  When the control circuit 53 detects that the white light observation mode is set, a predetermined gradation conversion function (for example, a predetermined gradation conversion function) is applied to the luminance value of each color component included in the image signal output from the color balance adjustment circuit 46. The gradation conversion circuit 47 is controlled to perform gradation conversion processing using a gamma curve).

  When the control circuit 53 detects that the white light observation mode is set, the control circuit 53 performs control for preventing the electronic zoom process from being performed on the image signal of each color component output from the gradation conversion circuit 47. 48.

  When the control circuit 53 detects that the white light observation mode is set, the control circuit 53 assigns the luminance value of the red color component among the color components included in the image signal output from the image processing circuit 48 to the R channel, The video signal generation circuit 49 is controlled to assign the luminance value of the green color component to the G channel and to assign the luminance value of the blue color component to the B channel.

  Then, the control as described above is performed in the control circuit 53 or the like, whereby an RGB color image is displayed on the monitor 5 as an observation image in the white light observation mode.

  On the other hand, the user places the distal end portion of the insertion portion 6 in the vicinity of a desired subject by inserting the insertion portion 6 into the subject while checking the RGB color image displayed on the monitor 5. . Then, the user sets the observation mode of the endoscope system 1 to the fluorescence observation mode after administering the fluorescent agent to the desired subject in a state where the distal end portion of the insertion portion 6 is disposed in the vicinity of the desired subject. For this purpose is performed on the operation panel 52.

  Here, specific operations performed when the observation mode of the endoscope system 1 is set to the fluorescence observation mode will be described. In the following description, an example in which ICG having an excitation wavelength (absorption peak wavelength) of 774 nm and a fluorescence wavelength (fluorescence peak wavelength) of 805 nm is administered as a fluorescent agent to a desired subject will be described as an example. In the following, for the sake of simplicity, the case where the distal end surface of the insertion portion 6 is gradually moved away from a desired subject, that is, the case where the observation distance gradually increases will be described as an example.

  When detecting that the fluorescence observation mode is set, the control circuit 53 generates a lens drive control signal for performing optical zoom at the maximum optical magnification MH, and outputs the lens drive control signal to the lens drive mechanism 23.

  The lens driving mechanism 23 performs an operation for placing the imaging lens 22 at the tele end in accordance with a lens driving control signal output from the control circuit 53.

  When detecting that the fluorescence observation mode is set, the control circuit 53 generates an illumination control signal for emitting the first illumination light for fluorescence observation from the light source device 3 and outputs the illumination control signal to the light source control circuit 34.

  The light source control circuit 34 performs control for lighting the xenon lamp 31 with a predetermined light amount AL in accordance with the illumination control signal output from the control circuit 53, and the first light path on the light path of the light emitted from the xenon lamp 31. Control for inserting the fluorescence observation filter 322 is performed on the filter switching device 32.

  Then, when the light source control circuit 34 performs the control as described above, excitation light having a wavelength band of 710 nm to 790 nm and having a light quantity of AL × TB, and a wavelength band of 400 nm to 570 nm and AL × The first reference light having a light quantity of TA is simultaneously emitted to a desired subject through the illumination lens 15, and fluorescence having a peak wavelength of 805 nm is emitted from a fluorescent agent administered to the desired subject; The optical image formed according to the fluorescence and the optical image formed according to the reflected light of the first reference light are respectively captured by the CCD 24 of the camera unit 2B. Further, by performing the control as described above in the light source control circuit 34, the red color component obtained by imaging the fluorescence transmitted through the R filter of the primary color filter 25 and the G filter of the primary color filter 25 are transmitted. A green color component obtained by imaging the reflected light of the first reference light, and a blue color component obtained by imaging the reflected light of the first reference light transmitted through the B filter of the primary color filter 25 , Are output from the CCD 24.

  When the control circuit 53 detects that the fluorescence observation mode is set, the control circuit 53 controls the color balance adjustment circuit 46 to adjust the color balance of the image signal output from the color separation circuit 45.

  Specifically, the control circuit 53, for example, the gain value Rg with respect to the luminance value Rs of the red color component corresponding to the fluorescence color component (fluorescence image) included in the image signal output from the color separation circuit 45. , The luminance value Rs × Rg obtained by multiplying the luminance value, the luminance value Gs of the green color component corresponding to the color component (reflected light image) of the reflected light of the reference light included in the image signal, and the luminance value of the blue color component The color balance adjustment circuit 46 is controlled to perform color balance adjustment so that the luminance value Gs + Bs obtained by adding Bs becomes the same luminance value.

  When detecting that the fluorescence observation mode is set, the control circuit 53 uses a gradation conversion function TF1 (described later) for the luminance value of each color component included in the image signal output from the color balance adjustment circuit 46. Control for performing gradation conversion processing is performed on the gradation conversion circuit 47.

  As shown in FIG. 8, for example, the gradation conversion circuit 47 applies the luminance values of the red, green, and blue color components included in the image signal output from the color balance adjustment circuit 46 according to the control of the control circuit 53. The tone conversion process using the tone conversion function TF1 which is a non-linear function is performed and output to the image processing circuit 48 and the control circuit 53. FIG. 8 is a diagram illustrating an example of the gradation conversion function TF1 used in the gradation conversion processing of the endoscope system according to the embodiment.

  Note that the input luminance value and the output luminance value in the gradation conversion function TF1 in FIG. 8 have a maximum luminance value corresponding to the number of gradations expressed by the A / D conversion processing of the A / D conversion circuit 44 as 100%. It is assumed that the ratio of the luminance value in each case is shown. Specifically, for example, when the number of gradations represented by the A / D conversion process of the A / D conversion circuit 44 is 256 gradations of 0 to 255, 50% in FIG. 8 corresponds to the luminance value 255. FIG.

  When the control circuit 53 detects that the fluorescence observation mode is set, the electronic zoom is performed at 1 / MH times corresponding to the reciprocal of the maximum optical magnification MH with respect to the image signal of each color component output from the gradation conversion circuit 47. Control for performing processing is performed on the image processing circuit 48.

  When detecting that the fluorescence observation mode is set, the control circuit 53 uses the luminance value of the red color component among the color components included in the image signal output from the image processing circuit 48 as the luminance value of the fluorescence image. Control for assigning the luminance value obtained by adding the luminance value of the green color component and the luminance value of the blue color component to the G channel and the B channel as the luminance value of the reflected light image. This is performed for the video signal generation circuit 49.

  Then, the control as described above is performed in the control circuit 53 or the like, whereby a pseudo color image is displayed on the monitor 5 as an observation image in the fluorescence observation mode.

  On the other hand, the user performs an operation of gradually moving the distal end surface of the insertion unit 6 away from a desired subject while checking the pseudo color image displayed on the monitor 5.

  The control circuit 53 sets the luminance value BLS obtained by adding the luminance value of the green color component and the luminance value of the blue color component included in the image signal output from the gradation conversion circuit 47 to the fluorescence observation mode. As a control for maintaining the luminance value BLF immediately after being set, a lens drive control signal is generated for performing control to gradually change the current optical magnification Ma of the optical zoom from the maximum optical magnification MH to the minimum optical magnification ML. And output to the lens driving mechanism 23. The luminance value BLF is, for example, immediately after the first fluorescence observation filter 322 is inserted on the optical path of the light emitted from the xenon lamp 31 and the imaging lens 22 is disposed at the tele end. It can be calculated by adding the luminance value of the green color component and the luminance value of the blue color component included in the image signal output from the tone conversion circuit 47.

  The lens driving mechanism 23 performs an operation for gradually moving the imaging lens 22 from the tele end side to the wide end side in accordance with the lens drive control signal output from the control circuit 53.

  The control circuit 53 controls the image processing circuit 48 to perform electronic zoom processing at 1 / Ma times corresponding to the reciprocal of the current optical magnification Ma of the optical zoom.

  On the other hand, the control circuit 53 emits the first fluorescence observation illumination light from the light source device 3 and changes the current optical magnification Ma of the optical zoom to the minimum optical magnification ML, and then the gradation conversion circuit. When it is detected that the luminance value BLS obtained based on the image signal output from 47 is less than the luminance value BLF, the current optical magnification Ma of the optical zoom is instantaneously changed from the minimum optical magnification ML to the maximum optical magnification MH. Output of a lens drive control signal for performing control to be changed to, and control for switching illumination light emitted from the light source device 3 from illumination light for first fluorescence observation to illumination light for second fluorescence observation (xenon Equivalent to control for switching the optical filter inserted in the optical path of the light emitted from the lamp 31 from the first fluorescence observation filter 322 to the second fluorescence observation filter 323). The output of the light control signal, the control for changing the gradation conversion function used in the gradation conversion processing for the luminance value of the red color component from TF1 to TF2 (described later), and the magnification of the electronic zoom processing are set to 1 / ML. And control for changing from 1 to MH at the same time.

  The lens driving mechanism 23 performs an operation for instantaneously moving the imaging lens 22 disposed at the wide end to the tele end in accordance with a lens driving control signal output from the control circuit 53.

  The light source control circuit 34 performs control for lighting the xenon lamp 31 with a predetermined light amount AL in accordance with the illumination control signal output from the control circuit 53, and the second light path on the optical path of the light emitted from the xenon lamp 31. The filter switching device 32 is controlled to insert the fluorescence observation filter 323.

  Then, when the light source control circuit 34 performs the control as described above, excitation light having a wavelength band of 710 nm to 790 nm and having a light quantity of AL × TB, and a wavelength band of 400 nm to 570 nm and AL × The second reference light having a light quantity of k × TA is simultaneously emitted to the desired subject through the illumination lens 15, and fluorescence having a peak wavelength of 805 nm is emitted from the fluorescent agent administered to the desired subject. The optical image formed according to the fluorescence and the optical image formed according to the reflected light of the second reference light are respectively captured by the CCD 24 of the camera unit 2B. Further, by performing the control as described above in the light source control circuit 34, the red color component obtained by imaging the fluorescence transmitted through the R filter of the primary color filter 25 and the G filter of the primary color filter 25 are transmitted. A green color component obtained by imaging the reflected light of the second reference light, and a blue color component obtained by imaging the reflected light of the second reference light transmitted through the B filter of the primary color filter 25 , Are output from the CCD 24.

  The gradation conversion circuit 47 performs, for example, a non-linear function as shown in FIG. 9 on the luminance value of the red color component included in the image signal output from the color balance adjustment circuit 46 under the control of the control circuit 53. And a tone conversion process using the tone conversion function TF1 on the luminance values of the green and blue color components included in the image signal. To the image processing circuit 48 and the control circuit 53. FIG. 9 is a diagram illustrating an example of the gradation conversion function TF2 used in the gradation conversion process of the endoscope system according to the embodiment.

  Note that the input luminance value and the output luminance value in the gradation conversion function TF2 in FIG. 9 have the maximum luminance value corresponding to the number of gradations expressed by the A / D conversion processing of the A / D conversion circuit 44 as 100%. It is assumed that the ratio of the luminance value in each case is shown. In the gradation conversion function TF2 in FIG. 9, the output luminance value with respect to the input luminance value is k times that of the gradation conversion function TF1, and the upper limit value of the output luminance value is the same value (100) as the gradation conversion function TF1. %) As a non-linear function.

  That is, the gradation conversion circuit 47 performs gradation conversion processing using the gradation conversion function TF2 on the luminance value of the fluorescent color component (fluorescence image) included in the image signal output from the color balance adjustment circuit 46. Thereby, the fluctuation | variation of the said luminance value at the time of the switch from the 1st fluorescence observation filter 322 to the 2nd fluorescence observation filter 323 can be suppressed.

  On the other hand, the gradation conversion circuit 47 of the present embodiment performs gradation conversion processing using the gradation conversion function TF2 on the luminance value of the red color component included in the image signal output from the color balance adjustment circuit 46. For example, a process of multiplying the luminance value of the red color component by the gain value calculated based on the gradation conversion function TF1 and the value of k may be performed.

  The control circuit 53 controls to instantaneously change the current optical magnification Ma of the optical zoom from the minimum optical magnification ML to the maximum optical magnification MH, and the illumination light emitted from the light source device 3 is the illumination light for the first fluorescence observation. Immediately after the luminance value BLS obtained on the basis of the image signal output from the gradation conversion circuit 47 is set to the fluorescence observation mode. As a control for maintaining the brightness value BLF of the lens, a lens drive control signal is generated for performing again control to gradually change the current optical magnification Ma of the optical zoom from the maximum optical magnification MH to the minimum optical magnification ML. Output to the drive mechanism 23.

  The lens driving mechanism 23 performs an operation for gradually moving the imaging lens 22 from the tele end side to the wide end side in accordance with the lens drive control signal output from the control circuit 53.

  The control circuit 53 controls the image processing circuit 48 to perform electronic zoom processing at 1 / Ma times corresponding to the reciprocal of the current optical magnification Ma of the optical zoom.

  That is, according to the operation of each unit as described above, when the observation mode of the endoscope system 1 is set to the fluorescence observation mode, at least the first illumination light for fluorescence observation is emitted from the light source device 3. From the observation distance D1 that is emitted and the optical zoom is performed at the maximum optical magnification MH, the second illumination light for fluorescence observation is emitted from the light source device 3, and the observation distance D2 at which the optical zoom is performed at the minimum optical magnification ML. In the section up to (provided that D1 <D2), a pseudo color image that can identify the site of the fluorescence emitted from the fluorescent drug administered to the desired subject can be displayed on the monitor 5. As a result, according to the present example, in the fluorescence observation, it is possible to perform the observation while maintaining as much as possible the state where the fluorescence generation site can be identified.

  Further, according to the present embodiment, for example, the monitor 5 that can be generated when the illumination light used in the fluorescence observation mode is switched from the illumination light for the first fluorescence observation to the illumination light for the second fluorescence observation. A change in the brightness of the displayed pseudo color image can be minimized.

  Further, according to this embodiment, for example, in the fluorescence observation mode, the reference light in the wavelength band of 520 nm to 540 nm, which is the wavelength band in which the sensitivity of the G filter provided in the primary color filter 25 is larger than the sensitivity of the B filter. For changing the luminance value allocation in the video signal generation circuit 49 based on the luminance value of the green color component included in the image signal output from the gradation conversion circuit 47 Control may be performed by the control circuit 53. Specifically, for example, in each pixel included in the image signal for one frame output from the gradation conversion circuit 47, the number of pixels in which the luminance value of the green color component reaches the above-described upper limit value is a predetermined number. If it is less than PT, control is performed to assign the luminance value of the green color component included in the image signal output from the image processing circuit 48 to the G channel and the B channel as the luminance value of the reflected light image. On the other hand, when the number of pixels in which the luminance value of the green color component has reached the above-described upper limit value is equal to or greater than the predetermined number PT, the blue color component included in the image signal output from the image processing circuit 48 The control may be performed so that the luminance value is assigned to the G channel and the B channel as the luminance value of the reflected light image.

  Moreover, according to the present Example, each part of the endoscope system 1 may be appropriately modified so as to have a configuration corresponding to other fluorescent agents other than ICG.

  Specifically, for example, when the configuration of the endoscope system 1 is modified to correspond to 5-aminolevulinic acid having an excitation wavelength (absorption peak wavelength) of 405 nm and a fluorescence wavelength (fluorescence peak wavelength) of 635 nm. The camera unit 2B may be configured except for the excitation light cut filter 21. Further, for example, in the case of modifying the configuration of the endoscope system 1 so as to correspond to 5-aminolevulinic acid, excitation light having a wavelength band of 380 nm to 440 nm and reference light having a wavelength band of 400 nm to 550 nm include What is necessary is just to deform | transform suitably each part of the light source device 3 so that it may be radiate | emitted as illumination light for fluorescence observation.

  On the other hand, according to the present embodiment, in the fluorescence observation mode, not only the operation described above but also the operation described below may be performed.

  Here, a modified example of specific operations performed when the observation mode of the endoscope system 1 is set to the fluorescence observation mode will be described. In the following, for the sake of simplicity, a specific description regarding the portion to which the above-described operation or the like can be applied will be omitted as appropriate.

  When detecting that the fluorescence observation mode is set, the control circuit 53 generates a lens drive control signal for performing optical zoom at the maximum optical magnification MH, and outputs the lens drive control signal to the lens drive mechanism 23.

  The lens driving mechanism 23 performs an operation for placing the imaging lens 22 at the tele end in accordance with a lens driving control signal output from the control circuit 53.

  When detecting that the fluorescence observation mode is set, the control circuit 53 generates an illumination control signal for emitting the first illumination light for fluorescence observation from the light source device 3 and outputs the illumination control signal to the light source control circuit 34.

  The light source control circuit 34 performs control for lighting the xenon lamp 31 with a predetermined light amount AL in accordance with the illumination control signal output from the control circuit 53, and the first light path on the light path of the light emitted from the xenon lamp 31. Control for inserting the fluorescence observation filter 322 is performed on the filter switching device 32.

  When the control circuit 53 detects that the fluorescence observation mode is set, the control circuit 53 controls the color balance adjustment circuit 46 to adjust the color balance of the image signal output from the color separation circuit 45.

  When the control circuit 53 detects that the fluorescence observation mode is set, for example, a gradation conversion function TF3 (described later) is applied to the luminance value of the red color component included in the image signal output from the color balance adjustment circuit 46. ) And a gradation conversion process using the gradation conversion function TF1 for the luminance values of the green and blue color components included in the image signal. This is performed for the gradation conversion circuit 47.

  The gradation conversion circuit 47 performs, for example, a non-linear function as shown in FIG. 10 on the luminance value of the red color component included in the image signal output from the color balance adjustment circuit 46 under the control of the control circuit 53. And a tone conversion process using the tone conversion function TF1 for the luminance values of the green and blue color components included in the image signal. To the image processing circuit 48 and the control circuit 53. FIG. 10 is a diagram illustrating an example of the gradation conversion function TF3 used in the gradation conversion process of the endoscope system according to the embodiment.

  Note that the input luminance value and the output luminance value in the gradation conversion function TF3 in FIG. 10 have a maximum luminance value corresponding to the number of gradations expressed by the A / D conversion processing of the A / D conversion circuit 44 as 100%. It is assumed that the ratio of the luminance value in each case is shown. Further, the gradation conversion function TF3 in FIG. 10 indicates the output luminance with respect to the input luminance value BL1 when the first fluorescent observation illumination light is emitted from the light source device 3 and the optical zoom is performed at the minimum optical magnification ML. It is shown as a non-linear function in which the value becomes the upper limit (100%) and the output luminance value for the input luminance value BL2 corresponding to 1 / k times the input luminance value BL1 becomes the upper limit (100%). .

  That is, the gradation conversion circuit 47 performs gradation conversion processing using the gradation conversion function TF3 on the luminance value of the fluorescent color component (fluorescence image) included in the image signal output from the color balance adjustment circuit 46. Thereby, the fluctuation | variation of the said luminance value at the time of the switch from the 1st fluorescence observation filter 322 to the 2nd fluorescence observation filter 323 can be suppressed.

  On the other hand, according to the present modification, in the gradation conversion process for the luminance value of the red color component included in the image signal output from the color balance adjustment circuit 46, for example, FIG. 11 instead of the gradation conversion function TF3. A gradation conversion function TF4 as shown in FIG. FIG. 11 is a diagram illustrating an example of the gradation conversion function TF4 used in the gradation conversion process of the endoscope system according to the embodiment.

  Note that the input luminance value and the output luminance value in the gradation conversion function TF4 in FIG. 11 have a maximum luminance value corresponding to the number of gradations expressed by the A / D conversion processing of the A / D conversion circuit 44 as 100%. It is assumed that the ratio of the luminance value in each case is shown. Further, the gradation conversion function TF4 in FIG. 11 indicates the output luminance with respect to the input luminance value BL3 when the first fluorescent observation illumination light is emitted from the light source device 3 and the optical zoom is performed at the minimum optical magnification ML. It is shown as a non-linear function in which the value becomes the upper limit value (100%) and the output luminance value for the input luminance value BL4 corresponding to 1 / k times the input luminance value BL3 becomes the upper limit value (100%). . Further, according to the gradation conversion function TF4 of FIG. 11, the output luminance value for the input luminance value of 10% or less corresponding to the luminance value corresponding to the noise component or the luminance value almost impossible to see with the naked eye is uniformly set. Gradation conversion processing (threshold processing) is performed such that the output luminance value for an input luminance value greater than 10% is uniformly set to the upper limit value (100%).

  That is, the gradation conversion circuit 47 performs gradation conversion processing using the gradation conversion function TF4 on the luminance value of the fluorescent color component (fluorescent image) included in the image signal output from the color balance adjustment circuit 46. Thereby, the fluctuation | variation of the said luminance value at the time of the switch from the 1st fluorescence observation filter 322 to the 2nd fluorescence observation filter 323 can be suppressed.

  When the control circuit 53 detects that the fluorescence observation mode is set, the electronic zoom is performed at 1 / MH times corresponding to the reciprocal of the maximum optical magnification MH with respect to the image signal of each color component output from the gradation conversion circuit 47. Control for performing processing is performed on the image processing circuit 48.

  When the control circuit 53 detects that the fluorescence observation mode is set, the control circuit 53 assigns the luminance value of the red color component among the color components included in the image signal output from the image processing circuit 48 to the R channel, and the green color. The video signal generation circuit 49 is controlled to assign the luminance value obtained by adding the luminance value of the blue color component and the luminance value of the blue color component to the G channel and the B channel, respectively.

  Then, the control as described above is performed in the control circuit 53 or the like, whereby a pseudo color image is displayed on the monitor 5 as an observation image in the fluorescence observation mode.

  On the other hand, the user performs an operation of gradually moving the distal end surface of the insertion unit 6 away from a desired subject while checking the pseudo color image displayed on the monitor 5.

  The control circuit 53 performs the current optical zoom as control for maintaining the luminance value BLS obtained based on the image signal output from the gradation conversion circuit 47 at the luminance value BLF immediately after being set to the fluorescence observation mode. A lens drive control signal for performing control to gradually change the optical magnification Ma from the maximum optical magnification MH to the minimum optical magnification ML is generated and output to the lens drive mechanism 23.

  The lens driving mechanism 23 performs an operation for gradually moving the imaging lens 22 from the tele end side to the wide end side in accordance with the lens drive control signal output from the control circuit 53.

  The control circuit 53 controls the image processing circuit 48 to perform electronic zoom processing at 1 / Ma times corresponding to the reciprocal of the current optical magnification Ma of the optical zoom.

  On the other hand, the control circuit 53 emits the first fluorescence observation illumination light from the light source device 3 and changes the current optical magnification Ma of the optical zoom to the minimum optical magnification ML, and then the gradation conversion circuit. When it is detected that the luminance value BLS obtained based on the image signal output from 47 is less than the luminance value BLF, the current optical magnification Ma of the optical zoom is instantaneously changed from the minimum optical magnification ML to the maximum optical magnification MH. Output of a lens drive control signal for performing control to be changed to, and control for switching illumination light emitted from the light source device 3 from illumination light for first fluorescence observation to illumination light for second fluorescence observation (xenon Equivalent to control for switching the optical filter inserted in the optical path of the light emitted from the lamp 31 from the first fluorescence observation filter 322 to the second fluorescence observation filter 323). Performing an output of the light control signal, and a control for changing the magnification of the electronic zoom processing from 1 / ML to 1 / MH, simultaneously.

  The lens driving mechanism 23 performs an operation for instantaneously moving the imaging lens 22 disposed at the wide end to the tele end in accordance with a lens driving control signal output from the control circuit 53.

  The light source control circuit 34 performs control for lighting the xenon lamp 31 with a predetermined light amount AL in accordance with the illumination control signal output from the control circuit 53, and the second light path on the optical path of the light emitted from the xenon lamp 31. The filter switching device 32 is controlled to insert the fluorescence observation filter 323.

  The control circuit 53 controls to instantaneously change the current optical magnification Ma of the optical zoom from the minimum optical magnification ML to the maximum optical magnification MH, and the illumination light emitted from the light source device 3 is the illumination light for the first fluorescence observation. Immediately after the luminance value BLS obtained on the basis of the image signal output from the gradation conversion circuit 47 is set to the fluorescence observation mode. As a control for maintaining the brightness value BLF of the lens, a lens drive control signal is generated for performing again control to gradually change the current optical magnification Ma of the optical zoom from the maximum optical magnification MH to the minimum optical magnification ML. Output to the drive mechanism 23.

  The lens driving mechanism 23 performs an operation for gradually moving the imaging lens 22 from the tele end side to the wide end side in accordance with the lens drive control signal output from the control circuit 53.

  The control circuit 53 controls the image processing circuit 48 to perform electronic zoom processing at 1 / Ma times corresponding to the reciprocal of the current optical magnification Ma of the optical zoom.

  That is, according to the operation of each part as described above, when the observation mode of the endoscope system 1 is set to the fluorescence observation mode, at least in the section from the observation distance D1 to D2, the desired subject It is possible to display a pseudo color image capable of identifying the site of occurrence of fluorescence emitted from the fluorescent drug administered to the monitor 5. As a result, according to the present modification, in the fluorescence observation, it is possible to perform the observation while maintaining as much as possible the state where the fluorescence generation site can be identified.

  The embodiment and the modification described above are not limited to those applied to the endoscope 2 configured to include the optical viewing tube 2A and the camera unit 2B. For example, the embodiment and the modification may be inserted into the subject. An electronic endoscope having an elongated insertion portion capable of being provided and having an imaging portion (color CCD) or the like for imaging a subject in the subject provided at the distal end portion of the insertion portion The same applies to the above.

  It should be noted that the present invention is not limited to the above-described embodiments and modifications, and it is needless to say that various changes and applications can be made without departing from the spirit of the invention.

  This application is filed on the basis of the priority claim of Japanese Patent Application No. 2014-225370 filed in Japan on November 5, 2014, and the above-mentioned disclosed contents include the present specification, claims, It shall be cited in the drawing.

In the endoscope system according to one aspect of the present invention, the transmittance in the first wavelength band including the excitation wavelength for exciting the fluorescent material to generate fluorescence is a predetermined transmittance, and the first wavelength A first optical filter formed with a transmission characteristic such that the transmittance of the second wavelength band, which is a wavelength band different from the band, is a first transmittance lower than the predetermined transmittance; The second wavelength band transmittance is the predetermined transmittance, and the second wavelength band transmittance is higher than the first transmittance and lower than the predetermined transmittance. wherein the second optical filter formed comprises a transmission characteristic such as the transmittance, comprising a first optical filter and the second optical filter on the optical path of light emitted from the light source The first optical filter or the second optical filter Or by causing interposed the Re, the a light of a first wavelength band, and light in the second wavelength band, a light source unit configured to emit, in the subject having the fluorescent substance The fluorescent light generated when the subject is irradiated with the light of the first wavelength band and the reflected light generated when the subject is irradiated with the light of the second wavelength band are imaged. The brightness of the reflected light image obtained by imaging the reflected light and the camera unit is maintained at a brightness reference value corresponding to the brightness after the first optical filter is inserted on the optical path. An optical filter inserted on the optical path when the brightness of the reflected light image is detected to be less than the brightness reference value after performing a predetermined control to perform the first control. Control for switching from the optical filter to the second optical filter. The and a control unit configured to perform relative to the light source device.

In the endoscope system according to one aspect of the present invention, the transmittance in the first wavelength band including the excitation wavelength for exciting the fluorescent material to generate fluorescence is a predetermined transmittance, and the first wavelength A first optical filter formed with a transmission characteristic such that the transmittance of the second wavelength band, which is a wavelength band different from the band, is a first transmittance lower than the predetermined transmittance; The second wavelength band transmittance is the predetermined transmittance, and the second wavelength band transmittance is higher than the first transmittance and lower than the predetermined transmittance. A second optical filter formed with transmission characteristics such as transmittance, the first optical filter, and the second optical filter, and the first optical filter and the second optical filter are provided on an optical path of light emitted from a light source 1 optical filter or the second optical filter By interposing them, a light source unit configured to emit the light in the first wavelength band and the light in the second wavelength band, and the inside of the subject having the fluorescent material The fluorescent light generated when the subject is irradiated with the light of the first wavelength band and the reflected light generated when the subject is irradiated with the light of the second wavelength band are imaged. A camera unit, an optical zoom mechanism provided in the camera unit and controlled to perform an optical scaling operation, and brightness of a reflected light image obtained by imaging the reflected light on the optical path. In order to maintain the brightness reference value corresponding to the brightness after the first optical filter is inserted in the current optical magnification in the optical scaling operation as a predetermined control, the maximum optical magnification And gradually change between the minimum optical magnification Later were control of fit with respect to the optical zoom mechanism, when the brightness of the reflected light image is detected that is less than the brightness reference value, the optical filter interposed in the optical path A control unit configured to perform control for switching from the first optical filter to the second optical filter with respect to the light source unit .

Claims (6)

The transmittance in the first wavelength band including the excitation wavelength for exciting the fluorescent agent administered into the subject to generate fluorescence is a predetermined transmittance and a wavelength different from the first wavelength band. A first optical filter formed with a transmission characteristic such that the transmittance of the second wavelength band, which is a band, is a first transmittance lower than the predetermined transmittance;
The second wavelength band transmittance is the predetermined transmittance, and the second wavelength band transmittance is higher than the first transmittance and lower than the predetermined transmittance. A second optical filter formed with transmission characteristics such as transmittance,
The first optical filter and the second optical filter are provided, and either the first optical filter or the second optical filter is inserted on an optical path of light emitted from a single light source. A light source device configured to emit light in the first wavelength band and light in the second wavelength band;
Imaging the fluorescence generated when the subject in the subject is irradiated with light in the first wavelength band and the reflected light generated when the subject is irradiated with light in the second wavelength band A camera unit configured to:
The brightness of the reflected light image obtained by imaging the reflected light is a predetermined value for maintaining a brightness reference value corresponding to the brightness immediately after the first optical filter is inserted on the optical path. After performing the control, when it is detected that the brightness of the reflected light image is less than the brightness reference value, an optical filter inserted on the optical path is moved from the first optical filter to the first optical filter. A control unit configured to perform control for switching to the two optical filters on the light source device;
An endoscope system comprising: An optical zoom mechanism provided in the camera unit and configured to perform an optical scaling operation in accordance with control of the control unit;
The control unit controls the optical zoom mechanism to gradually change the current optical magnification in the optical scaling operation between the maximum optical magnification and the minimum optical magnification as the predetermined control. The endoscope system according to claim 1, wherein the endoscope system is performed. The control unit detects that the brightness of the reflected light image is less than the brightness reference value after changing the current optical magnification in the optical scaling operation to the minimum optical magnification. At the same time, the light source device is controlled to switch the optical filter inserted on the optical path from the first optical filter to the second optical filter, and at the present time in the optical scaling operation. The endoscope system according to claim 2, wherein control for instantaneously changing the optical magnification of the optical zoom mechanism from the minimum optical magnification to the maximum optical magnification is performed on the optical zoom mechanism. An electronic zoom processing unit configured to electronically scale the reflected light image;
The control unit performs control for causing the electronic zoom processing unit to perform the electronic scaling process at a magnification corresponding to a reciprocal of a current optical magnification in the optical scaling operation. The endoscope system according to claim 2. The control unit controls the switching of the optical filter inserted on the optical path from the first optical filter to the second optical filter, and sets the current optical magnification in the optical scaling operation to the minimum. The endoscope system according to claim 3, wherein the predetermined control is performed again after performing the control for instantaneously changing the optical magnification from the optical magnification to the maximum optical magnification. The fluorescent image obtained by imaging the fluorescence is configured to perform a gradation conversion process for suppressing a variation in brightness when switching from the first optical filter to the second optical filter. The endoscope system according to claim 1, further comprising a gradation conversion processing unit.

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