JP2009022376A - Electronic endoscope system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic endoscope system observing not only the surface of tissue but also the tissue of the part deeper than the surface. <P>SOLUTION: The imaging unit 10 arranged in the leading end of an endoscope insertion part is moved in an optical axis direction by driving an actuator 16 and a focus position is altered. A variable wavelength light source 22 guides a laser beam selected from among a plurality of semiconductor lasers different in wavelength to the leading end of an endoscope through a light guide 23 to irradiate an object with the laser beam through a light distribution lens 24. A system controller 30 is constituted so as not only to change the focus position in a direction away from the leading end part of the endoscope but also to shift the wavelength of illumination light toward a long wavelength side in the case where observation depth is instructed to be deep by an observation depth indication lever 40 and also constituted so as not only to change the focus position in a direction of approaching the leading end part of the endoscope but also to shift the wavelength of illumination light toward a short wavelength side in the case where the observation depth is made shallow. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic endoscope system that electronically captures and displays an image of a target part such as a body cavity by an imaging device, and more particularly to a means for changing the observation depth of the target part.

  In an electronic endoscope system, an image of an object formed by an objective lens arranged at the tip of an endoscope insertion portion is picked up by an image pickup device, and a video signal output from the image pickup device is processed by an image processing device. Display on an external monitor screen. An operator observes an image displayed as a moving image or a still image on the monitor screen, and grasps the state of the part to be imaged.

  Recently, there is a demand for observing the shape and density of blood vessels for detailed analysis of a lesion and using it as a diagnostic judgment material. Compared with normal tissue in which capillaries run smoothly, lesions tend to have complicated and dense capillaries. Cancerated cells require a lot of blood and generate blood vessels in a short period of time, so this situation is likely to occur. Therefore, it is possible to determine the lesioned part by examining the degree of confusion and density of the capillaries.

  In the fluorescence observation endoscope that observes the fluorescence emitted from the tissue by irradiating the excitation light, the excitation light is absorbed by the blood, so that the confusion of the capillaries and the dense portion are displayed in black. Patent Document 1 discloses an endoscope system capable of this type of fluorescence observation.

Japanese Patent Laid-Open No. 2002-028125

  However, since the excitation light used for fluorescence observation has a shorter wavelength than the visible region, the above-described fluorescence observation endoscope can mainly obtain information on the tissue surface, and blood vessels and the like deeper than the tissue surface can be obtained. There is a problem that it cannot be observed.

  The present invention has been made in view of the problems of the prior art, and provides an electronic endoscope system capable of observing not only the surface of the tissue but also the tissue deeper than the surface. Is the purpose (problem).

  The electronic endoscope system of the present invention devised to solve the above-described problem is an imaging in which an image of an object formed by an objective lens arranged at the distal end of an endoscope insertion portion is captured by an imaging element. An optical system, a focus position changing unit that changes a focus position conjugate with an imaging element of the imaging optical system in the optical axis direction of the objective lens with respect to the distal end of the endoscope insertion portion, and a variable wavelength light source capable of changing the emission wavelength An illumination optical system that illuminates the object by guiding illumination light emitted from the variable wavelength light source to the distal end of the endoscope insertion section via a light guide, and an observation depth instruction means that is operated by an operator of the endoscope And a control means for controlling the focus position changing means and the variable wavelength light source in accordance with an instruction from the observation depth instruction means. When the observation depth is instructed by the observation depth instruction means, the control means controls the focus position changing means to change the focus position in a direction away from the endoscope distal end, and the variable wavelength light source. Shifts the wavelength of the illumination light emitted from the lens to the long wavelength side, and when instructed to reduce the observation depth, controls the focus position changing means to change the focus position in a direction approaching the endoscope tip, The wavelength of illumination light emitted from the variable wavelength light source is shifted to the short wavelength side.

  The variable wavelength light source is desirably capable of emitting excitation light that excites biological tissue to generate fluorescence. Further, it is desirable to further include a white light source that makes white light incident on the light guide. In this case, illumination light or excitation light from a variable wavelength light source and white light from a white light source are alternately incident on the light guide, and the image data captured when each light is incident is combined on the same screen. Can be displayed on the monitor.

  In addition, an imaging optical system may be configured as a confocal optical system in which a pinhole plate is disposed between the objective lens and the imaging device and blocks light from other than the focusing surface conjugate with the imaging surface of the imaging device.

  According to the electronic endoscope system of the present invention, the observation depth can be increased by shifting the wavelength of the illumination light to the long wavelength side and changing the focus position away from the distal end portion of the endoscope. In other words, since light with a longer wavelength reaches a deeper part than the tissue surface, it is possible to observe a state deeper than the tissue surface by using illumination light with a longer wavelength and focusing on the deep part. . Therefore, it is possible to observe the degree of confusion and density of capillaries deeper than the tissue surface, and based on this, it is possible to determine the lesioned part.

  Next, an embodiment for carrying out the present invention will be described based on the attached drawings. FIG. 1 is a block diagram illustrating a schematic configuration of the electronic endoscope system according to the embodiment. FIG. 1 shows the configuration of the distal end portion of an endoscope insertion portion that is elongated to be inserted into a body cavity, and the connection relationship of each circuit in the light source processor device connected to the insertion portion. .

  As shown in FIG. 1, the electronic endoscope system 1 includes an imaging unit 10 that is disposed at the distal end of an endoscope insertion portion and captures an image of an object through an objective window (shield glass) 11. The light emitted from the white light source 21 that emits white light or the variable wavelength light source 22 that can change the emission wavelength is guided to the tip of the endoscope insertion portion via the light guide 23, and the target object via the light distribution lens 24. And an illumination optical system 20 for irradiating the light.

  A cylindrical hood 2 is attached to the distal end portion of the endoscope. The distal end of the hood 2 protrudes from the objective window 11 and the light distribution lens 24, and is configured so that light irradiation and imaging can be performed even when the distal end portion of the endoscope is pressed against the observation site.

  As shown in FIGS. 2 and 3 in an enlarged manner, the imaging unit 10 includes an imaging optical system including an objective lens 12 and a charge storage type imaging device 13 that captures an image of an object formed by the objective lens 12. It has. The objective lens 12 and the image pickup device 13 are held in a movable lens barrel 15 housed in a fixed lens barrel 14 fixed to the distal end portion of the endoscope.

  The movable lens barrel 15 is slidable in the optical axis direction of the objective lens 12 by an actuator 16 such as a piezoelectric element disposed between the movable lens barrel 15 and the fixed lens barrel 14. 2 shows a case where the actuation amount of the actuator 16 is small, and the focus position conjugate with the imaging element 13 of the imaging optical system is close to the tip of the endoscope insertion portion. FIG. 3 shows that the actuation amount of the actuator 16 is large, The case where the focus position of the imaging optical system is far from the distal end of the endoscope insertion portion is shown. With the hood 2 pressed against the tissue surface, the setting of FIG. 2 focuses the imaging optical system on the tissue surface, and the setting of FIG. 3 focuses on a portion deeper than the tissue surface. That is, the movable lens barrel 15 and the actuator 16 function as focus position changing means for changing the focus position conjugate with the image pickup element 13 of the image pickup optical system in the optical axis direction of the objective lens 12 with respect to the distal end of the endoscope insertion portion. To do.

  On the linear optical path connecting the white light source 21 and the light guide 23, a rotary shutter 25, a half mirror 26, and a condenser lens 27 are sequentially arranged from the light source side. The variable wavelength light source 22 is arranged so that light is incident on the half mirror 26 perpendicular to the optical path. The rotary shutter 25 is a disc in which a fan-shaped window 25a having a central angle of about 180 ° is formed as shown in a planar shape in FIG. 4 and is in a state orthogonal to and offset from the optical axis of the condenser lens 27. Thus, it is fixed to the rotation shaft of the shutter motor 31. The size of the window 25a is set larger than the diameter of the white light, and the white light is turned on / off and transmitted intermittently by driving the shutter motor 31 and rotating the rotary shutter 25. Part of the white light from the white light source 21 that has passed through the rotary shutter 25 passes through the half mirror 26, is condensed by the condenser lens 27, and enters the light guide 23.

  The rotary shutter 25 is attached to the slide base 28 together with the shutter motor 31. By driving the slide motor 32, the rotary shutter 25 is moved to the set position in the optical path shown in FIG. It is possible to switch between a retreat position that is out of the range.

  On the other hand, the variable wavelength light source 22 incorporates a plurality of semiconductor lasers having different emission wavelengths. The variable wavelength light source 22 includes an excitation laser that emits light in a near-ultraviolet wavelength range that excites a living body to generate autofluorescence, and a plurality of illumination lasers that emit light at different wavelengths in the visible range. These semiconductor lasers selectively emit light, a part of which is reflected by the half mirror 26, condensed by the condenser lens 27, and incident on the light guide 23.

  As the variable wavelength light source 22, a monochromator can be used in addition to the above configuration. A monochromator is a device that creates an arbitrary spectral light source with a prism or grating and selects a narrow wavelength band for emission by an exit slit placed in the spectrum. By moving the spectrum of the light source that passes through the slit, The emission wavelength can be changed. In the case of a laser light source, the oscillation wavelength is stepwise, but in the case of a monochromator, the wavelength can be changed steplessly although the selected wavelength has a width. However, when using a monochromator and using a light source with slow on / off switching, it is necessary to dispose a shutter similar to the rotary shutter 25 for the white light source between the variable wavelength light source 22 and the half mirror 26. .

  An excitation light cut filter (not shown) for removing a wavelength component corresponding to the excitation light emitted from the excitation laser is incorporated between the objective lens 12 and the image sensor 13. As shown in FIG. 5, the excitation light cut filter has a characteristic of blocking the excitation light and transmitting light having a wavelength longer than that of the excitation light. As a result, the excitation light is incident on the image sensor 13 during fluorescence imaging. This makes it possible to capture only autofluorescence.

  In addition, a pinhole plate (not shown) is provided between the objective lens 12 and the image pickup device 13 in accordance with the focus of the objective lens 12, and the image pickup optical system is conjugated with the image pickup surface of the image pickup device 13. It is configured as a confocal optical system that blocks light from other than the focused surface.

  Next, a configuration of an electric system that processes an image signal picked up by the image pickup unit 10 and controls the light emission wavelength of the focus position changing unit and the variable wavelength light source 22 will be described. The electric system of the electronic endoscope system 1 is centered on a system controller 30 that controls the entire system, and a first driver 31a that drives a shutter motor 31, a second driver 32a that drives a slide motor 32, and the imaging unit 10. A third driver 33 that changes the focus position of the imaging optical system 10 by driving the actuator 16, a timing controller 34 that outputs a synchronization signal for controlling the imaging device 12, and an image that is synchronized with a signal from the timing controller 34. A fourth driver 35 that outputs a drive signal for driving the element 13 is provided.

  Further, as the image signal processing system, a pre-stage signal processing circuit 36 that processes a video signal output from the image sensor 13, and an image processing circuit that performs arithmetic processing on the digital video signal processed and output by the pre-stage signal processing circuit 36. 37, a post-stage signal processing circuit 38 for converting the video signal calculated by the image processing circuit 37 into a standardized video signal to be displayed on the monitor 39 and outputting it.

  Further, the operation unit connected to the endoscope insertion unit has an observation depth instruction lever 40 for instructing the observation depth, and the observation mode is switched between the normal observation mode, the fluorescence observation mode, and the depth observation mode. Mode changeover switch 50 is provided. These levers and switches are operated by an operator (operator) during observation with an endoscope.

  The observation depth instruction lever 40 is provided with a fan-shaped slit plate 41 so as to rotate integrally therewith, and a photo interrupter 42 is disposed across the slit plate 41. The photo interrupter 42 includes a light emitting element and a light receiving element disposed so as to face each other with the slit plate 41 interposed therebetween, and is configured as an incremental rotary encoder that outputs a pulse as the slit plate 41 rotates. Here, two sets of slit rows are arranged on the slit plate 41 with a half cycle shift, and a set of a light emitting element and a light receiving element is provided for each slit. Thereby, the rotation amount and the rotation direction can be detected.

  The operation by the observation depth instruction lever 40 is effective only in the depth observation mode, and a pulse signal from the photo interrupter 42 is input to the system controller 30 according to the operation, and the system controller 30 performs the third operation according to this pulse signal. The driver 33 is controlled to drive the actuator 16 to change the focus position, thereby shifting the wavelength of illumination light emitted from the variable wavelength light source 22 (in this example, switching to a semiconductor laser having a different wavelength). Specifically, when the system controller 30 is instructed to increase the observation depth by the observation depth instruction lever 40, the system controller 30 controls the actuator 16 to change the focus position away from the endoscope distal end, When instructed to shift the wavelength of the illumination light emitted from the variable wavelength light source 22 to the longer wavelength side and to reduce the observation depth, the actuator 16 is controlled to change the focus position closer to the distal end of the endoscope. At the same time, the wavelength of the illumination light emitted from the variable wavelength light source 22 is shifted to the short wavelength side. The observation depth instruction lever 40 corresponds to observation depth instruction means, and the system controller 30 corresponds to control means.

  As shown in FIG. 6, the imaging unit 10 is set at a position where the objective lens 12 and the imaging element 13 are retracted from the distal end of the endoscope when observing a tissue surface. As shown in FIG. 7, the objective lens 12 and the image sensor 13 are set at a position protruding to the endoscope distal end side. In the state of FIG. 7, the focus position conjugate with the image sensor 12 coincides with a portion deeper than the tissue surface. When the wavelength of the illumination light is shifted to the longer wavelength side, the longer the light, the deeper the tissue surface is reached, so that an image of blood vessels and the like inside the tissue can be taken.

  Further, the system controller 30 controls the first driver 31 a, the fourth driver 35, and the image processing circuit 37 via the timing controller 34. The variable wavelength light source 22 selects one of a plurality of semiconductor lasers according to a selection signal from the system controller 30 and performs chopping control of the selected semiconductor laser based on a synchronization signal from the timing controller 34.

  The image processing circuit 37 includes a composite image generation block used in the depth observation mode as shown in FIG. This block includes a low-pass filter 37a for cutting a high-frequency component of the video signal input from the preceding-stage video signal processing circuit 36, a high-pass filter 37b for cutting a low-frequency component, and image memories 37c and 37d connected to the respective filters. And an image enhancement unit 37e connected to one image memory 37d, and a synthesizer 37f that combines the output of the image enhancement unit 37e with the output of the image memory 37c.

  Next, the operation of the electronic endoscope system 1 configured as described above will be described. When the system is turned on, the system controller 30 is activated and the white light source 21 is turned on. The system controller 30 reads the setting of the mode changeover switch 50 and controls each part according to each observation mode. Hereinafter, the normal observation mode, the fluorescence observation mode, and the depth observation mode will be described in this order.

  When the normal observation mode is selected, the system controller 30 drives the slide motor 32 via the second driver 32a and retracts the rotary shutter 25 outside the optical path. The variable wavelength light source 22 remains off. Thereby, the illumination light emitted from the white light source 21 continuously reaches the endoscope distal end portion via the light guide 23 and illuminates the object via the light distribution lens. Reflected light from the object illuminated with white light is taken into the imaging unit 10 to form a color image of the object. The system controller 30 drives the actuator 16 via the third driver 33, and controls the focus position to coincide with the tissue surface of the object, as shown in FIGS. Further, the fourth driver 35 is controlled via the timing controller 34 to drive the image sensor 13 and output a video signal at a predetermined timing. The output video signal is processed by the pre-stage video signal processing circuit 36, the image processing circuit 37, and the post-stage signal processing circuit 38 to display a moving image of the object color image on the monitor 39.

  When the fluorescence observation mode is selected, the system controller 30 drives the slide motor 32 via the second driver 32a and sets the rotary shutter 25 in the optical path. Then, the shutter motor 31 is driven via the first driver 31 a to rotate the rotary shutter 25. Further, the system controller 30 selects the excitation light laser of the variable wavelength light source 22, and turns off the excitation light laser while white light passes through the rotary shutter 25 by the synchronization signal from the timing controller 34. Is cut off by the rotary shutter 25, the excitation light laser is emitted. As a result, white light emitted from the white light source 21 and excitation light emitted from the variable wavelength light source 22 are incident on the light guide 23 alternately. As in the normal observation mode, the focus position is controlled to coincide with the tissue surface of the object as shown in FIGS.

  While the excitation light is irradiated, the fluorescence from the excited tissue enters the imaging unit 10 together with the excitation light. However, since the excitation light is blocked by the excitation light cut filter, only the fluorescence reaches the image sensor 13. A fluorescent image signal is obtained. On the other hand, during a period in which white light is irradiated, reflected light from the tissue reaches the image sensor 13 and a signal of a color image of the tissue is obtained. The image processing circuit 37 combines the fluorescent image and the color image that are alternately output. At this time, the image processing circuit 37 compares the color image signal and the fluorescence image signal each time a set of the color image signal and the fluorescence image signal is acquired, and the brightness of the fluorescence image signal is compared with the brightness of the color image signal. Pixels whose ratio is lower than a certain value are identified as lesions, an image signal for displaying these pixels in red, for example, is generated, and this is combined with a color image signal, and a monitor 39 is connected via a post-stage video signal processing circuit 38. Output to. Based on the input image data, the monitor 39 displays an image in which the lesion is displayed in red on the image in the body cavity.

  When the depth observation mode is selected, the system controller 30 drives the slide motor 32 via the second driver 32a and sets the rotary shutter 25 in the optical path. Then, the shutter motor 31 is driven via the first driver 31 a to rotate the rotary shutter 25. Further, the system controller 30 selects an illumination laser other than the excitation laser from a plurality of semiconductor lasers included in the variable wavelength light source 22 based on the pulse from the observation depth instruction lever 40, and synchronizes from the timing controller 34. According to the signal, the illumination laser is turned off while white light passes through the rotary shutter 25, and the illumination laser is emitted while white light is blocked by the rotary shutter 25. Thereby, the white light emitted from the white light source 21 and the illumination light emitted from the variable wavelength light source 22 are incident on the light guide 23 alternately. Furthermore, the system controller 30 controls the third driver 33 based on the pulse from the observation depth instruction lever 40 to drive the actuator 16 and adjusts the focus position according to the observation depth. That is, when the observation depth is deep, a semiconductor laser having a longer wavelength is selected, and the focus position is adjusted to a portion deeper than the tissue surface. When the observation depth is shallow, a semiconductor laser having a shorter wavelength is selected, and the focus position is adjusted to a portion close to the tissue surface. The focus position can be changed on the order of several hundred microns.

  During the period in which white light is irradiated, the reflected light from the tissue reaches the image sensor 13 and a color image signal of the tissue is obtained. This image signal is input to the image processing device 37 via the pre-stage video signal processing circuit 36, the high frequency component is removed by the low pass filter 37a shown in FIG. 8, and the image signal is stored in the image memory 37c. On the other hand, since the reflected light from a portion deeper than the tissue surface is incident on the imaging unit 10 during the period when the single wavelength illumination light from the variable wavelength light source 22 is irradiated, an image signal including an image of a blood vessel or the like in the tissue is generated. can get. This image signal is input to the image processing device 37 via the pre-stage video signal processing circuit 36, and is stored in the image memory 37d via the high-pass filter 37b shown in FIG. 8 in order to extract high-frequency components such as blood vessels.

  The synthesizer 37f synthesizes the color image signal stored in the image memory 37c and the single-wavelength deep image signal stored in the image memory 37d and subjected to the contour enhancement processing by the image enhancement unit 37e. The signal is output to the monitor 39 via the signal processing circuit 38. Based on the input image data, the monitor 39 superimposes and displays a complicated blood vessel image on the color image in the body cavity.

  As described above, according to the electronic endoscope system 1 of the embodiment, the color image of the tissue surface in the body cavity is displayed on the monitor 39 in the normal observation mode according to the switching of the mode changeover switch 50, and the fluorescence observation is performed. In the mode, the lesion information obtained by fluorescence imaging is displayed superimposed on the color image of the tissue surface, and in the depth observation mode, the image of the site deeper than the tissue surface obtained at a specific wavelength is superimposed on the color image of the tissue surface. Displayed together.

  In the depth observation mode, the focus position of the imaging unit 10 and the wavelength of the illumination light emitted from the variable wavelength light source 22 can be changed according to the operation of the observation depth instruction lever 40, thereby changing the depth to be observed. it can. Therefore, it is possible to observe the degree of confusion and density of capillaries deeper than the tissue surface, and based on this, it is possible to determine the lesioned part.

It is a block diagram which shows the internal structure of the electronic endoscope system by one Embodiment of this invention. It is sectional drawing which shows the state which match | combined the focus position with the structure | tissue surface of the imaging unit contained in the electronic endoscope system of FIG. It is sectional drawing which shows the state which match | combined the focus position with the structure | tissue deep part of the imaging unit contained in the electronic endoscope system of FIG. It is a top view of the rotary shutter contained in the electronic endoscope system of FIG. It is a graph which shows the characteristic of the excitation light cut filter contained in the electronic endoscope system of FIG. It is explanatory drawing which shows the relationship between the focus position of the imaging unit contained in the electronic endoscope system of FIG. 1, and a structure | tissue, and shows the state which match | combined the focus position with the tissue surface. It is explanatory drawing which shows the relationship between the focus position of the imaging unit contained in the electronic endoscope system of FIG. 1, and a structure | tissue, and shows the state which match | combined the focus position with the tissue deep part. It is a block diagram which shows the synthetic | combination image generation block contained in the image processing apparatus of the electronic endoscope system of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic endoscope system 10 Imaging unit 12 Objective lens 13 Imaging element 16 Solenoid 20 Illumination optical system 21 White light source 22 Variable wavelength light source 23 Light guide 24 Light distribution lens 25 Rotary shutter 26 Half mirror 27 Condensing lens 30 System controller 34 Timing Controller 36 Front video signal processing circuit 37 Image processing circuit 38 Rear video signal processing circuit 39 Monitor 40 Observation depth instruction lever

Claims (5)

An imaging optical system that captures an image of an object formed by an objective lens disposed at the distal end of the endoscope insertion portion with an imaging element;
A focus position changing means for changing a focus position conjugate with an imaging element of the imaging optical system in an optical axis direction of the objective lens with respect to a distal end of an endoscope insertion portion;
A variable wavelength light source capable of changing the emission wavelength;
An illumination optical system for illuminating an object by guiding illumination light emitted from the variable wavelength light source to a tip of the endoscope insertion portion via a light guide;
An observation depth instruction means operated by an operator of the endoscope;
When the observation depth instruction means instructs to increase the observation depth, the focus position changing means is controlled to change the focus position in a direction away from the distal end portion of the endoscope, and the illumination emitted from the variable wavelength light source When instructed to shift the wavelength of light to the longer wavelength side and reduce the observation depth, the focus position changing means is controlled to change the focus position in a direction approaching the endoscope tip, and the variable An electronic endoscope system comprising: control means for shifting the wavelength of illumination light emitted from the wavelength light source to the short wavelength side.   The electronic endoscope system according to claim 1, wherein the variable wavelength light source is capable of emitting excitation light that excites a living tissue to generate fluorescence.   The electronic endoscope system according to claim 1, further comprising a white light source that makes white light incident on the light guide.   Illumination light or excitation light from the variable wavelength light source and white light from the white light source are alternately incident on the light guide, and image data captured at the time of each light incidence is combined on the same screen. 4. The electronic endoscope system according to claim 3, wherein the electronic endoscope system is displayed on a monitor.   The imaging optical system includes a pinhole plate between the objective lens and the imaging device, and is configured as a confocal optical system that blocks light from other than the focusing surface conjugate with the imaging surface of the imaging device. The electronic endoscope system according to any one of claims 1 to 4.