JP2005198794A - Endoscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for acquiring clear images in an area shallow from a viable tissue surface in addition to normal observation images. <P>SOLUTION: An endoscope comprises: a first light source part for emitting the light of a wide wavelength band; a second light source part for emitting the light of a short wavelength and a narrow wavelength band; a light source switching part for switching the first and second light source part and irradiating an observation surface; a first image memory part for temporarily recording an image signal obtained by first irradiation of first and second image signals obtained by image pickup at the time of irradiation with each light of the first and second light source parts; a video signal composite part for compositing the first and second image signals; and a second image memory part for tentatively recording the image signal obtained by latter irradiation of the first and second image signals. The second light source part is provided with a blue light source by a laser. The second image signal is obtained by taking out only high-frequency components from the image signals obtained at the time of the irradiation of the second light source part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an endoscope apparatus, and more particularly, to an endoscope apparatus using two light sources having different wavelength bandwidths.

  In an endoscopic device that observes and examines the body cavity, light with a short wavelength reaches the shallow area from the surface of the living tissue and reflects, and light with a long wavelength reaches the deep area from the surface of the living tissue and reflects. There has been proposed a light source device that can irradiate an observation surface with light having different wavelengths by using such characteristics.

In Patent Document 1, white light from a discharge lamp such as a xenon lamp is irradiated with three colors of R, G, and B having different wavelengths using a filter, and the degree of transmission of the filter is adjusted to adjust the degree of transmission of the filter. An apparatus for obtaining information on a desired depth is disclosed.
JP 2002-95635 A

  However, white light emitted from a discharge lamp such as a xenon lamp that is a light source in this apparatus has a wide wavelength band and a constant wavelength distribution. Therefore, even if a filter is used, it is difficult to narrow the wavelength band, and image information in a region other than the desired depth is obtained, so that a clear image cannot be obtained.

  FIG. 1 is a graph showing the spectral characteristics of a filter in a general CCD and the wavelength band of blue laser light described later. With white light having a wide wavelength band of about 400 to 700 nm, it is possible to perform spectrum centered on B, spectrum centered on G, and spectrum centered on R by a filter. It can be seen that it is difficult to suppress the wavelength band below a certain width.

  Further, white light has a wide wavelength band, but has many components in a wavelength band of 500 nm or more with a relatively long wavelength, and few components in a wavelength band of 500 nm or less with a relatively short wavelength. Therefore, there is no problem in obtaining a normal observation image. However, in order to obtain a clear image of a shallow region from the surface of a living tissue, if the light is split and irradiated only with light having a short wavelength, the amount of illumination light is insufficient. .

  Accordingly, an object of the present invention is to provide an apparatus for acquiring a clear image in a shallow region from the surface of a living tissue in addition to a normal observation image.

  An endoscope apparatus according to the present invention includes a first light source unit that emits light having a wide wavelength band, a second light source unit that emits light having a short wavelength and a narrow wavelength band, and first and second light source units. A light source switching unit that switches and irradiates the observation surface, and an image signal obtained by first irradiating the first and second image signals obtained by imaging at the time of irradiation of each light of the first and second light source units. An endoscope apparatus comprising: a first image memory unit that temporarily records; and a video signal synthesis unit that synthesizes first and second image signals. In this way, in addition to the image of the deep region from the surface of the biological tissue obtained by irradiation with white light, the image of the shallow region from the surface of the biological tissue obtained by irradiation with excitation light is synthesized to obtain a clear image of the observation surface Is possible.

  Preferably, the image processing apparatus further includes a second image memory unit that temporarily records an image signal obtained by subsequent irradiation of the first and second image signals.

  Preferably, the first light source unit includes a white light source using a discharge lamp.

  Preferably, the second light source unit has a blue light source using a laser. This makes it possible to irradiate light having a narrow wavelength region at a specific wavelength as excitation light.

  Preferably, the wavelength band of light emitted from the second light source unit is 400 nm to 420 nm.

  Preferably, the second image signal is obtained by extracting only a high-frequency component from the image signal obtained when the second light source unit is irradiated. As a result, the second image signal in which the contour portion of the image obtained by the excitation light irradiation is emphasized can be combined with the first image signal, and a shallow region image can be obtained more clearly from the surface of the living tissue. It becomes possible.

  More preferably, each of the pixel signals constituting the second image signal is a difference value of luminance information with the adjacent pixel in each of the pixel signals constituting the image signal obtained by imaging at the time of irradiation of the second light source unit. . Thereby, it becomes possible to easily obtain information on the contour portion of the image obtained by the excitation light irradiation.

  As described above, according to the present invention, it is possible to provide an apparatus that acquires a clear image in a shallow region from the surface of a living tissue in addition to a normal observation image.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 2 shows a configuration diagram of the endoscope apparatus. The endoscope apparatus according to the present embodiment includes an electronic scope 10, a color processor (electronic endoscope processor) 20, and a color monitor 40. The electronic scope 10 images the subject under the control of the color processor 20. The image signal obtained by imaging is converted by the color processor 20 into a video signal that can be output (screen display) on the color monitor 40. The converted video signal is transmitted to the color monitor 40 as an analog signal. The transmitted video signal is output by the color monitor 40. The user can observe the subject image captured by the electronic scope based on the output result from the color monitor 40.

  The electronic scope 10 includes an imaging unit 11 and an illumination unit 12, and the imaging unit 11 captures an image of the subject while the illumination unit 12 gives an appropriate amount of light to the subject.

  The imaging unit 11 includes an objective lens 11a and an imaging element 11b such as a CCD. The image sensor 11b is driven in accordance with a clock pulse output from a control circuit 24 described later. The charges accumulated in the image sensor 11b by imaging the subject are color-separated into R, G, and B as image signals and transferred to the video signal processing unit 21.

  The illuminating unit 12 emits white light, emits light from the first light source unit 26 that irradiates the living tissue via the light guiding member 12b and the light distribution lens 12a, and excitation light, and the light guiding member 12b and light distribution lens. The light from the 2nd light source part 27 which irradiates a biological tissue is supplied to an irradiation surface via 12a. The electronic scope 10 and the color processor 20 are electrically and optically connected by a connector portion (not shown).

  The color processor 20 includes a video signal processing unit 21, a control circuit 24, first and second light source units 26 and 27, and a light source switching unit 30. The color processor 20 captures an image signal captured by the electronic scope 10 and subjected to charge transfer. Then, it is converted into a video signal that can be output by the color monitor 40.

  The video signal processing unit 21 performs A / D conversion, gamma correction, contour enhancement, and amplification on the image signal sent from the electronic scope 10 by the preceding video signal processing circuit 21a, and the first signal is sent via the memory switching unit 21b. The second image memory units 21c and 21d are temporarily recorded sequentially. The memory switching unit 21b switches the memory for temporarily recording the image signal corresponding to the light source switched to one of the first and second light source units 26 and 27 by the light source switching unit 30 described later. The first image memory unit 21 c temporarily records the first image signal by the white light irradiation supplied from the first light source unit 26. The second image memory unit 21d temporarily records the second image signal by the excitation light irradiation supplied from the second light source unit 27. The second image signal is an image signal obtained by extracting only a high frequency component from the image signal based on the excitation light supplied from the second light source unit 27. The extraction of the high frequency component will be described later. The first and second image signals temporarily recorded in the first and second image memory units 21c and 21d are transferred to the subsequent video signal processing circuit 21e. The post-stage video signal processing circuit 21e synthesizes the transferred first and second image signals, converts them to video signals such as a video composite signal and a Y / C separation signal, and converts them into analog signals by the D / A converter 21f. After the conversion, the data is output to the color monitor 40.

  The control circuit 24 includes a CPU and a RAM (not shown), and controls each part of the endoscope apparatus and temporarily records signals.

  The first light source unit 26 has a white light source such as a xenon lamp that emits white light and a discharge lamp that starts discharge by emitting high voltage pulses and emits white light. The second light source unit 27 includes a blue light source using a laser that emits excitation light, such as a laser diode (LD) that emits blue laser light including excitation light. The emitted white light and excitation light are irradiated to the living tissue (observation surface) that is the subject through the light source switching unit 30, the light guiding member 12b such as an optical fiber, and the light distribution unit 12a. The user selects whether to irradiate white light or excitation light.

  White light from a discharge lamp is broadband light having a wide wavelength band from a short wavelength to a long wavelength. The excitation light of the blue laser light by the laser is narrow-band light with a short wavelength (400 nm to 420 nm) and a narrow wavelength band (see FIG. 1).

  The light source switching unit 30 includes first and second shutters 30a and 30b, a half mirror 30c, and an excitation light reflecting mirror 30d. The first and second shutters 30a and 30b transmit or block white light and excitation light by opening and closing. When the user selects to irradiate the observation surface with white light, the first shutter 30a is opened to transmit white light from the first light source unit 26, and the second shutter 30b is closed. Then, the excitation light from the second light source unit 27 is blocked. The transmitted white light passes through the half mirror 30c and is irradiated onto the observation surface through the light guiding member 12b and the light distribution unit 12a. When the user selects to irradiate the observation surface with excitation light, the first shutter 30a is closed to block white light from the first light source unit 26, and the second shutter 30b is opened. Then, the excitation light from the second light source unit 27 is transmitted. The transmitted excitation light is reflected by the excitation light reflecting mirror 30d and the half mirror 30c, and is irradiated onto the observation surface via the light guiding member 12b and the light distribution unit 12a. Control of the opening and closing of the first and second shutters 30a and 30b is performed by the control circuit 24 that receives a signal corresponding to the user's selection.

  The color monitor 40 is a commercially available color monitor that can capture and display a video signal, and outputs (screen display) the video signal that is captured by the electronic scope 10 and converted by the color processor 20.

  When white light is irradiated onto the living tissue via the light distribution lens 12a, the broadband light reflected or scattered by the living tissue is collected by the objective lens 11a and received by the imaging device 11b. When the living tissue is irradiated with the excitation light through the light distribution lens 12a, both the narrow-band light reflected or scattered by the living tissue and the autofluorescence emitted from the excited living tissue are condensed on the objective lens 11a. The image sensor 11c receives the light. However, since autofluorescence is weak light, it does not greatly affect the imaging result.

  The degree of light reaching the living tissue in the depth direction depends on the wavelength. That is, light having a short wavelength reaches only a shallow region from the surface of the living tissue, and light having a long wavelength reaches the deep region from the surface of the living tissue (see FIG. 3).

  White light from a discharge lamp with a wide wavelength band reaches the deep region from the surface of the living tissue, and reflects from the reach depth range. It becomes possible to project. Therefore, it is easy to grasp the entire image of the observation surface of the living tissue. However, since white light does not include many relatively short wavelength components, it is not possible to project capillaries or the like in a shallow region from the surface of the living tissue. FIG. 4 shows an example of an observation image using broadband light.

  The blue laser beam excitation light from a laser with a short wavelength and narrow wavelength band reaches only near the surface of the living tissue, and capillary blood vessels on the mucous membrane surface due to the narrowband light reflected and scattered from the reach depth range. It is possible to project the fine structure of. Therefore, it is useful for finding cancers that begin to progress from the surface of living tissue. However, blood vessels that are thicker than capillaries in a deep region from the surface of the living tissue cannot be projected. FIG. 5 shows an example of an observation image using narrowband light obtained by imaging the same observation surface of the subject as in FIG.

  Therefore, it is possible to obtain a clear image relating to the observation surface of the subject by combining the observation image based on the narrowband light with the observation image based on the broadband light of white light. FIG. 6 is an image example in which the observation image with narrowband light in FIG. 5 is combined with the observation image with broadband light in FIG. 4.

  The composition of the observation image using the broadband light and the observation image using the narrow-band light is obtained by temporarily recording the first image signal and the second image signal in the first and second image memory units 21c and 21d, respectively, and combining them. It is done. The second image signal may be an observation image as it is with narrow-band light, but a clearer image can be obtained by extracting only the information related to the contour lines constituting the image such as capillaries from the second image signal. I can do it.

  Extraction of information related to contour lines such as capillaries is performed by extracting only a high-frequency (high spatial frequency) component from an observation image using narrowband light. Specifically, in each of the pixel signals constituting the image signal by the edge enhancement processing in the preceding stage video signal processing circuit 21a, the difference value of the luminance information with the adjacent pixel, that is, the average of the luminance value of each pixel and the luminance of the adjacent pixel The difference value from the value is obtained. An image signal in which each pixel signal is composed of the difference value is temporarily recorded in the second image memory unit 21d as a second image signal and synthesized with the first image signal.

  These procedures will be described with reference to the flowchart of FIG. When the endoscope operation is started in step S11, the first shutter 30a is opened in step S12. At this time, the second shutter 30b is in a closed state. In step S13, white light is emitted from the first light source unit 26 toward the observation surface. In step S14, broadband light resulting from reflection of the irradiated white light is imaged, and the first image signal is temporarily recorded in the first memory 21c as a normal observation image. In step S15, the first shutter 30a is closed, and in step S16, the second shutter 30b is opened. In step S17, excitation light of blue laser light is emitted from the second light source unit 27 toward the observation surface. In step S18, the narrowband light resulting from the reflection of the irradiated excitation light is imaged and temporarily recorded in the second memory 21d as a narrowband light image. At this time, what is temporarily recorded as a narrow-band optical image is the second image signal in which information about the contour line is emphasized. In step S19, the second shutter 30b is closed. In step S20, the first image signal and the second image signal temporarily recorded in the first and second image memories 21c and 21d are synthesized. In step S21, the combined image signal is converted into a video signal and displayed on the color monitor 40. In step S22, it is determined whether or not to continue observation, that is, whether or not to continue video signal processing. When continuing observation, it returns to step S12 and starts the imaging procedure of the next frame. When ending without continuing observation, the process ends in step S23.

  Note that the light source switching unit 30 that switches the light source for irradiating the living tissue to either white light or excitation light has been described as using the first and second shutters 30a and 30b, but this is like a discharge lamp. This is effective when the light cannot be turned on and off instantaneously by an on / off signal. As long as the white light source can be turned on and off instantaneously, such as an LED, the first shutter 30a may not be used, and the light source switching unit 30 emits white light with the second light source unit 27 that emits excitation light. It is only necessary to have a function capable of performing on / off switching control alternately with a light source such as an LED.

  Moreover, although the form which has the 1st, 2nd image memory part 21c, 21d as a memory which records a 1st, 2nd image signal temporarily was demonstrated, the image signal (in this embodiment) corresponding to the light irradiated previously. (Corresponding to the first image signal) is temporarily recorded, and the image signal corresponding to the light to be irradiated later (corresponding to the second image signal in this embodiment) is not temporarily recorded, but directly transferred to the subsequent video signal processing circuit 21e. Alternatively, it may be combined with an image signal corresponding to the previously irradiated light.

A spectral characteristic of a filter in a general CCD and a wavelength band of blue laser light are shown in a graph. The block diagram of an endoscope apparatus is shown. The relationship between the wavelength of the irradiated light and the depth from the surface of the living tissue to which the light reaches is shown. The example of an image which imaged the deep area | region from the biological tissue surface by white light irradiation is shown. The example of an image which imaged the shallow area | region from the biological tissue surface by excitation light irradiation is shown. An image example in which an image example by white light irradiation and an image example by excitation light irradiation are combined is shown. The flowchart of the procedure which synthesize | combines two images by white light and excitation light irradiation is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electronic scope 11 Imaging part 12 Illumination part 20 Color processor 21 Video signal processing part 24 Control circuit 26 1st light source part 27 2nd light source part 30 Light source switching part 40 Color monitor

Claims (7)

A first light source unit that emits light having a wide wavelength band;
A second light source unit that emits light having a short wavelength and a narrow wavelength band;
A light source switching unit that switches the first and second light source units to irradiate the observation surface;
A first image memory unit for temporarily recording an image signal obtained by first irradiating the first and second image signals obtained by imaging at the time of irradiation of each light of the first and second light source units;
An endoscope apparatus comprising: a video signal synthesis unit that synthesizes the first and second image signals.   The endoscope apparatus according to claim 1, further comprising a second image memory unit that temporarily records an image signal obtained by subsequent irradiation of the first and second image signals.   The endoscope apparatus according to claim 1, wherein the first light source unit includes a white light source using a discharge lamp.   The endoscope apparatus according to claim 1, wherein the second light source unit includes a blue light source using a laser.   The endoscope apparatus according to claim 1, wherein a wavelength band of light emitted from the second light source unit is 400 nm to 420 nm.   The endoscope apparatus according to claim 1, wherein the second image signal is obtained by extracting only a high-frequency component from an image signal obtained by imaging at the time of irradiation of the second light source unit. Each of the pixel signals constituting the second image signal is a difference value of luminance information with an adjacent pixel in each of the pixel signals constituting the image signal obtained at the time of irradiation of the second light source unit. The endoscope apparatus according to claim 6.

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