JP2016049370A - Electronic endoscope system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To address such a problem that, when narrow-band light and wide-band light are applied to a subject, it is difficult to capture an image of a specific biological structure at a high contrast.SOLUTION: An electronic endoscope system includes: a narrow-band light source part for exiting narrow-band light; a wide-band light source part for exiting wide-band light; means for drivingly controlling the light source parts to alternately emit the narrow-band light and the wide-band light; means that captures an image of a subject to which the narrow-band light and the wide-band light are alternately applied, generates an image signal of the subject captured when the narrow-band light is applied thereto, as a first image signal, and generates an image signal of the subject captured when the wide-band light is applied thereto, as a second image signal; means that generates a first luminance signal on the basis of the first image signal and generates a second luminance signal on the basis of the second image signal, and generates a luminance signal of the subject on the basis of the generated first and second luminance signals; and means for generating a video signal of the subject using the generated luminance signal of the subject.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electronic endoscope system capable of imaging a subject such as a body cavity.

  An electronic endoscope system for observing a body cavity of a patient is known. For example, Patent Document 1 describes a specific configuration of this type of electronic endoscope system.

  The electronic endoscope system described in Patent Document 1 generates a spectral image that emphasizes a specific biological structure using light in a band (narrow band light) having high absorption characteristics in the specific biological structure. Specifically, the electronic endoscope system described in Patent Document 1 determines the light amount ratio between the narrowband light and the broadband light (white light) according to the type of the site to be observed in the body cavity. A site to be observed is irradiated with a light quantity ratio, a return light from the irradiated site to be observed is received, and a spectroscopic image that emphasizes a specific biological structure is generated using the received return light.

JP 2012-152333 A

  As described above, in the electronic endoscope system described in Patent Document 1, the site to be observed is irradiated and imaged with light in which narrowband light and broadband light are mixed. Therefore, there is a problem that information on a specific anatomy obtained by narrowband light is diluted with information on other anatomy obtained by broadband light, and the contrast of the specific anatomy is lowered.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to image a specific anatomy with high contrast even when a subject is irradiated with narrowband light and broadband light. It is to provide a possible electronic endoscope system.

  An electronic endoscope system according to an embodiment of the present invention includes a narrowband light source unit that emits narrowband light having a peak intensity in a first specific band suitable for highlighting a first biological structure, and a narrowband Driving control of the broadband light source unit that emits broadband light having a wider band than the light, and the narrow band light source unit and broadband light source unit to alternately emit narrow band light and at least broadband light. And imaging means for imaging a subject that is alternately irradiated with narrowband light and at least broadband light, and generating an image signal of the subject imaged during irradiation of the narrowband light as a first image signal And generating at least the image signal of the subject imaged during the irradiation of the broadband light as the second image signal, generating the first luminance signal based on the first image signal, and based on the second image signal Second luminance signal And a luminance signal generation means for generating a luminance signal of the subject based on the generated first and second luminance signals, and a video signal generation for generating a video signal of the subject using the generated luminance signal of the subject Means.

  According to such a configuration, the dilution of the information on the specific anatomy obtained by the narrowband light by the information on the other anatomy obtained by the broadband light is suppressed, and the contrast of the specific anatomy increases. .

  In one embodiment of the present invention, the luminance signal generation unit may generate the luminance signal of the subject by combining the first luminance signal and the second luminance signal at a predetermined ratio.

  The electronic endoscope system according to an embodiment of the present invention includes light that includes broadband light and at least narrow-band light having a peak intensity in a second specific band suitable for highlighting the second anatomy. It is good also as a structure provided with the optical filter which filters to (1).

  Further, an electronic endoscope system according to an embodiment of the present invention includes an optical path synthesis unit that guides narrowband light emitted from a narrowband light source unit and broadband light emitted from a broadband light source unit on the same optical path. It is good.

  In one embodiment of the present invention, the narrow-band light source unit is, for example, a monochromatic semiconductor laser or an LED (Light Emitting Diode).

  Moreover, in one Embodiment of this invention, a broadband light source part is white LED, for example.

  In addition, the electronic endoscope system according to the embodiment of the present invention may include a mode setting unit that sets the operation mode to the first or second operation mode. In the first operation mode, the light source unit drive control unit drives and controls the narrow band light source unit and the broadband light source unit to alternately emit narrow band light and at least broadband light, and the imaging unit transmits the narrow band light. An image signal of a subject imaged during irradiation is generated as a first image signal, and an image signal of a subject imaged during irradiation of at least broadband light is generated as a second image signal. A first luminance signal is generated based on the one image signal, a second luminance signal is generated based on the second image signal, and a luminance signal of the subject is generated based on the generated first and second luminance signals. In the second operation mode, the light source unit drive control unit drives and controls the narrow band light source unit and the broadband light source unit, and continuously emits the narrow band light and the broadband light. And an image signal of the subject imaged during the irradiation of the broadband light, and a luminance signal generation unit generates a luminance signal of the subject based on the generated image signal.

  According to an embodiment of the present invention, there is provided an electronic endoscope system capable of imaging a specific biological structure with high contrast even when a subject is irradiated with narrowband light and broadband light.

It is a block diagram which shows the structure of the electronic endoscope system of embodiment of this invention. Spectral characteristics of narrow-band light emitted from a narrow-band light source unit included in the electronic endoscope system according to the embodiment of the present invention (FIG. 2A) and spectral characteristics of white light emitted from a broadband light source unit (FIG. 2 (b)). It is a figure which shows the spectral characteristic of the optical filter with which the electronic endoscope system of embodiment of this invention is equipped. It is a figure which shows the spectral characteristics of the dichroic mirror with which the electronic endoscope system of embodiment of this invention is equipped. It is a figure which shows the example image (FIG.5 (a)) image | photographed at the time of normal mode, and the example image (FIG.5 (b)) image | photographed at the time of special mode.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, an electronic endoscope system will be described as an example of an embodiment of the present invention.

[Configuration of the entire electronic endoscope system 1]
FIG. 1 is a block diagram illustrating a configuration of an electronic endoscope system 1 according to the present embodiment. As shown in FIG. 1, the electronic endoscope system 1 includes an electronic scope 100, a processor 200, and a monitor 300.

  The processor 200 includes a system controller 202 and a timing controller 204. The system controller 202 executes various programs stored in the memory 212 and controls the entire electronic endoscope system 1 in an integrated manner. The system controller 202 is connected to the operation panel 214. The system controller 202 changes each operation of the electronic endoscope system 1 and parameters for each operation in accordance with a user instruction input from the operation panel 214. The input instruction by the operator includes, for example, an instruction to switch the operation mode of the electronic endoscope system 1. In the present embodiment, there are a normal mode and a special mode as operation modes. The timing controller 204 outputs a clock pulse for adjusting the operation timing of each unit to each circuit in the electronic endoscope system 1.

  The processor 200 includes a narrow band light source unit 206A, a broadband light source unit 206B, and a light source unit drive control circuit 206C. The light source unit drive control circuit 206C drives the band light source unit 206A and the broadband light source unit 206B under the control of the system controller 202.

  The narrow-band light source unit 206A is a monochromatic semiconductor laser or LED, and emits narrow-band light LA. The broadband light source unit 206B is a white LED and emits white light LB.

  FIG. 2A shows the spectral characteristics of the narrowband light LA emitted from the narrowband light source unit 206A. FIG. 2B shows the spectral characteristics of the white light LB emitted from the broadband light source unit 206B. In FIG. 2B, the solid line indicates the spectral characteristics of the white light LB. The broken line will be described later. In each of FIGS. 2A and 2B, the vertical axis indicates intensity (no unit for normalization), and the horizontal axis indicates wavelength (unit: nm).

  As shown in FIG. 2 (a), the narrowband light LA is light having a narrow half-value width having a peak intensity near 420 nm, and is used to capture a spectral image that emphasizes the blood vessel structure near the surface layer in the body cavity. Has suitable spectral characteristics. In addition, as shown in FIG. 2B, the spectral characteristics of the white light LB are not flat but are spread over the entire visible light region.

  The processor 200 includes a filter turret 206D and a turret control unit 206E. The turret control unit 206E includes a transmission mechanism such as a motor and a gear. When the motor of the turret control unit 206E is driven under the control of the system controller 202, the driving force is transmitted to the filter turret 206D by the transmission mechanism. The filter turret 206D is inserted on the optical path of the white light LB or retracted from the optical path of the white light LB according to the transmitted driving force.

  The filter turret 206D is provided with an optical filter 206Df. FIG. 3 shows two examples of spectral characteristics of the optical filter 206Df (an example in FIG. 3A and an example in FIG. 3B). In each of FIGS. 3A and 2B, the vertical axis indicates the transmittance (no unit for normalization), and the horizontal axis indicates the wavelength (unit: nm).

  As shown in each example of FIGS. 3A and 3B, the spectral characteristics of the optical filter 206Df have a transmission peak with a narrow half-value width in a plurality of bands including the vicinity of 550 nm, and between the transmission peaks. Has a transmissivity above a certain level. Therefore, when the filter turret 206D (optical filter 206Df) is inserted in the optical path, the white light LB emitted from the broadband light source unit 206B includes light including narrowband light having a peak intensity in the vicinity of at least 550 nm (for convenience, “ Filtered to “broadband light LB ′”). Narrow band light near 550 nm is light suitable for photographing a spectral image that emphasizes a deep blood vessel structure in a body cavity. FIG. 2B shows a spectral characteristic of the broadband light LB ′ filtered by the optical filter 206Df illustrated in FIG.

  The processor 200 includes a dichroic mirror 206F. FIG. 4 shows the spectral characteristics of the dichroic mirror 206F. In FIG. 4, the vertical axis indicates the transmittance (no unit for normalization), and the horizontal axis indicates the wavelength (unit: nm).

  As shown in FIG. 4, the dichroic mirror 206F has a cut-on wavelength near 420 nm, and mainly reflects light having a wavelength of about 420 nm or less and transmits light having a higher wavelength. Therefore, most of the narrowband light LA emitted from the narrowband light source unit 206A is reflected by the dichroic mirror 206F, and the white light LB (or the broadband light via the optical filter 206Df) emitted from the broadband light source unit 206B. Most of LB ′) is transmitted through the dichroic mirror 206F. The narrowband light LA reflected by the dichroic mirror 206F and the white light LB (broadband light LB ') transmitted through the dichroic mirror 206F are guided on the same optical path and are incident on the condenser lens 210.

[Operation in normal mode]
The operation of the electronic endoscope system 1 in the normal mode will be described.

  When the operation mode of the electronic endoscope system 1 is set to the normal mode, the filter turret 206D is retracted from the optical path of the white light LB, and the broadband light source unit 206B continuously emits the white light LB. Therefore, the white light LB emitted from the broadband light source unit 206B passes through the dichroic mirror 206F and enters the condenser lens 210.

  As shown in FIG. 2B, the white light LB has almost no intensity around 420 nm. Therefore, in addition to the white light LB, the narrowband light LA may be continuously emitted from the narrowband light source unit 206A. As a result, information that is missing only by the white light LB (for example, a blood vessel structure on the surface layer) is also imaged, so that the color rendering of the color image in the normal mode is improved. In this case, the narrowband light LA and the white light LB guided to the same optical path through the dichroic mirror 206F are incident on the condenser lens 210.

  The white light LB (and narrowband light LA) incident on the condensing lens 210 is condensed on the incident end face of an LCB (Light Carrying Bundle) 102 by the condensing lens 210 and is incident on the LCB 102.

  The white light LB (and narrowband light LA) incident on the LCB 102 propagates through the LCB 102 and is emitted from the exit end face of the LCB 102 disposed at the tip of the electronic scope 100, and enters the body cavity via the light distribution lens 104. The body tissue is irradiated. The return light from the living tissue irradiated with the white light LB (and the narrowband light LA) forms an optical image on the light receiving surface of the solid-state image sensor 108 via the objective lens 106.

  The solid-state image sensor 108 is a single-plate color CCD (Charge Coupled Device) image sensor having a Bayer pixel arrangement. The solid-state image sensor 108 accumulates an optical image formed by each pixel on the light receiving surface as a charge corresponding to the amount of light, and outputs an image signal of each pixel of R (Red), G (Green), and B (Blue). Generate and output. The solid-state imaging element 108 is not limited to a CCD image sensor, and may be replaced with a CMOS (Complementary Metal Oxide Semiconductor) image sensor or other types of imaging devices.

  A driver signal processing circuit 110 is provided in the connection portion of the electronic scope 100. An image signal of a living tissue irradiated with white light LB (and narrowband light LA) is input to the driver signal processing circuit 110 from the solid-state imaging device 108 at a frame period. The driver signal processing circuit 110 outputs the image signal input from the solid-state image sensor 108 to the previous signal processing circuit 220 of the processor 200.

  The driver signal processing circuit 110 also accesses the memory 112 and reads the unique information of the electronic scope 100. The unique information of the electronic scope 100 recorded in the memory 112 includes, for example, the number and sensitivity of the solid-state image sensor 108, the operable frame rate, the model number, and the like. The driver signal processing circuit 110 outputs the unique information read from the memory 112 to the system controller 202.

  The system controller 202 performs various calculations based on the unique information of the electronic scope 100 and generates a control signal. The system controller 202 controls the operation and timing of various circuits in the processor 200 using the generated control signal so that processing suitable for the electronic scope connected to the processor 200 is performed.

  The timing controller 204 supplies clock pulses to the driver signal processing circuit 110 according to timing control by the system controller 202. The driver signal processing circuit 110 drives and controls the solid-state imaging device 108 at a timing synchronized with the frame rate of the video processed on the processor 200 side, according to the clock pulse supplied from the timing controller 204.

  The pre-stage signal processing circuit 220 performs demosaic processing on the image signals of R, G, and B pixels that are input from the driver signal processing circuit 110 at a frame period. Specifically, interpolation processing by G and B peripheral pixels is performed on the R pixel, interpolation processing by R and B peripheral pixels is performed on the G pixel, and interpolation processing by R and G peripheral pixels is performed on the B pixel. Applied. As a result, all the image signals of each pixel having only information of one color component are all image signals having information of three color components of R, G, and B (hereinafter referred to as “RGB signals” for convenience). Converted. The pre-stage signal processing circuit 220 performs signal processing such as matrix operation on the RGB signal after demosaic processing and outputs the processed signal to the YC separation circuit 230.

The YC separation circuit 230 separates the RGB signal input from the pre-stage signal processing circuit 220 into a luminance signal Y and color difference signals Cb and Cr using the following equations.
Y = 0.299R + 0.587G + 0.114B
Cb = 0.564 (B−Y) = − 0.169R−0.331G + 0.500B
Cr = 0.713 (R−Y) = 0.500R−0.419G−0.081B

  The YC separation circuit 230 outputs the separated luminance signal Y and color difference signals Cb and Cr to the subsequent signal processing circuit 240.

  The post-stage signal processing circuit 240 converts the luminance signal Y and the color difference signals Cb and Cr input from the YC separation circuit 230 into predetermined video format signals. The converted video format signal is output to the monitor 300. Thereby, a color image of the living tissue is displayed on the display screen of the monitor 300.

[Operation in special mode]
Next, the operation of the electronic endoscope system 1 in the special mode will be described. In addition, description about the part which overlaps with the time of normal mode is abbreviate | omitted or simplified suitably.

  When the operation mode of the electronic endoscope system 1 is set to the special mode, the filter turret 206D is inserted into the optical path of the white light LB, and the narrowband light source unit 206A continuously emits the narrowband light LA. In addition, the broadband light source unit 206B emits white light LB while blinking at a ½ frame period. Therefore, single light source light (narrow band light LA) and two light source lights (narrow band light LA and broadband light LB ') are alternately incident on dichroic mirror 206F at a ½ frame period. Note that the narrow-band light source unit 206A and the broadband light source unit 206B may repeatedly blink alternately at a ½ frame period. In this case, single light source light (narrowband light LA) and single light source light (broadband light LB ') are alternately incident on the dichroic mirror 206F in a ½ frame period.

  A single light source light (narrow band light LA) and two light source lights (narrow band light LA and broadband light LB ') are alternately incident on the condenser lens 210 at a ½ frame period. The single light source light and the two light source light incident on the condenser lens 210 are condensed on the incident end face of the LCB 102 by the condenser lens 210 and are incident on the LCB 102. The single light source light and the two light source light incident on the LCB 102 propagate through the LCB 102 and are emitted from the emission end face of the LCB 102 disposed at the distal end of the electronic scope 100, and the living tissue in the body cavity via the light distribution lens 104. Is irradiated. The return light from the living tissue irradiated alternately with the single light source light and the two light source lights forms an optical image on the light receiving surface of the solid-state imaging device 108 via the objective lens 106.

  The solid-state image sensor 108 accumulates an optical image formed by each pixel on the light receiving surface as a charge corresponding to the amount of light at a ½ frame period, and generates an image signal for each of the R, G, and B pixels. Output. Hereinafter, for convenience of explanation, an image signal of a living tissue imaged by the solid-state imaging device 108 during irradiation with a single light source light (narrowband light LA) will be referred to as a “narrowband image signal”, and two light source lights (narrowband light LA) will be described. And the image signal of the living tissue imaged by the solid-state image sensor 108 during the irradiation of the broadband light LB ′) will be referred to as “broadband image signal”.

  A narrowband image signal and a broadband image signal are alternately input to the driver signal processing circuit 110 from the solid-state imaging device 108 at a ½ frame period. The driver signal processing circuit 110 outputs each image signal input from the solid-state image sensor 108 to the pre-stage signal processing circuit 220.

  The pre-stage signal processing circuit 220 performs demosaic processing on the narrowband image signal and the wideband image signal that are alternately input from the driver signal processing circuit 110 with a ½ frame period, and converts them into RGB signals. The pre-stage signal processing circuit 220 performs signal processing such as matrix operation on the RGB signal after demosaic processing and outputs the processed signal to the YC separation circuit 230.

Since the narrowband image signal (RGB signal) includes only information around 420 nm, it has substantially only B component information (B signal). Therefore, the YC separation circuit 230 sets the B signal in the narrowband image signal (RGB signal) input from the previous stage signal processing circuit 220 as the luminance signal Y ₁ (that is, Y ₁ = 1.000 B). Further, the YC separation circuit 230 converts the broadband image signal (RGB signal) that is subsequently input (within the same frame period) into the luminance signal Y ₂ and the color difference signals Cb and Cr using the same formula as in the normal mode. To separate.

YC separation circuit 230, by combining the luminance signal Y ₁ and the luminance signal Y ₂ at a predetermined ratio to generate a luminance signal Y. The synthesis ratio is, for example, 1: 1.

  The post-stage signal processing circuit 240 converts the luminance signal Y and the color difference signals Cb and Cr input from the YC separation circuit 230 into predetermined video format signals. The converted video format signal is output to the monitor 300. As a result, a color image of the biological tissue including the blood vessel structure near the surface layer emphasized by the narrow band light LA and the deep blood vessel structure emphasized by the broadband light LB ′ is displayed on the display screen of the monitor 300.

  FIG. 5A illustrates an image captured in the normal mode. FIG. 5B illustrates an image shot in the special mode.

  In the normal mode (when the white light LB is irradiated), the white light L has a spectral characteristic that spreads over the entire visible light region. Therefore, as shown in FIG. 5A, information is lost over a wide band. A living tissue image in which the suppression is suppressed is displayed. However, since the blood vessel structure is diluted by information of other anatomy in the captured image, the contrast is low and it is not displayed clearly.

  In the special mode (when the single light source light (narrowband light LA is irradiated)), the narrowband light LA has a peak intensity near 420 nm, so that image information having substantially only the surface blood vessel structure can be obtained. . In the special mode (during irradiation with two light sources (narrowband light LA and broadband light LB ′)), the broadband light LB ′ has a peak intensity in the vicinity of 550 nm and has an intensity in other bands. Image information having the blood vessel structure and other anatomy is obtained. In the special mode, the former and the latter image information (luminance signal) are synthesized, and as shown in FIG. 5 (b), the vascular structure of the surface layer and the deep layer (especially the surface layer) is diluted by other biological structures. A biological tissue image emphasized with high contrast is displayed.

  The above is the description of the exemplary embodiments of the present invention. Embodiments of the present invention are not limited to those described above, and various modifications are possible within the scope of the technical idea of the present invention. For example, the embodiment of the present application also includes an embodiment that is exemplarily specified in the specification or a combination of obvious embodiments and the like as appropriate.

In the present embodiment, YC separation circuit 230, the luminance signal Y ₁ and the luminance signal Y ₂ 1: Although generates a luminance signal Y are combined in one, more vascular structures near the surface layer on the display screen If you want to further enhancement, it may be with a ratio of the luminance signal Y _1. Also, if you want more to further emphasize the vasculature near the deep on the display screen, it may increase the ratio of the luminance signal Y _2.

1 Electronic Endoscope System 100 Electronic Scope 102 LCB
104 Light distribution lens 106 Objective lens 108 Solid-state imaging device 110 Driver signal processing circuit 112 Memory 200 Processor 202 System controller 204 Timing controller 206 Lamp power source igniter 206A Narrow band light source unit 206B Broadband light source unit 206C Light source unit drive control circuit 206D Filter turret 206Df Optical Filter 206E Turret control unit 206F Dichroic mirror 210 Condensing lens 212 Memory 214 Operation panel 220 Pre-stage signal processing circuit 230 YC separation circuit 240 Subsequent stage signal processing circuit

Claims (7)

A narrowband light source unit that emits narrowband light having a peak intensity in a first specific band suitable for highlighting the first anatomy;
A broadband light source that emits broadband light having a wider bandwidth than the narrowband light; and
Driving control of the narrow band light source unit and the broadband light source unit, light source unit drive control means for alternately emitting the narrow band light and at least the broadband light;
An imaging means for imaging a subject that is alternately irradiated with the narrowband light and the at least broadband light, and generating an image signal of the subject imaged during the irradiation of the narrowband light as a first image signal Generating an image signal of a subject imaged during the irradiation of at least the broadband light as a second image signal;
A first luminance signal is generated based on the first image signal, a second luminance signal is generated based on the second image signal, and the luminance signal of the subject is generated based on the generated first and second luminance signals. A luminance signal generating means for generating
Video signal generating means for generating a video signal of the subject using the generated luminance signal of the subject;
Comprising
Electronic endoscope system. The luminance signal generating means includes
Generating the luminance signal of the subject by combining the first luminance signal and the second luminance signal at a predetermined ratio;
The electronic endoscope system according to claim 1. An optical filter for filtering the broadband light into light including narrowband light having a peak intensity in a second specific band suitable for highlighting at least the second anatomy;
The electronic endoscope system according to claim 1 or 2. Optical path synthesis means for guiding narrowband light emitted from the narrowband light source unit and broadband light emitted from the broadband light source unit on the same optical path,
The electronic endoscope system according to any one of claims 1 to 3. The narrow-band light source unit is
It is a monochromatic semiconductor laser or LED (Light Emitting Diode),
The electronic endoscope system according to any one of claims 1 to 4. The broadband light source unit is
A white LED,
The electronic endoscope system according to any one of claims 1 to 5. Comprising mode setting means for setting the operation mode to the first or second operation mode;
In the first operation mode,
The light source unit drive control means includes:
Driving and controlling the narrowband light source unit and the broadband light source unit to alternately emit the narrowband light and the at least broadband light,
The imaging means includes
An image signal of a subject imaged during irradiation of the narrowband light is generated as the first image signal, and an image signal of an object imaged during irradiation of the at least broadband light is generated as the second image signal. ,
The luminance signal generating means includes
The first luminance signal is generated based on the first image signal, the second luminance signal is generated based on the second image signal, and the subject is detected based on the generated first and second luminance signals. Generate a luminance signal,
In the second operation mode,
The light source unit drive control means includes:
Driving and controlling the narrowband light source unit and the broadband light source unit to continuously emit the narrowband light and the broadband light,
The imaging means includes
Generating an image signal of a subject imaged during irradiation of the narrowband light and the broadband light;
The luminance signal generating means includes
Generating a luminance signal of the subject based on the generated image signal;
The electronic endoscope system according to any one of claims 1 to 6.