JP3965174B2 - Endoscope device - Google Patents

Description

  The present invention relates to an endoscope apparatus that captures an image of a living tissue and performs signal processing.

  2. Description of the Related Art Conventionally, endoscope apparatuses that irradiate illumination light and obtain an endoscopic image in a body cavity have been widely used. In this type of endoscope apparatus, an electronic endoscope having an image pickup unit that guides illumination light from a light source device into a body cavity using a light guide or the like and picks up an image of a subject using the return light is used. An image signal from the imaging means is signal-processed to display an endoscopic image on an observation monitor and observe an observation site such as an affected area.

  When performing normal biological tissue observation in an endoscopic device, the light source device emits white light in the visible light region, and irradiates the subject with surface sequential light through a rotating filter such as RGB, for example. A color image is obtained by synchronizing and processing the return light from the light with a video processor, or a color chip is arranged in front of the imaging surface of the imaging means of the endoscope, and the return light from the white light is converted to RGB by the color chip. A color image is obtained by picking up an image by separation and processing the image with a video processor.

On the other hand, in a living tissue, the light absorption characteristics and the scattering characteristics differ depending on the wavelength of the irradiated light. For example, in Japanese Patent Application Laid-Open No. 2002-95635, illumination light in the visible light region has a narrow spectral bandwidth. A narrow-band optical endoscope apparatus that irradiates a living tissue with RGB sequential light and obtains tissue information of a desired deep portion of the living tissue has been proposed.
JP 2002-95635 A

  In normal light observation, white balance is acquired in order to correct variations in various optical characteristics. In the white balance, a correction value for multiplying the R signal and the B signal is obtained, and the RGB signal output during white light observation is made uniform. Thereby, the influence on the color tone reproducibility by the variation can be suppressed.

  In narrow-band light observation (NBI observation), it is necessary to acquire white balance before starting the inspection, as in normal light observation. As a result, variations in the optical filter for narrow band light can be corrected, and color tone reproducibility is stabilized.

  Conventionally, when acquiring white balance, it is necessary to hold the tip of the scrub in the white cap until the white balance correction values for both normal light and narrowband light are obtained. There was a possibility that proper color reproduction could not be achieved.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an endoscope apparatus capable of performing white balance processing with normal light and narrow band light reliably and in a short time.

The endoscope apparatus of the present invention is
An illumination light supply means for supplying illumination light including a visible light region, an endoscope having an imaging means for illuminating the subject with the illumination light and imaging the subject with return light, and an imaging signal from the imaging means In an endoscope apparatus provided with signal processing means for processing,
Band limiting means for limiting the illumination light to narrow band light of a plurality of discrete band areas and irradiating the subject,
White balance means for performing white balance processing on the imaging signal of the subject by the illumination light,
The white balance means is
First white balance correction value storage means for storing a first white balance correction value for the illumination light;
Correction value calculation means for calculating a second white balance correction value for the narrowband light based on the first white balance correction value;
And a second white balance correction value storage means for storing the second white balance correction value calculated by the correction value calculation means.

  According to the present invention, there is an effect that white balance processing with normal light and narrowband light can be performed reliably and in a short time.

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

  1 to 19 relate to the first embodiment of the present invention, FIG. 1 is a configuration diagram showing the configuration of the endoscope apparatus, FIG. 2 is a configuration diagram showing the configuration of the rotary filter of FIG. 1, and FIG. FIG. 4 is a diagram showing the spectral characteristics of the second filter set of the rotary filter of FIG. 2, FIG. 5 is a diagram showing the spectral characteristics of the first filter set of the rotary filter, and FIG. FIG. 6 is a diagram illustrating a layer direction structure of a tissue, FIG. 6 is a diagram illustrating a state in which illumination light from the endoscope apparatus of FIG. 1 reaches a biological tissue in a layer direction, and FIG. FIG. 8 is a second diagram showing each band image by the surface sequential light transmitted through the first filter set in FIG. 3, and FIG. 9 is a diagram in FIG. FIG. 10 is a third view showing each band image by the surface sequential light that has passed through the first filter set, and FIG. 10 shows the second filter set in FIG. FIG. 11 is a second diagram showing each band image by plane sequential light transmitted through the second filter set of FIG. 4, and FIG. 12 is a diagram of FIG. FIG. 13 is a block diagram showing the configuration of the white balance circuit of FIG. 1, and FIG. 14 is a modified example of the white balance circuit of FIG. FIG. 15 is a block diagram showing the configuration of the first modification of the endoscope apparatus of FIG. 1, FIG. 16 is a block diagram showing the configuration of the white balance circuit of FIG. 15, and FIG. FIG. 18 is a block diagram showing the configuration of the white balance circuit of FIG. 17, and FIG. 19 shows the configuration of a modification of the white balance circuit of FIG. It is a block diagram.

  As shown in FIG. 1, an endoscope apparatus 1 according to the present embodiment includes an electronic endoscope 3 having a CCD 2 as an imaging unit that is inserted into a body cavity and images tissue in the body cavity, and illuminates the electronic endoscope 3. Signal processing is performed on the image pickup signal from the light source device 4 that supplies light and the CCD 2 of the electronic endoscope 3 to display an endoscopic image on the observation monitor 5, or the endoscopic image is encoded and image filing as a compressed image. And a video processor 7 for outputting to the apparatus 6.

  The light source device 4 includes a xenon lamp 11 that emits illumination light, a heat ray cut filter 12 that blocks heat rays of white light, a diaphragm device 13 that controls the amount of white light that passes through the heat ray cut filter 12, and illumination light. A rotation filter 14 for converting the surface sequential light, a condensing lens 16 for condensing the surface sequential light via the rotation filter 14 on the incident surface of the light guide 15 disposed in the electronic endoscope 3, and the rotation filter 14. And a control circuit 17 for controlling the rotation of the motor.

As shown in FIG. 2, the rotary filter 14 is formed in a disk shape and has a double structure with the center as a rotation axis, and the outer diameter portion has an overlap suitable for color reproduction as shown in FIG. An R1 filter unit 14r1, a G1 filter unit 14g1, and a B1 filter unit 14b1 constituting a first filter set for outputting the surface sequential light having the spectral characteristics are arranged, and the inner diameter portion is as shown in FIG. A G2 filter unit 14g2, a B2 filter unit 14b2, and an R2 filter 14r2 constituting a second filter set for outputting narrow-band surface-sequential light having discrete spectral characteristics capable of extracting desired deep tissue information are arranged. ing.

  As shown in FIG. 1, the rotary filter 14 is rotated by the drive control of the rotary filter motor 18 by the control circuit 17, and is rotated in the radial direction (the movement perpendicular to the optical path of the rotary filter 14 is rotated. The first filter group or the second filter group of the filter 14 is selectively moved on the optical path) by the mode switching motor 19 in accordance with a control signal from a mode switching circuit 42 in the video processor 7 described later.

  Note that power is supplied from the power supply unit 10 to the xenon lamp 11, the diaphragm device 13, the rotary filter motor 18, and the mode switching motor 19.

  The video processor 7 correlates with a CCD driving circuit 20 that drives the CCD 2, an amplifier 22 that amplifies an imaging signal obtained by imaging the body cavity tissue with the CCD 2 via the objective optical system 21, and an imaging signal that passes through the amplifier 22. A process circuit 23 that performs double sampling, noise removal, and the like, an A / D converter 24 that converts an imaging signal that has passed through the process circuit 23 into image data of a digital signal, and image data from the A / D converter 24 is white. A white balance circuit (WB) 25 that performs balance processing, a selector 26 and synchronization memories 27, 28, and 29 for synchronizing frame sequential light by the rotary filter 14, and synchronization memories 27, 28, and 29 An image processing circuit 30 that reads out each image data of the frame sequential light stored in the image processing unit and performs gamma correction processing, contour enhancement processing, color processing, and the like; From the D / A circuits 31, 32, 33 for converting the image data from the processing circuit 30 into analog signals, the encoding circuit 34 for encoding the image data from the image processing circuit 30, and the control circuit 17 of the light source device 4 And a timing generator (TG) 35 that inputs a synchronization signal synchronized with the rotation of the rotation filter 14 and outputs various timing signals to the circuits.

  Further, the electronic endoscope 2 is provided with a mode change switch 41, and an output of the mode change switch 41 is output to a mode change circuit 42 in the video processor 7. The mode switching circuit 42 of the video processor 7 outputs a control signal to the white balance circuit (WB) 25, the dimming circuit 43, the dimming control parameter switching circuit 44, and the mode switching motor 19 of the light source device 4. It has become. The dimming control parameter switching circuit 44 outputs a dimming control parameter corresponding to the first filter group or the second filter group of the rotary filter 14 to the dimming circuit 43, and the dimming circuit 43 is output from the mode switching circuit 42. Based on the control signal and the dimming control parameter from the dimming control parameter switching circuit 44, the diaphragm device 13 of the light source device 4 is controlled to perform appropriate brightness control.

  As shown in FIG. 5, the body cavity tissue 51 often has an absorber distribution structure such as blood vessels that differ in the depth direction. A large number of capillaries 52 are mainly distributed in the vicinity of the mucous membrane surface layer, and blood vessels 53 that are thicker than capillaries are distributed in the middle layer deeper than this layer, and thicker blood vessels 54 are further distributed in the deep layer. become.

  On the other hand, the depth of light in the depth direction with respect to the tissue 51 in the body cavity depends on the wavelength of the light, and the illumination light including the visible range is blue (B) as shown in FIG. In the case of light with such a short wavelength, the light reaches the surface layer only due to the absorption and scattering characteristics in the living tissue, and the light emitted from the surface is observed by being absorbed and scattered in the depth range up to that. Is done. In the case of green (G) light, which has a wavelength longer than that of blue (B) light, it reaches deeper than the range where blue (B) light deepens, absorbs and scatters within that range, and exits from the surface. Light is observed. Still further, red (R) light having a wavelength longer than that of green (G) light reaches a deeper range.

  During normal observation, the mode switching circuit in the video processor 7 is controlled by a control signal so that it is located on the optical path of the illumination light in the R1 filter 14r1, G1 filter 14g1, and B1 filter 14b1 as the first filter set of the rotary filter 14. The mode switching motor 19 is controlled.

Since the R1 filter unit 14r1, the G1 filter unit 14g1, and the B1 filter unit 14b1 during normal observation of the tissue 51 in the body cavity overlap each other as shown in FIG.
(1) A band image having shallow layer and middle layer tissue information including a lot of tissue information in the shallow layer as shown in FIG. 7 is captured in the image signal captured by the CCD 4 by the B1 filter unit 14b1.
(2) Further, the image signal picked up by the CCD 4 by the G1 filter 14g1 is picked up by a band image having a shallow layer and medium layer tissue information including a lot of tissue information in the middle layer as shown in FIG.
(3) Further, the image signal picked up by the CCD 4 by the R1 filter 14r1 picks up a band image having middle layer and deep layer tissue information including a lot of deep layer tissue information as shown in FIG.

  Then, the video processor 7 synchronizes these RGB image signals and performs signal processing, so that an endoscopic image having a desired or natural color reproduction can be obtained as an endoscopic image.

  On the other hand, when the mode switching switch 41 of the electronic endoscope 3 is pressed, the signal is input to the mode switching circuit 42 of the video processor 7. The mode switching circuit 42 outputs a control signal to the mode switching motor 19 of the light source device 4, thereby moving the first filter set of the rotary filter 14 that was on the optical path during normal observation to light the second filter set. The rotary filter 14 is driven with respect to the optical path so as to be disposed on the path.

The G2 filter unit 14g2, the B2 filter unit 14b2, and the R2 filter 14r2 at the time of the narrow band light observation of the body cavity tissue 51 by the second filter set, the illumination light is a narrow band having discrete spectral characteristics as shown in FIG. Because each wavelength region does not overlap with each other,
(4) A band image having tissue information in a shallow layer as shown in FIG. 10 is captured in the imaging signal captured by the CCD 4 by the B2 filter unit 14b2,
(5) Further, a band image having tissue information in the middle layer as shown in FIG. 11 is picked up on the image pickup signal picked up by the CCD 4 by the G2 filter unit 14g2,
(6) Furthermore, a band image having tissue information in the deep layer as shown in FIG. 12 is picked up on the image pickup signal picked up by the CCD 4 by the R2 filter 14r2.

  As shown in FIG. 13, the white balance circuit 25 includes a white balance correction unit 80, a selector 81, a normal light correction value storage unit 82, a lookup table (LUT) 83, and a narrowband light correction value storage unit 84. Composed.

  Prior to inspection by the endoscope apparatus 1, a white cap (not shown) is attached to the tip of the electronic endoscope 3 to acquire white balance with normal light.

  In the white balance circuit 25, the normal frame sequential R / G / B signal, which is image data from the A / D converter 24 when the white cap is mounted, is input to the white balance correction unit 80, and the normal frame sequential R / G / B is input. The white balance is performed on the signal, and the normal light correction value in the white balance is stored in the normal light correction value storage unit 82 via the selector 81, and the white balanced R ′ / G ′ / B ′ signal is stored. Output to the selector 26.

  At this time, in the white balance circuit 25, the narrowband light correction value based on the normal light correction value is read from the LUT 83 and stored in the narrowband light correction value storage unit 84.

  Specifically, the white balance correction unit 80 calculates the correction values of R and B from the average ratio G / R and G / B of the normal frame sequential R / G / B signal, and the mode switching circuit 42 detects the correction value. If the observation mode is the normal light mode, the normal light correction value is stored in the normal light correction value storage unit 82. If the observation mode is the narrow light mode, the normal light correction value and the correction value for the narrow light are obtained from the LUT 83. Is recorded in the correction value storage unit 84. Depending on the observation mode detected by the selector 81, the correction value from the normal light correction value storage unit 82 or the narrowband light correction value storage unit 84 is sent to the white balance correction unit 80, and the white balance correction unit 80 sets the correction value. Multiply and output R ′ and B ″ signals. At this time, the G signal is output as it is.

The LUT 83 is configured to store the correction value for narrowband light based on the correction value for normal light. However, the present invention is not limited to this, and as shown in FIG. 14, the correction value coefficient based on the correction value for normal light is used. k is stored in the LUT 83, and the correction value calculation unit 85 for narrowband light
The narrowband light correction value may be calculated from the narrowband light correction value = k × normal light correction value and stored in the narrowband light correction value storage unit 84. Note that k is a constant.

  As described above, in this embodiment, the correction value for narrowband light is calculated and corrected from the correction value for normal light, so that it is not necessary to obtain white balance with narrowband light, the operation can be simplified, and color reproduction due to an operation error can be achieved. Sexual defects can be avoided reliably.

  Note that, in the endoscope apparatus 1 of the above-described embodiment, an explanation will be given by taking as an example a frame sequential endoscope apparatus in which the light source device 4 supplies the frame sequential light and the video processor 7 synchronizes the plane sequential image information to form an image. However, the present invention is not limited to this, and can also be applied to a simultaneous endoscope apparatus.

  That is, as shown in FIG. 15, the light source device 4a for supplying white light, the electronic endoscope 3a having the color chip 100 on the front surface of the imaging surface of the CCD 2, and the image signal from the electronic endoscope 3a are processed. The present embodiment can also be applied to the simultaneous endoscope apparatus 1a including the video processor 7a.

  In the light source device 4a, the amount of white light from the xenon lamp 11 via the heat ray cut filter 12 is controlled by the diaphragm device 13 and emitted to the incident surface of the light guide 15 disposed in the electronic endoscope 3a. A narrow band limiting filter 14a for converting into narrow band light having discrete spectral characteristics as shown in FIG. 4 is detachably provided on the white light path.

  In the electronic endoscope 3 a, an image of the body cavity tissue 51 is captured by the CCD 2 via the color chip 100.

  In the video processor 7a, the image data from the A / D converter 24 is separated into the luminance signal Y and the color difference signals Cr and Cb by the Y / C separation circuit 101, converted into RGB signals by the RGB matrix circuit 102, and the white balance circuit. 25 is output. Other configurations and operations are the same as those of the endoscope apparatus of FIG.

  Then, the white balance circuit 25 acquires white balance for each signal of the RGB signals from the RGB matrix circuit 102 as shown in FIG. The white balance acquisition method at this time is the same as in this embodiment.

  Further, as shown in FIG. 17, a scope ID storage unit 110 that stores a scope ID including various types of scope information including a normal light correction value is provided in the electronic endoscope 3, and the normal light correction value in the scope ID is provided. 18 to the white balance circuit 25, as shown in FIG. 18, in the white balance circuit 25, the normal light correction value storage unit 82 uses the normal light correction value to obtain the narrowband light correction value from the LUT 83. The reading and narrowband light correction value calculation unit 85 may be configured to be stored.

Further, as shown in FIG. 19, the correction coefficient k based on the normal light correction value in the scope ID output to the white balance circuit 25 is stored in the LUT 83 and the narrowband light correction value calculation unit 85 described above. The narrowband light correction value may be calculated from the narrowband light correction value = k × normal light correction value and stored in the narrowband light correction value storage unit 84. Note that k is a constant.

  Note that the endoscope in FIG. 17 has been described by taking a frame sequential endoscope as an example, but the present invention is not limited to this and can be applied to a simultaneous type.

  The present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the scope of the present invention.

1 is a configuration diagram showing a configuration of an endoscope apparatus according to Embodiment 1 of the present invention. The block diagram which shows the structure of the rotation filter of FIG. The figure which shows the spectral characteristics of the 1st filter set of the rotation filter of FIG. The figure which shows the spectral characteristic of the 2nd filter set of the rotation filter of FIG. The figure which shows the layer direction structure of the biological tissue observed with the endoscope apparatus of FIG. The figure explaining the arrival state to the layer direction of the biological tissue of the illumination light from the endoscope apparatus of FIG. FIG. 3 is a first diagram showing each band image by frame sequential light transmitted through the first filter set of FIG. 2nd figure which shows each band image by the field sequential light which permeate | transmitted the 1st filter set of FIG. 3rd figure which shows each band image by the field sequential light which permeate | transmitted the 1st filter set of FIG. 1st figure which shows each band image by the field sequential light which permeate | transmitted the 2nd filter set of FIG. 2nd figure which shows each band image by the surface sequential light which permeate | transmitted the 2nd filter set of FIG. 3rd figure which shows each band image by the surface sequential light which permeate | transmitted the 2nd filter set of FIG. Block diagram showing the configuration of the white balance circuit of FIG. FIG. 13 is a block diagram showing a configuration of a modified example of the white balance circuit of FIG. The block diagram which shows the structure of the 1st modification of the endoscope apparatus of FIG. The block diagram which shows the structure of the white balance circuit of FIG. The block diagram which shows the structure of the 2nd modification of the endoscope apparatus of FIG. The block diagram which shows the structure of the white balance circuit of FIG. FIG. 17 is a block diagram showing a configuration of a modification of the white balance circuit of FIG.

Explanation of symbols

1 ... Endoscope device 2 ... CCD
DESCRIPTION OF SYMBOLS 3 ... Electronic endoscope 4 ... Light source device 5 ... Observation monitor 6 ... Image filing device 7 ... Video processor 10 ... Power supply part 11 ... Xenon lamp 12 ... Heat ray cut filter 13 ... Diaphragm device 14 ... Rotary filter 15 ... Light guide 16 ... Condensing lens 17 ... Control circuit 18 ... Rotary filter motor 19 ... Mode switching motor 19
DESCRIPTION OF SYMBOLS 20 ... CCD drive circuit 21 ... Objective optical system 22 ... Amplifier 23 ... Process circuit 24 ... A / D converter 25 ... White balance circuit 26 ... Selector 27, 28, 29 ... Synchronization memory 30 ... Image processing circuit 31, 32, 33 ... D / A circuit 34 ... encoding circuit 35 ... timing generator 41 ... mode switching switch 42 ... mode switching circuit 43 ... dimming circuit 44 ... dimming control parameter switching circuit 80 ... white balance correction unit 81 ... selector 82 ... normal Light correction value storage unit 83... LUT
84 ... Correction value memory for narrowband light Attorney Susumu Ito

Claims (4)

An illumination light supply means for supplying illumination light including a visible light region, an endoscope having an imaging means for illuminating the subject with the illumination light and imaging the subject with return light, and an imaging signal from the imaging means In an endoscope apparatus provided with signal processing means for processing,
Band limiting means for limiting the illumination light to narrow band light of a plurality of discrete band areas and irradiating the subject,
White balance means for performing white balance processing on the imaging signal of the subject by the illumination light,
The white balance means is
First white balance correction value storage means for storing a first white balance correction value for the illumination light;
Correction value calculation means for calculating a second white balance correction value for the narrowband light based on the first white balance correction value;
An endoscope apparatus comprising: a second white balance correction value storage unit that stores the second white balance correction value calculated by the correction value calculation unit. The endoscope according to claim 1, wherein the correction value calculation means is a look-up table storing a plurality of the second white balance correction values corresponding to the first white balance correction values. apparatus. The correction value calculating means includes
The second white balance correction value is obtained from a lookup table storing a plurality of white balance correction coefficients corresponding to the first white balance correction value, the white balance correction coefficient, and the first white balance correction value. The endoscope apparatus according to claim 1, further comprising correction value calculation means for calculating. The first white balance correction value storage unit is an endoscope identification unit that is provided inside the endoscope and stores information related to the endoscope. The endoscope apparatus described in 1.

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