JP2017144247A - Endoscope system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endoscope system capable of correcting change of a hue associated with a wavelength shift of a semiconductor light source.SOLUTION: A light source control part 21 controls a plurality of LED light sources in such a way that, in a normal observation mode, the light source control part 21 performs light source control for a normal observation mode to cause the light sources to emit light for the normal observation mode and that, in a special observation mode, the light source control part 21 performs light source control for the special observation mode to causes the light sources to emit light for the special observation mode. At least any one LED light source of the plurality of LED light sources generates light in which a peak wavelength more shifts as light emission intensity becomes higher. A color conversion part 68 changes a content of color conversion processing according to a drive amount applied to the plurality of LED light sources.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an endoscope system that illuminates a specimen using a plurality of semiconductor light sources such as LEDs.

  In the medical field, diagnosis using an endoscope system including a light source device, an endoscope device, and a processor device is widely performed. As a light source device of this endoscope system, a broadband light source such as a xenon lamp has been widely used so far, but a semiconductor light source such as an LED (Light Emitting Diode) or an LD (Laser Diode) is also being used.

  Here, it is known that the amount of emitted light varies in a semiconductor light source due to temperature variation or deterioration with time. When using a combination of semiconductor light sources of multiple colors, it is required that the ratio of the light emission amounts of the semiconductor light sources of the respective colors be set to a predetermined setting ratio regardless of the brightness. If the light emission amount of the semiconductor light source is fluctuated, there is a problem that the ratio of the light emission amount deviates from the set ratio and the color tone fluctuates.

  Therefore, in Patent Document 1, in order to prevent fluctuations in the amount of emitted light, the amount of emitted light is detected by a light receiving unit such as a sensor, and the color temperature of the emitted light is constant based on the detection result of the light receiving unit. The semiconductor light source is driven and controlled so that In Patent Document 2, in order to prevent fluctuations in the amount of emitted light, the temperature of the semiconductor light source is detected by a temperature sensor, and the gain multiplied by the image signal is changed in the processor device according to the detection result of the temperature sensor. doing. In Patent Document 2, the change in the image signal due to the change in the amount of emitted light is suppressed by changing the gain (however, in Patent Document 2, it cannot be detected until the deterioration with time). .

JP 2010-158413 A Japanese Patent No. 4787032

  It is known that a temperature drift (wavelength shift) occurs in a semiconductor light source in accordance with the amount of current applied to the semiconductor light source, that is, in accordance with the light emission intensity, in addition to the above-described fluctuation in the light emission amount. . In the case of the R-LED, as shown in FIG. 18, it is known that the peak wavelength shifts to the longer wavelength side due to the wavelength shift as the emission intensity increases (“weak” in FIG. 18, “Medium” and “Strong” indicate the intensity of light emission (the same applies to FIG. 20). Since this wavelength shift changes the color tone on the endoscopic image, it has various effects in endoscopic observation.

  For example, in the case of using crystal violet in observation using a dye, as shown in FIG. 19, the output value (the amount of reflected light) of crystal violet does not change linearly as the emission intensity of the R-LED increases. In particular, when the amount of light emitted from the R-LED increases, such as when viewing a distant view, the redness becomes stronger. As shown in FIG. 20, as the emission intensity increases, the peak wavelength of the R-LED shifts to the longer wavelength side, and the reflectance of crystal violet gradually increases on the longer wavelength side than 600 nm. This is because the amount of reflected light from the R-LED becomes excessive. If the redness of the crystal violet portion becomes stronger due to such a wavelength shift, the doctor may mistake the crystal violet for the bleeding site.

  As described above, the change in color tone due to the wavelength shift such as the color change of crystal violet needs to be corrected according to the wavelength shift, but the light source correction as in Patent Document 1 and the gain as in Patent Document 2 are necessary. It cannot be corrected by change.

  An object of this invention is to provide the endoscope system which can correct | amend the change of the color tone accompanying the wavelength shift etc. of a semiconductor light source.

  The endoscope system according to the present invention includes a plurality of LED light sources that generate light having different peak wavelengths as illumination light for illuminating a specimen, a light source device having a light source control unit, and a plurality of light source control units. A normal observation mode for emitting light for the normal observation mode by performing light source control for the normal observation mode for the LED light source, and a light source for the special observation mode for the plurality of LED light sources. A mode switching unit that performs control to switch between special observation modes that emit light for special observation mode, a color image sensor with a color filter on the imaging surface, and a specimen that is illuminated with illumination light is imaged with the color image sensor An image signal acquisition unit that acquires a first color image signal composed of a plurality of color signals, a light amount calculation unit that calculates a target light amount based on the first color image signal, and a first color image signal A color conversion unit that performs color conversion processing to convert the color image signal to a second color image signal different from the color image signal, and each LED light source of the plurality of LED light sources emits light having a peak wavelength in the transmission wavelength range of the color image sensor. At least one of the plurality of LED light sources generates light whose peak wavelength shifts as the light emission intensity increases, and the light source control unit is based on the target light amount calculated by the light amount calculation unit. The drive amount applied to the plurality of LED light sources is set, and the color conversion unit changes the content of the color conversion processing according to the drive amount applied to the plurality of LED light sources.

  The color conversion process is a process of converting the first color image signal to the second color image signal by multiplying the first coefficient by the first coefficient, and the first coefficient is associated with the driving amount applied to the plurality of LED light sources. It is preferable. The driving amount is preferably a current amount. In the light source controller, it is preferable to calculate the target light amounts of the plurality of LED light sources based on the set light amount ratio from the target light amount. When the normal observation mode is selected, it is preferable that the color conversion unit changes the content of the color conversion process.

  It is preferable to have a light amount measurement sensor that measures the amount of illumination light. It is preferable that at least two LEDs among the plurality of LED light sources are provided with a light amount measurement sensor for measuring the light amount of light emitted from each LED.

  The plurality of LED light sources are preferably B-LEDs, G-LEDs, and R-LEDs. Each of the B-LED, G-LED, and R-LED is provided with a light amount measurement sensor that measures the amount of light emitted from each LED, and the light source control unit is configured based on the set light amount ratio from the target light amount. B-LED target light quantity, G-LED target light quantity, R-LED target light quantity are calculated, and the B-LED, G-LED, R-LED light quantity measured by the light quantity measurement sensor and B- It is preferable to set the drive amounts of the B-LED, G-LED, and R-LED based on comparison with the target light amount of the LED, the target light amount of the G-LED, and the target light amount of the R-LED. The plurality of LED light sources are preferably V-LED, B-LED, G-LED, and R-LED. It is preferable that at least one LED light source among the plurality of LED light sources generates light whose peak wavelength shifts to the long wave side as the emission intensity increases.

  According to the present invention, it is possible to correct a change in color tone accompanying a wavelength shift of a semiconductor light source.

It is an external view of an endoscope system. It is a block diagram which shows the function of the endoscope system of 1st Embodiment. It is a graph which shows the emission spectrum of normal light. It is a graph which shows the emission spectrum of purple narrow-band light Vn and green narrow-band light Gn. It is a graph which shows the spectral transmittance of B filter, G filter, and R filter. It is a graph which shows the spectral transmittance of the complementary color filter of C (cyan), M (magenta), Y (yellow), and G (green). It is a block diagram which shows the function of the color conversion part for normal of 1st Embodiment. It is a flowchart which shows a series of flows in the normal observation mode in 1st Embodiment. It is a block diagram which shows the function of the color conversion part for normal of 2nd Embodiment. It is explanatory drawing which shows the large capacity memory in which the 1st matrix coefficient Mij was stored. It is explanatory drawing which shows operation | movement of the color conversion part for normal at the time of a moving image display. It is explanatory drawing which shows operation | movement of the color conversion part for normal at the time of a still image acquisition. It is a top view which shows a white version. It is explanatory drawing which shows the wavelength fluctuation | variation of purple narrow band light, blue-green narrow band light, green light, and red light by the increase in emitted light intensity. It is a block diagram which shows the optical path coupling | bond part and the light quantity measurement sensor which measures the light quantity of purple narrow band light, blue-green narrow band light, green light, and red light. It is explanatory drawing which shows 3DLUT. It is a graph which shows the emission spectrum of the normal light different from FIG. It is a graph which shows the spectral luminescence intensity of R-LED. It is a graph which shows the relationship between the emitted light intensity of R-LED, and the output value (reflected light amount value) of crystal violet. It is a graph which shows the normalization intensity | strength of R-LED and the spectral reflectance of crystal violet.

[First Embodiment]
As shown in FIG. 1, the endoscope system 10 according to the first embodiment includes an endoscope 12, a light source device 14, a processor device 16, a monitor 18, and a console 19. The endoscope 12 is optically connected to the light source device 14 and electrically connected to the processor device 16. The endoscope 12 includes an insertion portion 12a to be inserted into a specimen, an operation portion 12b provided at a proximal end portion of the insertion portion 12a, a bending portion 12c and a distal end portion 12d provided at the distal end side of the insertion portion 12a. Have. By operating the angle knob 12e of the operation unit 12b, the bending unit 12c performs a bending operation. With this bending operation, the tip 12d is directed in a desired direction.

  In addition to the angle knob 12e, the operation unit 12b is provided with a mode switching SW 13a and a freeze button 13b. The mode switching SW 13a is used for switching operation between two types of modes, a normal observation mode and a special observation mode. The normal observation mode is a mode in which a normal light image is displayed on the monitor 18 using white light, and the special observation mode can highlight a specific structure such as a surface blood vessel with a contrast difference from the mucous membrane. In this mode, a special light image is displayed on the monitor 18 using light of a specific wavelength.

  The freeze button 13 b transmits a freeze signal to the processor device 16. While receiving the freeze signal, the processor device 16 is set to the moving image mode and displays a moving image such as a normal light image or a special light image on the monitor 18. When the processor device 16 receives the freeze signal, the processor device 16 shifts from the moving image mode to the still image mode for a predetermined time after the reception. During this still image mode, a high-quality still image with no blur is selected from the currently acquired images, and the selected still image is stored in a still image memory (not shown).

  The processor device 16 is electrically connected to the monitor 18 and the console 19. The monitor 18 outputs and displays image information and the like. The console 19 functions as a UI (user interface) that receives input operations such as function settings. The processor device 16 may be connected to an external recording unit (not shown) for recording image information and the like.

  As shown in FIG. 2, the light source device 14 includes a V-LED (Violet Light Emitting Diode) 20a, a B-LED (Blue Light Emitting Diode) 20b, a G-LED (Green Light Emitting Diode) 20c, and an R-LED (Red). Light Emitting Diode) 20d, a light source control unit 21 that controls the driving of these four color LEDs, a green narrow band filter 22 that is inserted into and removed from the optical path of the G-LED, and light emitted from the four color LEDs 20a to 20d An optical path coupling unit 23 that couples optical paths, a glass plate 24, and a light amount measurement sensor 25 are provided.

  The light coupled by the optical path coupling unit 23 is irradiated into the sample through the light guide 41 and the illumination lens 45 inserted into the insertion unit 12a. The glass plate 24 transmits most of the red light R from the R-LED 20 d toward the optical path coupling unit 23 and reflects part of the red light R toward the light amount measurement sensor 25 by Fresnel reflection. The green narrow band filter 22 is inserted / removed by the filter insertion / removal unit 22a. An LD (Laser Diode) may be used instead of the LED.

  The V-LED 20a generates purple narrowband light Vn having a center wavelength of 405 nm and a wavelength range of 380 to 440 nm. The B-LED 20b generates blue-green narrowband light Bn having a center wavelength of 460 nm and a wavelength range of 420 to 500 nm. The G-LED 20c generates a normally distributed green light G having a wavelength range of 480 to 600 nm. The R-LED 20d generates red light R having a center wavelength of 620 to 630 nm and a wavelength range of 600 to 650 nm. The green narrow band filter 22 transmits the green narrow band light Gn of 530 to 550 nm out of the green light G emitted from the G-LED 20c.

  In the normal observation mode, the light source controller 21 lights all the V-LEDs 20a, B-LEDs 20b, G-LEDs 20c, and R-LEDs 20d with the green narrow band filter 22 retracted from the optical path of the G-LEDs 20c. As a result, as shown in FIG. 3, normal light is generated by mixing four colors of light of purple narrowband light Vn, blue-green narrowband light Bn, green light G, and red light R. On the other hand, in the special observation mode, the purple narrowband light Vn and the green narrowband light Gn are obtained by simultaneously lighting the V-LED 20a and the G-LED 20c with the green narrowband filter 22 inserted in the optical path of the G-LED 20c. Occur simultaneously. As a result, as shown in FIG. 4, the purple narrowband light Vn from the V-LED 20a and the green narrowband light Gn wavelength-limited by the green narrowband filter 22 are simultaneously generated.

  The light source control unit 21 adds a predetermined current amount (a kind of LED drive amount) to the V-LED 20a, B-LED 20b, G-LED 20c, and R-LED 20d, and controls the light emission amount of each of the LEDs 20a to 20d. The amount of current applied to the V-LED 20a, B-LED 20b, and G-LED 20c is determined according to a target light amount setting signal output from the light amount calculation unit 54 of the processor device. On the other hand, the amount of current applied to the R-LED 20d is determined based on the light amount of the red light R measured by the light amount measurement sensor 25 in addition to the target light amount setting signal. In the present embodiment, the current amount c applied to each of the LEDs 20a to 20d is represented by a bit conversion value, that is, a value between 0 and 1023 (10 bits).

  As shown in FIG. 2, the light quantity measurement sensor 25 receives the red light R reflected by the glass plate 24 and outputs a light quantity measurement signal corresponding to the light quantity of the received red light R to the light source control unit 21. The light source control unit 21 compares the light amount measurement signal output from the light amount measurement sensor 25 with the target light amount setting signal output from the light amount calculation unit 54 in the processor device, and based on the comparison result, the R-LED 20d A current amount c applied to the R-LED 20d is set so that the light emission amount becomes the target light amount. The set current amount c is output to the R-LED 20d, and a normal color conversion unit in the processor device is used to perform matrix processing that suppresses a change in color tone due to the wavelength shift of the R-LED 20d in the processor device. 68 and the special color converter 74.

  As described above, in the present embodiment, the light amount measurement sensor 25 is used to monitor the light emission amount of the red light R, and based on the monitoring result, the light amount of the R-LED 20d is feedback-controlled, thereby Even if the light emission changes due to temperature drift (wavelength shift) or deterioration over time, the change is corrected by resetting the amount of current applied to the R-LED 20d, so the light emission of the R-LED 20d always maintains the target light intensity. can do.

  The light guide 41 is built in a universal cord (not shown) that connects the light source device 14 and the endoscope 12, and propagates the light coupled by the optical path coupling unit 23 to the distal end portion 12 d of the endoscope 12. To do. A multimode fiber can be used as the light guide 41. As an example, a thin fiber cable having a core diameter of 105 μm, a cladding diameter of 125 μm, and a diameter of φ0.3 to 0.5 mm including a protective layer serving as an outer shell can be used.

  The distal end portion 12d of the endoscope 12 has an illumination optical system 30a and an imaging optical system 30b. The illumination optical system 30 a has an illumination lens 45, and light from the light guide 41 is irradiated into the sample through the illumination lens 45. The imaging optical system 30 b includes an imaging lens 46 and an imaging sensor 48. The reflected light from the specimen enters the image sensor 48 via the image pickup lens 46. As a result, a reflected image of the specimen is formed on the imaging sensor 48.

  The imaging sensor 48 is a color imaging device, captures a reflected image of the specimen, and outputs an image signal. The imaging sensor 48 is preferably a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary Metal-Oxide Semiconductor) image sensor, or the like. The image sensor used in the present invention is a color image sensor for obtaining image signals of three colors R (red), G (green), and B (blue), that is, so-called RGB having an RGB filter on the imaging surface. It is an image sensor. As shown in FIG. 5, the B filter of the RGB image sensor transmits light of 380 to 570 nm, the G filter transmits light of 450 to 630 nm, and the R filter transmits light of 580 to 770 nm.

  The imaging sensor 48 includes C (cyan), M (magenta), Y (yellow), and G (green) complementary color filters having spectral transmittances as shown in FIG. 6 instead of the RGB image sensor. A so-called complementary color image sensor may also be used. In the case of a complementary color image sensor, RGB three-color image signals can be obtained by color conversion from four CMYG image signals. In this case, it is necessary that either the endoscope 12 or the processor device 16 includes color conversion means for performing color conversion from the CMYG four-color image signal to the RGB three-color image signal.

  As shown in FIG. 2, the image signal output from the image sensor 48 is transmitted to the CDS / AGC circuit 50. The CDS / AGC circuit 50 performs correlated double sampling (CDS) and automatic gain control (AGC) on an image signal which is an analog signal. The image signal that has passed through the CDS / AGC circuit 50 is converted into a digital image signal by an A / D converter (A / D converter) 52. The A / D converted digital image signal is input to the processor device 16.

  The processor device 16 includes a receiving unit 53, a light amount calculating unit 54, a DSP 56, a noise removing unit 58, an image processing switching unit 60, a normal light image processing unit 62, a special light image processing unit 64, and a video signal. And a generation unit 66. The receiving unit 53 receives RGB digital image signals from the endoscope 12. The R image signal corresponds to a signal output from the R pixel (pixel provided with the R filter) of the imaging sensor 48, and the G image signal is output from the G pixel (pixel provided with the G filter) of the imaging sensor 48. The B image signal corresponds to the signal output from the B pixel (pixel provided with the B filter) of the image sensor 48.

  The light amount calculation unit 54 calculates an exposure amount based on the RGB digital image signal received by the reception unit 53 and calculates a target light amount based on the calculated exposure amount. And the light quantity calculation part 54 calculates the target light quantity of each V-LED 20a-20d based on the calculated target light quantity and the set light quantity ratio among V-LED 20a, B-LED 20b, G-LED 20c, and R-LED 20d. A predetermined target light amount setting signal is calculated.

  For example, when the light amount calculated by the light amount calculation unit 54 is “P” and the set light amount ratio is “V-LED: B-LED: G-LED: R-LED = a: b: c: d”, The target light amount of the V-LED 20a is “P × (a / (a + b + c + d))”, the target light amount of the B-LED 20b is “P × (b / (a + b + c + d))”, and the target light amount of the G-LED 20c is “P × (C / (a + b + c + d)) ”, and the target light quantity of the R-LED 20d is“ P × (d / (a + b + c + d)) ”. The light amount ratio is set by the console 19, and different light amount ratios are set in the normal observation mode and the special observation mode.

  The DSP 56 performs gamma correction and color correction processing on the RGB image signal. The noise removing unit 58 removes noise from the RGB image signal by performing noise removal processing (for example, a moving average method, a median filter method, etc.) on the RGB image signal subjected to gamma correction or the like by the DSP 56. The RGB image signal from which noise has been removed is transmitted to the image processing switching unit 60.

  The image processing switching unit 60 transmits the RGB image signal to the normal light image processing unit 62 when the mode switching SW 13a is set to the normal observation mode, and when set to the special observation mode, The RGB image signal is transmitted to the special light image processing unit 64.

  The normal light image processing unit 62 includes a normal color conversion unit 68, a normal color enhancement unit 70, and a normal structure enhancement unit 72, and displays a normal light image in which the inside of the specimen is expressed in the color tone of a normal living body. Generate. The normal color conversion unit 68 outputs a color-converted RGB image signal by performing a color conversion process on the RGB 3-channel digital image signal. In the normal color conversion unit 68, as will be described in detail later, matrix processing is performed to suppress a change in color tone due to wavelength shift or deterioration with time of the R-LED 20d.

  The normal color converter 68 further performs gradation conversion processing on the color-converted RGB image signal and outputs a gradation-converted RGB image signal. The normal color enhancement unit 70 performs various color enhancement processes on the gradation-converted RGB image signal. The normal structure enhancement unit 72 performs structure enhancement processing such as sharpness and contour enhancement on the color enhancement processed RGB image signal. The RGB image signal subjected to the structure enhancement processing by the normal structure enhancement unit 72 is input to the video signal generation unit 66.

  As shown in FIG. 7, the normal color conversion unit 68 includes a 3 × 3 matrix circuit 80, an RGB image signal input unit 82, an RGB image signal output unit 84, and nine LUT # Mij (i, j are , Each of 0, 1 and 2) (corresponding to the first table of the present invention), multipliers 86a to 86i, and adders 88a to 88f. Each LUT # Mij stores a first matrix coefficient Mij # c corresponding to the current amount c of the R-LED 20d for 10 bits (c is 0 or an integer from 1 to 1023). The first matrix coefficient Mij # c is a parameter for correcting the wavelength shift and deterioration with time of the R-LED 20d.

  Each LUT # Mij is connected between the light source control unit 21 in the light source device and the multipliers 86a to 86i. With respect to the input of the current amount c of the R-LED 20d from the light source control unit 21, The first matrix coefficient Mij # c corresponding to the input current amount c is output. The output first matrix coefficient Mij # c is multiplied by the RGB image signal from the RGB image signal input unit 82 by the multipliers 86a to 86i.

The adder 88a adds the R image signal multiplied by the first matrix coefficient M00 # c and the G image signal multiplied by the first matrix coefficient M01 # c. The adder 88b further adds the B image signal multiplied by the first matrix coefficient M02 # c to the image signal added by the adder 88a. The image signal that has passed through the adder 88b is output from the RGB image signal output unit 84 as a color-converted R image signal expressed by the following equation (1).
Color-converted R image signal = M00 # c × R image signal + M01 # c × G image signal + M02 # c × B image signal (1)

As described above, by performing calculations using the adders 88c to 88f, the color-converted G image signal and the color-converted B image signal represented by the following equations (2) and (3) are output as RGB image signals. Output from the unit 84.
Color-converted G image signal = M10 # c × R image signal + M11 # c × G image signal + M12 # c × B image signal (2)
Color-converted B image signal = M20 # c × R image signal + M21 # c × G image signal + M22 # c × B image signal (3)

  The correspondence relationship between the current amount c of the R-LED 20d stored in each LUT # Mij and the first matrix coefficient Mij is obtained by measurement at the time of shipment of the endoscope, and is determined as follows. First, the minimum amount of current Cmin is applied to the R-LED 20d to emit red light R, the specimen under illumination is imaged with the red light R, and an RGB image signal is output. Based on the output RGB image signal and the target RGB image signal, the first matrix coefficient Mij # 0 is determined. The determined first matrix coefficient Mij # 0 is stored in LUT # Mij. Next, each time the current amount c applied to the R-LED 20d is gradually increased and increased, the first matrix coefficient Mij # p (q is an integer between 1 and 1023) is calculated by the same procedure, and the LUT is calculated. Store in #Mij.

  Since the peak wavelength of the R-LED shifts to the longer wavelength side as the emission intensity increases, that is, the current amount c increases (see FIGS. 18 and 20), the color tone associated with this wavelength shift. The first matrix coefficient Mij # c is determined so that the change in is corrected. For example, when observing a dye using crystal violet, redness increases as the emission intensity of the R-LED increases. To correct this, when the amount of current c exceeds a certain value, the color converted R The first matrix coefficients M00 # c, M01 # c, and M02 # c may be determined so that the image signal becomes small. For example, M00 # c multiplied by the R image signal may be reduced, or M01 # c and M02 # c multiplied by the G image signal and the R image signal may be increased.

  The special light image processing unit 64 includes a special color conversion unit 74, a special color enhancement unit 76, and a special structure enhancement unit 78, and generates a special light image in which a specific structure such as a surface blood vessel is highlighted. . The special color conversion unit 74 outputs a color-converted RGB image signal by performing a color conversion process on the RGB 3-channel digital image signal. The special color conversion unit 74 performs pseudo color display of the special light image in the same manner as the normal color conversion unit 68 in addition to suppressing the change in color tone due to the wavelength shift of the R-LED 20d and deterioration with time. Matrix processing is performed.

  The special color conversion unit 74 further performs gradation conversion processing on the color-converted RGB image signal and outputs a gradation-converted RGB image signal. The special color enhancement unit 76 performs various color enhancement processes on the gradation-converted RGB image signal. The special structure emphasizing unit 78 performs structure emphasis processing such as sharpness and contour emphasis on the color enhancement processed RGB image signal. The RGB image signal that has undergone the structure enhancement processing by the special structure enhancement unit 78 is input to the video signal generation unit 66.

  The video signal generation unit 66 converts the RGB image signal input from the normal light image processing unit 62 or the special light image processing unit 64 into a video signal to be displayed as a displayable image on the monitor 18. Based on the converted video signal, the monitor 18 displays a normal light image in the normal observation mode and displays a special light image in the special observation mode.

  Next, the operation of the present invention will be described with reference to the flowchart shown in FIG. When the normal observation mode is set by the mode switching SW 13a, all of the V-LED 20a, B-LED 20b, G-LED 20c, and R-LED 20d are lit. As a result, normal light obtained by combining the purple narrowband light Vn, the blue-green narrowband light Bn, the green light G, and the red light R is emitted into the specimen. The specimen illuminated with normal light is imaged by the imaging sensor 48. An RGB image signal is output from the image sensor 48.

  In the light source device 14, the light amount of the red light R emitted from the R-LED 20 d is measured by the light amount measurement sensor 25. The light quantity measurement signal measured by the light quantity measurement sensor 25 is output to the light source control unit 21. The light source control unit 21 compares the light amount measurement signal with the target light amount setting signal output from the light amount calculation unit 54 in the processor device, and based on the comparison result, the light emission amount of the R-LED 20d becomes the target light amount. Next, the amount of current c applied to the R-LED 20d is set. The set current amount c is output to the R-LED 20d and also to the normal color conversion unit 68 in the processor device.

  The current amount c of the R-LED 20 d output from the light source control unit 21 is input to the 3 × 3 matrix circuit 80 in the normal color conversion unit 68. In the 3 × 3 matrix circuit 80, the current amount c is input to each LUT # Mij. Each LUT # Mij outputs a first matrix coefficient Mij # c corresponding to the input current amount c. Matrix processing based on the output first matrix coefficient Mij # c is performed on the RGB image signal. Thereby, a color-converted RGB image signal is obtained. A normal light image is generated based on the color-converted RGB image signal and displayed on the monitor 18. In the normal light image, the change in color tone caused by the wavelength shift of the R-LED 20d or deterioration with time is suppressed.

[Second Embodiment]
In the first embodiment, the first matrix coefficient Mij # c corresponding to all of the current amount c of the R-LED (i, j is 0, 1, or 2 and c is 0 or an integer from 1 to 1023). Is stored in the LUT # Mij in the matrix circuit 80 and the matrix processing is performed. In this case, since the amount of memory becomes enormous, in the second embodiment, the matrix circuit 80 differs from the LUT # Mij The first matrix coefficient Mij # c corresponding to all of the current amount c of the R-LED is stored in the large-capacity memory, and the first matrix coefficient Mij # c is read from the large-capacity memory and the matrix is read as necessary. Process.

  As shown in FIG. 9, the normal color conversion unit 68 of the second embodiment includes a control unit 101, a large-capacity memory 102, a bit, in addition to the 3 × 3 matrix circuit 80 similar to the first embodiment. And a shift circuit 103. The control unit 101 is connected to the light source control unit 21 and the freeze button 13b, and receives the current amount c from the light source control unit 21 and the freeze signal from the freeze button 13b. The control unit 101 is connected to the large-capacity memory 102 via the bit shift circuit 103, and the bit shift circuit 103 is connected to the 3 × 3 matrix circuit 80. In the large-capacity memory 102, as shown in FIG. 10, the first matrix coefficient Mij # c (i, j is 0, 1, or 2) corresponding to the current amount c of the R-LED 20d for 10 bits. c is 0 or an integer from 1 to 1023). Note that the special color conversion unit 74 of the second embodiment also has the same configuration as described above.

  When the freeze signal is not input to the processor device 16, the control unit 101 reads only a part of the matrix coefficients Mij from the large-capacity memory 102 and the part of the read first matrix coefficients Mij in the matrix circuit 80. The matrix processing is performed by storing in LUT # Mij. As a result, the number of first matrix coefficients Mij stored in LUT # Mij can be reduced, so that the memory capacity can be reduced. For example, as shown in FIG. 10, when the first matrix coefficients for all current amounts are stored in each LUT # Mij, a memory capacity of 3 × 3 × 1024 is required, but 7 bits (128 ), The memory capacity is only 3 × 3 × 8.

  On the other hand, the control unit 101 reads out the first matrix coefficient Mij corresponding to the current amount c from the large-capacity memory 102 in the still image mode in which the freeze signal is input to the processor device 16, and this read first Matrix processing is directly performed based on the matrix coefficient Mij. Therefore, LUT # Mij in the matrix circuit 80 is not used when acquiring a still image.

  The reading of the first matrix coefficient M00 is performed as follows. In the moving image mode, as shown in FIG. 11, M00 # 0, M00 # 128, M00 # 256... M00 # 896 are selected by the bit shift circuit 103 from M00 # 0 to M00 # 1023 of the large capacity memory. Thus, the first matrix coefficient M00 is thinned out and read out. The thinned first matrix coefficient M00 is stored in LUT # M00. Next, the matrix coefficient changeover switch 105 connects the LUT # M00 and the multiplier 86e. During the moving image mode, matrix processing is performed based on the first matrix coefficient stored in LUT # M00. For example, when the current amount c is input, the first matrix coefficient corresponding to the current amount closest to the input current amount c is selected from the first matrix coefficients stored in the LUT # M00. Then, matrix processing is performed based on the selected first matrix coefficient.

  On the other hand, in the still image mode, as shown in FIG. 12, the matrix coefficient changeover switch 105 disconnects the LUT # M00 from the multiplier 86e while the control unit 101 and the multiplier 86e are disconnected. The connection state is established. Next, the first matrix coefficient M00 corresponding to the current amount c is read from the large-capacity memory 102. The read first matrix coefficient M00 is directly multiplied by the R image signal by the multiplier 86a without passing through the LUT # M00. The reading of the first matrix coefficients M01 to M22 is performed in the same manner as the reading of the first matrix coefficient M00.

In the second embodiment, in the still image mode, the first matrix coefficient corresponding to the current amount c is read from the large-capacity memory and the matrix processing is performed. Instead, in the moving image mode, the matrix circuit 80 includes Interpolation processing may be performed based on the first matrix coefficient Mij stored in the LUT # Mij, and matrix processing may be performed using the first matrix coefficient obtained by this interpolation processing. For example, in the LUT # Mij, when the first matrix Mij thinned out at intervals of 7 bits (128) is stored, the interpolation process when the current amount c is between 128 and 256 is as follows: This is performed as shown in the following equation (4).
Mij # c = ((c-128) × Mij # 256 + (256-c) × Mij # 128) / 128 (4)

[Third Embodiment]
In the first and second embodiments, the change in color tone due to the wavelength shift and deterioration with time of the R-LED is corrected by matrix processing. In addition to this, individual differences between scopes, that is, the spectrum of the imaging sensor 48 is corrected. A change in color tone due to sensitivity variations may be performed by matrix processing. In the third embodiment, the second matrix coefficient for performing calibration in advance before endoscopic diagnosis to absorb individual differences between scopes, that is, for correcting variations in spectral sensitivity of the imaging sensor 48. CMij (i, j is 0, 1, or 2) is calculated. Similar to the first and second embodiments, using the correction matrix coefficient Mij # c ′ obtained by multiplying the first matrix coefficient Mij # c and the second matrix coefficient CMij as shown in the following equation (5). The matrix processing is performed by the method of.
Mij # c ′ = CMij × Mij # c (5)

  The calculation method of the second matrix coefficients (9 coefficients of CM00 to CM22) by calibration is performed in the following procedure. First, four types of monochromatic light of purple narrow-band light Vn, blue-green narrow-band light Bn, green light G, and red light R are irradiated toward the white plate 110 shown in FIG. To output an R image signal, a G image signal, and a B image signal for three colors. As a result, a total of 12 image signals (4 types of light irradiation × 3 color image signals) are obtained during monochromatic light irradiation.

  Next, two-color mixed light in which two colors of light are combined from the purple narrow-band light Vn, blue-green narrow-band light Bn, green light G, and red light R, that is, six types of mixed light are respectively irradiated. For each irradiation, the image sensor 48 outputs an R image signal, a G image signal, and a B image signal for three colors. As a result, a total of 18 image signals (6 types of light irradiation × 3 color image signals) can be obtained when two-color mixed light irradiation is performed. Further, three-color mixed light obtained by combining three colors of light from purple narrow-band light Vn, blue-green narrow-band light Bn, green light G, and red light R, that is, three kinds of mixed light are respectively irradiated. For each irradiation, the image sensor 48 outputs an R image signal, a G image signal, and a B image signal for three colors. As a result, a total of nine image signals (3 types of light irradiation × 3 color image signals) are obtained when the three-color mixed light irradiation is performed.

  Finally, each color LED is turned on to emit normal light, or each color LED is turned off to emit Bk light and each, and for each irradiation, an R image signal for three colors, G Output image signal and B image signal. Thus, a total of 6 image signals (2 types of light irradiation × 3 color image signals) can be obtained during normal light and Bk light irradiation.

  As described above, a total of 45 image signals are obtained by irradiation with monochromatic light, two-color mixed light, three-color mixed light, normal light, and Bk light. Based on the 45 image signals and the targeted 45 image signals, second matrix coefficients (CM00 to CM22) are calculated. Although the second matrix coefficient is calculated using 45 colors of light, the second matrix coefficient may be calculated using light of 45 colors or less.

  As in this embodiment, instead of the endoscope system including four-color LEDs of V-LED 20a, B-LED 20b, G-LED 20c, and R-LED 20d, R-LED, G-LED, B-LED In the case of the endoscope system including the three colors of LEDs, the second matrix coefficient is calculated as follows. First, toward the white plate 110 (see FIG. 13), “R light (R-LED lights up)”, “G light (G-LED lights up)”, “B light (B-LED lights up)”, “ C light (B-LED and G-LED are turned on simultaneously), M light (B-LED and R-LED are turned on simultaneously), Y light (G-LED and R-LED are turned on simultaneously), “W light (B-LED, G-LED, R-LED are turned on simultaneously)” and “Bk light (B-LED, G-LED, R-LED are all turned off)” are emitted. The image sensor 48 outputs R image signals, G image signals, and B image signals for three colors. Thereby, a total of 24 image signals (8 types of light irradiation × 3 color image signals) are obtained. Based on the 24 image signals and the target 24 image signals, the second matrix coefficients (CM00 to CM22) are calculated. Although the second matrix coefficient is calculated using light of eight colors, the second matrix coefficient may be calculated using light of eight colors or less.

  In the third embodiment, the second matrix coefficient is calculated by calibration. However, when the endoscope is manufactured, the second matrix coefficient is calculated by performing processing corresponding to the calibration. The second matrix coefficient and the scope ID of the endoscope may be associated with each other and stored in a memory (not shown (corresponding to the second memory of the present invention)) in the processor device. When the endoscope is actually used, when the endoscope is connected to the processor device, the scope ID is read by the ID reading unit in the processor device, and the second matrix coefficient corresponding to the read scope ID is used. Perform matrix processing.

  In the first to third embodiments, only the R-LED 20d is measured for light emission, and the matrix processing is performed in the processor device based on the measurement result. However, the V-LED 20a and B-LED 20b for other colors are used. As for G-LED 20c, as shown in FIG. 14, when the emission intensity is increased, a wavelength shift occurs in which the center wavelengths of purple narrowband light Vn, blue-green narrowband light Bn, and green light G shift to the longer wavelength side. . In FIG. 14, “Vn (large)” has higher emission intensity than “Vn (small)”, and “Bn (large)” has higher emission intensity than “Bn (small)”. “G (large)” indicates that the emission intensity is greater than “G (small)”, and “R (large)” indicates that the emission intensity is greater than “R (small)”.

  Therefore, the V-LED 20a, the B-LED 20b, and the G-LED 20c may each measure the light emission amount and perform matrix processing based on the measurement result. As shown in FIG. 15, the light emission amounts of the V-LED 20 a, B-LED 20 b, and G-LED 20 c are measured by the light amount measurement sensors 120 to 122 in the same manner as the light amount measurement sensor 25. The light quantity measuring sensors 120 to 122 measure the light emission amounts of the purple narrow band light Vn, the blue-green narrow band light Bn, and the green light G reflected by the glass plates 125 to 127. The glass plates 125 to 127 are the same as the glass plate 25, and transmit most of the purple narrowband light Vn, blue-green narrowband light Bn, and green light G toward the optical path coupling unit 23, and partly. Is reflected toward the light quantity measuring sensors 120 to 122.

  The light source controller 21 sets the amount of current applied to each LED 20a to 20d based on the light amount measurement signal output from each light amount measurement sensor 25 and 120 to 122 and the target light amount setting signal of each LED 20a to 20d. Here, the current amount of the V-LED 20a is cv, the current amount of the B-LED 20b is cb, the current amount of the G-LED 20c is cg, and the current amount of the R-LED 20d is cr. The set current amount is output to each of the LEDs 20 a to 20 d and also output to the normal color conversion unit 68 and the special color conversion unit 74.

  The normal color conversion unit 68 and the special color conversion unit 74 perform matrix processing for correcting color unevenness due to wavelength shift or the like of each of the LEDs 20a to 20d. Therefore, the normal color conversion unit 68 and the special color conversion unit 74 include the V-LED 20a and the B-LED 20b in addition to the first matrix coefficient Mij # cr for correcting the wavelength shift and deterioration with time of the R-LED 20d. The first matrix coefficients Mij # cv, Mij # cb, Mij # cg for correcting the wavelength shift and deterioration with time of the G-LED 20c are stored in association with the current amounts cv, cb, cg, cg, respectively. . At the time of actual matrix processing, Mij # cv × Mij # cb × Mij # cg obtained by multiplying the four first matrix coefficients corresponding to the current amounts cv, cb, cg, and cg set by the light source control unit 21, respectively. Multiply the RGB image signal by × Mij # cr. Thereby, a color converted RGB image signal in which color unevenness due to wavelength shift or the like is corrected is obtained.

  In the first to third embodiments, the 3 × 3 matrix circuit 80 is used to correct the change in color tone due to the wavelength shift and deterioration with time of the R-LED 20d. Instead, the 3DLUT (3 You may correct | amend using the dimension look-up table (3-Dimesion Look Up Table) (equivalent to the 2nd table of this invention). As shown in FIG. 16, the 3DLUT 130 stores an RGB image signal and a color-converted RGB image signal in association with each other, and outputs a color-converted RGB image signal in response to the input of the RGB image signal. A plurality of 3DLUTs 130 are provided for each current amount of the R-LED 20d.

  Accordingly, during actual matrix processing, a 3DLUT corresponding to the amount of current applied to the R-LED 20d is selected from among the plurality of 3DLUTs 130. The RGB image signal is converted into a color-converted RGB image signal by the selected 3DLUT. As a method for creating the 3DLUT, a large number of relationships between the RGB image signal and the color-converted RGB image signal when light is emitted with a predetermined current amount are stored in association with the current amount, and the stored current amount, A method of creating a 3DLUT based on the correlation between the RGB image signal and the color-converted RGB image signal is conceivable.

In the above embodiment, four colors of light having an emission spectrum as shown in FIG. 3 are used, but the emission spectrum is not limited to this. For example, as shown in FIG. 17, the green light G and the red light R are light having the same spectrum as that in FIG. 3, while the purple narrowband light Vn ^* is at a center wavelength of 410 to 420 nm. 3 is a light having a wavelength range slightly longer than the purple narrow-band light Vn, and the blue-green narrow-band light Bn ^* has a central wavelength of 445 to 460 nm and is slightly more than the blue-green narrow-band light Bn of FIG. Light having a wavelength range on the short wavelength side may be used.

10 Endoscope systems 20a to 20d V-LED, B-LED, G-LED, R-LED (semiconductor light source)
21 Light source control unit 25, 120-122 Light quantity measurement sensor 48 Imaging sensor (image signal acquisition means)
68 Normal color converter (color converter)
74 Special color converter (color converter)
80 3 × 3 matrix circuit 102 Large capacity memory (first memory)
130 3DLUT (second table)

Claims (11)

A light source device having a plurality of LED light sources that generate light having different peak wavelengths as illumination light for illuminating the specimen, and a light source control unit;
A normal observation mode in which the light source control unit performs light source control for a normal observation mode to emit light for a normal observation mode with respect to the plurality of LED light sources, and the light source control unit includes the plurality of LED light sources. On the other hand, a mode switching unit that performs light source control for the special observation mode and switches between the special observation mode that emits the light for the special observation mode,
A color imaging device having a color filter on the imaging surface;
An image signal acquisition unit that captures an image of the specimen illuminated with the illumination light with the color image sensor and acquires a first color image signal composed of a plurality of color signals;
A light amount calculation unit for calculating a target light amount based on the first color image signal;
A color conversion unit that performs a color conversion process for converting the first color image signal into a second color image signal different from the first color image signal;
Each LED light source of the plurality of LED light sources emits light having a peak wavelength in the transmission wavelength range of the color imaging element, and at least one of the plurality of LED light sources has a high emission intensity. The more the peak wavelength is shifted,
The light source control unit sets a drive amount to be applied to the plurality of LED light sources based on the target light amount calculated by the light amount calculation unit,
The said color conversion part is an endoscope system which changes the content of the said color conversion process according to the drive amount added to these LED light sources. The color conversion process is a process of converting the first color image signal to the second color image signal by multiplying the first color image signal by a first coefficient,
The endoscope system according to claim 1, wherein the first coefficient is associated with a driving amount applied to the plurality of LED light sources.   The endoscope system according to claim 1, wherein the driving amount is a current amount. In the light source control unit,
The endoscope system according to any one of claims 1 to 3, wherein a target light amount of the plurality of LED light sources is calculated from the target light amount based on a set light amount ratio.   The endoscope system according to any one of claims 1 to 4, wherein, when the normal observation mode is selected, the color conversion unit changes the content of the color conversion processing.   The endoscope system according to claim 1, further comprising a light amount measurement sensor that measures a light amount of the illumination light.   The endoscope system according to any one of claims 1 to 5, wherein at least two LEDs among the plurality of LED light sources are provided with a light amount measurement sensor for measuring a light amount of light emitted from each LED.   The endoscope system according to claim 1, wherein the plurality of LED light sources are B-LED, G-LED, and R-LED. The B-LED, the G-LED, and the R-LED are each provided with a light amount measurement sensor that measures the amount of light emitted from each LED.
The light source controller is
From the target light amount, based on a set light amount ratio, calculate the target light amount of the B-LED, the target light amount of the G-LED, and the target light amount of the R-LED,
The light quantity of the B-LED, G-LED, and R-LED measured by the light quantity measurement sensor, the target light quantity of the B-LED, the target light quantity of the G-LED, and the target light quantity of the R-LED The endoscope system according to claim 8, wherein the drive amount of the B-LED, the G-LED, and the R-LED is set based on a comparison with.   The endoscope system according to claim 1, wherein the plurality of LED light sources are V-LED, B-LED, G-LED, and R-LED.   The endoscope system according to any one of claims 1 to 10, wherein at least one LED light source among the plurality of LED light sources generates light whose peak wavelength shifts to a long wave side as the emission intensity increases.

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