Processor for endoscope and control method for endoscope processor

Abstract

To provide a processor for an endoscope in which an automatic dimming function appropriately operates even if a tip end of the endoscope is in the vicinity of or in contact with biological tissue.SOLUTION: The processor for an endoscope comprises an imaging signal acquisition unit that acquires an imaging signal from an imaging element 46, and a dimming unit 30 that controls a light source 28 that illuminates an observation field on the basis of the imaging signal. The dimming unit 30 has: a luminance index acquisition unit 33 that acquires, on the basis of the imaging signal, a first index related to the luminance of a first color and a second index related to the luminance of a second color; a generation unit 34 that generates a photometric signal on the basis of the first index and the second index; and a dimming output unit 31 that outputs a dimming signal to the light source 28 on the basis of the photometric signal.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a processor for an endoscope and a control method for the processor for an endoscope. [Background technology]

[0002] Endoscope processors are used that have an automatic light control function that automatically adjusts the brightness of the illumination light based on the brightness of the endoscopic image.An endoscope processor has been proposed that automatically adjusts the light control mode to reduce halation when halation occurs in the endoscopic image (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 126531 Summary of the Invention [Problem to be solved by the invention]

[0004] The automatic brightness adjustment function ensures that the endoscopic image is maintained at a brightness suitable for diagnosis, even when the doctor operates the endoscope to change the field of view.

[0005] However, when the tip of the endoscope is close to or in contact with biological tissue such as mucous membrane, the endoscopic field of view is not illuminated sufficiently. Therefore, the endoscopic image is dark. In such a situation, even if the illumination light is increased, the endoscopic image cannot be made bright enough. Therefore, the automatic light control function does not work properly.

[0006] In one aspect, an object of the present invention is to provide an endoscope processor that allows an automatic light control function to operate appropriately even when the tip of the endoscope is close to or in contact with biological tissue. [Means for solving the problem]

[0007] The endoscope processor includes an image signal acquisition unit that acquires an image signal from an image sensor, and a light control unit that controls a light source that illuminates an observation field based on the image signal. The light control unit includes a brightness index acquisition unit that acquires a first index related to the brightness of a first color and a second index related to the brightness of a second color based on the image signal, a generation unit that generates a photometric signal based on the first index and the second index, and a light control output unit that outputs a light control signal to the light source based on the photometric signal. The first color is blue and the second color is green. [Effects of the Invention]

[0008] According to one aspect, it is possible to provide an endoscope processor that allows the automatic light control function to operate appropriately even when the tip of the endoscope is close to or in contact with biological tissue. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram illustrating a configuration of an endoscope system. [Figure 2] FIG. [Figure 3] 3A and 3B are explanatory diagrams illustrating the configuration and function of a light control unit. [Figure 4] 10A and 10B are diagrams illustrating the influence of the distance between the tip and the biological tissue on the imaging signal. [Figure 5] 10 is a graph illustrating the influence of the distance between the tip and the biological tissue on the imaging signal. [Figure 6] 10 is a graph illustrating a coefficient K. [Figure 7] 10 is a flowchart illustrating the flow of operations of a light control unit. [Figure 8] FIG. 10 is an explanatory diagram illustrating a contact determination method according to the second embodiment. [Figure 9] 10 is a flowchart illustrating the flow of processing of a program according to the second embodiment. [Figure 10] 10 is a flowchart illustrating a process flow of a contact determination subroutine. [Figure 11] 11 is a flowchart illustrating the flow of processing of a program according to the third embodiment. [Figure 12] 10 is a flowchart illustrating the flow of processing of a program according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Embodiment 1] 1 is an explanatory diagram illustrating the configuration of an endoscope system 10. The endoscope system 10 includes an endoscope processor 20, an endoscope 40, a display device 16, and an input device 17. The endoscope processor 20 includes a control unit 21, a main memory device 22, an auxiliary memory device 23, a communication unit 24, a display device I / F (Interface) 26, an input device I / F 27, a light source 28, a light control unit 30, an endoscope connector 29, and a bus.

[0011] The endoscope 40 includes an insertion section 44, an operation section 43, a universal cord 49, and a scope connector 48. The insertion section 44 is long, and one end is connected to the operation section 43 via a folding stopper. The insertion section 44 has, in order from the operation section 43 side, a flexible section 441, a bending section 442, and a tip section 443. The bending section 442 bends in response to operation of a bending knob provided on the operation section 43.

[0012] The universal cord 49 is long, and a first end is connected to the operation unit 43, and a second end is connected to the scope connector 48. The universal cord 49 is flexible. The scope connector 48 has a substantially rectangular parallelepiped shape. The scope connector 48 includes a signal transmission connector and an illumination light connector. An air / water supply pump (not shown) is connected to the endoscope 40.

[0013] The control unit 21 is an arithmetic and control device that executes the program of this embodiment. The control unit 21 uses one or more CPUs (Central Processing Units) or multi-core CPUs, etc. The control unit 21 is connected to each hardware component that constitutes the endoscope processor 20 via a bus.

[0014] The display device 16 is, for example, a liquid crystal display device or an organic EL (Electro Luminescence) display device. The input device 17 is, for example, a keyboard, a touch panel, a foot switch, or the like.

[0015] The main memory device 22 is a storage device such as an SRAM (Static Random Access Memory), a DRAM (Dynamic Random Access Memory), or a flash memory. The main memory device 22 temporarily stores information required during processing performed by the control unit 21 and programs currently being executed by the control unit 21.

[0016] The auxiliary storage device 23 is a storage device such as an SRAM, a flash memory, a hard disk, etc. The auxiliary storage device 23 stores programs to be executed by the control unit 21 and various data required for executing the programs.

[0017] The communication unit 24 is an interface that performs data communication between the endoscope processor 20 and the network. The display device I / F 26 is an interface that connects the endoscope processor 20 and the display device 16. The input device I / F 27 is an interface that connects the endoscope processor 20 and the input device 17.

[0018] Light source 28 is a high-intensity light source such as an LED (Light Emitting Diode). Light source 28 may be a combination of a light source that emits broadband light, such as a xenon lamp, and an optical filter. Light source 28 may also be an illumination LED built into tip 443.

[0019] The light source 28 is connected to the bus via a driver (not shown). The control unit 21 controls the turning on and off, brightness changes, and color changes of the light source 28. The illumination light emitted from the light source 28 is supplied to the endoscope 40 via the endoscope connector 29 and the scope connector 48. The illumination light is guided by an illumination optical fiber inside the endoscope 40 to an illumination window 52 (see FIG. 2) provided at the tip 443.

[0020] 2 is an external view of the end face of the tip portion 443. At the tip of the tip portion 443, an observation window 51, two illumination windows 52, an air supply nozzle 53, a water supply nozzle 54, a channel outlet 55, etc. are arranged.

[0021] 2 is an example of the appearance of the end face of the tip portion 443, and the arrangement of each component is not limited to that shown in FIG. 2. For example, the arrangement of the air supply nozzle 53 and the water supply nozzle 54 may be reversed. The number of illumination windows 52 may be one or three or more. The endoscope 40 may be a side-viewing type in which the viewing direction is directed to the side of the insertion portion 44, an oblique-viewing type, or the like.

[0022] 3 is an explanatory diagram illustrating the configuration and functions of the light control unit 30. The light control unit 30 includes a light control output unit 31 and a photometric unit 32. The photometric unit 32 includes a brightness index acquisition unit 33 and a generation unit .

[0023] The observation field is illuminated by illumination light emitted from the illumination window 52. For example, light reflected by biological tissue within the observation field passes through the observation window 51 and an observation optical system (not shown) to form an image on the image sensor 46. An imaging signal generated by the image sensor 46 is transmitted to the endoscope processor 20 via the scope connector 48. The endoscope connector 29 to which the scope connector 48 is connected functions as an imaging signal acquisition unit that acquires the imaging signal from the image sensor 46.

[0024] In the following description, an endoscope system 10 using a so-called primary color imaging element 46 that outputs color signals of three colors, R (Red), G (Green), and B (Blue), will be described as an example. Blue is an example of a first color. Green is an example of a second color having a longer wavelength than the first color. Note that a complementary color imaging element 46 may be used instead of a primary color imaging element.

[0025] The control unit 21 performs image processing based on the imaging signal and outputs an endoscopic image 61 (see FIG. 8) with image quality suitable for endoscopic examination to the display device 16. The brightness index acquisition unit 33 acquires a brightness index based on the imaging signal. The brightness index is an index related to the brightness of the image captured by the imaging element 46. In conventional light adjustment units 30, an index related to the brightness of the B component of the image is often used. The brightness index will be described in detail later.

[0026] The generation unit 34 generates a photometric signal based on the brightness index and outputs it to the dimming output unit 31. The dimming output unit 31 generates a photometric signal based on the photometric signal, the model of the endoscope 40, and an operation mode set by the user, and outputs it to the light source 28. The operation mode is, for example, a normal light observation mode and a special light observation mode. The light source 28 emits illumination light with a brightness and color based on the dimming signal.

[0027] The above loop performs automatic dimming, automatically adjusting the brightness of the illumination light in real time. The dimming unit 30 is, for example, a custom IC (Integrated Circuit) such as an ASIC (Application Specific Integrated Circuit) or a PLD (Programmable Logic Device) such as an FPGA (Field-Programmable Gate Array). The dimming unit 30 may be a dedicated IC chip designed for the automatic dimming of this embodiment.

[0028] The dimming output unit 31, photometry unit 32, brightness index acquisition unit 33, and generation unit 34 that make up the dimming unit 30 are each logic circuits configured inside an IC. By performing high-speed dimming using hardware, it is possible to provide an endoscope system 10 in which the dimming function quickly follows changes in the observation field of view.

[0029] The light control unit 30 may be integrated with a driver IC for controlling the light source. The light control unit 30 may be integrated into an IC chip together with the control unit 21. If the speed of the control unit 21 and the bus is sufficiently high, the processing of the light control unit 30 may be realized by the control unit 21 in software.

[0030] Fig. 4 is a diagram for explaining the influence of the distance between the tip 443 and the living tissue on the imaging signal. Fig. 4 schematically shows the influence of the distance between the tip 443 and the living tissue. The hatched area indicates the living tissue.

[0031] "Strong contact" refers to a state in which the tip 443 is pressed against the biological tissue. The illumination light emitted from the illumination window 52 propagates through the inside of the biological tissue and reaches the observation window 51. "Light contact" refers to a state in which the tip 443 and the biological tissue are in light contact with each other, and a layer of liquid such as mucus or water is generated between them due to surface tension. The illumination light emitted from the illumination window 52 propagates through the inside of the liquid layer and the surface of the biological tissue and reaches the observation window 51.

[0032] In the "light contact" and "strong contact" states, most of the energy of the illumination light is absorbed by the living tissue, and therefore only a small amount of light reaches the observation window 51. Even if the illumination light is set to a bright state, the image captured by the image sensor 46 remains dark.

[0033] "Near" is a state in which the tip 443 is closer to the biological tissue than the focal range of the observation optical system. In the "near" state, the endoscopic image 61 is in a so-called "out-of-focus" state. "Medium distance" is a state in which the state of the biological tissue can be observed in detail using the endoscope 40. "Long distance" is a state in which a wide range of biological tissue can be observed using the endoscope 40. A doctor normally performs an endoscopic examination by operating the endoscope 40 so that it is in the "long distance" or "medium distance" state.

[0034] In the "close," "middle distance," and "long distance" states, the illumination light emitted from the illumination window 52 is reflected by the surface of the biological tissue and reaches the observation window 51. Changes in the brightness of the illumination light are directly reflected in the brightness of the image captured by the image sensor 46.

[0035] Fig. 5 is a graph illustrating the effect of the distance between the tip 443 and biological tissue on the imaging signal. The horizontal axis of Fig. 5 represents each state described using Fig. 4. The vertical axis represents the ratio of each color component of R, G, and B that constitutes the image captured by the imaging element 46. The dashed line represents the ratio of the R component, the broken line represents the ratio of the G component, and the solid line represents the ratio of the B component.

[0036] At "close," "medium," and "long distance," the component ratios are nearly constant, with the B component being the most abundant, followed by the G component and the R component. The ratio of the R component hardly changes at "light contact" and "strong contact." At "light contact," the G component is more abundant than the B component. At "strong contact," the ratio of the G component increases even further.

[0037] An overview of the automatic light adjustment performed by the endoscope system 10 of this embodiment will be described. When the B component is greater than the G component, the generation unit 34 generates a photometric signal based on a brightness index related to the B component. When the photometric signal indicates that an image brighter than a predetermined standard has been captured, the light adjustment output unit 31 outputs a light adjustment signal that reduces the output of the light source 28. When the photometric signal indicates that an image darker than a predetermined standard has been captured, the light adjustment output unit 31 outputs a light adjustment signal that increases the output of the light source 28.

[0038] The tip 443 does not come into contact with living tissue, and changes in the brightness of the illumination light due to automatic light adjustment are directly reflected in the brightness of the image captured by the image sensor 46. Therefore, even if the state of the observation field of view changes, the brightness of the illumination light is quickly adjusted, allowing the doctor to smoothly continue the endoscopic examination.

[0039] When the G component is greater than the B component, the tip 443 is in contact with biological tissue. Therefore, the change in brightness of the illumination light due to automatic light adjustment is not fully reflected in the brightness of the image captured by the image sensor 46. If automatic light adjustment is performed based on the brightness of the B component in this state, the automatic light adjustment function will not operate appropriately, and the light source 28 will continue to operate at maximum output.

[0040] If the light source 28 continues to operate at maximum output for a long period of time, the life of the light source 28 will be shortened. Heat generated by the light source 28 will heat up the inside of the endoscope processor 20, which is likely to cause malfunctions and failures of electronic components such as the control unit 21 and the dimming unit 30. There is also the problem of an unnecessarily increased power consumption of the light source 28. There is also the risk that the light emitted from the illumination window 52 will be unnecessarily strong, which may have an adverse effect on living tissue.

[0041] To prevent the problems listed above, when the G component is greater than the B component, the generator 34 of this embodiment outputs a photometric signal that is large relative to the brightness index, i.e., a photometric signal similar to that output when the image captured by the image sensor 46 is brighter than the actual image. The dimming output unit 31 operates based on the photometric signal. This prevents the output of the light source 28 from increasing unnecessarily, thereby preventing the various problems described above from occurring.

[0042] A specific example of the brightness index will be described. The brightness index is, for example, the average brightness of each of G and B over the entire surface of an image captured by the image sensor 46. The brightness index may also be the average brightness of each of G and B in a predetermined area of ​​the image captured by the image sensor 46. In the following description, the predetermined area used to calculate the brightness index may be referred to as a photometric area.

[0043] The photometric region is, for example, the center of the image. The photometric region may also be a region near the middle between the center and edge of the image. The control unit 21 may accept a photometric region designated by a doctor and instruct the photometric control unit 30. The control unit 21 may also set a lesion detected by AI (Artificial Intelligence) as the photometric region and instruct the photometric control unit 30.

[0044] Instead of the average brightness, a statistical value such as a median value or a central value of brightness may be used as the brightness index. The control unit 21 may receive a specification of a method for calculating the brightness index and instruct the light control unit 30 to use the specified method.

[0045] A specific example of the operation of the generation unit 34 that generates a photometric signal based on the luminance index will be described below. The generation unit 34 outputs a photometric signal calculated based on, for example, equation (1). M=PB+K×PG (1) M is the photometric signal. PB is the brightness index for B. PG is a brightness index related to G. K is a coefficient.

[0046] In equation (1), PB is an example of a first index related to the luminance of the first color, and PG is an example of a second index related to the luminance of the second color.

[0047] FIG. 6 is a graph illustrating the coefficient K. The horizontal axis of FIG. 6 represents the value obtained by dividing the luminance index PB for B by the luminance index PG for G. The vertical axis of FIG. 6 represents the coefficient K. When PB / PG is less than threshold A1, the coefficient K is 1. When PB / PG is equal to or greater than threshold A2, the coefficient K is 0. When PB / PG is in the range of A1 or greater and less than A2, the coefficient K changes smoothly from 1 to 0.

[0048] For example, threshold A1 is 1.0, and threshold A2 is 1.3. The region where PB / PG is less than threshold A1 is the range in Fig. 5 where the B component is smaller than the G component, and is the region where the tip 443 is in contact with the biological tissue. The region where PB / PG is equal to or greater than threshold A2 is the region in Fig. 5 where the B component is 1.3 times or more the G component, and is the region where the tip 443 is not in contact with the biological tissue.

[0049] Therefore, the photometric signal calculated based on equation (1) is (PB+PG) when the tip 443 is in contact with the living tissue, and is PB when the tip 443 is not in contact with the living tissue. In an intermediate state between contact and non-contact, such as when a portion of the tip 443 is in contact with the living tissue, a photometric signal intermediate between contact and non-contact is calculated.

[0050] As described above, it is possible to provide an endoscope system 10 that reduces the output of the light source 28 when the tip portion 443 is in contact with biological tissue. As shown in Fig. 6, the coefficient K changes smoothly between 0 and 1, so it is possible to avoid sudden fluctuations in the output of the light source 28 when a portion of the tip portion 443 is in contact with biological tissue, when the contact area is fluctuating, etc. Therefore, it is possible to provide an endoscope system 10 that prevents sudden fluctuations in the brightness of an endoscopic image.

[0051] The generating unit 34 may output a photometric signal calculated based on, for example, equation (2). M = PB + K × (PG + PR) ... (2) PR is a brightness index related to R. When formula (2) is used, the photometric signal output from the generation unit 34 becomes larger when the tip end portion 443 is in contact with biological tissue compared to when formula (1) is used. Therefore, it is possible to provide an endoscope system 10 that further reduces the output of the light source 28 when the tip end portion 443 is in contact with biological tissue.

[0052] The generating unit 34 may output a photometric signal calculated based on, for example, equation (3). M = (1 - K)PB + K × PG (3) According to equation (3), (1-K) indicates the contribution rate of the B component to the photometric signal M, and K indicates the contribution rate of the G component to the photometric signal M, and the sum of the usage rates of both is 100 percent.

[0053] The generating unit 34 may output a photometric signal calculated based on, for example, equation (4).

[0054]

number

[0055] According to equation (4), when PB is greater than PG, the photometric signal M is a luminance index for the B component, and when PB is equal to or less than PG, the photometric signal M is a luminance index for the G component. Equation (4) means that in the graph described using Figure 5, when the luminance index PB for B is greater than the luminance index PG for G, the luminance index PB is used as the photometric index M, and when the luminance index PB is equal to or less than the luminance index PG, the luminance index PG is used as the photometric index M.

[0056] That is, equation (4) means that when PB is equal to or smaller than PG, it is determined that the tip 443 is in contact with the living tissue, and PG is used as the photometric signal M.

[0057] The generating unit 34 may output a photometric signal calculated based on, for example, equation (5).

[0058]

number

[0059] Equation (5) indicates that when PB is equal to or less than PG, it is determined that the tip 443 is in contact with the living tissue, and (PG+PR) is used as the photometric signal M.

[0060] The calculation formulas for the photometric signal exemplified by formulas (1) to (5) are all examples and are not limited to these. For example, the generation unit 34 may use a value obtained by multiplying the left side of formulas (1) to (5) by an arbitrary constant as the photometric signal. The generation unit 34 may switch the calculation formula to be used depending on conditions such as the model of the endoscope 40 or the operating mode currently being used.

[0061] According to the calculation formulas for the photometric signal exemplified by equations (1) to (5), when PB is equal to or less than PG, a photometric signal is calculated in which PG has a higher contribution than when PB exceeds PG.

[0062] Fig. 7 is a flowchart illustrating the flow of operation of the light control unit 30. In parallel with the processing described using Fig. 7, the control unit 21 performs image processing based on the imaging signal acquired from the imaging element 46 to generate an endoscopic image, which is then displayed on the display device 16. For example, when a doctor performs an operation to change the operating mode from normal light observation to special light observation, the control unit 21 notifies the light control unit 30 of the change in operating mode. The processing performed by the control unit 21, such as the generation of an endoscopic image, is well known and will not be described here.

[0063] The light adjustment unit 30 acquires an imaging signal from the imaging element 46 (step S501). The brightness index acquisition unit 33 calculates a brightness index PB for B based on the imaging signal (step S502). The brightness index acquisition unit 33 calculates a brightness index PG for G based on the imaging signal (step S503). The generation unit 34 calculates a photometric signal M based on the calculation formulas exemplified as formulas (1) to (4), for example (step S504).

[0064] The dimming output unit 31 outputs a dimming signal based on the photometric signal and the operation mode instructed by the control unit 21 (step S505). For example, when the operation mode is the normal light observation mode, the dimming output unit 31 outputs a dimming signal to the light source 28 to cause the light source 28 to emit white light with a luminance corresponding to the photometric signal. Similarly, when the operation mode is the special light observation mode, the dimming output unit 31 outputs a dimming signal to the light source 28 to cause the light source 28 to emit narrowband light with a luminance corresponding to the photometric signal.

[0065] The light control unit 30 determines whether to end the process (step S506). For example, if the doctor stops the illumination light, the light control unit 30 determines to end the process. If it is determined not to end the process (NO in step S506), the light control unit 30 returns to step S501. If it is determined to end the process (YES in step S506), the light control unit 30 ends the process.

[0066] According to this embodiment, an endoscopic system 10 can be provided in which the automatic dimming function operates appropriately to prevent the output of the light source 28 from becoming too high, even when the tip of the endoscope 40 is close to or in contact with biological tissue.

[0067] 3 is similar to the operation of the automatic light control function that has been conventionally used. Therefore, with a relatively small design change to the conventional light control unit 30, it is possible to realize an endoscope processor 20 with an improved operation of the automatic light control function.

[0068] [Embodiment 2] This embodiment relates to an endoscope system 10 that determines whether or not a tip 443 is in contact with living tissue based on an image of the end of an imaging element 46. Explanation of parts common to the first embodiment will be omitted.

[0069] Fig. 8 is an explanatory diagram illustrating a contact determination method according to embodiment 2. Fig. 8A schematically shows an endoscopic image 61 when tip 443 is not in contact with biological tissue. The black corners indicate areas where so-called image vignetting occurs due to the lens frame of the imaging optical system.

[0070] 8B is a schematic diagram of an endoscopic image 61 when the distal end 443 is in contact with biological tissue. Stray light occurs due to refraction of light by mucus, and the upper right and lower right corners of the endoscopic image 61 are bright.

[0071] The way image vignetting occurs is easily affected by variations in the assembly state between the image sensor 46 and the lens frame. The control unit 21 displays the endoscopic image 61 on the display device 16 after electronic masking has been performed on areas where image vignetting may occur. The masking process prevents individual differences in the appearance of the four corners of the endoscopic image 61.

[0072] 8B, even when an endoscopic image 61 with bright corners is captured, the control unit 21 displays the endoscopic image 61 with the four corners painted black on the display device 16. Therefore, a user such as a doctor will not notice the change in brightness of the four corners.

[0073] The endoscope system 10 of this embodiment determines whether or not the tip 443 is in contact with the living tissue, using data from the four corners that are normally masked.

[0074] 9 is a flowchart illustrating the processing flow of the program according to the second embodiment. The control unit 21 acquires an imaging signal from the imaging element 46 (step S601). The control unit 21 performs known signal processing on the imaging signal to generate an endoscopic image 61 (step S602). The control unit 21 displays the endoscopic image 61, the four corners of which have been masked, on the display device 16 (step S603).

[0075] The control unit 21 starts a contact determination subroutine (step S604). The contact determination subroutine is a subroutine for determining whether or not the tip portion 443 is in contact with a living tissue. The processing flow of the contact determination subroutine will be described later.

[0076] The control unit 21 determines whether or not contact has been determined by the contact determination subroutine (step S605). If it is determined that contact has not occurred (NO in step S605), the control unit 21 instructs the light control unit 30 to adjust the light (step S606). The light control unit 30 performs light control to adjust the brightness of the light source 28 based on the luminance of the B component of the imaging signal, as has been conventionally done. The light control unit 30 may perform the same operation as in the first embodiment.

[0077] If it is determined that contact has occurred (YES in step S605), or after step S606 is completed, the control unit 21 determines whether or not to end the process (step S607). For example, if the doctor performs an operation to stop the illumination light, the control unit 21 determines to end the process. If it is determined not to end the process (NO in step S607), the control unit 21 returns to step S601. If it is determined to end the process (YES in step S607), the control unit 21 ends the process.

[0078] 10 is a flowchart illustrating the processing flow of the contact determination subroutine. The contact determination subroutine is a subroutine that determines whether or not the tip portion 443 is in contact with biological tissue. The contact determination subroutine allows the control unit 21 to realize the function of the contact determination unit of this embodiment.

[0079] The control unit 21 calculates the luminance of each of the four corner areas based on the endoscopic image 61 before masking (step S611). For example, the control unit 21 calculates the average value of the luminance of pixels in an area where vignetting always occurs regardless of variations in manufacturing the endoscope 40. The control unit 21 may also calculate the luminance of an area where vignetting occurs in the endoscopic image 61 at the time of white balance adjustment performed before the endoscopic examination. The luminance may be, for example, the luminance of one or two of the colors R, G, and B. Instead of the average value, any statistical value such as a median value or central value may be used.

[0080] The control unit 21 determines whether the brightness of each of the four corners exceeds a predetermined threshold (step S612). If it is determined that the brightness of all corners exceeds the predetermined threshold (YES in step S612), the control unit 21 determines that the contact state determination result is "contact" (step S613). If it is determined that there is a corner whose brightness does not exceed the predetermined threshold (NO in step S612), the control unit 21 determines that the contact state determination result is "non-contact" (step S614). After step S613 or step S614 is completed, the control unit 21 ends the process.

[0081] In step S612, the control unit 21 may determine whether the brightness of three or fewer corners exceeds a predetermined threshold. Even when only a small portion of the tip portion 443 is in contact with biological tissue, the endoscope system 10 can detect the contact.

[0082] According to this embodiment, dimming is not performed when the tip 443 is in contact with biological tissue, so an endoscope system 10 can be provided that prevents an increase in the output of the light source 28 when the endoscopic image becomes dark due to contact.

[0083] The light control unit 30 may perform the contact determination explained in the contact determination subroutine to determine whether or not the light control operation can be performed.

[0084] [Embodiment 3] This embodiment relates to an endoscope system 10 that can switch between a normal mode and a dark place mode that is suitable for imaging in dark places. Explanation of parts common to the second embodiment will be omitted.

[0085] 11 is a flowchart illustrating the processing flow of the program according to embodiment 3. The processing up to step S605 is the same as the processing flow of the program according to embodiment 2 described using FIG. 9, and therefore the description thereof will be omitted.

[0086] If it is determined that there is contact (YES in step S605), the control unit 21 sets the endoscope system 10 to the dark place mode (step S621). The dark place mode is an operating mode suitable for observation in dark places. If it is determined that there is no contact (NO in step S605), the control unit 21 sets the endoscope system 10 to the normal mode (step S622). The normal mode is an operating mode suitable for normal endoscopic examination.

[0087] The difference between the dark place mode and the normal mode will now be described. The dark place mode is, for example, a mode in which the analog gain of the image sensor 46 is increased compared to the normal mode, or a mode in which the electronic shutter speed is slowed compared to the normal mode. The dark place mode may also be a mode in which both the analog gain and the electronic shutter speed are changed from those in the normal mode. In steps S621 and S622, the control unit 21 realizes the function of an element control unit that controls the settings of the image sensor 46.

[0088] Let's take a specific example. The analog gain in normal mode is 1x, and in dark mode it is 4x greater than in normal mode. The electronic shutter speed in normal mode is 1 / 240 sec, and in dark mode it is 1 / 60 sec, slower than in normal mode.

[0089] After step S621 or step S622 is completed, control unit 21 instructs light control unit 30 to adjust the light intensity (step S623). Light control unit 30 performs light control to adjust the brightness of light source 28 based on the luminance of the B component of the imaging signal, as has been conventionally done. Note that when the dark place mode is set, light control unit 30 outputs a light control signal to make the illumination light darker than in normal mode.

[0090] The control unit 21 determines whether to end the process (step S624). For example, if the doctor stops the illumination light, the control unit 21 determines to end the process. If it is determined not to end the process (NO in step S624), the control unit 21 returns to step S601. If it is determined to end the process (YES in step S624), the control unit 21 ends the process.

[0091] Although not shown in a flowchart, it is desirable that the analog gain or electronic shutter be gradually switched over a period of about three seconds when switching between the normal mode and the dark mode, thereby providing an endoscope system 10 that prevents the user from feeling uncomfortable due to sudden changes in the endoscopic image 61.

[0092] According to the present embodiment, when the distal end portion 443 is in contact with biological tissue, the endoscope system 10 is set to the dark place mode. In the dark place mode, the dimming unit 30 outputs a dimming signal to make the illumination light darker than in the normal mode, so that the endoscope system 10 can be provided that prevents an increase in the output of the light source 28 when the endoscopic image 61 is dark due to contact.

[0093] [Variation 3-1] Instead of starting the contact determination subroutine described using FIG. 10, the control unit 21 may determine that the tip 443 is in contact with the biological tissue when PB is equal to or less than PG, as described in equation (5) of embodiment 1.

[0094] [Variation 3-2] The control unit 21 may gradually switch the endoscope system 10 to the dark place mode when PB / PG described in the first embodiment falls below 1, and gradually switch the endoscope system 10 to the normal mode when PB / PG exceeds 2. It is possible to provide an endoscope system 10 that prevents frequent switching between the dark place mode and the normal mode when the tip end 443 and the biological tissue region continue to be in a delicate state of being in contact with each other.

[0095] [Embodiment 4] This embodiment relates to an endoscope system 10 that changes the components of illumination light when the distal end portion 443 is in contact with living tissue. Explanation of parts common to the third embodiment will be omitted.

[0096] 12 is a flowchart illustrating the processing flow of the program according to embodiment 4. The processing up to step S605 is the same as the processing flow of the program according to embodiment 2 described using FIG. 9, and therefore the description thereof will be omitted.

[0097] If it is determined that contact has occurred (YES in step S605), the control unit 21 instructs the light control unit 30 to perform light control in contact mode (step S631). If it is determined that contact has not occurred (NO in step S605), the control unit 21 instructs the control unit 21 to perform light control in normal mode (step S632).

[0098] After step S631 or step S632 is completed, control unit 21 determines whether or not to terminate the process (step S624). If it is determined not to terminate (NO in step S624), control unit 21 returns to step S601. If it is determined to terminate (YES in step S624), control unit 21 terminates the process.

[0099] The difference between dimming in contact mode and dimming in normal mode will be explained. Contact mode is a mode in which light source 28 outputs illumination light with fewer short-wavelength light components than normal mode. This will be explained using special light observation as an example. In normal mode, light source 28 emits light that is a mixture of purple light and green light in an energy ratio of 4:1. In contact mode, light source 28 emits light that is a mixture of purple light and green light in an energy ratio of 2:1.

[0100] Illumination light in which purple light and green light are mixed in an energy ratio of 4:1 is an example of illumination light with a first component ratio. Illumination light in which purple light and green light are mixed in an energy ratio of 2:1 is an example of illumination light with a second component ratio, in which the proportion of purple light, a short-wavelength component, is lower than that of the first component ratio.

[0101] By reducing the proportion of purple light that is easily absorbed by biological tissue, it is possible to suppress the extent of reduction in the amount of light incident on the image sensor 46 even when the distal end 443 is in contact with biological tissue. Therefore, it is possible to provide an endoscope system 10 that prevents an increase in the output of the light source 28 even when the distal end 443 is in contact with biological tissue.

[0102] [Variation 4-1] The control unit 21 may gradually switch the endoscopic system 10 to contact mode when the PB / PG described in embodiment 1 falls below 1, and gradually switch the endoscopic system 10 to normal mode when the PB / PG exceeds 2.

[0103] The technical features (constituent elements) described in each embodiment can be combined with each other, and by combining them, new technical features can be formed. The embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0104] 10 Endoscopy System 16 Display device 17 Input Devices 20 Endoscope processor 21 Control Unit 22 Main storage 23 Auxiliary storage device 24 Communications Department 26 Display device I / F 27 Input device I / F 28 light source 29 Endoscope connector 30 Dimming unit 31 Dimming output section 32 Photometry section 33 Brightness index acquisition unit 34 Generation part 40 Endoscopy 43 Operation section 44 Insertion section 441 Soft part 442 curved section 443 Tip 46 image sensor 48 Scope Connector 49 Universal Code 51 Observation window 52 Lighting window 53 Air supply nozzle 54 Water nozzle Channel 55 Exit 61 Endoscopic images

Claims

1. an imaging signal acquisition unit that acquires an imaging signal from the imaging element; a light control unit that controls a light source that illuminates the observation field based on the imaging signal, The light control unit a brightness index acquiring unit that acquires a first index related to the brightness of a first color and a second index related to the brightness of a second color based on the imaging signal; a generation unit that generates a photometric signal based on the first index and the second index; a dimming output unit that outputs a dimming signal to the light source based on the photometric signal, the first color is blue; The second color is green. Endoscope processor.

2. The generation unit When the first index is smaller than the second index, the photometric signal is generated in which the contribution of the second index is higher than when the first index is larger than the second index. The endoscope processor according to claim 1 .

3. The generation unit If the first index is greater than the second index, the first index is used as the photometric signal; When the first index is smaller than the second index, the photometric signal is generated to be larger than the first index. The endoscope processor according to claim 1 .

4. a contact determination unit that determines that the tip of the endoscope is in contact with biological tissue when the first index is smaller than the second index; The endoscope processor according to claim 1 .

5. an element control unit that controls settings of the imaging element; When the contact determination unit determines that no contact has occurred, the sensor control unit sets the image sensor to a normal mode for normal image capture; When the contact determination unit determines that contact has occurred, the image sensor control unit sets the image sensor to a dark place mode that is more suitable for taking pictures in dark places than a normal mode. The endoscope processor according to claim 4 .

6. and a contact determination unit that determines, based on the image pickup signal, that the luminance of the corner of the image pickup element is higher than a predetermined luminance, that the tip of the endoscope is in contact with biological tissue. The endoscope processor according to claim 1 .

7. an element control unit that controls settings of the imaging element; When the contact determination unit determines that no contact has occurred, the sensor control unit sets the image sensor to a normal mode for normal image capture; When the contact determination unit determines that contact has occurred, the image sensor control unit sets the image sensor to a dark place mode that is more suitable for taking pictures in dark places than a normal mode. The endoscope processor according to claim 6 .

8. The dark place mode is a mode in which the analog gain is higher than that of the normal mode. The endoscope processor according to claim 7 .

9. The dark place mode is a mode in which the shutter speed of the electronic shutter is slower than that of the normal mode. The endoscope processor according to claim 7 .

10. When the contact determination unit determines that there is no contact, the generation unit uses the first index for the photometric signal; When the contact determination unit determines that contact has occurred, the generation unit generates the photometric signal that is greater than the first index. The endoscope processor according to claim 4 .

11. When the contact determination unit determines that no contact has occurred, the light control unit outputs a light control signal for irradiating illumination light having a predetermined first component ratio; When the contact determination unit determines that contact has occurred, the light adjustment unit outputs a light adjustment signal to irradiate illumination light having a second component ratio in which the proportion of short wavelength components is lower than that of the first component ratio.

11. The endoscope processor according to claim 4.

12. Acquires an image signal from the image sensor, obtaining a first index related to blue luminance and a second index related to green luminance based on the imaging signal; generating a photometric signal based on the first index and the second index; outputting a light control signal based on the photometric signal; A light source that illuminates the observation field is controlled based on the light modulation signal. A method for controlling an endoscope processor in which a control unit of the endoscope processor executes processing.

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