Endoscope control processing device, endoscope system, and method for operating endoscope control processing device

Abstract

An endoscope control processing device (3) acquires an image signal in units of frames from an endoscope (2) having an imaging element (11). The imaging element (11) has an electronic shutter function for controlling the exposure time. A processor (30a) provided in an endoscope control processing device (3) performs dimming detection on an image signal, calculates a target exposure time value, calculates an electronic shutter control value on the basis of the target value, calculates an actual exposure time value on the basis of the electronic shutter control value, and calculates an exposure time ratio between the actual value and the target value. An image signal of a new frame captured on the basis of the electronic shutter control value is acquired from the endoscope (2), and the gain of the image signal of the new frame is adjusted on the basis of the exposure time ratio.

Description

Technical Field

[0001] The present invention relates to an endoscope control processing device, an endoscope system, and a working method of the endoscope control processing device that acquire an image signal from an imaging element having an electronic shutter function and process the image signal. Background Art

[0002] Conventionally, an aperture, an electronic shutter, gain, etc. have been used for dimming control. The aperture changes the brightness of the optical image to perform dimming control. The electronic shutter changes the exposure time, that is, the charge accumulation time, to perform dimming control. Gain performs dimming control by amplifying the image signal.

[0003] For example, Japanese Unexamined Patent Application Publication No. 2018-14680 describes a technique for achieving a large dimming dynamic range in a digital still camera. In the technique of this publication, the following dimming control is performed during the period when the subject changes from a dark state to a bright state.

[0004] In the case where the subject is darkest, the aperture is opened, the gain is maximized, and on top of that, the degree to which the electronic shutter is slower than the frame rate is controlled. In the case where the subject is slightly dark, the aperture is opened, the electronic shutter is set to the frame rate, and on top of that, the gain is controlled between the maximum and 0. In the case where the subject is slightly bright, the electronic shutter is set to the frame rate, the gain is set to 0, and on top of that, the aperture is controlled. In the case where the subject is bright, the gain is set to 0, the aperture is minimized as much as possible, and on top of that, the degree to which the electronic shutter is faster than the frame rate is controlled.

[0005] In this way, in the above publication, as the subject changes from a dark state to a bright state, dimming control is performed in the order of "electronic shutter control" → "gain control" → "aperture control" → "electronic shutter control". That is, it becomes the following technique: when performing dimming control using only any one of the electronic shutter, gain, and aperture, which one of the electronic shutter, gain, and aperture to use is changed according to the brightness of the subject. Therefore, the case of performing control using two or more at the same time is not described in the above publication.

[0006] In addition, in the exposure control based on the electronic shutter, generally, the exposure time is discrete. The light-shielding state of the electronic shutter is realized, for example, by eliminating useless charges of pixels. The exposure time is the time from when the elimination stops and the charge starts to accumulate until the charge of the pixel is read out. In an imaging element in which pixels are arranged in rows, exposure control based on the electronic shutter is performed by setting which row is in the exposure state and which of the remaining rows is in the light-shielding state at a certain time.

[0007] That is, in exposure control based on an electronic shutter, the exposure time is quantized in units of one row or the like, and thus quantization error occurs with respect to the target brightness. The shorter the exposure time, the larger the proportion of the quantization error in the image signal. That is, the influence of the quantization error becomes larger in the case where the number of exposed rows (the number of rows in the exposure state) is small compared to the case where the number of exposed rows is large. The state where the number of exposed rows is the minimum (the state where the number of blocked rows is the maximum) is called aperture closing.

[0008] In an endoscope system, a subject with a large dimming dynamic range from the dark part deep in the lumen to the mucosa at the closest distance is the observation target. In particular, when observing a moving image of the surface layer of the mucosa at the closest distance (that is, in a state where the subject is bright), the electronic shutter is sometimes controlled near aperture closing. In addition, when, for example, a laser is irradiated onto a lesion part, the amount of light in the field of view sometimes increases sharply. In this case, in order to suppress the generation of halation in the image, the electronic shutter is sometimes controlled near aperture closing. However, since the dimming accuracy deteriorates as described above near aperture closing, the brightness of the moving image fluctuates frame by frame and flickers, which hinders image observation.

[0009] On the other hand, there is the following method: by increasing the number of exposed rows corresponding to the aperture closing of the electronic shutter, the upper limit of the proportion of the quantization error in the image signal is reduced, thereby suppressing flicker. For example, if the number of exposed rows corresponding to the aperture closing of the electronic shutter is set to 20 rows, even if a quantization error of one row occurs, the fluctuation of the brightness per frame can be suppressed to 5% or less. However, if this method is used, the dimming dynamic range becomes narrow.

[0010] The present invention has been made in view of the above circumstances, and an object thereof is to provide an endoscope control processing apparatus, an endoscope system, and a working method of the endoscope control processing apparatus that can ensure a large dimming dynamic range and suppress flicker of an image near the aperture closing of an electronic shutter. Summary of the Invention

[0011] Means for Solving the Problem

[0012] An endoscopic control processing device according to one embodiment of the present invention acquires an image signal from an endoscope having an imaging element in units of frames and processes the image signal. The imaging element has an electronic shutter function for controlling the exposure time. The endoscopic control processing device includes a processor configured to perform dimming detection on the image signal acquired in the first frame, calculate a target exposure time value for a second frame that is later in time than the first frame, calculate an electronic shutter control value for the second frame based on the target exposure time value, calculate an actual exposure time based on the electronic shutter control value, calculate an exposure time ratio of the actual exposure time to the target exposure time value, cause the imaging element to perform imaging based on the electronic shutter control value to acquire the image signal of the second frame from the endoscope, and adjust the gain based on the exposure time ratio in the image processing performed on the image signal of the second frame.

[0013] An endoscopic system according to one embodiment of the present invention includes: an endoscope having an imaging element with an electronic shutter function for controlling the exposure time; and an endoscopic control processing device having a processor that acquires an image signal from the endoscope in units of frames and processes the image signal. The processor is configured to perform dimming detection on the image signal acquired in the first frame, calculate a target exposure time value for a second frame that is later in time than the first frame, calculate an electronic shutter control value for the second frame based on the target exposure time value, calculate an actual exposure time based on the electronic shutter control value, calculate an exposure time ratio of the actual exposure time to the target exposure time value, cause the imaging element to perform imaging based on the electronic shutter control value to acquire the image signal of the second frame from the endoscope, and adjust the gain based on the exposure time ratio in the image processing performed on the image signal of the second frame.

[0014] A method for operating an endoscope control processing apparatus according to an aspect of the present invention is a method for operating an endoscope control processing apparatus that acquires an image signal from an endoscope having an imaging element on a frame-by-frame basis and processes the image signal. The imaging element has an electronic shutter function for controlling an exposure time. In the method for operating the endoscope control processing apparatus, a dimming detection is performed on the image signal acquired in a first frame, and a target value of an exposure time for a second frame that is temporally later than the first frame is calculated. An electronic shutter control value for the second frame is calculated based on the target value of the exposure time, an actual exposure time is calculated based on the electronic shutter control value, an exposure time ratio between the actual exposure time and the target value of the exposure time is calculated, and the imaging element is caused to perform imaging based on the electronic shutter control value to acquire the image signal of the second frame from the endoscope. In the image processing performed on the image signal of the second frame, the gain is adjusted based on the exposure time ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 FIG. 6 is a view showing the appearance of an endoscope system according to a first embodiment of the present invention.

[0016] Figure 2 FIG. 10 is a block diagram showing the electrical configuration of the endoscope system according to the first embodiment described above.

[0017] Figure 3 FIG. 14 is a block diagram showing an example of the configuration of an endoscope control processing apparatus according to the first embodiment described above.

[0018] Figure 4 FIG. 18 is a timing chart showing the operation of the endoscope system when capturing a moving image according to the first embodiment described above.

[0019] Figure 5 FIG. 22 is a flowchart showing the operation of the endoscope control processing apparatus when capturing a moving image according to the first embodiment described above.

[0020] Figure 6 FIG. 26 is a flowchart showing the process of electronic shutter control performed by the endoscope control processing apparatus according to the first embodiment described above.

[0021] Figure 7 FIG. 30 is a view showing an example of a table stored in a memory and representing the correspondence between the automatic dimming brightness level and the dimming detection target value according to the first embodiment described above.

[0022] Figure 8 FIG. 34 is a graph showing the relationship between the exposure time and the electronic shutter control value according to the first embodiment described above.

[0023] Figure 9It is a graph showing the relationship between the exposure time and the electronic shutter control value in the above-described first embodiment.

[0024] Figure 10 It is a flowchart showing the process of flicker correction in step S3 of the above-described first embodiment. Figure 5 of.

[0025] Figure 11 It is a flowchart showing the process of calculating the exposure time ratio in step S22 of the above-described first embodiment. Figure 10 of.

[0026] Figure 12 It is a graph showing the relationship between the brightness control value and the electronic shutter control value in the above-described first embodiment.

[0027] Figure 13 It is a graph showing the magnification near the maximum value of the brightness control value and the exposure time in the above-described first embodiment. Figure 12 of.

[0028] Figure 14 It is a graph showing the magnification near the minimum value of the brightness control value and the exposure time in the above-described first embodiment. Figure 12 of.

[0029] Figure 15 It is a graph showing the ratio of the change amount of the exposure time to the exposure time when the electronic shutter control value changes by one row in the above-described first embodiment.

[0030] Figure 16 It is a graph showing the case where the discretely changing exposure time is substantially corrected using gain and magnifying the vicinity of the minimum value of the brightness control value in the above-described first embodiment.

[0031] Figure 17 It is a block diagram showing the electrical configuration of the endoscope system in the second embodiment of the present invention.

[0032] Figure 18 It is a flowchart showing the process of flicker correction in step S3 of the above-described second embodiment. Figure 5 of.

[0033] Figure 19 It is a diagram showing a structural example of an endoscope control processing device that also serves as a light source device in Related Art 1.

[0034] Figure 20 It is a block diagram showing a structural example of a control circuit, a light source drive circuit, and a light source in Related Art 1.

[0035] Figure 21It is a diagram showing an example of a light emission mode of an endoscope control processing device that also serves as a light source device in Related Art 1.

[0036] Figure 22 It is a diagram showing a more detailed structural example of a light source drive circuit and a light source in Related Art 1.

[0037] Figure 23 It is a diagram showing an example where the drive current detected by the current detection circuit in each light emission mode is within the normal range and an example where the drive current is within the abnormal range in Related Art 1.

[0038] Figure 24 It is a timing chart showing an example of the timing at which the current detection circuit performs current detection in Related Art 1.

[0039] Figure 25 It is a diagram showing an example of applying one current detection circuit in a structure where a plurality of light emitting element drivers respectively drive a plurality of light emitting elements in Related Art 1.

[0040] Figure 26 It is a diagram showing an example of applying one current detection circuit in a structure where one light emitting element driver drives a plurality of light emitting elements in Related Art 1.

[0041] Figure 27 It is a diagram showing an example of applying one current detection circuit in a structure where a plurality of light emitting element drivers drive one light emitting element in Related Art 1.

[0042] Figure 28 It is a diagram showing a structural example of an endoscope control processing device that also serves as a light source device in Related Art 2.

[0043] Figure 29 It is a diagram showing a first example of conversion parameters for converting a current control value I into a pulse brightness L in Related Art 2.

[0044] Figure 30 It is a diagram showing a second example of conversion parameters for converting a current control value I into a pulse brightness L in Related Art 2.

[0045] Figure 31 It is a timing chart for explaining uneven exposure between frames in the case where the imaging element is in the global shutter mode in Related Art 2.

[0046] Figure 32 It is a timing chart for explaining uneven exposure between rows in the case where the imaging element is in the rolling shutter mode in Related Art 2.

[0047] Figure 33This is a diagram showing a structural example of an endoscope control processing device that also serves as a light source device in Related Art 3.

[0048] Figure 34 This is a diagram showing an example of a functional equation for calculating a color correction value based on a dimming control value in Related Art 3.

[0049] Figure 35 This is a diagram showing a structural example of an endoscope processor that supplies power for a sound input circuit through an insulator element in Related Art 4.

[0050] Figure 36 This is a diagram for explaining the situation in Related Art 4 where, when the input sound pressure to the microphone is below the threshold value, an amplification row with a large gain is used, and when the input sound pressure to the microphone is greater than the threshold value, an amplification row with a small gain is used.

[0051] Figure 37 This is a diagram showing a structural example of an endoscope processor having a plurality of magnification mechanisms with different magnifications in Related Art 4. Detailed Embodiments

[0052] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited by the embodiments described below.

[0053] In addition, in the description of the drawings, the same or corresponding elements are appropriately labeled with the same reference numerals. Additionally, it should be noted that the drawings are schematic, and for the sake of simplicity of explanation, the relationship between the lengths of the elements within one drawing, the ratio of the lengths of the elements, the number of the elements, etc. may sometimes be different from the actual situation. Also, there may be parts where the relationship and ratio of the lengths between multiple drawings are different from each other.

[0054] [First Embodiment]

[0055] Figures 1 to 16 This is a diagram showing the first embodiment of the present invention. Figure 1 This is a diagram showing the appearance of the endoscope system 1.

[0056] The endoscope system 1 includes an endoscope 2, an endoscope control processing device 3, and a monitor 4.

[0057] The endoscope 2 includes an insertion portion 5, an operation portion 6, and a general cable 7.

[0058] The insertion portion 5 is an elongated portion inserted into the body of the subject. In addition, as an example, the subject into which the insertion portion 5 is inserted is assumed to be a human body, but it is not limited to a human body and may also be a living organism such as an animal, or a non-living object such as a machine or a building.

[0059] ​The insertion section 5 includes, in order from the front end side toward the base end side, a front end component section 5a, a bending section 5b, and a flexible tube section 5c.

[0060] The endoscope 2 is configured as an electronic endoscope, and an imaging system is provided in the front end component section 5a. The imaging system includes: an objective lens 14 (refer to Figure 19 ), which forms an optical image of the subject; and an imaging element 11 (refer to Figure 2 etc.), which performs photoelectric conversion on the optical image formed by the objective lens 14 and outputs an electrical signal. The imaging element 11 generates an image signal in units of frames and transmits the image signal to the endoscope control processing device 3.

[0061] In addition, the imaging element 11 is not limited to being provided in the front end component section 5a of the insertion section 5. For example, the following structure may also be adopted: a relay optical system is provided in the insertion section 5 and the operation section 6, and a camera is mounted on the operation section 6. In this structure, the optical image formed by the objective lens 14 is transmitted through the relay optical system, and the imaging element 11 in the camera is used for imaging.

[0062] The bending section 5b is, for example, a portion that can bend in two directions, up and down, or in four directions, up, down, left, and right. The bending section 5b is disposed on the base end side of the front end component section 5a. When the bending section 5b bends, the direction of the front end component section 5a changes, and the irradiation direction of the illumination light and the observation direction of the imaging system change. In addition, the bending section 5b also bends to improve the insertability of the insertion section 5 into the subject.

[0063] The flexible tube section 5c is a flexible tube section. The flexible tube section 5c is disposed on the base end side of the bending section 5b. In addition, an example is given here where the endoscope 2 is a flexible endoscope having a flexible tube section 5c. However, the endoscope 2 may also be a rigid endoscope in which the portion corresponding to the flexible tube section 5c is in a rigid form. In addition, the endoscope 2 may also be any one of an endoscope that is disposable as a whole, an endoscope that can be reused after pretreatment as a whole, and an endoscope that is disposable in part.

[0064] The operation section 6 is disposed on the base end side of the insertion section 5. The operation section 6 has a grip section 6a, a bending operation knob 6b, operation buttons 6c, and an access port 6d for treatment instruments.

[0065] The grip section 6a is the portion where the user grips the endoscope 2 with the palm of the hand.

[0066] The bending operation knob 6b is an operating device for operating to bend the bending section 5b. For example, the thumb of the hand holding the grip section 6a is used to operate the bending operation knob 6b. The bending operation knob 6b is connected to the bending section 5b by a bending wire. When the bending operation knob 6b is operated, the bending wire is pulled, and the bending section 5b bends.

[0067] The operation buttons 6c include multiple buttons for operating the endoscope 2. Several examples of the operation buttons 6c are the air / water supply button, the suction button, the buttons associated with imaging, and the like.

[0068] The treatment instrument insertion port 6d is an opening provided at the proximal end side of the treatment instrument channel that is disposed inside from the insertion section 5 to the operation section 6. When a treatment instrument is inserted through the treatment instrument insertion port 6d, the front end of the treatment instrument protrudes from the opening at the front end side of the treatment instrument channel provided in the front end forming section 5a. In this state, various treatments are performed on the subject using the treatment instrument.

[0069] The general cable 7 extends from, for example, the side surface on the proximal end side of the operation section 6 and is connected to the endoscope control processing device 3.

[0070] The endoscope control processing device 3 receives an image signal from the imaging element 11 in units of frames. The endoscope control processing device 3 performs image processing on the acquired image signal and outputs the processed image signal to the monitor 4. In addition, the endoscope control processing device 3 controls the endoscope 2. That is to say, the endoscope control processing device 3 functions as both an endoscope image processing device that processes the image signal acquired by the endoscope 2 and an endoscope control device that controls the endoscope 2.

[0071] The monitor 4 is a display device that receives the image signal and displays the endoscope image. In addition, the monitor 4 does not need to be an inherent structure of the endoscope system 1, and a separate monitor 4 can also be connected to the endoscope control processing device 3.

[0072] Figure 2 It is a block diagram showing the electrical structure of the endoscope system 1.

[0073] As described above, the endoscope 2 is equipped with the imaging element 11. The imaging element 11 is a two-dimensional imaging element in which a plurality of pixels are arranged two-dimensionally in the matrix direction. The arrangement in the row direction of the pixels is called a row. Examples of the imaging element 11 are a CCD (Charge Coupled Device) imager, a CMOS (Complementary Metal Oxide Semiconductor) imager, and the like.

[0074] The imaging element 11 photoelectrically converts the optical image of the subject to generate an image signal and outputs the image signal. The imaging element 11 has an electronic shutter function for electronically controlling the exposure time. The imaging element 11 achieves a state of not accumulating charge, a so-called light-shielded state, by discharging (eliminating) the charge of the pixels. The electronic shutter starts accumulating charge by stopping the discharge of the charge of the pixels. The time from the start of accumulating charge to the reading out of the accumulated charge is the exposure time. In the electronic shutter function, for example, the discharge of the charge of the pixels for achieving the light-shielded state is performed in units of rows.

[0075] The exposure period within one frame is set to the longest period that can be used for exposure within the frame period. Then, the exposure period and the readout period are separated. In the case of the imaging element 11 where exposure cannot be performed during the readout period, the period obtained by removing the readout period and the like from the frame period is the exposure period.

[0076] The time obtained by dividing the exposure period within one frame by the total number of rows provided in the imaging element 11 is called a specific time. The electronic shutter function of the imaging element 11 can control the exposure time in units of the specific time and as an integer multiple of the specific time. Therefore, the electronic shutter function discretely controls the exposure time.

[0077] Specifically, let the exposure period within one frame be Tep, and let the total number of rows provided in the imaging element 11 be N. Then, the specific time, which is the unit for the imaging element 11 to control the exposure time, is (Tep / N). In addition, the exposure period Tep is defined according to the specifications of the imaging element 11. <{

[0078] The endoscope control processing device 3 includes a first image processing circuit 21, a flicker correction circuit 22, a second image processing circuit 23, a dimming detection operation circuit 24, an electronic shutter control value calculation circuit 25, an exposure time ratio calculation circuit

[0079] Figure 3 It is a block diagram showing a structural example of the endoscope control processing device 3.

[0080] Figure 2 Each circuit of the endoscope control processing device 3 shown can also be constituted by an electronic circuit. Additionally, Figure 2 All or part of each circuit of the endoscope control processing device 3 shown can also be constituted by, for example, Figure 3It consists of a processor 30a and a memory 30b as shown. The processor 30a is composed of an ASIC (Application Specific Integrated Circuit) including a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), etc. The memory 30b stores a processing program for realizing the functions of each circuit. The processor 30a realizes the functions of each circuit in the endoscope control processing device 3 by reading and executing the processing program stored in the memory 30b.

[0081] The first image processing circuit 21 receives the image signal output from the imaging element 11 and performs first image processing. The first image processing is, for example, magnification processing, demosaicing processing, noise removal processing, etc.

[0082] The flicker correction circuit 22 performs the following image processing: amplifying the image signal output from the first image processing circuit 21 by using the flicker correction gain received from the flicker correction gain calculation circuit 27 to correct the flicker of the frame image.

[0083] The second image processing circuit 23 performs second image processing on the image signal output from the flicker correction circuit 22. The second image processing is, for example, shading correction processing, white balance processing, contrast correction processing, gamma transformation processing, format conversion processing, etc. In addition, the second image processing circuit 23 can also superimpose various information such as text information and guiding information on the image signal. The second image processing circuit 23 outputs the image signal converted into a format matching the monitor 4 to the monitor 4.

[0084] In addition, several examples of the first image processing and several examples of the second image processing are shown above, but the processing included in the first image processing and the second image processing is not limited to these. Also, which processing is included in the first image processing performed before the flicker correction circuit 22 and which other processing is included in the second image processing performed after the flicker correction circuit 22 are not limited to the above examples.

[0085] The dimming detection operation circuit 24 performs dimming detection on the image signal output from the first image processing circuit 21 to obtain a dimming detection value.

[0086] The dimming detection operation circuit 24 calculates the target exposure time value of the second frame that is later in time than the first frame based on the dimming detection value of the image signal obtained in the first frame. In addition, in the following Figure 4Specifically, in this case, the first frame is set as frame n, and the second frame is set as frame (n + 2) for explanation. The target exposure time value of the second frame is calculated in such a way that the dimming detection value of the image signal obtained in the second frame becomes the dimming detection target value. Here, as will be described later, the user can set the automatic dimming brightness level that provides the dimming detection target value from the user interface 29.

[0087] The electronic shutter control value calculation circuit 25 receives the target exposure time value from the dimming detection operation circuit 24 and calculates the electronic shutter control value to be applied in the second frame. The target exposure time value is calculated as an arbitrary non-discrete value. In contrast, the electronic shutter control value is calculated as a value representing a discrete exposure time (e.g., an integer multiple of a specific time as described above).

[0088] The exposure time ratio calculation circuit 26 obtains the target exposure time value and the electronic shutter control value from the electronic shutter control value calculation circuit 25. The exposure time ratio calculation circuit 26 calculates the ratio of the electronic shutter control value to the target exposure time value as the exposure time ratio. In addition, in Figure 2 the exposure time ratio calculation circuit 26 obtains the target exposure time value from the electronic shutter control value calculation circuit 25, but the present invention is not limited thereto. The exposure time ratio calculation circuit 26 may also receive the target exposure time value from the dimming detection operation circuit 24.

[0089] The flicker correction gain calculation circuit 27 obtains the exposure time ratio from the exposure time ratio calculation circuit 26, calculates the reciprocal of the exposure time ratio as the flicker correction gain, and sends the flicker correction gain to the flicker correction circuit 22.

[0090] In addition, in the above, the exposure time ratio is calculated as the ratio of the electronic shutter control value to the target exposure time value, but it is not limited thereto, and it may also be calculated as the ratio of the target exposure time value to the electronic shutter control value. In this case, the flicker correction gain calculation circuit 27 may simply send the exposure time ratio as the flicker correction gain to the flicker correction circuit 22. Additionally, in this case, the exposure time ratio calculation circuit 26 can also serve as the flicker correction gain calculation circuit 27, which can simplify the structure.

[0091] The electronic shutter control value sending circuit 28 receives the electronic shutter control value from the electronic shutter control value calculation circuit 25 and sends the electronic shutter control value to the imaging element 11. In addition, the endoscope control processing device 3 sends an operation clock and power to the imaging element 11. The imaging element 11 performs shooting with the electronic shutter control value so that the subject is exposed, thereby generating an image signal. As described above, the imaging of the moving image by the imaging element 11 is performed sequentially in units of frames. Thus, the frame-based image signals related to the moving image are sequentially output from the endoscope 2 to the endoscope control processing device 3.

[0092] The user interface 29 is an interface for making various settings for the endoscope system 1 through user operations. For example, the on / off of the exposure time control based on the electronic shutter is set through the user interface 29. In the present embodiment, the description is made on the premise that the exposure time control based on the electronic shutter is set to on. In addition, the user can set the automatic dimming brightness level through the user interface 29.

[0093] The monitor 4 receives the image signal output from the second image processing circuit 23 and displays the endoscope image.

[0094] Figure 4 is a timing chart showing the operation of the endoscope system 1 when shooting a moving image. In Figure 4 it, the frame numbers are shown in (A), the shooting operations are shown in (B), the image processing operations are shown in (C), the operation of calculating the electronic shutter control value is shown in (D), the operation of calculating the flicker correction gain is shown in (E), the operation of applying the electronic shutter control value is shown in (F), and the operation of applying the flicker correction gain is shown in (G).

[0095] As Figure 4 shown in (A) of, the time t(n) to t(n + 1) is the period of frame n, the time t(n + 1) to t(n + 2) is the period of frame (n + 1), the time t(n + 2) to t(n + 3) is the period of frame (n + 2), and the time t(n + 3) to t(n + 4) is the period of frame (n + 3).

[0096] As Figure 4 shown in (B) of, in each frame, exposure is performed in the first half of the frame period, and the image signal is read out in the second half of the frame period.

[0097] In frame n, the imaging element 11 performs the exposure of the image of frame n and the readout of the image signal. Next, a series of processes performed by the endoscope control processing device 3 based on the image signal acquired in frame n will be described. In Figure 4 it, the corresponding blocks are shaded and the blocks are connected with arrows.

[0098] In frame (n + 1), the first image processing circuit 21 and the second image processing circuit 23 perform image processing (C) on the image signal of frame n. In addition, the dimming detection operation circuit 24 and the electronic shutter control value calculation circuit 25 perform the calculation (D) of the electronic shutter control value for shooting frame (n + 2). Further, the exposure time ratio calculation circuit 26 and the flicker correction gain calculation circuit 27 perform the calculation (E) of the flicker correction gain for the image acquired in frame (n + 2).

[0099] At frame (n + 2), the electronic shutter control value transmission circuit 28 transmits an electronic shutter control value (F) to the imaging element 11. The transmitted value is the electronic shutter control value for frame (n + 2) to be applied to the imaging element 11. The imaging element 11 exposes the image of frame (n + 2) with the received electronic shutter control value and reads out the generated image signal (B).

[0100] At frame (n + 3), the first image processing circuit 21 processes the image signal obtained at frame (n + 2) (C). The flicker correction circuit 22 applies a flicker correction gain for frame (n + 2) to the processed image signal to correct the flicker of the image (G). The second image processing circuit 23 further processes the image signal with corrected flicker (C).

[0101] Figure 5 It is a flowchart showing the operation of the endoscope control processing device 3 when shooting a moving image.

[0102] When starting to shoot a moving image, the endoscope control processing device 3 waits to receive an image signal from the imaging element 11 of the endoscope 2 in units of frames (step S1).

[0103] If an image signal is received, the first image processing circuit 21 performs first image processing on the image signal (step S2).

[0104] The flicker correction circuit 22 performs flicker correction on the image signal output from the first image processing circuit 21 (step S3).

[0105] The second image processing circuit 23 performs second image processing on the image signal output from the flicker correction circuit 22 (step S4).

[0106] The second image processing circuit 23 outputs the processed image signal to the monitor 4 (step S5).

[0107] The endoscope control processing device 3 determines whether there is an end instruction for shooting a moving image from the user (step S6). If there is no end instruction, it returns to step S1 and waits to receive the image signal of the next frame. If there is an end instruction, the shooting process ends.

[0108] Figure 6 It is a flowchart showing the process of electronic shutter control performed by the endoscope control processing device 3. Figure 6 The process of, for example, performing image processing for display on the monitor 4 Figure 5 is performed in parallel with the process of.

[0109] When executed from the main process (not shown) Figure 6When processing, the dimming detection operation circuit 24 waits to receive the image signal that has been subjected to flicker correction from the flicker correction circuit 22 (step S11).

[0110] If the image signal is received, the dimming detection operation circuit 24 performs dimming detection based on the image signal and calculates the target value of the exposure time (step S12).

[0111] Figure 7 It is a diagram showing an example of a table stored in the memory 30b representing the correspondence between the automatic dimming brightness level and the dimming detection target value.

[0112] According to how much brighter (level = +1, +2, +3,...) or darker (level = -1, -2, -3,...) the brightness of the image is than the standard brightness (level = 0), etc., the automatic dimming brightness level set by the user from the user interface 29 is set. The correspondence between the automatic dimming brightness level and the dimming detection target value is stored in the memory 30b in advance in the form of a table, graph, function, etc., for example.

[0113] Here, the correspondence between the automatic dimming brightness level and the dimming detection target value varies depending on whether the endoscope 2 connected to the endoscope control processing device 3 is a flexible endoscope or the type using a camera, etc. Therefore, the correspondence for each model of the endoscope 2 is stored in the memory 30b. In Figure 7 An example of the correspondence in the case where the endoscope 2 is a flexible endoscope is shown.

[0114] The dimming detection operation circuit 24 refers to the memory 30b and determines the dimming detection target value based on the automatic dimming brightness level set through the user interface 29. In addition, when the automatic dimming brightness level is not set from the user interface 29, the dimming detection target value is automatically set to the value corresponding to the standard brightness (level = 0).

[0115] Furthermore, the dimming detection operation circuit 24 extracts, for example, the luminance signal from the image signal received from the flicker correction circuit 22 and calculates the average value (or weighted average, peak of the luminance histogram, median, etc.) of the luminance signal values within the dimming area set for the whole image or a part of the image as the dimming detection value.

[0116] The dimming detection operation circuit 24 calculates the first detection ratio, for example, by dividing the dimming detection value by the dimming detection target value, and calculates the exposure time target value by dividing the exposure time target value within the first frame ( Figure 4 such as frame n in) by the first detection ratio. The exposure time target value is expressed in seconds (Sec), for example.

[0117] If numerical examples are given, assume that the target value of the exposure time in the first frame is 0.001 (Sec) and the first detection ratio is 0.5. Then, the target value of the exposure time is calculated as 0.001 / 0.5 = 0.002 (Sec).

[0118] In addition, the dimming detection operation circuit 24 can also calculate the second detection ratio by dividing the dimming detection target value by the dimming detection value instead of the first detection ratio. In this case, the dimming detection operation circuit 24 can calculate the target value of the exposure time by multiplying the target value of the exposure time in the first frame by the second detection ratio.

[0119] The electronic shutter control value calculation circuit 25 receives the target value of the exposure time from the dimming detection operation circuit 24 and calculates the electronic shutter control value (step S13). As described below, the relationship between the electronic shutter control value and the exposure time is determined in advance according to the specifications of the imaging element 11.

[0120] Figure 8 is a graph showing the relationship between the exposure time and the electronic shutter control value. Figure 9 is a graph showing the relationship between the exposure time and the electronic shutter control value.

[0121] In addition, in this embodiment including Figure 8 and Figure 9 a numerical example will be described while showing that the total number of lines N of the imaging element 11 is 1120 and the frame rate is 60 (fps). However, of course, it is not limited to this numerical example.

[0122] As described above, the exposure time is controlled in integer multiples of a specific time (Tep / N). Therefore, when n is a positive integer less than or equal to N, the exposure time is represented by n × (Tep / N).

[0123] Let the maximum value of the exposure time be Tmax. The maximum value Tmax of the exposure time is the value when n = N, and is Tmax = N × (Tep / N) = Tep. That is, when all lines are in the exposure state and the exposure time coincides with the exposure period Tep, it is the maximum value Tmax of the exposure time.

[0124] In addition, let the minimum value of the exposure time be Tmin. The minimum value Tmin of the exposure time is not necessarily the time (Tep / N) corresponding to n = 1. According to the specifications of the imaging element 11, it is set to an integer value of 1 or more such as n = 4, for example. If the minimum value of n that can be taken according to the specifications of the imaging element 11 is set to n(min), then the minimum value Tmin of the exposure time is Tmin = n(min) × (Tep / N). The minimum value Tmin of the exposure time corresponds to the aperture closing of the electronic shutter (the state where the number of exposed lines is the minimum: the state where the number of light-shielded lines is the maximum).

[0125] Therefore, the exposure time n×(Tep / N) is controlled within the range of n = n(min), {n(min)+1}, …, (N-1), N.

[0126] The endoscope control processing device 3 uses ES = (N-n) as the electronic shutter control value ES for the imaging element 11. This electronic shutter control value ES is a value indicating which row among all the rows N has become the light-shielded state. Therefore, as Figure 8 and Figure 9 shown, the shorter the exposure time, the greater the increase in the electronic shutter control value (the number of light-shielded rows). However, it is not limited thereto, and it may also be configured to represent the electronic shutter control value using the number of rows in the exposed state.

[0127] Let the exposure time target value received by the electronic shutter control value calculation circuit 25 from the dimming detection operation circuit 24 be Tgt. In addition, let the minimum value of the electronic shutter control value ES be ESmin, and the maximum value of the electronic shutter control value ES be ESmax.

[0128] The minimum value ESmin of the electronic shutter control value ES corresponds to the maximum value Tmax of the above exposure time, and ESmin = 0.

[0129] The maximum value ESmax of the electronic shutter control value ES corresponds to the minimum value Tmin of the above exposure time, and ESmax = {N-n(min)}.

[0130] As described above, the exposure time of each row in the imaging element 11 is controlled in integer multiples of a specific time (Tep / N). Therefore, the electronic shutter control value calculation circuit 25 obtains the electronic shutter control value ES that can achieve the "exposure time closest to the exposure time target value Tgt" as follows.

[0131] That is, the electronic shutter control value calculation circuit 25 uses the ceiling function ceil(x) and calculates the electronic shutter control value ES according to the exposure time target value Tgt using the following formula 1. Here, as is well known, the ceiling function ceil(x) is a function that gives the smallest integer greater than or equal to the real number x (that is, a function that rounds up the decimal part).

[0132] ES = ceil(ESmax-α×{Tgt-Tmin})…(Formula 1)

[0133] Here, -α represents Figure 8 the slope of the graph shown, and α is given by the following formula 2.

[0134] α = (ESmax-ESmin) / (Tmax-Tmin)…(Formula 2)

[0135] In addition, here, the ceiling function ceil(x) is used to round up the decimal part. Instead, the floor function floor(x) can also be used to discard the decimal part.

[0136] Among them, as described above, Tmax = Tep and ESmin = 0. Therefore, Equation 2 is expressed by the following Equation 2'.

[0137] α = ESmax / (Tep - Tmin) … (Equation 2')

[0138] In addition, in the case where n(min) = 4 in the above example, the maximum value ESmax of the electronic shutter control value ES is (N - 4), and the minimum value Tmin of the exposure time is 4 × (Tep / N).

[0139] In this way, if Tmin, ESmax, Tep determined according to the specifications of the imaging element 11 and α determined based on them are used, the electronic shutter control value ES is calculated according to the exposure time target value Tgt by Equation 1.

[0140] In addition, if the electronic shutter control value ES representing the number of rows set to the light-shielded state is subtracted from all the number of rows N, the number of rows n in the exposure state is obtained, and n = (N - ES).

[0141] As in the above numerical example, when the exposure time target value Tgt calculated by the dimming detection operation circuit 24 is 0.002 (Sec), as the electronic shutter control value ES that does not exceed 0.002 (Sec) but can achieve the exposure time closest to 0.002 (Sec), 986 (rows) is calculated (refer to Figure 9 the arrow column).

[0142] Therefore, the electronic shutter control value calculation circuit 25 can also use Figure 9 the table shown to obtain the electronic shutter control value ES instead of Equation 1. The Figure 9 table shown or Figure 8 the mathematical expressions of the chart shown can also be stored in the memory 30b in advance and read out by the electronic shutter control value calculation circuit 25.

[0143] The electronic shutter control value transmission circuit 28 receives the electronic shutter control value ES from the electronic shutter control value calculation circuit 25 and transmits the electronic shutter control value ES to the imaging element 11 (step S14). Thereby, the imaging element 11 performs electronic shutter control based on the electronic shutter control value ES in the next frame ( Figure 4 for example, frame (n + 2) in).

[0144] If the process of step S14 is performed, the process returns to the main process (not shown).

[0145] Figure 10 is a flowchart showing Figure 5 the process of flicker correction in step S3.

[0146] When the endoscopic control processing device 3 enters the flicker correction process in Figure 5 step S3, it executes the Figure 10 shown process. Then, the exposure time ratio calculation circuit 26 waits to receive the exposure time target value Tgt and the electronic shutter control value ES from the electronic shutter control value calculation circuit 25 (step S21).

[0147] If the exposure time ratio calculation circuit 26 receives the exposure time target value Tgt and the electronic shutter control value ES, it calculates the exposure time ratio er (step S22).

[0148] Figure 11 is a flowchart showing Figure 10 the process of calculating the exposure time ratio in step S22.

[0149] The exposure time ratio calculation circuit 26 calculates the actual exposure time Texp according to the electronic shutter control value ES and the above-mentioned α by the following formula 3 (step S31).

[0150] Texp = -ES / α + Tmax…(Formula 3)

[0151] As described above, since Tmax = Tep, formula 3 is expressed by the following formula 3'.

[0152] Texp = -ES / α + Tep…(Formula 3')

[0153] In addition, the exposure time ratio calculation circuit 26 is not limited to obtaining the actual exposure time Texp by using a mathematical formula, and can also refer to Figure 9 the graph (or Figure 8 the graph) to obtain the actual exposure time Texp.

[0154] As in the above numerical example, when the electronic shutter control value ES = 986 (lines), for example, referring to Figure 9 the arrow column, the actual exposure time Texp is 0.001990134 (Sec).

[0155] The exposure time ratio calculation circuit 26 calculates the exposure time ratio er according to the exposure time target value Tgt and the actual exposure time Texp by the following formula 4 (step S32).

[0156] r = Texp / Tgt…(Formula 4)

[0157] As in the numerical example described above, when the target exposure time Tgt is 0.002 (Sec) and the actual exposure time Texp is 0.001990134 (Sec), the exposure time ratio is er = 0.001990134 / 0.002 = 0.995067. Therefore, the actual exposure time Texp is short of the target exposure time Tgt by 0.4933%.

[0158] The exposure time ratio calculation circuit 26 sends the calculated exposure time ratio er to the flash correction gain calculation circuit 27 (step S33). If step S33 is executed, the process returns to Figure 10 the process of.

[0159] In Figure 10 the process of, the flash correction gain calculation circuit 27 calculates the reciprocal of the exposure time ratio er received from the exposure time ratio calculation circuit 26 as the flash correction gain Ga as shown in Equation 5 below (step S23).

[0160] Ga = 1 / er…(Equation 5)

[0161] As in the numerical example described above, when the exposure time ratio er is 0.995067, the flash correction gain Ga is Ga = 1 / 0.995067 = 1.004957.

[0162] The flash correction gain calculation circuit 27 sends the calculated flash correction gain Ga to the flash correction circuit 22.

[0163] Figure 12 is a graph showing the relationship between the luminance control value and the electronic shutter control value ES. The luminance control value is a value proportional to the exposure time for controlling the luminance of the image. In Figure 12 an example is shown in which the luminance control value is represented by a 16-bit (0 to 65535) value.

[0164] As described above, the electronic shutter control value ES is a value indicating which row within all the rows N (in the above example, N = 1120 rows) has become the light-shielded state. Therefore, the smaller the electronic shutter control value ES, the larger the luminance control value. When the electronic shutter control value ES is the minimum value ESmin = 0, the luminance control value takes the maximum value 65535.

[0165] In addition, as described above, according to the specifications of the imaging element 11, the minimum value n(min) of n is set to n(min) = 4, for example. In this case, for all the rows N = 1120, the maximum value ESmax of the electronic shutter control value ES is 1116. The luminance control value at this time is, for example, 118.

[0166] Figure 13 is a graph that magnifies the vicinity of the maximum value of the brightness control value in Figure 12 and shows it together with the exposure time. In Figure 13 (and Figure 14 , Figure 16 described later), the solid curve represents the electronic shutter control value ES, and the dash-dot curve represents the exposure time.

[0167] As described above, the control of the exposure time based on the electronic shutter is performed, for example, on a row-by-row basis. Therefore, the exposure time changes discretely (stepwise).

[0168] Figure 14 is a graph that magnifies the vicinity of the minimum value of the brightness control value in Figure 12 and shows it together with the exposure time.

[0169] The case where the exposure time changes discretely is the same as Figure 13 . However, the amount of change in the brightness of the image when the electronic shutter control value ES changes by 1 row is very different near the opening of the electronic shutter shown in Figure 13 and near the aperture closing of the electronic shutter shown in Figure 14 . Regarding this point, an explanation will be given with reference to Figure 15 .

[0170] Figure 15 is a graph showing the ratio of the change amount of the exposure time to the exposure time when the electronic shutter control value ES changes by 1 row. In Figure 15 , the portion surrounded by the double dash-dot line represents the vicinity of the aperture closing of the electronic shutter, and the portion surrounded by the dash-dot line represents the other portion.

[0171] Near the minimum value ESmin of the electronic shutter control value ES, for example, when the electronic shutter control value ES is 120 (rows), the number of exposed rows is 1000 (rows). When the electronic shutter control value ES is changed by +1 row (or -1 row), the number of exposed rows changes by -1 row (or +1 row) to become 999 (rows) (or 1001 (rows)). At this time, the absolute value of the change rate of the brightness is 1 / 1000 = 0.1 (%).

[0172] In contrast, near the maximum value ESmax of the electronic shutter control value ES, for example, when the electronic shutter control value ES is 1115 (rows), the number of exposed rows is 5 (rows). When the electronic shutter control value ES is changed by +1 (or -1) row, the number of exposed rows changes by -1 (or +1) row to become 4 (or 6) (rows). At this time, the absolute value of the change rate of the brightness is 1 / 5 = 20 (%).

[0173] Therefore, the variation in the brightness of the image between frames caused by the control of discrete exposure times is negligible except in the vicinity of the aperture closing of the electronic shutter. On the other hand, in the vicinity of the aperture closing of the electronic shutter, if the electronic shutter control value ES changes by only one row, the brightness of the image changes significantly, resulting in image flickering between different frames.

[0174] In Figure 15 Figure 5, the electronic shutter control value ESa indicated by the dashed line is an example of the electronic shutter control value ES used to distinguish whether the image flickering caused by the control of discrete exposure times is significant. The electronic shutter control value ESa is the value obtained by subtracting the amount of "100 / target dimming accuracy" rows from all the number of rows N. For example, when all the number of rows N = 1120 and the target dimming accuracy = 5%, the electronic shutter control value ESa = 1120 - 100 / 5 = 1100.

[0175] However, it goes without saying that the above values can be appropriately changed according to all the number of rows N, specifications, etc. of the imaging element 11.

[0176] Figure 16 Figure 6 is a graph showing the case where the discretely varying exposure time is substantially corrected by gain and magnifying the vicinity of the minimum value of the brightness control value. In Figure 16 Figure 6, the dashed curve represents the actual exposure time after flicker correction.

[0177] The flicker correction circuit 22 receives the flicker correction gain Ga from the flicker correction gain calculation circuit 27, amplifies the image signal received from the first image processing circuit 21 using the flicker correction gain Ga, and performs flicker correction (step S24).

[0178] In the case of the above numerical example, although the exposure time of the image signal before flicker correction is insufficient by 0.4933%, by amplifying the image signal using the flicker correction gain Ga = 1.004957, the insufficient part of the exposure time can be eliminated.

[0179] Through the image processing of flicker correction by the flicker correction circuit 22, Figure 16 the stepped exposure time change shown by the dash-dot line in Figure 7 becomes the smooth straight-line exposure time shown by the dashed line, and the image flickering between frames caused by the control of discrete exposure times is corrected.

[0180] According to such a first embodiment, the error in dimming control (quantization error of exposure time) caused by discretely controlling the exposure time using an electronic shutter is corrected by gain adjustment in image processing. Therefore, it is possible to suppress the flicker of the brightness of the image that occurs near the aperture closing of the electronic shutter, and it is easy to observe the image displayed on the monitor 4. Thus, the diagnosis and treatment by the doctor observing the monitor 4 are not hindered by the flicker of the image.

[0181] Moreover, the gain adjustment is performed using the exposure time ratio er calculated based on the exposure time target value Tgt and the actual exposure time Texp, so that the variation in brightness per frame can be suppressed with good accuracy.

[0182] Since it is possible to suppress the flicker of the image near the aperture closing of the electronic shutter, the electronic shutter control value ES corresponding to the aperture closing of the electronic shutter can be set to a value close to all the number of lines N. Thereby, a large dimming dynamic range can be ensured.

[0183] [Second Embodiment]

[0184] Figure 17 And Figure 18 FIGs. are diagrams showing a second embodiment of the present invention. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is appropriately omitted. In the second embodiment, the points different from the first embodiment are mainly described.

[0185] Figure 17 is a block diagram showing the electrical configuration of the endoscope system 1.

[0186] The endoscope control processing device 3 of the present embodiment Figure 2 adds a flicker correction on / off control circuit 31 to the structure of the first embodiment shown.

[0187] The flicker correction on / off control circuit 31 receives the electronic shutter control value ES from the electronic shutter control value calculation circuit 25, generates a control signal, and sends the control signal to the flicker correction circuit 22.

[0188] Figure 18 is a flowchart showing the Figure 5 processing of flicker correction in step S3.

[0189] When the endoscope control processing device 3 enters the flicker correction processing in Figure 5 step S3, it executes the Figure 18 processing shown.

[0190] Then, the exposure time ratio calculation circuit 26 waits to receive the exposure time target value Tgt and the electronic shutter control value ES from the electronic shutter control value calculation circuit 25, and the flicker correction on / off control circuit 31 waits to receive the electronic shutter control value ES from the electronic shutter control value calculation circuit 25 (step S21').

[0191] When the flicker correction on / off control circuit 31 receives the electronic shutter control value ES, it determines whether the electronic shutter control value ES is equal to or greater than the threshold value ESth (step S25).

[0192] Here, the threshold value ESth is an electronic shutter control value ES that is a standard for determining whether the brightness variation of each frame caused by the error of the dimming control due to the electronic shutter that discretely controls the exposure time is significant as image flicker. The threshold value ESth is preset according to the specifications of the imaging element 11 and the like.

[0193] Specifically, the threshold value ESth is set to a value equal to or greater than the value obtained by subtracting the amount of "100 / target dimming accuracy" rows from all the number of rows N as shown by the electronic shutter control value ESa in Figure 15 and a smaller value.

[0194] When the electronic shutter control value ES is equal to or greater than the threshold value ESth, the flicker correction on / off control circuit 31 generates a flicker correction on control signal and sends this flicker correction on control signal to the flicker correction circuit 22. When the flicker correction circuit 22 receives the flicker correction on control signal, it performs flicker correction in step S24 and returns to Figure 5 the processing of.

[0195] In addition, when the electronic shutter control value ES is less than the threshold value ESth, the flicker correction on / off control circuit 31 generates a flicker correction off control signal and sends this flicker correction off control signal to the flicker correction circuit 22. When the flicker correction circuit 22 receives the flicker correction off control signal, it does not perform the flicker correction in step S24 but returns to Figure 5 the processing of.

[0196] Therefore, when the electronic shutter control value ES is less than the threshold value ESth, there is no gain adjustment involved in the flicker correction, but the dimming is performed by the electronic shutter control using the electronic shutter control value ES calculated based on the dimming detection.

[0197] In addition, when the electronic shutter control value ES is less than the threshold value ESth, it is also possible to skip only the processing of step S24 after the processing of step S22 and step S23 is performed. However, in Figure 18In the process, not only step S24 is skipped, but also the processes of step S22 and step S23 are skipped. In this case, the flicker correction on / off control circuit 31 preferably sends a process stop control signal to the exposure time ratio calculation circuit 26 and the flicker correction gain calculation circuit 27. Thereby, it is possible to more effectively reduce the power consumption in the case where flicker correction is not performed.

[0198] As illustrated by citing a numerical example in the first embodiment, when the number of exposed lines is 5 (lines), the absolute value of the change rate of brightness when the electronic shutter control value ES is changed by 1 line is 20 (%). On the other hand, when the number of exposed lines is 1000 (lines), the absolute value of the change rate of brightness is 0.1 (%).

[0199] Therefore, when the electronic shutter control value ES is less than the threshold value ESth and is far from the vicinity of aperture closing, the change in brightness per frame is minute and hardly noticeable as the flicker of the image.

[0200] According to the second embodiment, substantially the same effects as those of the first embodiment described above are exhibited. And according to the second embodiment, signal amplification is not performed in a scene where the flicker of the image is not obvious, so that it is possible to avoid deterioration of the image quality due to amplification of noise components.

[0201] [Related Art 1]

[0202] In addition, the endoscope control processing device 3 may also have a structure that doubles as a light source device, for example. Figure 19 FIG. is a diagram showing a structural example of the endoscope control processing device 3 that doubles as a light source device in Related Art 1.

[0203] In addition to the above-described imaging element 11, the endoscope 2 further includes an optical waveguide 12, an illumination lens 13, an objective lens 14, and a drive circuit 15.

[0204] The optical waveguide 12 transmits the illumination light provided from the endoscope control processing device 3 to the front end side of the endoscope 2. The optical waveguide 12 is constituted by, for example, an optical fiber bundle in which optical fibers are bundled.

[0205] The illumination lens 13 is provided on the front end side of the endoscope 2. The illumination lens 13 irradiates the illumination light transmitted through the optical waveguide 12 onto the subject.

[0206] The objective lens 14 forms an optical image of the subject irradiated with the illumination light on the imaging element 11.

[0207] The drive circuit 15 is electrically connected to the imaging element 11, sends a drive signal to the imaging element 11, receives the image signal acquired by the imaging element 11, and sends the image signal to the endoscope control processing device 3.

[0208] The endoscope control processing device 3 includes a first image processing circuit 21, a second image processing circuit 23, a control circuit 34, a light source drive circuit 35, a light source 36, and a multiplexer 37.

[0209] For example, the first image processing circuit 21, the second image processing circuit 23, and the control circuit 34 are composed of a processor 30a and a memory 30b as Figure 3 shown. However, similarly to the above, a part or all of them may also be composed of electronic circuits.

[0210] The first image processing circuit 21 performs basic image processing on the image signal received from the endoscope 2.

[0211] The second image processing circuit 23 generates an image signal for observation on the monitor 4 based on the image signal processed by the first image processing circuit 21, and outputs the image signal to the monitor 4.

[0212] The control circuit 34 controls each part in the endoscope control processing device 3 including the first image processing circuit 21 and the light source drive circuit 35, and also controls the endoscope 2.

[0213] The control circuit 34 includes a brightness detection circuit 38 and a dimming control circuit 39. The brightness detection circuit 38 receives the image signal from the first image processing circuit 21, performs dimming detection, and detects the brightness of the image. The dimming control circuit 39 performs dimming control based on the brightness of the image detected by the brightness detection circuit 38. The dimming control performed by the dimming control circuit 39 includes control of the electronic shutter of the imaging element 11 via the drive circuit 15 and control of the light source 36 via the light source drive circuit 35.

[0214] The light source drive circuit 35 controls the light source 36 based on an instruction from the dimming control circuit 39 to cause the light source 36 to emit light.

[0215] The light source 36 includes a white light source that emits white illumination light, and also includes a special light source that emits special light as needed. Examples of the special light source include a laser light source for irradiating a calculus, a light source for causing fluorescence to emit from a subject, a light source for performing NBI (Narrow Band Imaging), etc.

[0216] Specifically, the light source 36 includes a plurality of light-emitting elements that emit light with different wavelengths, such as LEDs (Light Emitting Diodes), etc. For example, the LEDs that make up a white light source include white LEDs. Alternatively, the LEDs that make up a white light source may also be configured to include LEDs that emit green (G) light, LEDs that emit red (R) light, and LEDs that emit blue (B) light. The special light source includes light-emitting elements such as LEDs and LDs (Laser Diodes) that emit light with other wavelengths.

[0217] The light source 36 emits light from one or more light-emitting elements under the control of the light source drive circuit 35.

[0218] The multiplexer 37 multiplexes multiple beams of light with different wavelengths emitted from the light source 36 and provides the combined light as illumination light to the endoscope 2.

[0219] In addition, the light source device and the endoscope control processing device 3 may be provided separately.

[0220] Figure 20 It is a block diagram showing a structural example of the control circuit 34, the light source drive circuit 35, and the light source 36 in the related art 1.

[0221] The control circuit 34 is configured to include, for example, an FPGA 34a as the processor 30a.

[0222] The light source drive circuit 35 includes a light-emitting element driver 35a, a conduction / cutoff and feedback circuit 35b, and a current detection circuit 35c. For a more specific structure of the light source drive circuit 35, refer to Figure for description later.

[0223] The light source 36 includes a light-emitting element 36a.

[0224] ​ It is a diagram showing an example of the light-emitting mode of the endoscope control processing device 3 that also serves as a light source device in the related art 1.

[0225] The endoscope control processing device 3 emits illumination light in multiple light-emitting modes. In ​ the example shown, as the light-emitting modes of the illumination light, a flash light-emitting mode, a WLI (White Light Imaging) light-emitting mode, and an NBI light-emitting mode can be set in the endoscope control processing device 3.

[0226] As described above, the light-emitting element 36a includes a plurality of light-emitting elements (a first light-emitting element, a second light-emitting element, etc.). For example, if the first light-emitting element is focused on, then as ​As shown, the first light-emitting element is driven in three light-emitting modes with different current drive ranges and different time division periods of light emission, respectively.

[0227] Moreover, in different light-emitting elements, for example, the first light-emitting element and the second light-emitting element, the current drive ranges and the time division periods of light emission in the three light-emitting modes are different.

[0228] ​ FIG. is a diagram showing a more detailed structural example of the light source drive circuit 35 and the light source 36 in the related art 1.

[0229] The light-emitting element driver 35a is configured as an integrated circuit (IC: Integrated circuit), for example, and includes a plurality of output terminals and a plurality of input terminals.

[0230] The drive output terminal DRIVE_OUT of the light-emitting element driver 35a is connected to the anode of the light-emitting element 36a configured as an LED, for example. The cathode of the light-emitting element 36a is connected to the conduction / cutoff and feedback circuit 35b.

[0231] The conduction / cutoff and feedback circuit 35b includes three transistors Q1 to Q3 that function as switches, and six resistors R1 to R6.

[0232] The transistors Q1 to Q3 are each configured as an enhancement-type and N-channel power MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), for example. The enhancement-type MOSFET does not conduct drain current when the voltage between the gate and the source is 0.

[0233] The transistors Q1 to Q3 are arranged in parallel, and their respective drains are connected to the cathode of the light-emitting element 36a. The control output terminal PWM_OUT1 of the light-emitting element driver 35a is connected to the gate of the transistor Q1, the control output terminal PWM_OUT2 of the light-emitting element driver 35a is connected to the gate of the transistor Q2, and the control output terminal PWM_OUT3 of the light-emitting element driver 35a is connected to the gate of the transistor Q3.

[0234] One ends of the resistors R1 and R2 arranged in parallel are connected to the source of the transistor Q1. The other ends of the resistors R1 and R2 are connected to the ground.

[0235] One ends of the resistors R3 and R4 arranged in parallel are connected to the source of the transistor Q2. The other ends of the resistors R3 and R4 are connected to the source of the transistor Q1 and one ends of the resistors R1 and R2.

[0236] One end of the resistors R5 and R6 in parallel configuration is connected to the source of the transistor Q3. The other ends of the resistors R5 and R6 are connected to the source of the transistor Q2 and one end of the resistors R3 and R4.

[0237] In addition, if multiple resistors are arranged in parallel, the temperature of each resistor can be reduced, which has the advantage of being able to take thermal countermeasures.

[0238] A positive input terminal LED_ISP of the light-emitting element driver 35a is connected between the source of the transistor Q3 and one end of the resistors R5 and R6.

[0239] A current detection circuit 35c is connected across the parallel resistors R1 and R2. The other ends of the resistors R1 and R2 are connected to a negative input terminal LED_ISN of the light-emitting element driver 35a. The light-emitting element driver 35a performs feedback control on each output based on the inputs of the positive input terminal LED_ISP and the negative input terminal LED_ISN.

[0240] In ​ In the structure shown, when the light-emitting element 36a emits light, the three transistors Q1 to Q3 are selectively controlled so that only one transistor is turned on.

[0241] In the flash light-emitting mode, the transistor Q1 is controlled to be turned on, and the transistors Q2 and Q3 are controlled to be turned off. The current path in the flash light-emitting mode is indicated by a solid line through P1. The light-emitting element driver 35a controls the light emission amount in the flash light-emitting mode by controlling the current value of the current path P1 and the time (the time when the current flows) for which the transistor Q1 is turned on.

[0242] In addition, in the WLI light-emitting mode, the transistor Q2 is controlled to be turned on, and the transistors Q1 and Q3 are controlled to be turned off. The current path in the WLI light-emitting mode is indicated by a one-dot chain line through P2. At this time, the light-emitting element driver 35a controls the light emission amount in the WLI light-emitting mode by controlling the current value of the current path P2 and performing PWM (Pulse-Width Modulation) control on the transistor Q2.

[0243] In the NBI light-emitting mode, the transistor Q3 is controlled to be turned on, and the transistors Q1 and Q2 are controlled to be turned off. The current path in the NBI light-emitting mode is indicated by a double-dot chain line through P3. At this time, the light-emitting element driver 35a controls the light emission amount in the NBI light-emitting mode by controlling the current value of the current path P3 and performing PWM control on the transistor Q3.

[0244] Set the current in current path P1 to I1, and set the input voltage of current detection circuit 35c in the flash light emission mode to V1. Set the current in current path P2 to I2, and set the input voltage of current detection circuit 35c in the WLI light emission mode to V2. Set the current in current path P3 to I3, and set the input voltage of current detection circuit 35c in the NBI light emission mode to V3. Here, the minimum value within the driving range of each current is denoted by min, and the maximum value is denoted by max. In addition, the resistance values of the respective resistors R1 to R6 are denoted by the same symbols R1 to R6. Also, the symbol " / / " is used to denote the combined resistance value when two resistors are connected in parallel.

[0245] Specifically, the respective combined resistance values (R1 / / R2), (R3 / / R4), (R5 / / R6) are the values shown in the following equations 6 to 8.

[0246] (R1 / / R2) = R1 × R2 / (R1 + R2) … (Equation 6)

[0247] (R3 / / R4) = R3 × R4 / (R3 + R4) … (Equation 7)

[0248] (R5 / / R6) = R5 × R6 / (R5 + R6) … (Equation 8)

[0249] The current detection circuit 35c detects the current value based on the voltage value across the combined resistor (R1 / / R2). Thus, the ranges of the voltages V1, V2, V3 detected by the current detection circuit 35c as being within the normal range are as shown in the following equations 9 to 11.

[0250]

[0251] In this way, different current paths P1 to P3 are set for each light emission mode, and the current paths P1 to P3 are combined to perform current detection. At this time, by appropriately designing the respective combined resistance values (R1 / / R2), (R3 / / R4), (R5 / / R6) corresponding to the current driving ranges of the respective light emission modes, it is possible to detect the current in each light emission mode using one current detection circuit 35c.

[0252] A generally considered structure is a structure in which a plurality of current detection circuits are provided for a plurality of current paths respectively. In this case, the current detection circuit can be designed to match the current driving range of each light emission mode, but one current detection circuit needs to be provided for each current path.

[0253] Compared with the general structure in which current detection circuits are provided separately for each light emission mode, according to the ​ shown structure, only one current detection circuit 35c is required, so the circuit structure can be simplified.

[0254] ​ This is a graph showing an example in the related art 1 where the drive current detected by the current detection circuit 35c is within the normal range and within the abnormal range in each light emission mode.

[0255] In ​ it, the current values corresponding to the table of ​ and the voltages within the normal range shown in Expressions 9 to 11 are indicated by arrows, and the current values corresponding to the abnormal range are represented by shaded bar graphs. In the illustrated example, the median value of the normal range of the current values becomes lower in the order of the flash light emission mode (current path P1), the WLI light emission mode (current path P2), and the NBI light emission mode (current path P3).

[0256] The FPGA 34a of the control circuit 34 receives the current value detected by the current detection circuit 35c and determines whether the received current value is within the normal range or within the abnormal range in the current light emission mode.

[0257] For example, when operating in the WLI light emission mode, if it is assumed that a component fails and the light emitting element 36a is driven in the flash light emission mode, it will cause strong light to be irradiated to the subject. The FPGA 34a compares the current value detected by the current detection circuit 35c with the normal drive current range to detect an abnormal state such as operating in an undesired light emission mode. If the FPGA 34a detects an abnormal state, it controls the light emitting element driver 35a, for example, by turning off all of the transistors Q1 to Q3 to stop the light emission.

[0258] In addition, not limited to this, it may also be that when the FPGA 34a detects an abnormal state, it performs control to switch to another safe drive state (or safe drive path). For example, it may also be that when an abnormal state is detected, it switches to the NBI light emission mode with the lowest median value of the normal range of the current values among the three light emission modes.

[0259] ​ This is a timing chart showing an example of the timing at which the current detection circuit 35c performs current detection in the related art 1.

[0260] The current detection circuit 35c receives, for example, a current detection timing signal sent from the control circuit 34 and performs current detection at the received timing. The current detection timing signal is, for example, a pulse signal that becomes high level at a certain period t2. The current detection circuit 35c performs current detection when the pulse signal becomes high level.

[0261] ​The drive indication signal is a signal output from the control output terminals PWM_OUT1 to PWM_OUT3 of the light-emitting element driver 35a. The period during which the drive indication signal is at a high level and the transistors Q1 to Q3 are turned on is set as t1. Then, the period t2 of the current detection timing signal is set to be shorter than the period t1 (t1 > t2). Thereby, within the period t1 during which the transistors Q1 to Q3 are turned on, the current detection circuit 35c reliably performs current detection one or more times.

[0262] By performing current detection within the period t1, it is possible to confirm whether the light-emitting element 36a is driven with the desired current. For example, in the WLI light-emitting mode, it is possible to confirm whether the light-emitting element 36a does not operate within the current drive range of the flash light-emitting mode.

[0263] Moreover, by performing current detection during a period other than the period t1, it is possible to confirm whether current flows through the light-emitting element 36a at a timing when current drive is not indicated, that is, at an undesired timing. For example, in the flash light-emitting mode, it is possible to confirm whether the light-emitting element 36a does not emit light at the extinguishing timing during the flash light emission.

[0264] In addition, since the period t1 varies depending on the light-emitting mode, the period t2 is also set separately according to the light-emitting mode. Alternatively, the period t2 can be set to be shorter than the period t1 in any light-emitting mode.

[0265] ​ FIG. shows an example in which one current detection circuit 35c is applied to a structure in which a plurality of light-emitting element drivers 35a1, 35a2, 35a3,... respectively drive a plurality of light-emitting elements 36a1, 36a2, 36a3,... in the related art 1.

[0266] The light-emitting element driver 35a includes a plurality of light-emitting element drivers 35a1, 35a2, 35a3,... In addition, resistance elements Ra1, Ra2, Ra3,... are arranged on the current paths P1 to P3 as described below.

[0267] In addition, the number of the light-emitting elements, the light-emitting element drivers, and the resistance elements may be two or more than three, but the following description is an example of three. In addition, in the following ​ , ​ , the description is also given according to the example of three.

[0268] In the first light-emitting mode (for example, the flash light-emitting mode), the light-emitting element 36a1 is driven by the light-emitting element driver 35a1, and the current path P1 passes through the light-emitting element 36a1 and the resistance element Ra1.

[0269] In the second light emission mode (e.g., WLI light emission mode), the light emitting element 36a2 is driven by the light emitting element driver 35a2, and the current path P2 passes through the light emitting element 36a2 and the resistance elements Ra2 and Ra1.

[0270] In the third light emission mode (e.g., NBI light emission mode), the light emitting element 36a3 is driven by the light emitting element driver 35a3, and the current path P3 passes through the light emitting element 36a3 and the resistance elements Ra3, Ra2, and Ra1. Further, in the same manner as described above, the current paths P1 to P3 are selectively selected.

[0271] The current paths P1 to P3 merge at the resistance element Ra1. The current detection circuit 35c is configured to measure the current value based on the voltage of the resistance element Ra1.

[0272] Thus, in the ​ structure, by appropriately setting the respective resistance values of the resistance elements Ra1, Ra2, and Ra3, it is also possible to detect the current values flowing in the plurality of current paths P1 to P3 using one current detection circuit 35c.

[0273] ​ FIG. is an example showing the application of one current detection circuit 35c in a structure in which a plurality of light emitting elements 36a1, 36a2, and 36a3 are driven by one light emitting element driver 35a in related art 1.

[0274] ​ The structure of ​ drives a plurality of light emitting elements 36a1, 36a2, and 36a3 through different channels ch1, ch2, ch3,... of one light emitting element driver 35a, as compared with the structure of

[0275] The channel ch1 is connected to the light emitting element 36a1, the channel ch2 is connected to the light emitting element 36a2, and the channel ch3 is connected to the light emitting element 36a3. ​ The structures of the light emitting elements 36a1, 36a2, and 36a3, the resistance elements Ra1, Ra2, and Ra3, and the current detection circuit 35c are substantially the same as those of

[0276] For example, the first light emission mode (e.g., flash light emission mode) is controlled through the channel ch1, the second light emission mode (e.g., WLI light emission mode) is controlled through the channel ch2, and the third light emission mode (e.g., NBI light emission mode) is controlled through the channel ch3.

[0277] The current paths P1 to P3 merge at the resistance element Ra1. The current detection circuit 35c is configured to measure the current value based on the voltage of the resistance element Ra1.

[0278] Therefore, similar to the structure of ​ , in the structure of ​ , it is also possible to detect the current values flowing in the multiple current paths P1 to P3 by using one current detection circuit 35c.

[0279] ​ FIG. shows an example in which one current detection circuit 35c is applied to a structure in which one light-emitting element 36a is driven by multiple light-emitting element drivers 35a1, 35a2, and 35a3 in related art 1.

[0280] The multiple light-emitting element drivers 35a1, 35a2, and 35a3 drive the light-emitting element 36a in different light-emitting modes, respectively.

[0281] In the first light-emitting mode (e.g., flash light-emitting mode), the light-emitting element 36a is driven by the light-emitting element driver 35a1, and the current path P1 passes through the light-emitting element 36a and the resistance element Ra1.

[0282] In the second light-emitting mode (e.g., WLI light-emitting mode), the light-emitting element 36a is driven by the light-emitting element driver 35a2, and the current path P2 passes through the light-emitting element 36a and the resistance elements Ra2 and Ra1.

[0283] In the third light-emitting mode (e.g., NBI light-emitting mode), the light-emitting element 36a is driven by the light-emitting element driver 35a3, and the current path P3 passes through the light-emitting element 36a and the resistance elements Ra3, Ra2, and Ra1. In addition, similar to the above, the current paths P1 to P3 are alternatively selected.

[0284] The current paths P1 to P3 merge at the resistance element Ra1. The current detection circuit 35c is configured to measure the current value based on the voltage of the resistance element Ra1.

[0285] Therefore, similar to the structure of ​ and ​ , in the structure of ​ , it is also possible to detect the current values flowing in the multiple current paths P1 to P3 by using one current detection circuit 35c.

[0286] According to ​ shown in related art 1, there are multiple current paths passing through the light-emitting element 36a, and a circuit element or path that commonly conducts current regardless of which current path drives the light-emitting element 36a is provided in the light source drive circuit 35 where the current drive ranges of the respective current paths are different. Moreover, one current detection circuit 35c is used to detect the current on this circuit element or path.

[0287] Therefore, no matter which current path drives the light-emitting element 36a, the current can be detected by one current detection circuit 35c. Thus, the abnormal current during a fault can be detected by one current detection circuit 35c to prevent malfunction of the light source device.

[0288] When an abnormal state is detected, the FPGA 34a switches the light source drive circuit 35 and the light source 36 to a safe drive state (or a safe drive path). Thereby, it is possible to reliably prevent continuous irradiation of illumination light to the subject in the abnormal state. Thus, the subject is not continuously irradiated with, for example, strong light.

[0289] [Related Art 2]

[0290] ​ FIG. shows a structural example of an endoscope control processing device 3 that also serves as a light source device in Related Art 2.

[0291] In an endoscope, observation in a stroboscopic light emission mode (stroboscopic observation mode) is performed in synchronization with the periodic vibration of the subject. An example of the observation object in the stroboscopic observation mode is the periodically vibrating vocal cords. Another example of the observation object in the stroboscopic observation mode can be a periodically beating heart, a periodically pulsating artery, etc.

[0292] In such stroboscopic observation, in order to correct uneven exposure between frames or lines, an unevenness elimination process is performed.

[0293] For example, Japanese Unexamined Patent Application Publication No. 2020-151402 discloses the following: When controlling the LED current for dimming in the stroboscopic observation mode, the unevenness elimination process is performed based on the peak value of the LED current. That is, in this publication, the peak value (current value) of the LED current is used as the brightness information of each pulsed light.

[0294] However, generally, the relationship between the current and brightness of an LED is not completely linear (proportional). Therefore, if the peak value of the LED current is directly used as the brightness information of each light pulse, an error occurs between the brightness based on the peak value and the actual brightness, and the accuracy of the unevenness elimination process decreases.

[0295] Therefore, ​ FIG. shows a structural example for improving the accuracy of the unevenness elimination process.

[0296] The endoscope system 1 includes an endoscope 2, an endoscope control processing device 3, and a monitor 4 in the same manner as described above.

[0297] The endoscope 2 is configured as an electronic endoscope in the same manner as described above and includes an imaging element 11.

[0298] The endoscope control processing device 3 includes the above-described first image processing circuit 21, second image processing circuit 23, dimming detection arithmetic circuit 24, user interface 29, light source drive circuit 35, and light source 36. The endoscope control processing device 3 further includes a light source control circuit 41, a memory 42, a pulse brightness calculation circuit 43, and a non-uniformity elimination circuit 44.

[0299] As described above, the light source 36 includes, for example, a light-emitting element 36a configured as an LED (see ​ etc.).

[0300] The light source control circuit 41 obtains a dimming detection value from the dimming detection arithmetic circuit 24. The light source control circuit 41 generates a signal for controlling the light source 36 via the light source drive circuit 35 based on the dimming detection value.

[0301] The signal generated by the light source control circuit 41 includes, for example, a PWM control signal and a current value control signal. The PWM control signal in the flash emission mode is a signal synchronized with the periodic vibration of the subject. The light source drive circuit 35 supplies a rectangular pulse-shaped current to the light source 36 at the timing indicated by the PWM control signal. The light source 36 emits pulsed light when the current is supplied.

[0302] The memory 42 functions as a conversion parameter storage circuit. The memory 42 stores non-volatile conversion parameters for converting the current control value I represented by the current value control signal into the pulse brightness L. The memory 42 may be ​ a part of the memory 30b shown, or may be provided separately from the memory 30b.

[0303] The current value control signal generated by the light source control circuit 41 is also sent to the pulse brightness calculation circuit 43. The pulse brightness calculation circuit 43 reads the conversion parameters from the memory 42 and converts the current control value I represented by the current value control signal into information on the pulse brightness L.

[0304] ​ is a graph showing a first example of the conversion parameters for converting the current control value I into the pulse brightness L in the related art 2.

[0305] As ​ shown by the curve L(I), the current control value I and the pulse brightness L generally do not have a linear relationship. Let the maximum value of the current control value I be Imax, and let the maximum value of the pulse brightness when I = Imax be Lmax = L(Imax). At this time, if it is assumed that a straight line connects (I, L) = (0, 0) and (I, L) = (Imax, Lmax) linearly and the pulse brightness L is calculated based on the current control value I, the error between the calculated pulse brightness L and the actual pulse brightness becomes large.

[0306] Therefore, as ​ shown by the straight line L1(I), a straight line closer to the curve L(I) is set. Let the minimum value of the current control value I be Imin, and let the minimum value of the pulse brightness when I = Imin be Lmin = L(Imin). The straight line L1(I) is set as the straight line connecting (I, L) = (Imin, Lmin) and (I, L) = (Imax, Lmax). Using the slope k1 and the intercept m1, the straight line L1(I) is represented by the linear function formula shown in the following formula 12.

[0307] L1(I) = k1 × I + m1…(Formula 12)

[0308] Observing ​ it can be seen that generally, even if the straight line L1(I) is extended, it will not pass through (I, L) = (0, 0). Moreover, it can be seen that the straight line L1(I) has a smaller error from the curve L(I) representing the actual pulse brightness than the straight line passing through (I, L) = (0, 0).

[0309] The slope k1 and the intercept m1, or (Imin, Lmin) and (Imax, Lmax) are stored in the memory 42 as conversion parameters.

[0310] The pulse brightness calculation circuit 43 reads out, for example, the slope k1 and the intercept m1 from the memory 42, and converts the current control value I represented by the current value control signal into information on the pulse brightness L based on Formula 12. However, instead, the pulse brightness calculation circuit 43 can also read out (Imin, Lmin) and (Imax, Lmax) from the memory 42, and calculate the pulse brightness L corresponding to the current control value I through interpolation operations or the like.

[0311] ​ is a diagram showing a second example of the conversion parameter for converting the current control value I into the pulse brightness L in the related art 2.

[0312] In ​ it, the straight line L1(I) connecting the minimum value point (Imin, Lmin) and the maximum value point (Imax, Lmax) is obtained, but ​ is an example of further adding the intermediate value point (Imid, Lmid) and approximating the curve L(I) using a broken line.

[0313] The intermediate value point (Imid, Lmid) is preferably set, for example, as the point that minimizes the sum of the area surrounded by the curve L(I) and the straight line L1a(I) and the area surrounded by the curve L(I) and the straight line L1b(I).

[0314] Alternatively, it can be set that Imid = (Imin + Imax) / 2 and Lmid = L(Imid). Also, it can be set that Lmid = (Lmin + Lmax) / 2 and Imid = L^(-1)(Lmid). Here, L^(-1)(L) represents the inverse function of the curve L(I).

[0315] The straight line L1a(I) is set as the straight line connecting (I, L) = (Imin, Lmin) and (I, L) = (Imid, Lmid). Using the slope k1a and the intercept m1a, the straight line L1a(I) is represented by the linear function formula shown in Equation 13 below.

[0316] L1a(I) = k1a × I + m1a … (Equation 13)

[0317] The straight line L1b(I) is set as the straight line connecting (I, L) = (Imid, Lmid) and (I, L) = (Imax, Lmax). Using the slope k1b and the intercept m1b, the straight line L1b(I) is represented by the linear function formula shown in Equation 14 below.

[0318] L1b(I) = k1b × l + m1b … (Equation 14)

[0319] If ​ is compared with ​ it can be seen that the error between the broken line formed by the straight lines L1a(I) and L1b(I) and the curve L(I) representing the actual pulse brightness is smaller than that of the straight line L1(I).

[0320] The slope k1a, the intercept m1a, or (Imin, Lmin) and (Imid, Lmid) are stored in the memory 42 as the first conversion parameters. In addition, the slope k1b, the intercept m1b, or (Imid, Lmid) and (Imax, Lmax) are stored in the memory 42 as the second conversion parameters.

[0321] When the current control value I < Imid, the pulse brightness calculation circuit 43 reads out, for example, the slope k1a and the intercept m1a from the memory 42, and converts the current control value I into the information of the pulse brightness L based on Equation 13. However, instead, the pulse brightness calculation circuit 43 can also read out (Imin, Lmin) and (Imid, Lmid) from the memory 42, and calculate the pulse brightness L corresponding to the current control value I through interpolation operations or the like.

[0322] On the other hand, when the current control value I ≥ Imid, the pulse luminance calculation circuit 43 reads out, for example, the slope k1b and the intercept m1b from the memory 42, and converts the current control value I into information on the pulse luminance L based on Equation 14. However, instead, the pulse luminance calculation circuit 43 may also read out (Imid, Lmid) and (Imax, Lmax) from the memory 42, and calculate the pulse luminance L corresponding to the current control value I through interpolation calculation or the like.

[0323] In addition, in ​ a broken line is formed by three points, but a broken line may also be formed by four or more points. The number of types of the linear function formulas calculated in this case is "the number of acquired data points - 1".

[0324] As ​ or ​ shown, the conversion parameters are obtained in the process inspection. That is, in the process inspection, for two or more points including the point (Imin, Lmin) of the minimum value and the point (Imax, Lmax) of the maximum value, the relationship between the current control value I and the pulse luminance L is acquired. Then, based on the straight line connecting two points or the broken line connecting three or more points, the conversion parameters are calculated.

[0325] In addition, the process inspection may also be performed on each individual of the endoscope control processing device 3. Alternatively, the results of the process inspection performed on a representative individual of the endoscope control processing device 3 may be applied to each individual of the same product.

[0326] Moreover, although a linear function formula is used above, it is not limited thereto, and a function formula of the second order or higher may also be used.

[0327] In addition, above, the pulse luminance calculation circuit 43 reads out and uses the conversion parameters stored in the memory 42, but it is not limited thereto. For example, if the pulse luminance calculation circuit 43 using an arithmetic circuit preconfigured corresponding to the above function formula is used, the memory 42 may not be provided. For example, when using the conversion parameters of each individual, it is preferable to use the memory 42. In addition, when using common conversion parameters for each individual of the same product, either the structure using the memory 42 or the structure not using the memory 42 may be adopted.

[0328] ​ is a timing chart for explaining the uneven exposure between frames when the imaging element 11 is in the global shutter mode in the related art 2.

[0329] As described above, the pulsed light emission of the light source 36 is synchronized with the vibration of the subject (for example, the vibration of the vocal cords as described above). Therefore, the pulsed light emission of the light source 36 generally is not synchronized with the frame frequency.

[0330] In the case where the imaging element 11 is a global shutter type such as a CCD imager, the number of pulsed light emissions during the exposure period of one frame may be different between different frames.

[0331] ​ An example where the light emission period Ti is shorter than the frame period Tf, Ti < Tf, is shown. During the exposure period of frame n, pulsed light emission is performed twice, but during the exposure period of frame (n + 1), pulsed light emission is performed only once, resulting in uneven exposure between frames. This uneven exposure between frames is also referred to as flicker.

[0332] ​ It is a timing chart for explaining uneven exposure between rows in the case where the imaging element 11 is a rolling shutter type in Related Art 2.

[0333] In the case where the imaging element 11 is a rolling shutter type such as a CMOS imager, the number of pulsed light emissions during the exposure period may be different depending on the row within one frame.

[0334] ​ An example where the light emission period Ti is shorter than the frame period Tf, Ti < Tf, is shown. If we focus on frame n, pulsed light emission is performed twice during the exposure period of row 1, but for example, only once during the exposure period of the last row, resulting in uneven exposure between rows.

[0335] The unevenness elimination circuit 44 obtains information on the pulsed luminance L from the pulsed luminance calculation circuit 43, and corrects the uneven exposure between frames as shown, for example, by applying a gain based on the luminance ratio. ​ or the uneven exposure between rows as shown ​ in.

[0336] According to ​ Related Art 2 shown, by using a functional formula with a small error from the actual pulsed luminance to obtain the pulsed luminance L from the current control value I, it is possible to correct the uneven exposure between frames or between rows with higher accuracy.

[0337] In addition, by using a linear function formula, high-speed operation can be performed with a small computational load. In addition, by using multiple linear function formulas configured as broken lines, the correction accuracy of uneven exposure can be further improved.

[0338] [Related Art 3]

[0339] ​ It is a diagram showing a structural example of the endoscope control processing device 3 that also serves as a light source device in Related Art 3.

[0340] For example, Japanese Unexamined Patent Application Publication No. 2018-498 discloses an endoscope system including a correction value setting unit and a recording unit. The correction value setting unit sets a white balance correction value. The recording unit records coefficients used in a function representing the relationship between the white balance correction value of a reference light source and the white balance correction values of other light sources. The endoscope system sets a new white balance correction value used for white balance correction of the reference light source. When the endoscope system switches from the reference light source to another light source, it uses the new white balance correction value and the coefficients to calculate the white balance correction value of the other light source. The endoscope system performs white balance correction of the other light source using the calculated white balance correction value. In addition, in this publication, as light sources, xenon lamps, halogen lamps, metal halide lamps, LED lamps, etc. are described.

[0341] In addition, even if the light source 36 is the same, the white balance (emission color) sometimes varies depending on the emission brightness of the light source 36.

[0342] Therefore, ​ A structural example for correcting color changes when the dimming control value changes is shown.

[0343] The endoscope system 1 includes an endoscope 2, an endoscope control processing device 3, and a monitor 4 in the same manner as described above.

[0344] The endoscope 2 is configured as an electronic endoscope in the same manner as described above and includes an imaging element 11.

[0345] The endoscope control processing device 3 includes the above-described first image processing circuit 21, second image processing circuit 23, dimming detection operation circuit 24, user interface 29, light source drive circuit 35, light source 36, and light source control circuit 41. The endoscope control processing device 3 further includes a memory 46, a color correction value calculation circuit 47, and a color correction circuit 48.

[0346] As described above, the light source 36 includes a light emitting element 36a configured as an LED (see ​ etc.).

[0347] The memory 46 functions as a storage circuit for color correction value calculation parameters and stores the color correction value calculation parameters non-volatilely. Here, the color correction value calculation parameters are parameters for color-correcting an image signal based on the dimming control value. The memory 46 may be ​ a part of the memory 30b shown, or may be provided separately from the memory 30b.

[0348] The dimming detection operation circuit 24 receives an image signal from the first image processing circuit 21, and makes a dimming detection value by adding and averaging the luminance signals within the pixel regions of the imaging element 11 (image sensor) that forms the optical image of the endoscope 2. Further, the dimming detection operation circuit 24 compares this dimming detection value with a dimming detection target value to produce a dimming control value for determining the next light emission luminance of the light source 36, and outputs this dimming control value to the light source control circuit 41. The light source control circuit 41 linearly controls the light emission luminance of the light source 36 in response to the dimming control value. At this time, the dimming control value generated by the dimming detection operation circuit 24 is also sent to the color correction value calculation circuit 47. The color correction value calculation circuit 47 reads out the parameters for color correction value calculation from the memory 46, and calculates the color correction value based on the dimming control value.

[0349] For example, it is assumed that the image signal is composed of a red (R) signal, a green (G) signal, and a blue (B) signal. Also, it is assumed that no gain for color correction is applied to the green (G) signal. In this case, the color correction value corresponds to the gain for color correction for the red (R) signal and the gain for color correction for the blue (B) signal.

[0350] ​ It is a diagram showing an example of a functional formula for calculating the color correction value based on the dimming control value in the related art 3.

[0351] As ​ shown, the color correction value calculation circuit 47 calculates the color correction value based on the dimming control value. ​ The functional formula shown is a linear function formula. If the dimming control value is set as x, the color correction value is set as y, the slope is set as u, and the intercept is set as v, then this functional formula is represented by the following formula 15.

[0352] y = u×x + v…(Formula 15)

[0353] More specifically, if the slope for the red (R) signal is set as ur and the intercept is set as vr, then based on the dimming control value x, the color correction value yr (R gain) for the red (R) signal is obtained by the following formula 16.

[0354] yr = ur×x + vr…(Formula 16)

[0355] In addition, if the slope for the blue (B) signal is set as ub and the intercept is set as vb, then based on the dimming control value x, the color correction value yb (B gain) for the blue (B) signal is obtained by the following formula 17.

[0356] yb = ub×x + vb…(Formula 17)

[0357] In the process inspection, spectral data is obtained when the light source 36 emits light with different luminous intensities, and based on the obtained spectral data, the slope ur and intercept vr for the red (R) signal and the slope ub and intercept vb for the blue (B) signal are calculated. As the spectral data, for example, it is preferable to obtain the B / G ratio, R / G ratio, peak wavelength, etc.

[0358] Here, the luminous intensity of the light source 36 varies according to the light emission mode of the illumination light. Specifically, in the flash emission mode, the light source 36 emits light at a high luminous intensity for only a short time due to a large current. In the WLI emission mode, the light source 36 emits light at a medium (i.e., lower than the flash emission mode) luminous intensity due to a medium current. In the NBI emission mode, the light source 36 emits light at a low (i.e., lower than the WLI emission mode) luminous intensity due to a small current.

[0359] Therefore, in the process inspection, based on the spectral data obtained when the light source 36 emits light in each emission mode (especially the WLI emission mode and flash emission mode for observing the object to be inspected in normal colors), the slope ur and intercept vr for the red (R) signal and the slope ub and intercept vb for the blue (B) signal are calculated as parameters for calculating color correction values.

[0360] Specifically, in the WLI emission mode, the dimming control value x1, R / G ratio RG1, and B / G ratio BG1 are obtained. And in the flash emission mode, the dimming control value x2, R / G ratio RG2, and B / G ratio BG2 are obtained.

[0361] In addition, the R / G ratio of the reference white light is set as RG0, and the B / G ratio is set as BG0. At this time, the following respective ratios r1, r2, b1, and b2 are calculated.

[0362] r1 = RG1 / RG0

[0363] r2 = RG2 / RG0

[0364] b1 = BG1 / BG0

[0365] b2 = BG2 / BG0

[0366] Moreover, the slope ur and intercept vr of Equation 16 are calculated in such a way that (x, yr) = (x1, r1) and (x, yr) = (x2, r2). Similarly, the slope ub and intercept vb of Equation 17 are calculated in such a way that (x, yb) = (x1, b1) and (x, yb) = (x2, b2). The calculated parameters for calculating color correction values are non-volatilely stored in the memory 46 as described above.

[0367] In addition, process inspections can be performed on each individual of the endoscope control processing device 3. Further, the results of process inspections performed on a representative individual of the endoscope control processing device 3 can be applied to each individual of the same product.

[0368] The color correction circuit 48 is configured, for example, as a white balance circuit or a paint circuit. The color correction circuit 48 obtains color correction values yr and yb obtained based on the dimming control value x from the color correction value calculation circuit 47. The color correction circuit 48 performs color correction by applying the color correction value yr (R gain) to the red (R) signal and applying the color correction value yb (B gain) to the blue (B) signal.

[0369] In addition, a first-order functional expression was used above, but it is not limited thereto, and a second-order or higher-order functional expression can also be used.

[0370] Further, in the above, the color correction value calculation circuit 47 reads and uses the color correction value calculation parameters stored in the memory 46, but it is not limited thereto. For example, if the color correction value calculation circuit 47 that uses an arithmetic circuit preconfigured to correspond to the above functional expression is used, the memory 46 may not be provided. For example, when using the color correction value calculation parameters for each individual, it is preferable to use the memory 46. Further, when using common color correction value calculation parameters for each individual of the same product, either a structure using the memory 46 or a structure not using the memory 46 can be adopted.

[0371] Moreover, in the above, an example of calculating the color correction value based on the dimming control value output from the dimming detection arithmetic circuit 24 was described, but the color correction value can also be calculated based on the current control value I represented by the current value control signal generated by the light source control circuit 41.

[0372] In addition, the structure for obtaining the color correction value based on the dimming control value or the like as shown in Equations 15 to 17 can be applied to all light emission modes, but a relatively high effect can also be obtained even with the following simple structure.

[0373] That is, the NBI light emission mode is not a mode for observing the subject with normal color balance, so color correction is omitted. Further, in the WLI light emission mode, it is regarded as ​The color deviation of the image within the indicated current drive range is small. Therefore, even when the drive current changes in the WLI emission mode, color correction is omitted. Also, the light emitted in the WLI emission mode is regarded as the reference white light (that is, the color correction values yr and yb are regarded as 1 in the WLI emission mode), and color correction is performed only in the flash emission mode. At this time, in the flash emission mode, according to the magnitude of the drive current (that is, according to the dimming control value), processing for obtaining the color correction values yr and yb according to the dimming control value and the like as shown in Equations 16 and 17 is performed, and color correction is implemented by the color correction circuit 48.

[0374] According to ​ the related art 3 shown, it is possible to satisfactorily correct the imbalance of the white balance of the image caused by, for example, the difference in the spectral characteristics of the light source 36 between the WLI emission mode and the flash emission mode.

[0375] Also, in the same emission mode (especially the flash emission mode), it is possible to satisfactorily correct the change in the color of the image caused by the change in the spectral characteristics of the light source 36 due to the magnitude of the drive current corresponding to the dimming control.

[0376] [Related Art 4]

[0377] In addition, the present invention can also be applied to an endoscope processor including the following structure. ​ FIG. shows a structural example of an endoscope processor that supplies power for a sound input circuit through an insulator element 53 in the related art 4.

[0378] As ​ exemplified, the endoscope processor has a structure that supplies power for the endoscope from a primary power supply 51 as a structure for the endoscope, and has a structure that supplies power for the sound input circuit from a secondary power supply 52 through an insulator element 53 incorporating an insulation transformer as a structure for sound input. In the ​ structure, it becomes a structure that also transmits a sound signal to the secondary circuit using the insulator element 53.

[0379] An endoscope processor having a structure such as ​ can be connected to an endoscope. And the endoscope processor can be connected to a microphone for acquiring the pronunciation of a patient. The endoscope processor can perform stroboscopic laryngoscopy. In stroboscopic laryngoscopy, frequency components are extracted from the pronunciation acquired using the microphone. Then, lighting control of the flash emission synchronized with the frequency of the vocal cord vibration is performed, whereby it is possible to perform observation with suppressed jitter of the vocal cord vibration in stroboscopic laryngoscopy. The microphone has a type that contacts the patient to acquire pronunciation. In the case of using this type of microphone, there is also the following effect: it is possible to​ A structure including an insulator element 53 protects a patient from electric shock in case of equipment failure and is less likely to subject a sound signal to noise.

[0380] In addition, an endoscope processor capable of performing stroboscopic laryngoscopy may also have the following structure. ​ It is a diagram for explaining that in related art 4, an amplification line with a large gain is used when the input sound pressure to a microphone is below a threshold value, and an amplification line with a small gain is used when the input sound pressure to the microphone is greater than the threshold value. ​ It is a diagram showing a structural example of an endoscope processor having a plurality of amplification mechanisms with different magnification factors in related art 4.

[0381] The endoscope processor includes: a sound input unit 61 that receives a patient's pronunciation and acquires a sound signal; a plurality of amplification mechanisms (amplification units) 63 as exemplified below that amplify the acquired sound signal; a buffer circuit 62 that suppresses the influence of impedance differences caused by different magnification factors; a sound processing unit 64 that converts the sound signal from an analog signal to a digital signal; and a control unit 65 that controls the sound processing unit 64. ​ The amplification mechanism 63 includes a first amplification mechanism 63a and a second amplification mechanism 63b. The first amplification mechanism 63a is used when the sound input signal is small and has a greater gain than the gain of the second amplification mechanism 63b. The second amplification mechanism 63b is used when the sound input signal is large and has a smaller gain than the gain of the first amplification mechanism 63a. The first amplification mechanism 63a has an ALC (Automatic Level Control) function. An amplification mechanism having an ALC function reduces the magnification factor when an input above a specified level is input to prevent distortion of the input sound. When measuring the magnitude of a patient's pronunciation (dB detection), as

[0382] shown, the amplification line is switched according to the patient's pronunciation, that is, the input sound pressure to the microphone. Specifically, when the input sound pressure is below the threshold value, the amplification line passing through the first amplification mechanism 63a with a large gain is used, and when the input sound pressure becomes greater than the threshold value, the amplification line is switched to the one passing through the second amplification mechanism 63b with a small gain. The amplification line passing through the first amplification mechanism 63a with a large gain has an ALC function as described above and automatically reduces the gain when the input sound pressure is large. Therefore, it is not possible to use only the amplification line with a large gain for dB detection. ​ As shown, the amplification line is switched according to the patient's pronunciation, that is, the input sound pressure to the microphone. Specifically, when the input sound pressure is below the threshold value, the amplification line passing through the first amplification mechanism 63a with a large gain is used, and when the input sound pressure becomes greater than the threshold value, the amplification line is switched to the one passing through the second amplification mechanism 63b with a small gain. The amplification line passing through the first amplification mechanism 63a with a large gain has an ALC function as described above and automatically reduces the gain when the input sound pressure is large. Therefore, it is not possible to use only the amplification line with a large gain for dB detection.

[0383] The pronunciation of the patient varies in volume depending on the severity of the disease and the efficiency of each individual's voice production. Along with this, the range of the volume of the sound acquired by the endoscope device becomes wider. Also, the magnitude of the sound signal acquired by the endoscope device varies depending on the sensitivity of the microphone that acquires the sound. Therefore, when amplifying the received sound with a single gain, the acquired sound becomes quieter, or conversely, the sound is distorted due to excessive amplification. However, by having a plurality of amplification mechanisms as described above, it is possible to optimize the sound input volume.

[0384] In addition, an endoscope processor capable of performing stroboscopic laryngoscopy may also have the following configuration.

[0385] The endoscope processor includes: a sound input unit 61 that acquires the pronunciation of the patient; a microphone detection unit that detects the connection of the microphone; and a circuit that cuts off the sound signal output from the sound input unit 61 when the microphone is not connected. By having a circuit that cuts off the sound signal output from the sound input unit 61, noise is not recorded when the microphone is not connected and the endoscope image is being recorded. Alternatively, it may also be configured as follows: the sound processing unit 64 determines the level of the input sound, and if the level of the input sound is below a certain value, the sound signal output is cut off.

[0386] When the microphone is not connected, the dark noise is amplified, so noise with a large volume is recorded. In particular, if the ALC function is mounted, the gain is maximized when the microphone is not connected, so the magnitude of the noise becomes larger. In contrast, by providing a circuit that cuts off the sound signal output from the sound input unit 61, it is possible to prevent the recording of noise.

[0387] In addition, an endoscope processor capable of performing stroboscopic laryngoscopy may also have the following configuration.

[0388] The endoscope processor includes: a sound input unit 61 that acquires the pronunciation of the patient; a setting unit that is used to select connection device information; and a sound output unit that outputs the sound after signal processing.

[0389] The line level of the sound (the voltage level of the sound signal) is not a unified standard and is designed at various voltage levels for each device. Therefore, the voltage level of the sound signal output by the endoscope device may not be suitable for the sound recording device. In contrast, by adopting the above configuration, it is possible to adjust the level of the output sound signal to be optimal according to the externally connected device (connected device) that is set (selected).

[0390] In addition, in the above description, it has been mainly described that the present invention is an endoscopic control processing device and an endoscopic system including the endoscopic control processing device, but it is not limited thereto. For example, the present invention may also be a working method of the endoscopic control processing device. Further, the present invention may also be a computer program for causing a computer to perform the same processing as the endoscopic control processing device and the like. Moreover, the present invention may also be a computer-readable non-volatile recording medium that records the computer program and the like.

[0391] Here, several examples of the recording medium storing the computer program product are a floppy disk, a CD-ROM (Compact Disc Read only memory), a DVD (Digital Versatile Disc), and other removable recording media, or a recording medium such as a hard disk. The program stored in the recording medium is not limited to the entire computer program, and may also be a part of the computer program. Further, the whole or a part of the computer program may be distributed or provided via a communication network. By installing the computer program from the recording medium to the computer by the user, or downloading the computer program via the communication network and installing it in the computer, the computer can read the computer program and execute all or part of the operations, thereby executing the operations of the endoscopic control processing device and the like described above.

[0392] In addition, the present invention is not directly limited to the above-described embodiments. At the implementation stage of the present invention, the components can be deformed and embodied within the scope not departing from the gist of the invention. Further, a plurality of components disclosed in the above-described embodiments can be appropriately combined to form various inventive aspects. For example, several components may be deleted from all the components disclosed in the embodiments. Moreover, the components of different embodiments can be appropriately combined. Needless to say, various deformations and applications can be made within the scope not departing from the gist of the invention.

Claims

1. An endoscope control processing device that acquires an image signal from an endoscope having an imaging element in units of frames and processes the image signal, wherein the imaging element has an electronic shutter function for controlling an exposure time, and the endoscope control processing device is characterized in that it includes a processor, the processor is configured to: perform dimming detection on the image signal acquired in the first frame, and calculate a target exposure time value for a second frame that is later in time than the first frame, calculate an electronic shutter control value for the second frame based on the target exposure time value, calculate an actual exposure time according to the electronic shutter control value, calculate an exposure time ratio between the actual exposure time and the target exposure time value, cause the imaging element to perform shooting based on the electronic shutter control value to acquire the image signal of the second frame from the endoscope, in the image processing for the image signal of the second frame, adjust the gain based on the exposure time ratio.

2. The endoscope control processing device according to claim 1, wherein the processor is configured to: compare the electronic shutter control value with a threshold value, distinguish whether to adjust the gain based on the exposure time ratio according to whether it is larger or smaller than the threshold value.

3. The endoscope control processing device according to claim 2, wherein the imaging element can control the electronic shutter in units of one row, the electronic shutter control value is the number of rows for shading during exposure, the processor is configured to: when the electronic shutter control value is equal to or greater than the threshold value, in the image processing for the image signal of the second frame, adjust the gain based on the exposure time ratio, when the electronic shutter control value is less than the threshold value, in the image processing for the image signal of the second frame, do not adjust the gain based on the exposure time ratio.

4. The endoscope control processing device according to claim 3, wherein the threshold value is set to a value that is equal to or greater than the value obtained by subtracting "100 / target dimming accuracy" rows from all the rows of the imaging element and is a smaller value.

5. An endoscope system, characterized in that, It includes: an endoscope having an imaging element with an electronic shutter function for controlling an exposure time; and an endoscope control processing device having a processor that acquires an image signal from the endoscope in units of frames and processes the image signal, wherein the processor is configured to: perform dimming detection on the image signal acquired in the first frame, and calculate a target exposure time value for a second frame that is later in time than the first frame, calculate an electronic shutter control value for the second frame based on the target exposure time value, calculate an actual exposure time according to the electronic shutter control value, calculate an exposure time ratio between the actual exposure time and the target exposure time value, cause the imaging element to perform shooting based on the electronic shutter control value to acquire the image signal of the second frame from the endoscope, in the image processing for the image signal of the second frame, adjust the gain based on the exposure time ratio.

6. The endoscope system according to claim 5, wherein The processor is configured to: Compare the electronic shutter control value with a threshold value, Based on whether it is larger or smaller than the threshold value, distinguish whether to adjust the gain based on the exposure time ratio.

7. The endoscope system according to claim 6, wherein The imaging element can control the electronic shutter in units of one row, The electronic shutter control value is the number of rows that are shaded during exposure, The processor is configured to: When the electronic shutter control value is equal to or greater than the threshold value, in the image processing performed on the image signal of the second frame, adjust the gain based on the exposure time ratio, When the electronic shutter control value is less than the threshold value, in the image processing performed on the image signal of the second frame, do not adjust the gain based on the exposure time ratio.

8. The endoscope system according to claim 7, wherein The threshold value is set to be greater than or equal to a value obtained by subtracting the amount of "100 / target dimming accuracy" rows from all the rows of the imaging element and less than a small value.

9. A method of operating an endoscope control processing device, which is a method of operating an endoscope control processing device that acquires an image signal from an endoscope having an imaging element in units of frames and processes the image signal, the imaging element having an electronic shutter function for controlling the exposure time, and the method of operating the endoscope control processing device is characterized in that Perform dimming detection on the image signal acquired in the first frame, and calculate the target exposure time value for the second frame that is later in time than the first frame, Calculate the electronic shutter control value for the second frame based on the target exposure time value, Calculate the actual exposure time based on the electronic shutter control value, Calculate the exposure time ratio of the actual exposure time to the target exposure time value, Based on the electronic shutter control value, cause the imaging element to perform shooting to acquire the image signal of the second frame from the endoscope, In the image processing performed on the image signal of the second frame, adjust the gain based on the exposure time ratio.

10. The method of operating an endoscope control processing device according to claim 9, wherein Compare the electronic shutter control value with a threshold value, Based on whether it is larger or smaller than the threshold value, distinguish whether to adjust the gain based on the exposure time ratio.

11. The method of operating an endoscope control processing device according to claim 10, wherein The imaging element can control the electronic shutter in units of one row, The electronic shutter control value is the number of rows that are shaded during exposure, When the electronic shutter control value is equal to or greater than the threshold value, in the image processing performed on the image signal of the second frame, adjust the gain based on the exposure time ratio, When the electronic shutter control value is less than the threshold value, in the image processing performed on the image signal of the second frame, do not adjust the gain based on the exposure time ratio.

12. The method of operating an endoscope control processing device according to claim 11, wherein The threshold value is set to a value greater than or equal to the value obtained by subtracting the number of lines equal to "100 / target dimming accuracy" from all the lines of the imaging element, and is the minimum value.

Images